Warning about Routers

[Mark Hennebury]

I am posting this as a public safety announcement.
I am not looking for a discussion on my practices.

So i have used my Makita router for internal and external grinding.
The router has electronic speed control from 8000, -24,000 adjustable by a graduated wheel.
I have done ID grinding with the small grinding wheels 1/2" - 1" dia max rated rpm 30,000 with with speed dial set to full speed 24,000rpm.
And i have done some external grinding with a large 4" diameter wheel with the speed dial set at 8000 rpm.

I haven't used it for some time (many months)
I went to use it the other day and got injured quite seriously.

I had the dial set to 8000 for the larger wheel, turned the router on to let it warm up for a few seconds before using it, it was running fine for a while, i turned away to get something and the router ramped up to full speed for no apparent reason, the noise startled me and i turned around just as the wheel exploded. I didn't have any time to do anything, i got hit in the face with a piece of grinding wheel.
It hit me on the left side of my nose, below the cheek bone, broke my palate and pushed a couple of teeth and the bone that holds them into my mouth, split open my face, cut up my tongue, and bled profusely, inside and outside my mouth. I have had the first emergency surgery to do the initial patchup to remove the chunks of grinding wheel that embedded inside my mouth and had my face sewn up. I have to go to another surgery to get my palette repaired and my teeth put back where they belong, when the swelling goes down. For now i eating through a straw.


So other than the normal safety procedures you may follow, the take away from this is;
1. Routers electronic control are not to be trusted.
2. The can and do randomly change the speed without warning.
3. Don't run anything in the router that is not rated for the full speed of the router.
4. Electronic controls can and do malfunction when operating under normal circumstances.

From the manufacturer:
Variable Speed Control Dial Enables User To Match The Speed To The Application And The Electronic Speed Control Maintains Constant Speed Under Load

411014

411016

[Jacob Reverb]

Whoa, sorry to hear of this bad news. Thanks for warning the forum. I've had (non-speed-adjustable) angle grinders go insane with changing rpm speed...definitely will watch the router with big bits now that you mention it.

I won't run a grinder without guard and a face shield, as I've heard of bad injuries and even deaths due to wheels breaking and arteries getting severed...maybe I'll start using a face shield when running routers, too.

Hope you heal up back to 100%. Take care.

[Edwin Santos]

Sorry to hear of your injury, which sounds really terrible.
Thank you for posting the details of the incident. Very decent and professional thing to do seeing as how your report might save one or more from a similar accident.

I don't have anything credible to add in terms of analyzing the root cause of what went wrong, but I would like to wish you all the best with your recovery. I think I might invest in a face shield.

Edwin

[Rick Potter]

I hope you get well quickly Mark. That must have smarted.

[Mark Hennebury]

Thanks guys, i am doing well, a little shaken as i have about a dozen routers, all electronic speed control, and will now be a little nervous using them. Everything in my shop is dangerous and can seriously hurt you; i am okay with danger as long as long as it is predictable, this caught me by surprise.
The funny thing is i saw this video a month ago.


https://www.facebook.com/Dandjprecisionmachine/videos/vb.597557260342694/2294066584184740/?type=2&theater

[Doug Dawson]

I've heard of other Makita VS routers doing this (sudden lack of speed control.)

Sorry to hear about the accident.

I have a Makita VS angle grinder, which of course comes with the guards, etc. One significant safety feature of it is a paddle control, so that you're always hands on with the unit when it's running. The On/Off switch units cause me some concern, and I wouldn't use them. Same with the Makita VS die grinder, pucker factor w/o the paddle.

[Andrew More]

Sorry to hear about the accident, hopefully the recovery will go well.

If you have not done so already, I would contact a lawyer. The change in speed in the router sounds like a failure of the tool in a manner that places the liability on the manufacturer, and not on you or your usage.

[Rod Sheridan]

Hi Mark, I’m glad to hear that you weren’t seriously injured.

Normal industrial practise is to use a wheel with a speed rating greater than the tool speed rating.

I think your incident is a great illustration of why that’s standard practise.........Regards, Rod

P.S. Unfortunately most power semi-conductors fail in a shorted manner which would cause the router to go to maximum speed. This means that the pulse width controllers are not failsafe.

[Bruce Page]

Mark, your accident description made me wince. I did a lot of OD/ID grinding and was always worried about exploding wheels. You should look into picking up a Dumore tool post grinder. There are several for sale on eBay
I hope you have a speedy recovery.

[Mark Hennebury]

Rod, I would think that standard industrial practice would be to; 1. Use a reliable technology when manufacturing equipment 2. Give sufficient information with the product so that you know what can happen and how to protect yourself. If the manufacture knows that the speed control can and will at some point fail, do they not have a duty to warn you. I felt i had a duty to warn you and i didn't manufacture the router. It would not take to many lines of text to add in the manual. "Only use tooling rated for maximum rpm as the router may occasionally and randomly, just for fun, run it up to full speed."

Did you look at the video link that i posted. It seems to me that normal industrial practice was to set the machine speed to suit the tooling, as i did. In the video they ran a large slow speed fly cutter, the machine randomly ran it up to full 12,000rpm far above what the tooling could tolerate and turned into a ballistic missile capable of killing.

[Mark Hennebury]

Bruce, thanks,
Yes i am a convert to belt and pulley speed control from here on.


Mark, your accident description made me wince. I did a lot of OD/ID grinding and was always worried about exploding wheels. You should look into picking up a Dumore tool post grinder. There are several for sale on eBay
I hope you have a speedy recovery.

[Brian Holcombe]

Mark, glad you are on the mend. Sorry to hear about the accident, I hope you heal quickly.

Might be worth considering a switch to CBN or Diamond abrasives, I don’t think they can turn higher but they won’t come apart (as far as I'm aware)

[Mark Hennebury]

Thanks Brian, i may indeed switch to CBN or Diamond as you say, but regardless whatever i go with, it will be on a manual belt and pulley speed control. You have to have reliable equipment that you can depend on to do what it is supposed to.


Mark, glad you are on the mend. Sorry to hear about the accident, I hope you heal quickly.

Might be worth considering a switch to CBN or Diamond abrasives, I don’t think they can turn higher but they won’t come apart (as far as I'm aware)

[Jay Kepley]

Mark, I'm very sorry about this accident. I hope you heal as fast as possible. Thanks for letting all of us know about the experience.

[mreza Salav]

Sorry to hear about the injury. I hope you heal soon and well. I had a fall incident once with a few broken teeth and fractured jaw. Accidents happen.
I would use a guard/shield for procedures like that. Not only electronic controlled devices can fail (as experienced here), a pulley controlled mechanism doesn't eliminate other dangers. I've seen grinding wheels "explode" due to tiny fractures (fatigue?) and can hit all over place. I tend to consider the possibility of a device/item failing to do what it's supposed to do and keep another layer of "just in case" protection.

[Mike Henderson]

Wow, sounds like a bad injury. I hope you recover quickly.

Mike

[Jim Becker]

Yikes! 'Glad you are ok and hope you heal quickly. Our tools are all dangerous, even when used as indicated. "stuff happens". "Off Label" use can raise the risk, too. Not much I can say that hasn't been mentioned already...so thanks for the warning and bringing this up here in the forum!

[Bob Cooper]

So sorry to hear about your injury. I’m having trouble understanding the use case. ID/OD grinding with a router? What’s a bit look like?

[Chapel Eastland]

Sorry to hear about the accident, hopefully the recovery will go well.

If you have not done so already, I would contact a lawyer. The change in speed in the router sounds like a failure of the tool in a manner that places the liability on the manufacturer, and not on you or your usage.

