# Electromagnetic clamps?



## Tonto1 (Nov 10, 2016)

I see a lot of effort going into designing & laying out dogholes for work tables. Has anybody ever thought instead, to use a sheet of steel under the top piece of plywood and an electromagnet as a clamp. You could place your piece wherever you wand it, place the magnet on it & turn it on. And there it would stay.

Round Electromagnets > EM137-115ac-222

Talk about easy...depending on the article you are clamping, you could use 2, 3 or 4 magnets. Whatever is needed. I think it would be a real timesaver as well. 

Just a thought! Am I crazy?


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## Stick486 (Jan 4, 2013)

Tonto1 said:


> I see a lot of effort going into designing & laying out dogholes for work tables. Has anybody ever thought instead, to use a sheet of steel under the top piece of plywood and an electromagnet as a clamp. You could place your piece wherever you wand it, place the magnet on it & turn it on. And there it would stay.
> 
> Round Electromagnets > EM137-115ac-222
> 
> ...


costs come to mind and I believe those magnets aren't strong enough to hold securely w/ a sheet of plywood under them..
also there is the cords that may get in the way...
and if you hit one of those mags w/ your tooling... ewwww boy...

and... and... and...


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## Tonto1 (Nov 10, 2016)

I considered that. But I see that those magnets are 12 volt, you could put a battery on top of them. That site has magnets that hold up to 640 lbs. Even if you used the 44 lb one I linked, if you used 2 or three of them, how much force is a screw down clamp exerting? Imagine being able to place a block anywhere to be used as a stop for cutting fixed lengths. Couldn't get much easier than that. But then again, just thinking out loud. Thought it would be fun to kick it around!


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## Herb Stoops (Aug 28, 2012)

They work great on metal working ,such as welding set up benches that have a steel top, But I agree with Stick it would be cost prohibitive for wood working.
Herb


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## Stick486 (Jan 4, 2013)

I like the KISS/MISS route the best and old technology tools...
and what will those magnetic fields (think EMP) do to your high tech stuff...


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## woodknots (Mar 7, 2012)

Quentin, I think the effort you're seeing by some members in the design and layout of dog holes isn't out of necessity but out of a desire to do it - at least that's my opinion.
I on the other hand, have a workbench made out of dimensional lumber with two sheets of 3/4" mdf on top. A row of dog holes in line with my vice is all I use. That bench has lasted me for years. I too believe in KISS - keep it simple s.......d. Electromagnets as clamps is really putting a lot of effort into it. No need to reinvent the wheel.


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## hawkeye10 (Jul 28, 2015)

Tonto1 said:


> I see a lot of effort going into designing & laying out dogholes for work tables. Has anybody ever thought instead, to use a sheet of steel under the top piece of plywood and an electromagnet as a clamp. You could place your piece wherever you wand it, place the magnet on it & turn it on. And there it would stay.
> 
> Round Electromagnets > EM137-115ac-222
> 
> ...


You might be crazy but maybe not. All you have to do is develop and market it and you are rich.


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## MT Stringer (Aug 15, 2012)

Stick486 said:


> ...and what will those magnetic fields (think EMP) do to your high tech stuff...


Or your heart! :surprise::grin:


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## tomp913 (Mar 7, 2014)

Back when I was working, we had a couple of guys with pacemakers - they had to follow a proscribed - and very well defined - path through the shop to avoid the equipment that put out a field that would mess up the pacemaker. There was even a problem with one of the portable MPI machines, they used to put up tape barriers so that the affected workers would know not to get too close.


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## Stick486 (Jan 4, 2013)

MT Stringer said:


> Or your heart! :surprise::grin:


pacemaker or hearing aide...
insulin pump...
digital watch...
digital tools...


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## RainMan 2.0 (May 6, 2014)

tomp913 said:


> Back when I was working, we had a couple of guys with pacemakers - they had to follow a proscribed - and very well defined - path through the shop to avoid the equipment that put out a field that would mess up the pacemaker. There was even a problem with one of the portable MPI machines, they used to put up tape barriers so that the affected workers would know not to get too close.


