Scary Stuff - Saw Starts Due to Vibration!

[Hans Braul]

I had a scary incident a few days ago and thought I'd post this as a warning. I accidently bumped the side of my starter and the saw started! Hit the kill switch and it didn't stop! Here are pics of the starter...
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The starter block was not securely attached inside the enclosure, so when I bumped the box, the block moved enough for the green start microswitch to become depressed. The enclosure is designed such that the block should "click" into catches on the side of the box, but these were not well designed, and there was no clear, positive engagement. I fixed it by bolting the block to the box, and have had no problems since.

BIG lesson learned: I will NEVER again touch the blade of my saw without unplugging the machine first!

Regards
Hans

[Dan Hintz]

What kind of saw is it?

[Bruce Volden]

What kind of saw is it?

Dan, I'm thinking ---table saw:D

Bruce

[Dan Hintz]

Dan, I'm thinking ---table saw:D

Bruce

Sorry, should have said "brand" ;)

At least you didn't reply "The sharp kind..." :p

[Steve Peterson]

I was adjusting the tabletop on my PM66 saw and had the bolts snug, but not fully tightened. I needed a little bit more adjustment and hit the side of the table with a rubber mallet. This vibrated the magnetic starter enough for the saw to start up. My hands were well away from the blade, but I am now much more careful about unplugging it when adjusting anything.

The next thing I did was cut the cord in half and install twist-lock plugs so I can unplug it without crawling underneath the table to reach the wall plug. It makes it so much easier.

[Don Jarvie]

Steve, thats a pretty good idea. I'll have to file that one away.

[Matt Meiser]

I bought a $20 disconnect switch at Lowes and installed it right before the receptacle for my TS. Now its REAL easy to walk 3' to it and throw the handle--and as a result I do. Something like:

http://www.lowes.com/pd_12587-1318-LF211NU_0__?catalogId=10051&productId=1008293&UserSearch=siemens+disconnect&Ntt=siemens+disconnect&N=0&langId=-1&storeId=10151&rpp=24

Since there's a breaker in the panel feeding this, and since the TS has its own motor protection, I just installed the biggest fuses that they sold that fit. 30A I think.

[fRED mCnEILL]

Its a well known fact that magnetic starters can engage with a bump. I have a big honkin receptacle on the saw so its easy to unplug it (its also 3 phase)

[Van Huskey]

I bought a $20 disconnect switch at Lowes and installed it right before the receptacle for my TS. Now its REAL easy to walk 3' to it and throw the handle--and as a result I do. Something like:

http://www.lowes.com/pd_12587-1318-LF211NU_0__?catalogId=10051&productId=1008293&UserSearch=siemens+disconnect&Ntt=siemens+disconnect&N=0&langId=-1&storeId=10151&rpp=24

Since there's a breaker in the panel feeding this, and since the TS has its own motor protection, I just installed the biggest fuses that they sold that fit. 30A I think.

I used a A/C disconnect, since they are required by code they are inexpensive and I just got one with a breaker.

[Larry Browning]

I ave never had mine do that. But you guys are scaring me! I would have to crawl under the table to unplug mine so I don't do it. I am thinking I will start looking for a safety cut off switch of some kind. When I think about what could happen if the saw came on at just wrong time.... Oh my!!!!!

[Rick Moyer]

I have been sometimes changing blades etc. without unplugging, not often , but sometimes. I will now unplug always! Thanks for the heads-up. It's only a step to unplug for me, was just lazy. I will now unplug whenever I am not using the saw.

[Hans Braul]

What kind of saw is it?

General 350. Same problem could apply to any machine. I'm glad my experience has served as a heads up to potentially dangerous situations.

Hans

[Ed Edwards]

Did you notice where the switch was imported from??

Ed ;)

[Hans Braul]

Did you notice where the switch was imported from??

Ed ;)

The switch was from Poland.

[Andrew Kertesz]

I unplug every tool that I have used when I am done in the shop.

[Ryan Baker]

Like Matt, I have a switch on the wall right next to my saw, before the outlet, so that I do not have to go digging for the plug. That switch stays off whenever I am not cutting -- especially when I am making any adjustments near the blade. If you don't have some sort of convenient disconnect, you won't use it. The odds of a problem are slim, but the consequences are severe. A 220V DPDT switch only costs a few bucks at Lowes.

[Myk Rian]

I ALWAYS unplug the machines before servicing them. Always have, always will. Ford Motor drilled safety and lockout into us. It stuck, at least with me it did.

[Gary Herrmann]

I unplug when I work on a machine and when I leave the shop. Have seen an example of what can happen when you don't and once was enough for me.

[Mike Heidrick]

I have never really seen the point of using a mag starter and not having true momentary power buttons seperated from the mag starter? Why would you have the switches hitting buttons on the starter??