I'm not a lawyer, but a suit brought by a plaintiff using a router as a grinder in what a manufacturer could easily prove was beyond the scope of the tool and an utter disregard of safety warnings, would be dismissed.

The OP survived and hopefully will consider himself lucky and educated.

This is a good lesson for all.

[Mark Hennebury]

Hi Bob, thanks.

I was using my router to do grinding. so i had grinding wheels in it not router bits. if you look at the original post there are two photos that show the operation.


So sorry to hear about your injury. I’m having trouble understanding the use case. ID/OD grinding with a router? What’s a bit look like?

[marty fretheim]

Sorry to hear about the accident, hopefully the recovery will go well.

If you have not done so already, I would contact a lawyer. The change in speed in the router sounds like a failure of the tool in a manner that places the liability on the manufacturer, and not on you or your usage.


I ain't a lawyer but we all know what a router is designed for and its not that. No judgement here Mark, I have done similar things, many times. The only way my conscience would allow me to get a lawyer involved is to use one for a human shield in case something explodes again :D.

I hope you heal quickly

[Mikail Khan]

Thanks for posting.

Hope u recover quickly.

MK

[Mark Hockenberg]

Mark - Best wishes for a speedy recovery!

You'll get no discussion on your practices or judgement from me. I just appreciate you sharing with the community.

After getting whacked in the chest with a scrap from the table saw and watching another scrap hit the window behind the saw, I started wearing a full face shield. After that I got hit right between the eyes (with the shield on, so no harm).

Maybe the lesson for me is to wear the face shield around other tools also.

Thanks,
Mark

[Bert McMahan]

I have heard that full face shields are meant to be worn over standard eye protection. Just a tip. I know the face shield I have is much weaker than my safety glasses, so it'll protect from "nuisance" particles but it won't save something really barreling towards my face. Get well soon, Mark.

[Frederick Skelly]

I'm sorry you've been injured so badly Mark. I hope you'll heal up soon and without too much pain.
Fred

[johnny means]

I can't be the only one who thinks that setup looks like a "Hold my beer" meme.

[Greg R Bradley]

I can't be the only one who thinks that setup looks like a "Hold my beer" meme.
Not really, the only difference between that setup and a typical internal/external grinding setup is that a router was used for the grinding instead of a belt drive on a different motor.
Look at the linked video of the overspeed on the flycutter. That would have gone through several people completely as well a the walls that it went through completely.

[Jeff Bartley]

Thanks guys, i am doing well, a little shaken as i have about a dozen routers, all electronic speed control, and will now be a little nervous using them. Everything in my shop is dangerous and can seriously hurt you; i am okay with danger as long as long as it is predictable, this caught me by surprise.
The funny thing is i saw this video a month ago.


https://www.facebook.com/Dandjprecisionmachine/videos/vb.597557260342694/2294066584184740/?type=2&theater

Thanks for sharing your experience Mark, sorry you were injured and I hope you recover soon!

If anyone here hasn't watched this vid I would recommend it. What an eye opening video! After seeing the vid I can only imagine what it was like when your grinding wheel came apart. Scary stuff!

[Dan Friedrichs]

Wow. Mark, best wishes for your recovery. The fact that a very experienced, skilled, and wise individual such as yourself could sustain such a serious injury should give us all pause. Thank you for sharing.

Do you think a full-face shield would have helped? It almost seems insufficient given the injuries you describe.

[Mark Hennebury]

Dan, thanks very much; I have given it some thought of course, I usually wear safety glasses and try not to be in direct line of fire for grinding. Small parts that i grind are pretty delicate grinding to bring to tolerance, so nothing aggressive. The face shield that i have, may have reduced the impact and damage, or may just had added plastic to the mix. I don't know how big of a piece hit me, i thought that all of my teeth were gone, but i found out that was probably mostly broken grinding wheel that i was spitting out. i really won't know exactly until after the visit on Tuesday with the oral surgeon. My face was far too swollen to see much. The thing is i probably wouldn't have had the shield on as i wasn't actually grinding at that time, i was just stood next to the router maybe two feet away sorting something out. There are many things that i could have done different and everyone knows that. If it broke loose at 24,000 rpms it was moving in my direction pretty fast and would have been bad news whatever part of me it hit. I turned the router on again a few times and sometimes it runs fine and sometimes it ramps up, sometimes it ramps up almost in an instant. I will take a video if i can.



Wow. Mark, best wishes for your recovery. The fact that a very experienced, skilled, and wise individual such as yourself could sustain such a serious injury should give us all pause. Thank you for sharing.

Do you think a full-face shield would have helped? It almost seems insufficient given the injuries you describe.

[Rick Potter]

I find myself using cut off wheels and metal grinding discs on my angle grinder a lot, and have not been using any protection other than safety glasses (sometimes). I think it is time to put on my big boy pants, and dig out my face shield.

I have also been trying to figure out how to put an old drill chuck on a handle to use when working with bolts and other smalls on my grinder. Seems it would be safer than what I do now...Vise grips.

[Larry Edgerton]

Sorry about your injury buddy! I have had the same thing happen to a PC 3 1/4 VS running a 4 1/2" cove bit, speed control burnt out and defaulted to 21,000. Had hands on and shut it off but it scared the daylights out of me. I got rid of the internal speed control and went with a separate for the rest of that job. In my case I feel that it was probably overloaded as the bit is a very heavy Nordic Tool custom bit, but in your out of cut blowout ???.

Been doing this and construction my whole life and injuries happen, as you have said it is dangerous work and sometimes things beyond our control line up against us. All we can do is look at what happened and change our procedure. I think the guys that do this for a living and make it through their whole life without a mishap are the exception rather than the rule. Hope you heal well.

[peter gagliardi]

Mark, sorry to hear about your injury. That is a pretty serious amount of damage to you, and I hope the healing goes well without the onset of infection.
Tiny bits of the wheel not seen and removed can really hamper recovery and lead to infection. I wish you the best with it.

Sadly, the 1/2 dozen or so VS routers I have had over the years have all exhibited lack of ability to keep a set speed. As such, I was aware early on about that issue and bit size and what I used the router for.
Now, I only run bits sized to take full speed.
The only routers I have that have not exhibited this phenomena YET are the mid sized Festools. I am NOT endorsing or saying they are better, just that they have thus far proven to be more reliable on the speed issue. I fully expect it is a case of “when”, and not just “if” the speed control goes haywire.
Most of my new routers are the old Stanley and Porter Cable single speed types from the 70’s or before.

[Andrew More]

I find myself using cut off wheels and metal grinding discs on my angle grinder a lot, and have not been using any protection other than safety glasses (sometimes). I think it is time to put on my big boy pants, and dig out my face shield.

Please also use the safety guard, these sorts of accidents are exactly what it's designed to prevent.

[Jim Becker]

I was thinking about this and unrelated to a different way of spinning the grinding wheel, a machine operation like this would benefit from a heavy, clear Lexan shield mounted to the machine, itself. This is in addition to eye and face protection. Grinding wheels are what they are and by their nature they can shatter for any number of reasons, even on a "traditional grinder". A machine mounted shield can be the "first line of protection" during an automated process like shown. This is yet another reason I'm working myself up to replace my wheels with CBN.

[Mike Cutler]

Mark
Sorry to hear about your injury, that must have hurt like Hades once the adrenaline wore off. I can't imagine what must have been going through your mind. Heal well and do everything the doc's tell you do and if possible, don't be in a hurry to get back to work until you're completely healed.

I've never really trusted the speed control knobs on routers either. They can fault, and some can be bumped inadverdantly. I use them, but when the bits get bigger, that's just a boatload of energy at the outer circumference. Always a little bit of pucker factor when swinging a bigger bit, whether by hand, or mounted in a table.
I think that's what I like about the Shaper/Spindle Moulder so much. It makes a using a large cutter "safer". Wouldn't thave helped what you were doing though.

