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Thread: Warning about Routers

  1. #1
    Join Date
    Jul 2007
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    Inkerman, Ontario, Canada
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    Warning about Routers

    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

    1-ID grinding.jpg

    1-ODgrinding.JPG

  2. #2
    Join Date
    Apr 2008
    Location
    East Virginia
    Posts
    679
    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.
    Last edited by Jacob Reverb; 06-07-2019 at 11:54 AM.

  3. #3
    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

  4. #4
    Join Date
    Mar 2003
    Location
    Upland CA
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    4,231
    I hope you get well quickly Mark. That must have smarted.
    Rick Potter

    DIY journeyman,
    FWW wannabe.
    AKA Village Idiot.

  5. #5
    Join Date
    Jul 2007
    Location
    Inkerman, Ontario, Canada
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    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/Dandjprecis...=2&theater

  6. #6
    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.

  7. #7
    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.

  8. #8
    Join Date
    Dec 2006
    Location
    Toronto Ontario
    Posts
    9,374
    Hi Mark, Iím glad to hear that you werenít 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 thatís 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.

  9. #9
    Join Date
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    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.
    Please help support the Creek.

    My mechanic told me, "I couldn't repair your brakes, so I made your horn louder."

    - Steven Wright

  10. #10
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    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.

  11. #11
    Join Date
    Jul 2007
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    Inkerman, Ontario, Canada
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    Bruce, thanks,
    Yes i am a convert to belt and pulley speed control from here on.

    Quote Originally Posted by Bruce Page View Post
    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.

  12. #12
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    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)
    Last edited by Brian Holcombe; 06-07-2019 at 1:50 PM.
    Bumbling forward into the unknown.

  13. #13
    Join Date
    Jul 2007
    Location
    Inkerman, Ontario, Canada
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    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.

    Quote Originally Posted by Brian Holcombe View Post
    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)

  14. #14
    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.

  15. #15
    Join Date
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    Location
    Edmonton, Canada
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    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.

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