Wow I'm glad I never got one put in . I have a nasty case of A-fib , and I told them it's not going to happen . Pills don't work unfortunately, so my resting heart beat is around 130 bpm. 
But I'll be damned if I'm going to worry about EMP all the dam time . Sooner just die early


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## tomp913 (Mar 7, 2014)

Tonto1 said:


> I see a lot of effort going into designing & laying out dogholes for work tables. Has anybody ever thought instead, to use a sheet of steel under the top piece of plywood and an electromagnet as a clamp. You could place your piece wherever you wand it, place the magnet on it & turn it on. And there it would stay.
> 
> Round Electromagnets > EM137-115ac-222
> 
> ...


I have a couple of the MagSwitch products - featherboard and bandsaw fence - and the magnets hold very well, no problem with the bandsaw fence moving while you're resawing, even with the lighter magnet.

As far as the dog hole pattern, the concern for accuracy is when using the holes with a set of dogs to form an accurate 90° when setting up for a cutting operation.


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## Tonto1 (Nov 10, 2016)

I'll ask one of the Cardiologists tomorrow about the magnetic fields. I'm pretty sure they have got the insulation on them down now days. We'll know tomorrow for sure.

Rick, that A-fib can have several causes. If medicine doesn't control it, check into an ablation procedure. Many times A-fib can come from the nerves originating in the nerves in the veins connecting to the heart as well as in the heart itself. They use radio waves to burn the nerves...A-fib gone!


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## CharlesWebster (Nov 24, 2015)

Stick486 said:


> pacemaker or hearing aide...
> insulin pump...
> digital watch...
> digital tools...


Most of those things are immune to DC magnetic fields. They have to be to meet standards. 

But the OPs idea is still NG because of the electricity required. If my workbench becomes a 300W appliance, along with my 1400W router, my 1200W saw....

I'm a high-tech kind of guy, so I can see where an electromagnet clamp might be useful, like when you can't get around the outside of the object with a conventional clamp, but the complexity, capital cost, and energy cost adds up to, in my opinion, a non-starter.


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## jj777746 (Jan 17, 2015)

Stick486 said:


> pacemaker or hearing aide...
> insulin pump...
> digital watch...
> digital tools...


Hey Tonto 1,I like the way you think but the dogs/dog holes are the simplest,most efficient method for holding your work in this instance. Next thing we'll have magnets holding mobile work benches,etc to steel floors.It is plainly over-kill.Jamesjj


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## jj777746 (Jan 17, 2015)

Tonto1 said:


> I'll ask one of the Cardiologists tomorrow about the magnetic fields. I'm pretty sure they have got the insulation on them down now days. We'll know tomorrow for sure.
> 
> Rick, that A-fib can have several causes. If medicine doesn't control it, check into an ablation procedure. Many times A-fib can come from the nerves originating in the nerves in the veins connecting to the heart as well as in the heart itself. They use radio waves to burn the nerves...A-fib gone!


@ Tonto 1, in regards to your advice to Rick,my sister in law had the same condition & procedure & was cured straight away but I'm sure she said Laser was used.What ever it was,it fixed her up & she has never had a relapse.Jamesjj.


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## jw2170 (Jan 24, 2008)

Rick, Easy cure.....I have a heart condition which will give palpitations, no effect for some time, thank goodness. My specialist gave some methods to regain beat.. 

I like the one that says. "hold your breath until you fall unconscious. Your heart will reset"......LOL...


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## Nickp (Dec 4, 2012)

Tonto1 said:


> I considered that. But I see that those magnets are 12 volt, you could put a battery on top of them. That site has magnets that hold up to 640 lbs. Even if you used the 44 lb one I linked, if you used 2 or three of them, how much force is a screw down clamp exerting? Imagine being able to place a block anywhere to be used as a stop for cutting fixed lengths. Couldn't get much easier than that. But then again, just thinking out loud. Thought it would be fun to kick it around!


The one you linked weighs 44pounds...don't think I'll be kicking that around...


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## AndyL (Jun 3, 2011)

Tonto1 said:


> I see a lot of effort going into designing & laying out dogholes for work tables. Has anybody ever thought instead, to use a sheet of steel under the top piece of plywood and an electromagnet as a clamp. You could place your piece wherever you wand it, place the magnet on it & turn it on. And there it would stay.
> 
> Round Electromagnets > EM137-115ac-222
> 
> ...