As an aside, and because Bruce Page expressed similar trepidation with the function you were performing, is there a different tool, or process, that performs this function?
No arm chair quarter backing here, just not familiar with exactly what you both are referring to.

[Larry Edgerton]

I was thinking about this and unrelated to a different way of spinning the grinding wheel, a machine operation like this would benefit from a heavy, clear Lexan shield mounted to the machine, itself. This is in addition to eye and face protection. Grinding wheels are what they are and by their nature they can shatter for any number of reasons, even on a "traditional grinder". A machine mounted shield can be the "first line of protection" during an automated process like shown. This is yet another reason I'm working myself up to replace my wheels with CBN.

Or maybe a solid shield [metal] on the working side and do the work from a mirror on the side away from you? May take some practice, and this is just a random thought so don't shoot me.;)

[Ole Anderson]

Sorry to hear of your accident, hope the healing goes swiftly and well.

It comes at quite a price, but reading of accidents tends to keep us all on our toes, at least for a while. As far as not putting on a tool not rated for full router speed, that becomes problematic for anyone using full size raised panel bits on a router table. Typically they are limited to 8000 rpm in a router capable of 24,000. And even good face shields don't always protect us in our shop, remembering a lady wood turner that lost her life when a (bowl?) she was turning exploded in her face. I believe she was wearing the same face shield I trust. One of the few lessons I remember from my school shop days was to always stand to the side of a grinder until it comes up to full speed. Your experience will remind me to start doing that again. Interesting setup on that metalworking lathe BTW.

I would be concerned with that long shaft on that id grinder. It reminds me of a situation that happened to the guy that used to turn my 72" long barefoot booms. He was turning down the end of a 1.75" diameter solid aluminum rod and had the end stuck out the rear of the lathe, unsupported. It was a rather large lathe able to accommodate the size of the stock. Apparently he had the rpm set too high and the free end started to wobble and became totally unbalanced, bending the rod while rotating at high rpm. It started walking the multi-thousand pound machine across the floor while slowly pulling the rod through the chuck as the free end spun closer and closer to the floor, bent at about a 60 degree angle. He finally got it turned off and then was able to leave to change his shorts.

[Mark Hennebury]

Hi Mike, thanks.

There are other options for id & od grinding, with small belt driven spindle and a standard motor. The set up and grinding wheels are the same. In fact there is nothing wrong with my setup for the small diameter ID, those wheels are rated at over 30,000 rpm, so running them at 24,000 is no problem. There would be no problem with my setup running the large wheels at 8000, if it stayed at 8000. Of course you can add any layer of safety your feel will help, from standing out of the line of fire, goggles, face shield, stationary shield as Jim suggested. Had things gone as normal i would have been standing to one side and wearing safety glasses when i started grinding. I must also emphasize this is super light duty grinding, barely touching the part, not putting a strain on the router at all. I will still use the router and set-up for ID grinding at 24,000. I may have a little more security, and be a little more tense due to traumatic memories..... but that's life.


Mark
Sorry to hear about your injury, that must have hurt like Hades once the adrenaline wore off. I can't imagine what must have been going through your mind. Heal well and do everything the doc's tell you do and if possible, don't be in a hurry to get back to work until you're completely healed.

I've never really trusted the speed control knobs on routers either. They can fault, and some can be bumped inadverdantly. I use them, but when the bits get bigger, that's just a boatload of energy at the outer circumference. Always a little bit of pucker factor when swinging a bigger bit, whether by hand, or mounted in a table.
I think that's what I like about the Shaper/Spindle Moulder so much. It makes a using a large cutter "safer". Wouldn't thave helped what you were doing though.

As an aside, and because Bruce Page expressed similar trepidation with the function you were performing, is there a different tool, or process, that performs this function?
No arm chair quarter backing here, just not familiar with exactly what you both are referring to.

[Mark Hennebury]

HI Ole, and thanks.

The big lathe is an awesome beast, 7.5hp 6000LB sleeping monster that can turn you into mincemeat without slowing down. Lots of horror stories and some nasty videos. The lathe has lots of evil tricks to get you. When you have to get things done, you make judgement calls, you learn what you can about the machine and operation, weigh the risks and make your decisions on what you think is doable, and what is most likely to happen, where you need to be for a "reasonable" degree of safety and get on with it. Hopefully you have made a sound judgement and if anything goes wrong you have considered that and accounted for it by putting yourself, body parts out of harms way. 100% safety is not to do anything. Driving on the road back and forth to work entails far more risk than anything that i have ever done in the shop.


Sorry to hear of your accident, hope the healing goes swiftly and well.

It comes at quite a price, but reading of accidents tends to keep us all on our toes, at least for a while. As far as not putting on a tool not rated for full router speed, that becomes problematic for anyone using full size raised panel bits on a router table. Typically they are limited to 8000 rpm in a router capable of 24,000. And even good face shields don't always protect us in our shop, remembering a lady wood turner that lost her life when a (bowl?) she was turning exploded in her face. I believe she was wearing the same face shield I trust. One of the few lessons I remember from my school shop days was to always stand to the side of a grinder until it comes up to full speed. Your experience will remind me to start doing that again. Interesting setup on that metalworking lathe BTW.

I would be concerned with that long shaft on that id grinder. It reminds me of a situation that happened to the guy that used to turn my 72" long barefoot booms. He was turning down the end of a 1.75" diameter solid aluminum rod and had the end stuck out the rear of the lathe, unsupported. It was a rather large lathe able to accommodate the size of the stock. Apparently he had the rpm set too high and the free end started to wobble and became totally unbalanced, bending the rod while rotating at high rpm. It started walking the multi-thousand pound machine across the floor while slowly pulling the rod through the chuck as the free end spun closer and closer to the floor, bent at about a 60 degree angle. He finally got it turned off and then was able to leave to change his shorts.

[Chapel Eastland]

I must also emphasize this is super light duty grinding, barely touching the part, not putting a strain on the router at all. I will still use the router and set-up for ID grinding at 24,000.

That says it all right there. Nothing else to know.

[Mark Gibney]

Mark your story made me wince. I know how these things can come out of the blue.
Hope your recovery is complete.

And thanks for making us all the wiser.

[Bill Space]

Mark,

I hope your recovery is a speedy one.

I was was thinking about your unfortunate experience as I was cutting several acres of grass this afternoon. For me this is a reminder of the importance of matching ratings of components in a system. Especially because, in a case like yours, I am likely at some point to forget to set the speed to the proper level, and could experience a wheel explosion without having router failure.

Ole Anderson brings up a good point. How about raised panel cutters? I use them in my router table. Never considered the speed rating and what might happen if I forgot to turn the speed down before installing one. And NEVER thought about a router speed control failure like you experienced.

I am am going to have to rethink their use in my router now...

Bill

[Eric Danstrom]

Thank you for sharing this. I'm sorry for you injury and hope you heal well.

[David Buchhauser]

I was thinking about this and unrelated to a different way of spinning the grinding wheel, a machine operation like this would benefit from a heavy, clear Lexan shield mounted to the machine, itself. This is in addition to eye and face protection. Grinding wheels are what they are and by their nature they can shatter for any number of reasons, even on a "traditional grinder". A machine mounted shield can be the "first line of protection" during an automated process like shown. This is yet another reason I'm working myself up to replace my wheels with CBN.

