Are you using pads for aluminum bar clamps? I never used pads on that style clamp at all, only on the cast iron pipe clamp ends. Food for thought.
You will certainly need to insure that you clamping force is flat on the wood surface.
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is a supplier I get electronic parts from and have bought very strong magnets from. (While I am very satisfied with this place, I am not trying to advertise, just giving an example.) The NEODYMIUM magnets are really strong, hard to believe. (The rubber strip magnets are very much weaker!) There are quite a few places selling them. But availability has decreased since there are fears young kids will swallow them. If you get two or more in your guts they can pull the tubing around and close it off, which also shows how strong the magnets are. I have a friend who had a pet die after swallowing some.
Some are as thin as 0.2 inches, in that ad. There might be thinner ones elsewhere. But even for thicker ones you could put the magnets in the clamps, where you can use more depth without having to use thick pads, then a thin piece of sheet steel on the back of the pads. Before drilling you could test picking up some of whatever sheet steel you have with one magnet, two, etc., to see what is needed to achieve strength you want. I think one would probably do it, even for the very small magnets, but it would be better to test before drilling holes in your clamps. Don't make holes in a clamp that a magnet will just barely fit into, though, if the surrounding metal is iron or steel! The surrounding ferrous metal will "short circuit" the magnetic field. But if you make a hole somewhat larger, say 3/8 inch for a 1/4 inch magnet, and fill the space around the magnet with something like epoxy glue, then the combination of the magnet itself and the surrounding metal as a pole-piece will actually make the attraction even stronger.
I have Bessey clamps that I mostly use for nice glue-ups, but I also have a number of other clamps this might be good for. (I have just been putting in wooden shims as pads when necessary.) And I already have some of those magnets, so I think I will give it a try. (I also have chronic pains that sap most of my energy so it could be a long time before that happens!) Bob Wilson
Those are exactly what I have been chasing around the shop for the past few years.
Notice the difference between those pads and the Rockler ones. It's the wide open backs of the HF ones that cause them to fall off.
How do you avoid damaging the wood? Metal clamped to wood tends to leave a mark, doesn't it?
I'm talking about these.
The Bessey's came with pads and they stay on fine. My old Jorgensens came naked and those are the ones that are wearing me out, chasing the pads across the shop. None of the generic pads fit.
I found links for Jorgensen 7437 pads but Amazon, Sears, B&H Photo, just about everyone that carried them say they are no longer available. The one place that claims they have them wants $4.31 for 4 pairs. Not bad, but get this: Shipping is $12.95 for one set, 21.95 for 2 sets and $29.95 for 3 sets. WTF!
I'll keep looking for another source because those seem like they should work.
Those clamps would still dent softer woods, woodn't they? ;-)
Ok I'm sorry, I thought you might have been talking aluminum bar clamps. Cast iron surfaces tend to be rough and very small clamping surfaces will damage the wood.
Clamps with large, flat, and smooth surfaces normally are not an issue.
You will probably need an adhesive with ANY replacemnet pad...
3d print some that will clip on
or ditch them and use a scrap of wood and make it fit the clamp
Electric Comet on Mon, 5 Feb 2018
10:47:00 -0800 typed in rec.woodworking the following:Barge cement.
That stuff will hold just about everything.
Electric Comet wrote in news:p5a369$o98$1 @dont-email.me:
contact cement
drum roll please as this is the ultimate solution
shrink tubing
ta da
well it depends on the shape of the pad and clamp there
one benefit is that you can cut off the shrink tubing and put on new ones
not sure why i never thought of this before but i will try it for a couple of slipping pads
if you get the tubing for underground cabling is has extra gunk so it might work instead without the pads at all
could get on the work though
The Jorgensen clamp pads are made of a thermoplastic elastomer which gives them their resiliency. Without resorting to a patent search to learn exact grade of polymer I would guess it is an olefin based elastomer like a polyp ropylene or polyethylene. This type of material is typically molded in its net shape without additional processing steps. In over 50 years of woodwork ing I swear by the Jorgensen clamps. I have passed on all of my pipe clamps however I still have ~ 2 dozen Pony Bar clamps that I use for smaller proj ects over the past 35+ years.
In that time due to clamping and compressing the pads have become loose fit ting so as a retired polymer engineer here is a tip. You can "post-cure" th ese elastomeric clamp pads in a typical kitchen oven. I have done this 2 or 3 times over the past 30+ years with acceptable results.
Remove the clamp pads from the clamp and I set them on a sheet of parchment paper on a cookie sheet. Preheat the over to 280F and set a time for about 35 minutes. Remove them when done and reinstall them on the clamps. My exp erience has been better to install the pads while they are still warm vs. l etting them completely cool. They slip on easier and seem to hold their sha pe better. If the material is as I suspect there id no fear for harmful vap ors or ingredients to leech out and contaminate your oven or your home. I h ope this helps
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