On my "Mikie's Controller" G540 cnc boxes I build, I use through door disconnects on my nema 4/12 enclosures. Its just safer. You have to bypass it to have it live beyond the disconnect if the door is open. Factorymation makes adding Din rail mounted disconnects real easy. They also make ones that are internally switched/disconnected for boxes you do not want a through door disconnects on. I used one of those on my spindle's VFD enclosure as I wanted to be able to access the front panel of the VFD on occassion.

http://i39.photobucket.com/albums/e169/BloomingtonMike/Cast CNC/P2283847.jpg

http://i39.photobucket.com/albums/e169/BloomingtonMike/Cast CNC/box3.jpg

You can see the switched disconnect on the lower rail in my VFD cabinet.

http://i39.photobucket.com/albums/e169/BloomingtonMike/Cast CNC/PC264065.jpg

[Hans Braul]

So ... after my experience and listening to others I get why it is REALLY not wise to get anywhere near the blade with the machine plugged in. But why the extra precaution of unplugging everything before leaving the shop?

Hans

[Rod Sheridan]

No idea Hans, unless you have a starter with a control transformer and you want to save a penny or two on energy consumption.

The only machine I would disconnect is an air compressor, either via a built in switch or a disconnect switch, that way a failed hose on't have the compressor running unexpectedly.......Rod.

[Ken Fitzgerald]

I always unplug my table saw when changing blades. The only thing I regularly turn off is my air compressor. When I leave town for an extended period of time, I trip the breaker on my DC. It has a remote control and in case it fails, I wouldn't want it running until I got back into town.

[Andrew Kertesz]

Depending on where your shop is you never now who is going to be in there. Just an extra safety feature for me and only takes a couple of extra seconds. My shop is in the basement and while all the kids are grown and moved out I still continue to do this.

[Ray Newman]

I always unplug all of the power before leaving the shop. Up here, power surges “happen”. I would hate to replace half-a-dozen 1 HP + electric motors and switches. Also try to unplug whatever is not necessary in the house.

Since power outages also “happen” in this area, I now have magnetic starters on my stationary power tools. Before converting all of the them, I ’nevva’ thought about installing more until one day there was a power outage while working the router table. Just started to move the work away when it came back on. Good thing for a soft start and quick reflexes….

[Joe Hillmann]

I also unplug all my power tools when not in use. You never know who might get in the shop and start pushing buttons. The only tools that I don't unplug every time I change a blade are the drill press and the lathe.

[Larry Browning]

I always unplug all of the power before leaving the shop. Up here, power surges “happen”. I would hate to replace half-a-dozen 1 HP + electric motors and switches. Also try to unplug whatever is not necessary in the house.

Since power outages also “happen” in this area, I now have magnetic starters on my stationary power tools. Before converting all of the them, I ’nevva’ thought about installing more until one day there was a power outage while working the router table. Just started to move the work away when it came back on. Good thing for a soft start and quick reflexes….

Sounds to me like you are a good candidate for a whole house surge protector. In my area the elec company has one they will install and maintain for a small addition to my monthly bill. If anything goes wrong with it, they replace it. I am thinking that I get most of the cost back from an insurance premium reduction as well. If that is not available, you can have one installed by an electrician.

[Rick Potter]

Like Fred said. A few years ago there was a rash of reports on magnetic switches going on when bumped. I remember one of the magazines doing a story on it. Wish I could remember what the conclusions were.

Rick Potter

[Larry Browning]

What would be the simplest for this? I was thinking I could get one of those pull switch boxes you see out by the AC compressor units. Or maybe a "paddle" type switch. You could mount that to the saw cabinet I guess. This sounds like a case where you could get real fancy and spend a lot of money, but when given some thought, could be done simply, cheap and effective.

To all you unplugers out there: I applaud your discipline, but I'm just not wired that way!(pun intended) This thread has me being cautious now, but I know me. After a period of time, I will stop crawling under my TS to unplug it just to change out the blade. I will have to install something that is quick, convenient and in plain sight to remind me.

[Ken Fitzgerald]

Larry, my power cable is just a few inches behind and below the front rail for the fence system on my saw. Even though I broke my back 11 years ago and am somewhat stiff, it's not a problem to bend over, lift the cable up and disconnect it from the extension cord. The ends of these two disconnected cables are then hung through a hole in the left cast iron extension wing of my table saw. They are readily accessible for reconnecting once I am finished with my adjustments.

[Larry Browning]

Larry, my power cable is just a few inches behind and below the front rail for the fence system on my saw. Even though I broke my back 11 years ago and am somewhat stiff, it's not a problem to bend over, lift the cable up and disconnect it from the extension cord. The ends of these two disconnected cables are then hung through a hole in the left cast iron extension wing of my table saw. They are readily accessible for reconnecting once I am finished with my adjustments.
Ken, unless I do something additional, I literally have to get on my hands and knees, crawl in under the table about 3 feet to unplug the saw. So I am going to have to do something to make it more convenient to disconnect the power. Maybe I could add an extension plug set right at the mag switch sort of like you describe. A simple AC pull switch mounted in a convenient place seems like a reasonable solution too. My other stationary tools have easy access to the plug, and I don't access the joiner and planer blades very often.