Hi Jim,
This is exactly what I have on my larger conventional lathe. I made this up when I bought the lathe back in 2007. The top guard utilizes a 1/2" thick Lexan widow, which is hinged to swing up out of the way when not in use. In addition to the safety factor, it keeps cutting oil (for certain operations) from being slung up into my face. I also made some sheet metal pieces that fit below the top cover for additional protection. Of course - I also wear safety glasses while running the machine. I would most definitely have the guard in place for any tool post grinding operations.

I've also added some photos of my larger cnc machines. In an industrial environment - these safety protective covers are mandatory. The cnc lathe includes metal bars embedded into the clear cover to protect against high speed explosion of the part being machined. The redline for this lathe is 4500 rpm.
David

411093 411094 411095 411096 411113 411114411114 411115

[Rick Potter]

Just curious, does my PC 7518 with the 5 speed switch have this speed up problem? Only problem I have had is once when it wouldn't turn on, and I opened up the switch and blew the sawdust out. Then it worked fine.

[Bill Dufour]

I often use a loggers helmet when using power tools. It has a face screen, not shield, so it does not fog up and earmuffs. Great for mowing the lawn and planer, shaper, tablesaw use.

[Frederick Skelly]

I often use a loggers helmet when using power tools. It has a face screen, not shield, so it does not fog up and earmuffs. Great for mowing the lawn and planer, shaper, tablesaw use.

Bill, I would be interested in seeing the helmet that works for you. Looks like there are a few different types - can you post a picture or link to yours?

Thank you.
Fred

[Mark Hennebury]

A general guideline for safe maximum operating speed from an article from the Rockler website Printed on January 17 2019

https://www.rockler.com/learn/router-bit-speed/

Manufacturers don't always agree on top speeds for router bits of a given diameter, and as mentioned above, there are other factors to consider. For a rough guide, here's a typical maximum router bit speed chart:

Router Bit Diameter....Maximum Speed

Up to 1"........................22,000 - 24,000 rpm
1" to 2".........................18,000 - 22,000 rpm
2" to 2-1/2"..................12,000 - 16,000 rpm
2-1/2" to 3-1/2"............8,000 - 12,000 rpm

Remember, that's just a reference; Always follow manufacturers recommendations and the sage advice that if something doesn't feel like it's working right, there's a good chance that it isn't. Better yet, pick up a Router Book and get to know your router inside and out.

[Brian Holcombe]

I usually err on the slower side since my router is loud and slowing it down really helps in that regard and seems to do very little to reduce the quality of cut. I run router bits in a knee mill at 3000 rpms and never get chip outs, poor cut, burning or poor chip evacuation. Come to find out, after speaking with Whiteside they actually test their bits using knee mills.

[Darcy Warner]

Thanks guys, i am doing well, a little shaken as i have about a dozen routers, all electronic speed control, and will now be a little nervous using them. Everything in my shop is dangerous and can seriously hurt you; i am okay with danger as long as long as it is predictable, this caught me by surprise.
The funny thing is i saw this video a month ago.


https://www.facebook.com/Dandjprecisionmachine/videos/vb.597557260342694/2294066584184740/?type=2&theater

Holy $#!^ that counter weight took off like a missile.
Super lucky.

[Patrick Walsh]

Yeah that is just crazy.

Those of us that use machinery daily to make a living probably take quite a bit for granted.

[Arash Korangy]

Sorry to hear about your accident and thanks for the cautionary tale. Best of luck with the recovery.

[Anuj Prateek]

kind of related:

I have a DeWalt and Bosch router.

DeWalt has switch on the top and I have to extend my fingers to reach it. It always made me a little nervous when switching router on/off - as it compromises the grip on knobs/handle. Now this router stays in router table and I use paddle switch with it.

Bosch (mr23) has on/off switch on handle. This despite being heavy feels more safe.

[Michael Todrin]

A truly terrible accident. I wish you a speedy recovery.

[Mel Fulks]

Mark, just read the whole post. I guess I guessed it was the end of a finger. Some of us will now be using full face shields.
Thanks for reinforcing safety by relating what must be a most painful and complex injury. "Rule number 1....Obey all rules!" And that applies to Doctor's instructions. But I believe
in demanding good pain killers ! Wishing you a full and speedy return to full health and confidence in the future.

[Bill Space]

I contacted the vendor where I usually buy my router bits, specifically expressing my concern about what might happen if I had a 3.5” raised panel bit in my router and the speed control failed full on. Looks like the bits, regardless of size, are rated for 25,000 rpm and will stay intact if the router speed control fails.

Our bits are designed to perform balanced at speeds up to 25,000 rpm. That being said, the larger bits are not recommended to be used at that high of an rpm due to high velocity tip speed generated as the cutter gets wider. For that reason, a 3-1/2" bit is recommended to be used at a speed somewhere between 12,000 to 14,000 rpm. At the same time several shallow, incremental depth passes are suggested rather than a single hog out attempt be made.

[Jim Becker]

Bill, the big thing with swinging the larger bits with high speeds is the force they generate when they contact the material. So while the cutter might be perfectly fine at the high speed relative to strength and staying together, the effect when/if it grabs a piece of material could have an impact on how many changes of underwear you need to make that day... ;) ...or worse. That's yet another reason why the big cutters must/should be used in a table situation and not with a hand-held router.

[David Buchhauser]

Bill, the big thing with swinging the larger bits with high speeds is the force they generate when they contact the material. So while the cutter might be perfectly fine at the high speed relative to strength and staying together, the effect when/if it grabs a piece of material could have an impact on how many changes of underwear you need to make that day... ;) ...or worse. That's yet another reason why the big cutters must/should be used in a table situation and not with a hand-held router.

So the key thing here is the router bit tip surface speed at a particular RPM. Here is a video that explains this in detail. I have also added a router bit speed chart that lists the maximum safe operating speeds for different router bit diameters. I hope that some find this useful.
David


https://www.youtube.com/watch?v=qOUF2Cmq2ws

411203 411204
(https://www.youtube.com/watch?v=qOUF2Cmq2ws)

[al heitz]

This is just to confirm that switches do sometimes have a mind of their own and are not to be trusted.

Fortunately my experiences were nowhere near as catastrophic as Mark's, but they are a lesson to be learned. I had my DeWalt RO Sander turn itself on at least twice before I learned to pull the plug whenever I am not standing right by it. On one occasion I turned my back and it started, wearing rings in the plastic surface where it was sitting. Another time it turned itself on while I was on vacation - bounced off the counter, landed upright on the floor, and skittered for some time, leaving worn rings in my concrete floor before somehow turning itself off again. Shame on me, but things do have a way of their own sometimes.

[Thomas McCurnin]

I've never heard of using a router designed for woodwork for grinding.

[Bill Space]

Bill, the big thing with swinging the larger bits with high speeds is the force they generate when they contact the material. So while the cutter might be perfectly fine at the high speed relative to strength and staying together, the effect when/if it grabs a piece of material could have an impact on how many changes of underwear you need to make that day... ;) ...or worse. That's yet another reason why the big cutters must/should be used in a table situation and not with a hand-held router.

I think most of us realize that Jim,

My concern was whether a large 3.5” bit would come apart or stay together if my router speed control failed like Mark’s did.

The answer that the large bits are rated for 25,000 RPM is reassuring. (Looking a different web sites I was unable to find specific speed ratings for the larger bits. Hence the question to the vendor.)

That was the point I was trying to convey. I was Addressing a safety concern, and in no way suggesting one might want to run large bits at such high speeds...

[Frank Pratt]

That's a known thing with older Dewalt ROS's. Mine has done it too.

[Edwin Santos]

--
I've gone back and forth on this in my mind since reading the original post. Initially I found myself thinking it was an inappropriate application for a woodworking router. After some thought I've come down with the conclusion that a router is simply a motor with a spinning shaft, so what's the problem? Especially seeing as he was using it for very light passes and minimal material removal and (attempting) to stay within the speed ratings of his grinding wheels.