That magnet will hold 44lb if in direct contact with a piece of steel. But used as you described, it's separated from the steel bench by the thickness of your workpiece. The magnetic force falls off rapidly with distance.

Maybe you could use the magnet as a moveable base for a conventional clamp as some sort. But looking over at the Record Power web site, I see a 4" G clamp is rated for 1321kgf (nearly 3000lb!) of clamping force, so you would easily pry the magnetic base off the table with a screw clamp.

For an idea of the kind of force that a screw can exert, think about how easy it is to lift a corner of your car off the ground with a scissor jack. You can get magnets that will lift cars too, but they're a bit unwieldy for the wood shop


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## Wildwood (Aug 14, 2010)

Imagine if electromagnetic clamping was the norm, and then somebody came up with ........dogholes!


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## Tonto1 (Nov 10, 2016)

Well it sounds like we kicked it around pretty good! Agreed it would have some problems. Nice concept though if it was as easy as hoped. Thanks guys.


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## Cherryville Chuck (Sep 28, 2010)

I'm a little late to this and you already seem to have figured out that it might not be an ideal clamping method but I'll add a little to it. As mentioned magnetic force drops off rapidly with distance. But there is also a problem with coefficient of friction on the table surface and the average surface of a bench wouldn't have much. One of the ways to separate powerful magnets is to slide them apart so I suspect a magnet wouldn't want to stay put.

As for drilling bench dog holes, I found it very easy. I marked the locations with a set of crossmarks and used a brad point bit and drilled the first 1/16 to 1/8" freehand. Then I took a piece of 4x4 and drilled a hole through it with the bit in a drill press to get a vertical drilling guide. Then I put the bit through the guide and located the bit into the started holes and drilled them the rest of the way out. Only took a few minutes and was more than accurate enough. Very quick and very easy.


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## Tonto1 (Nov 10, 2016)

Hey Chuck, seems like it would be more trouble that its worth. I suspect it would change table construction as the steel plate would be the biggest part. You would not need plywood at all. Just glue a piece of Formica (or facsimile)to it. I envisioned the top would be laid out with common patterns (marked with a sharpie or the likes of). To break down a sheet of plywood, for example, you would lay a straight edge on that mark, clamp it & run a saw along it. With a glue on ruler, just place a stop on the measurement, clamp it & cut all the required pieces to length. With magnets inside your fence, you could place it anywhere & just turn on the magnet. Fences could be longer extending the length of the table. I agree the wires would be a potential problem getting in the way. But it would be a cool set up if it could be figured out. Again, probably more trouble than its worth! Did generate a good bit of discussion though! :smile:


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## Stick486 (Jan 4, 2013)

a strong magnet is difficult if not impossible to pick up...
but easy to slide...


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## jj777746 (Jan 17, 2015)

Tonto1 said:


> Hey Chuck, seems like it would be more trouble that its worth. I suspect it would change table construction as the steel plate would be the biggest part. You would not need plywood at all. Just glue a piece of Formica (or facsimile)to it. I envisioned the top would be laid out with common patterns (marked with a sharpie or the likes of). To break down a sheet of plywood, for example, you would lay a straight edge on that mark, clamp it & run a saw along it. With a glue on ruler, just place a stop on the measurement, clamp it & cut all the required pieces to length. With magnets inside your fence, you could place it anywhere & just turn on the magnet. Fences could be longer extending the length of the table. I agree the wires would be a potential problem getting in the way. But it would be a cool set up if it could be figured out. Again, probably more trouble than its worth! Did generate a good bit of discussion though! :smile:


Quentin,you certainly did generate some good discussion.As I said,I like the way you think & I reckon quite a few others do too. Keep 'em coming mate.James jj


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## Tonto1 (Nov 10, 2016)

Thanks James, I don't know why I think about things like that. I guess it comes from growing up in the country with little money. Had to figure out how to do stuff on my own. Now I find myself always looking for better options. My friends call them Quentenisms!


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## Tonto1 (Nov 10, 2016)

Oh, and I checked on the pacemakers. They are not shielded from magnetism...would be a big problem!


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## RÖENTGEEP (Feb 18, 2014)

Tonto1 said:


> Oh, and I checked on the pacemakers. They are not shielded from magnetism...would be a big problem!


Did you checked about MRI (magnetic resonance imaging) and pacemakers ? :surprise:


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