Either way, the cautionary tale here has not to do with the use of a router for grinding, it has to do with the risks of unreliable speed control.

Unreliable electronic speed control could create issues in many situations including classic woodworking routing and the OP can be commended for sharing his misfortune to alert others to these risks.

I've never had this happen myself, but I have taken a Bosch router apart before and noticed the speed control dial mechanism was not particularly robust, even fussy you might say. I wonder if dust, vibration, heat over time might have interfered with it. Or maybe it was a failure in the electronic aspect of the speed control.

I wonder if the OP will have the router itself examined for the root cause of the failure and report back. I feel really sorry for his injuries.

[Tony Pisano]

Wow, You are so unfortunate and lucky at the same time. I'm sorry to hear of your accident. I spent my whole career working in machine shops. I've witnessed a few accidents, some that made me cringe. Some types og grinding were always scarier than others. The 30 inch dia blanchard grinder had a magnetic chuck to hold multiple parts. If the power went out, the parts flew. I would never use it during a thunderstorm.
I also ran a big vertical turrett NC milling machine and found out one day that electronics can and do fail.
After machining a few parts, the rapid traverse spindle came down and instead of stopping 100 thou above the work, it kept going and buried the cutter in work pc, shattering in the process. I felt something fly through my hair. When all was over, I took off my safety glasses to see that one of the lenses was all ctacked, but didn't completely shatter. That's when I really got shaky, thinking of what might have happened.

[Pat Barry]

Sorry you got hurt, but I just don't quite understand what you were trying to accomplish with this setup. Is it deburring? It certainly isn't precision dimensional machining. Can you explain please?

[Mark Hennebury]

Pat, Thanks.

Hi Pat,


What I was trying to accomplish with my setup is irrelevant;

I started the thread to warn people of the potential for sudden failure of speed control, that they may adapt the way they work as necessary to protect themselves from the consequences of such a failure.


Sorry you got hurt, but I just don't quite understand what you were trying to accomplish with this setup. Is it deburring? It certainly isn't precision dimensional machining. Can you explain please?

[Jacques Gagnon]

I started the thread to warn people of the potential for sudden failure of speed control, that they may adapt the way they work as necessary to protect themselves from the consequences of such a failure.


Mark,

I hope you are recovering well. I read your post with a view to learn, not to judge. Thanks for sharing your experience.

Regards,

J.

[Frank Pratt]

What I was trying to accomplish with my setup is irrelevant;

I started the thread to warn people of the potential for sudden failure of speed control, that they may adapt the way they work as necessary to protect themselves from the consequences of such a failure.

And good on ya for doing it. Hope you heal quickly.

[Pat Barry]

Pat, Thanks.

Hi Pat,


What I was trying to accomplish with my setup is irrelevant;

I started the thread to warn people of the potential for sudden failure of speed control, that they may adapt the way they work as necessary to protect themselves from the consequences of such a failure.

I understand Mark. Surely speed controls can fail and unfortunately you found out the worst way. I'm curious though about two things 1) what speed is/was the lathe running when this happened, and 2) does the router speed control still function properly if the router is running alone, without load?

[Larry Edgerton]

kind of related:

I have a DeWalt and Bosch router.

DeWalt has switch on the top and I have to extend my fingers to reach it. It always made me a little nervous when switching router on/off - as it compromises the grip on knobs/handle. Now this router stays in router table and I use paddle switch with it.

Bosch (mr23) has on/off switch on handle. This despite being heavy feels more safe.

Two things I like about the big PC plunge are the trigger switch along with a master switch, and that the plunge can easily be used while operating with its perfectly placed lever. I have Festool plunges but I just don't like them. As far as spinning a bit they are fine, but they are clumsy. I often work with inside patterns and the PC is just better, get the router in position and pull the switch.

Mark, I very seldom post on things that went wrong for the very reason you have found. Sad to say.

[Carl Beckett]

I started the thread to warn people of the potential for sudden failure of speed control, that they may adapt the way they work as necessary to protect themselves from the consequences of such a failure.

Thank you for posting Mark. I have a neighbor that is sometimes an expert witness in court on just these type of electronic failures. Talking to him was eye opening to me (toasters with electronic controls he feels are especially high risk!). I was trusting electronic designs more than I should, and your experience is yet another reminder for me, so thank you for sharing your experience.

I hope you heal quickly, and fully.

[Len Mullin]

Mark, I am truly sorry to read about you being injured, but, I am also very sorry to read that you blame everything that happened, on your router and how its speed is controlled. You must admit, that if you had not been doing something that the router is not made for, you probably would not have been injured. It's of no consequence how many times you've done this in the past, it was just an accident waiting to happen. Yes, it was good of you, to inform people about the variable speed adjustment not being trustworthy. But, it was not smart of you, to use the router as you were using it. And you never ever turn your back on any tool that is as dangerous as a router could be, we all know that. So even though I am sorry that you got injured, it's very easy to read between the lines, and realize just how dangerous you were being.

Len

[Dave Zellers]

Mark, just read the whole post... Some of us will now be using full face shields.

Mine just arrived. Appreciate the heads up from the OP. I own 2 PC 7518 VS routers. Plus a shop full of dangerous tools. No point in pressing my luck any farther.

[Pat Barry]

The reason I was asking the questions was to get at the root cause of the problem. Having actually designed and worked with various motor speed controls I thought it would be wise to understand your circumstances better. Not having that, however, I will say that the type of speed control on a router like the one you used is an open loop design. It simply reduces the input voltage supplied to the motor by limiting the peak voltage and / or duration of each of tje 60 Hz voltage cycles. It has no way to monitor the actual speed or do anything to 'control' it. I suspect, in your situation, the rotational speed of the lathe, coupled with the speed of the router itself caused the router to be overcome by the lathe rotational speed. There is no way the router could do anything but "go along for the ride". Effectively the router couldn't keep up and because of the grinding frictional load on the grinding wheel, the wheel ultimately broke. The noise you heard was the wheel fracturing and disintegrating. Again, this wasn't a failure of the router speed control but simply overload due to the conditions that were set up. Maybe this worked for you previously and you were lucky, maybe this time the wheel was degraded enough from previous uses to fail, maybe the load was greater this time, maybe there wad a metal fragment that got into the motor speed adjuster, etc. Who knows.

Sorry for your injury. Thanks for your initial posting. We can all learn the need for more personal protection when using machines.

[brent stanley]

The reason I was asking the questions was to get at the root cause of the problem. Having actually designed and worked with various motor speed controls I thought it would be wise to understand your circumstances better. Not having that, however, I will say that the type of speed control on a router like the one you used is an open loop design. It simply reduces the input voltage supplied to the motor by limiting the peak voltage and / or duration of each of tje 60 Hz voltage cycles. It has no way to monitor the actual speed or do anything to 'control' it. I suspect, in your situation, the rotational speed of the lathe, coupled with the speed of the router itself caused the router to be overcome by the lathe rotational speed. There is no way the router could do anything but "go along for the ride". Effectively the router couldn't keep up and because of the grinding frictional load on the grinding wheel, the wheel ultimately broke. The noise you heard was the wheel fracturing and disintegrating. Again, this wasn't a failure of the router speed control but simply overload due to the conditions that were set up. Maybe this worked for you previously and you were lucky, maybe this time the wheel was degraded enough from previous uses to fail, maybe the load was greater this time, maybe there wad a metal fragment that got into the motor speed adjuster, etc. Who knows.

Sorry for your injury. Thanks for your initial posting. We can all learn the need for more personal protection when using machines.

Hi Pat, I understood from his description that he was not grinding with it when it happened so the wheel wasn't in contact with the piece in the lathe. Also, even if the lathe and router were rotating in complimentary directions , the lathe was probably much slower.

[Mark Hennebury]

Pat.

The grinding wheel was NOT in contact with the part in the lathe or anything else.
I turned the lathe on at 65 rpm
I turned the router on at 8000 rpm
I left them run for a few minutes to warm up, prior to startling.
The router ran fine at 8000 for a while, then shot up to 24,000 rpm.
The grinding wheel exploded from the force produced by 24,000 rpm.
The noise that i heard was the router increase speed.
The grinding wheel exploded in an instant, i didn't see it, i didn't hear it, i just felt it.

[Mark Hennebury]

Pat.

From the manufacture;

The RF1101 has a powerful 11 AMP motor with soft start for smoother start-ups, and electronic speed control that maintains constant speed under load. The variable speed control dial allows the user to match the speed to the application, with 8,000 - 24,000 RPM.

[Malcolm McLeod]

Mark, just read the whole post. I guess I guessed it was the end of a finger. Some of us will now be using full face shields.
Thanks for reinforcing safety by relating what must be a most painful and complex injury. "Rule number 1....Obey all rules!" And that applies to Doctor's instructions. But I believe
in demanding good pain killers ! Wishing you a full and speedy return to full health and confidence in the future.


Mine just arrived. Appreciate the heads up from the OP. I own 2 PC 7518 VS routers. Plus a shop full of dangerous tools. No point in pressing my luck any farther.

Personal Protective Equipment (PPE) is actually the least effective....
411344
It is much better to take the human element as far out of the equation as possible, but of course ultimately depends on the willingness of the human.

[Mel Fulks]

Yeah, not doing the job would be pretty safe.

[Malcolm McLeod]

Yeah, not doing the job would be pretty safe.

Not implying we separate the human from the job; only the human from the hazard. ;) But they gotta be willing.

[Larry Edgerton]

Mark, I saw a VFD somewhere that was designed for 110 1ph, maybe the Factorymation catalog. May offer a better way to go, something I should look into as well. Saw it but did not relate it to my router speed comtrol. https://www.wolfautomation.com/blog/vfds-for-single-phase-motors/

Another option if you could find one would be a 3 ph router. I think Stanley made one that looked like an old Speedmatic 3 hp. I remember looking at one that was for sale but its a bit foggy.

[Frank Pratt]

Mark, I saw a VFD somewhere that was designed for 110 1ph, maybe the Factorymation catalog. May offer a better way to go, something I should look into as well. Saw it but did not relate it to my router speed comtrol. https://www.wolfautomation.com/blog/vfds-for-single-phase-motors/

Another option if you could find one would be a 3 ph router. I think Stanley made one that looked like an old Speedmatic 3 hp. I remember looking at one that was for sale but its a bit foggy.

A universal motor speed is independent of line frequency, so that wouldn't work for this. I am almost certain that there is no such thing as a 3 phase line voltage hand held router.

The closest thing I've seen to a 3 phase router was a big machine (I think called an inline contour shaper) that had a huge 3 phase 'router' that was 3 phase, but used a motor/generator set to feed it with a much higher frequency in order to run at the needed rpm. It ran along the 10' length of the machine & followed a pattern that was copied onto the board.

[Mark Hennebury]

I have tried the router probable 100 times since the accident on June 4th; On the day after the accident it went crazy again when i tried it, so i set camera up to catch it,the following week it worked fine with the exception of two little twitches. The last time i tried it today it went wild a few times while i had the camera rolling.

Please forgive my speech I have a hard time speaking at the moment, and as you can see i am more than a little nervous when it ramps up, i am actually quite nervous around the blender right now.

So the issues of course are that there is no warning of when it will fail, no apparent reason for it to fail, there is the problem of it going from 8000 rpm to 24,000 rpm plus the torque caused be the acceleration. Either way this is a dangerous situation that can happen in an instant.


https://youtu.be/pNhtXgBHijw

[Bob Cooper]

Wow....thanks Mark for sharing.

[Jacob Reverb]

https://youtu.be/pNhtXgBHijw

That thing is possessed. Fortunately, "the exorcist" is right there in the frame (at the bottom right-hand corner).

If it were me, I think I might tame it down some for 15 or 20 minutes – until I was winded or until the sledgehammer broke, whichever came first – then pour it into a box back to Makita, along with a copy of the video and your doctors' bills.

[Grant Wilkinson]

I hope you that you recover well, Mark?

I may have missed this in the thread, but have you contacted Makita, especially with a copy of your video. If so, what was their reply?

[James Biddle]

I don't own any Makita routers, but that doesn't sound normal even before the speed jump. Is that the way they all sound?

[Eric Danstrom]

That Makita router isn't designed for fault tolerance, it's call FMEA or failure mode effects analysis. We can be grateful those Makita engineers don't work in the appliance or automotive industries. The just of Design FMEA is to assure a single point failure can't allow the device to fall in a dangerous mode. In the OP's example something has failed intermittently and the result is the router runs full speed without any input from the user. A recent example of a bad design relying on a single sensor for critical data with no backup mode is the 737MAX.

I'm sure Makita has seen this failure already, I'd give them a call a listen to their reaction. I might contact the CPSC and see if they want to investigate. If there's a UL listing I'd contact them too.

[Pat Barry]

Thanks Mark. Very convincing that there is something very wrong with that machine. Engineer in me would take it apart so the speed control could be inspected closely, probably cleaned up, reassembled and retested. Otherwise, scrap it out.

[Bill Space]

That Makita router isn't designed for fault tolerance, it's call FMEA or failure mode effects analysis. We can be grateful those Makita engineers don't work in the appliance or automotive industries. The just of Design FMEA is to assure a single point failure can't allow the device to fall in a dangerous mode. In the OP's example something has failed intermittently and the result is the router runs full speed without any input from the user. A recent example of a bad design relying on a single sensor for critical data with no backup mode is the 737MAX.

I'm sure Makita has seen this failure already, I'd give them a call a listen to their reaction. I might contact the CPSC and see if they want to investigate. If there's a UL listing I'd contact them too.

We need to keep in mind that any device can fail, and protect ourselves by only using components (in the case of a router, bits) that can survive failure of the equipment being used (within reason anyway) when it fails in the full speed mode.

It would be prudent to only put in a router things that can withstand the maximum speed the router can attain.

Besides high speeds caused by speed control failure, there is always the potential for high speeds due to operator error. At least in my case (whoops! I forgot to turn the speed down!)...can't speak for others. In either case the result could be the same.

I would be willing to bet most router manufacturers have seen this same failure mode at least once. But don't think that is the root issue. The message in this thread is that router speed controls can and will fail full on. So don't put anything in your router chuck that cannot withstand the maximum speed the router can turn. (Or in any other tool for that matter).

[Stephen Tashiro]

t the type of speed control on a router like the one you used is an open loop design. It simply reduces the input voltage supplied to the motor by limiting the peak voltage and / or duration of each of tje 60 Hz voltage cycles. It has no way to monitor the actual speed or do anything to 'control' it. I suspect, in your situation, the rotational speed of the lathe, coupled with the speed of the router itself caused the router to be overcome by the lathe rotational speed. There is no way the router could do anything but "go along for the ride".


I get the general idea that routing against something that is rotating (or just moving quickly) can affect the speed of a router, but I don't understand the details. Are you saying that the moving "work" spun the grinding wheel and the router shaft at the same speed the shaft would have rotated if the router motor wasn't turned on?

[Edwin Santos]

We need to keep in mind that any device can fail, and protect ourselves by only using components (in the case of a router, bits) that can survive failure of the equipment being used (within reason anyway) when it fails in the full speed mode.

It would be prudent to only put in a router things that can withstand the maximum speed the router can attain.

Besides high speeds caused by speed control failure, there is always the potential for high speeds due to operator error. At least in my case (whoops! I forgot to turn the speed down!)...can't speak for others. In either case the result could be the same.

I would be willing to bet most router manufacturers have seen this same failure mode at least once. But don't think that is the root issue. The message in this thread is that router speed controls can and will fail full on. So don't put anything in your router chuck that cannot withstand the maximum speed the router can turn. (Or in any other tool for that matter).

This advice basically means completely eliminating all router bits over 1" in diameter.

[Dan Friedrichs]

This advice basically means completely eliminating all router bits over 1" in diameter.

Did you see Bill Space's post #57 (https://sawmillcreek.org/showthread.php?274839-Warning-about-Routers&p=2932930#post2932930) in this thread?

[David Buchhauser]

I own and operate several PlasmaCAM cnc plasma cutting systems. Although it has not happened to me yet (probably because of the limited use they see), some of the other PlasmaCAM owners have seen the controller have intermittent malfunction due to an accumulation of plasma cutting dust (fine metal particles) inside the control box. In most cases - the remedy has been to open up the control box, clean and blow out the plasma cutting dust, reassemble the box, and then it works fine again. I have thought about this and I believe that it may be possible that over time, with the metal grinding operations this particular router has been exposed to, that fine metal particles from the grinding operations may have made their way into the router motor affecting the speed control reliability. In particular, if the router speed adjustment wheel that you turn with your finger is actually a potentiometer (variable resistor) then is is possible that fine metal particles from the grinding have contaminated this and are causing the resistance to change sporadically. There may also be other circuitry inside the router head that could be adversely effected by this metal dust. I theorize that since the original intended use of this wood router is for use with wood or maybe other non-metallic materials, the designers may not have considered that it might be used for grinding metal and thus not taken this into consideration when designing and testing this tool. As an electrical engineer, I would be very interested to examine the particular router in question (in its current "contaminated" condition) to try to evaluate exactly what is causing this sporadic loss of speed control.

David

(MSEE, BSME)

[Mark Hennebury]

I did a quick look online and found a few conversations on this problem dating back to 2006


CNC Zone 03-10-2006
https://www.cnczone.com/forums/diy-cnc-router-table-machines/18394-cnc.html

I have a home built cnc router with a 2 1/2 hp Makita router. One of those ones thats suppose to be real quiet. The problem it has been devoloping is that the rpm goes up and down instead of remaining constant. Its constantly reving up /down. Has anyone had a problem like this with a router? Am i going to need to buy a new one or is there a fix?


Router Forums 06-21-2009
https://www.routerforums.com/general-routing/14981-makita-speed-control.html
Hi.

I have a Makita RF1101 (http://i.viglink.com/?key=04ca82dd35e8dc8397eb28825312ba18&insertId=c5b03345bcaa52b7&type=H&exp=60%3ACI1C55A%3A20&libId=jwzv2y8y0100zey8000DAbhnrg71k&loc=https%3A%2F%2Fwww.routerforums.com%2Fgeneral-routing%2F14981-makita-speed-control.html&v=1&iid=c5b03345bcaa52b7&opt=true&out=https%3A%2F%2Fwww.amazon.com%2Fdp%2FB00004YN3N&ref=https%3A%2F%2Fwww.google.com%2F&title=Makita%20speed%20control%20-%20Router%20Forums&txt=%3Cspan%3EMakita%20%3C%2Fspan%3E%3Cspan%3ERF11 01%3C%2Fspan%3E) which functioned beautifully for years, until a few weeks ago. Now the speed is erratic, changing at random intervals to random speeds during operation. The brushes (http://i.viglink.com/?key=04ca82dd35e8dc8397eb28825312ba18&insertId=adf4473a4a40c5d5&type=CD&exp=60%3ACI1C55A%3A20&libId=jwzv2y8y0100zey8000DAbhnrg71k&loc=https%3A%2F%2Fwww.routerforums.com%2Fgeneral-routing%2F14981-makita-speed-control.html&v=1&iid=adf4473a4a40c5d5&opt=true&out=https%3A%2F%2Fwww.amazon.com%2Fs%2Fref%3Dnb_sb _noss%3Furl%3Dsearch-alias%253Dtools%26field-keywords%3Dbrushes&ref=https%3A%2F%2Fwww.google.com%2F&title=Makita%20speed%20control%20-%20Router%20Forums&txt=%3Cspan%3Ebrushes%3C%2Fspan%3E) are in good shape, and I suspect that the problem is the motor control (part #63139702) but I was looking for at least some confirmation of this before I drop $70.00 plus shipping on the part.
Any help is appreciated.



posted 10-16-2012 10:04 PM
https://www.lumberjocks.com/topics/42433
My router (after 7 years) has decided to speed up and slow down. I checked the brushes and they don’t look that bad. Controller board?? Anyone got a suggestion?



03-11-2016
https://www.cnczone.com/forums/diy-cnc-router-table-machines/18394-cnc-2.html
Re: makita router rpm constantly reving up/down any one had this problem?
file:///C:\DOCUME~1\Owner\LOCALS~1\Temp\msohtmlclip1\01\cl ip_image001.gif Originally Posted by tsalaf file:///C:\DOCUME~1\Owner\LOCALS~1\Temp\msohtmlclip1\01\cl ip_image001.gif (https://www.cnczone.com/forums/diy-cnc-router-table-machines/18394-cnc-post370310.html#post370310)
This is a defect in some earlier Makita routers and was repaired on both of mine free of charge, even after the warranty had expired.

That is a very interesting observation, tsalaf. My Makita RF1101 has the same problem.
Do you recall how you want about receiving this service? How did you learn that they'd take care of this for you?

[David Buchhauser]

Mark,
I will have to admit that your anecdotal evidence is compelling. It's hard to believe that in over 10 years, Makita has not corrected this problem. I wonder how many of the other router manufacturers (if any) have similar problems with the speed control. In any case, we will probably never know the exact cause of the problem with your particluar router. Unfortunately, the damage has been done. On the positive side, I think that your cautionary tale has inspired many at SMC to rethink some of their practices with the power tools they use. Good luck with your speedy recovery.
David

[Pat Barry]

I get the general idea that routing against something that is rotating (or just moving quickly) can affect the speed of a router, but I don't understand the details. Are you saying that the moving "work" spun the grinding wheel and the router shaft at the same speed the shaft would have rotated if the router motor wasn't turned on?

I wasn't sure whether the work was turn in ng in the lathe at the time, since clarified by the OP that it wasn't, but, yes, if the grinding wheel in the router was contacting the work, and the work was rotating, the frictional force would cause the grinding wheel to keep up with the lathes rotational speed.

[David Buchhauser]

The grinding wheel would typically be turning at around 8000 rpm. No way this particular lathe can keep up. I would guess the top speed on this lathe is no higher than 2500 rpm, maybe slower. Depending on the pressure applied to the work piece from the grinding wheel, the surface speeds of each could and most likely would be much different.

[Larry Edgerton]

A universal motor speed is independent of line frequency, so that wouldn't work for this. I am almost certain that there is no such thing as a 3 phase line voltage hand held router.




https://www.allbids.com.au/c/industrial-tools-building-supplies/tools-hardware/scheer-hm40d-3-phase-router-693833

[Brian Holcombe]

I wasn't sure whether the work was turn in ng in the lathe at the time, since clarified by the OP that it wasn't, but, yes, if the grinding wheel in the router was contacting the work, and the work was rotating, the frictional force would cause the grinding wheel to keep up with the lathes rotational speed.


The grinding wheel would typically be turning at around 8000 rpm. No way this particular lathe can keep up. I would guess the top speed on this lathe is no higher than 2500 rpm, maybe slower. Depending on the pressure applied to the work piece from the grinding wheel, the surface speeds of each could and most likely would be much different.


I get the general idea that routing against something that is rotating (or just moving quickly) can affect the speed of a router, but I don't understand the details. Are you saying that the moving "work" spun the grinding wheel and the router shaft at the same speed the shaft would have rotated if the router motor wasn't turned on?

https://en.wikipedia.org/wiki/Cylindrical_grinder

Grinding a cylinder on the OD is typically done with the part rotating counter to that of the grinding wheel. This is done to avoid having the grinder influence the speed of the part or vice versa.

[Mark Hennebury]

Top speed of old bessy is 1400 rpm.


The grinding wheel would typically be turning at around 8000 rpm. No way this particular lathe can keep up. I would guess the top speed on this lathe is no higher than 2500 rpm, maybe slower. Depending on the pressure applied to the work piece from the grinding wheel, the surface speeds of each could and most likely would be much different.

[Frank Pratt]

https://www.allbids.com.au/c/industrial-tools-building-supplies/tools-hardware/scheer-hm40d-3-phase-router-693833

I should have qualified currently made for the North American market. All of Scheer's current routers are universal motor.

[Jeff Davies]

Hey Mark, thanks for posting that. Its a drag that it did not miss you like the video you linked, but you sound pretty tough -my sincere wishes for a speedy healing. Being nonchalant after near 5 decades on shop floors as I am , I don't pay much attention to shop stories--but I was taken by yours, and the shocking video --I will never rely on an electronic speed control. Thank YOU . Best wishes , J.J.

[David Buchhauser]

It looks like Makita is not the only manufacturer with this problem. Apparently the Dewalt routers have had similar problems with the speed control.

https://sawmillcreek.org/showthread.php?117519-Router-variable-speed-failure

[Malcolm McLeod]

Top speed of old bessy is 1400 rpm.

Don't neglect the gearing effect: With some rough math, if a 12" dia work-piece is turning 1400 RPM with no slippage between work-piece and grinder, the lathe would drive a 1" dia grinder at something close to 16,800 RPM.

No idea of your respective dimensions, but something to keep in mind.

[Jeff Bartley]

Mark,
How are you healing up? I just relayed this story to another woodworking friend, thanks again for sharing this warning about router speed controls.

[Mark Hennebury]

Hi Jeff,

doing well thanks, my face is healing quite well, i will have a nice scar, but the doctor did a good job sewing it back together considering the mess. I still have some swelling on my lip and cheek, i have started eating solid food, its a bit awkward because of the damage inside my mouth and my my teeth hurt and a few are loose. I have a few more followup appointments, then off to the dentist to see what the damage to the teeth is. I had bruising all around my left eye down my cheek, past my chin and down to the bottom of my neck, and a bruise on my chest. I still can't speak properly, but that is improving. All in all that's life, incredibly lucky and unlucky at the same time. I am feeling good and have been working on the next machine rebuild.

Thank you for asking and i thank everyone that wished me well.


Mark,
How are you healing up? I just relayed this story to another woodworking friend, thanks again for sharing this warning about router speed controls.

[Patrick Walsh]

Wow Mark so sorry..

In a moment just about anything can happen.

I never let consequence influence my decision making when recreating “not that I intentional do risky or stupid things” when there is a “safer” alternative. Point is I never let fear guide my decision making.

On the flip side my worst fear is kinda like yours where you don’t end up dead but maybe seriously handicapped.

I myself took a 30’ direct groundfall onto a rock ledge rock climbing and shattered my ankle. It messed my life up for a year real bad not to mention my head and I never climbed again. It shook me enough I couldn’t help but realize had I just bumped my head the wrong way on the way down I coulda been a burden to those I love for a lifetime. I don’t much care about dying “not that I want to” but I’m not concerned by deaths the slightest. But resining someone else’s life or losing a hand when I a workaholic man o man...

Heal up and get us some sexy inspiring pictures would yah...

I hope for your sake this will not dissuade your from continuing to work. I regret it a little bit everyday that I let fear take me away from my passion. I climbed 3-5 days a week for a good five years. I figured I’d get old in the mountains. I replaced that passion with Woodworking. Not that Woodworking as you well know is not without risk. Hopefully not quite the same.

I did pull a 19 hour straight work day yesterday. I couldn’t help but think at 2 am 18 hrs in that it was very dangerous using large shop machinery.

[Mark Hennebury]

Hi Malcolm,

The router and the part in the lathe were not in contact at any time.
The router and the lathe would be turning in opposite directions if and when in contact.
The lathe was running at 65rpm.
To call this grinding is really a gross misrepresentation of the work, this should be referred to as honing; the grinding wheel is barely touching the metal parts, maybe taking a 0.0001" or so at most. per pass.
This operation is done after machining to within a 0.001- 0.002" So creep up on the final dimension a tiny bit at a time and check a hundred times.

411725


Don't neglect the gearing effect: With some rough math, if a 12" dia work-piece is turning 1400 RPM with no slippage between work-piece and grinder, the lathe would drive a 1" dia grinder at something close to 16,800 RPM.

No idea of your respective dimensions, but something to keep in mind.

[Mark Hennebury]

Hi Patrick, Thanks and don't worry about me, i am fine.

Life is an unnecessary risk.
We live with danger and take risks and place trust in every aspect of our lives, From everything in our homes, cars, buildings roads, bridges, cars, airplanes, medications, food chain and water supply etc.. Then ad what risk we take in lifestyle and entertainment, it surprising anyone lives to old age.

There is only so much that we have control over, and we each must make our own judgement on how much risk we are comfortable with, that is different for everyone.

I am 65, i have worked with dangerous machinery and equipment all of my life, i have worked continuously long hours, 44 on one weekend, worked many days around the clock, on my own. I am okay with that, nobody messes with my stuff, nobody distracts me, i know my machines and work with confidence. I have never been afraid of my equipment; this problem with the router has changed that, i don't know how that will work going forward.
I would rather work 24 hours on my own than 8 with others around.

Anyway, we will see how it goes from here.

30' is a big drop, i did my two story roof, preferred working in the night when i couldn't see the ground.

Thanks Again Patrick.



Wow Mark so sorry..

In a moment just about anything can happen.

I never let consequence influence my decision making when recreating “not that I intentional do risky or stupid things” when there is a “safer” alternative. Point is I never let fear guide my decision making.

On the flip side my worst fear is kinda like yours where you don’t end up dead but maybe seriously handicapped.

I myself took a 30’ direct groundfall onto a rock ledge rock climbing and shattered my ankle. It messed my life up for a year real bad not to mention my head and I never climbed again. It shook me enough I couldn’t help but realize had I just bumped my head the wrong way on the way down I coulda been a burden to those I love for a lifetime. I don’t much care about dying “not that I want to” but I’m not concerned by deaths the slightest. But resining someone else’s life or losing a hand when I a workaholic man o man...

Heal up and get us some sexy inspiring pictures would yah...

I hope for your sake this will not dissuade your from continuing to work. I regret it a little bit everyday that I let fear take me away from my passion. I climbed 3-5 days a week for a good five years. I figured I’d get old in the mountains. I replaced that passion with Woodworking. Not that Woodworking as you well know is not without risk. Hopefully not quite the same.

I did pull a 19 hour straight work day yesterday. I couldn’t help but think at 2 am 18 hrs in that it was very dangerous using large shop machinery.