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| Built my own cam clamps, just won't hold tight! http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10122&t=38051 |
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| Author: | Steve Jeffries [ Tue Oct 23, 2012 11:30 am ] |
| Post subject: | Built my own cam clamps, just won't hold tight! |
Hello all. My first post here, and hopefully somebody may be able to offer a bit of advice. I built a few cam clamps in my shop over the past couple days and, while they look very pleasing to the eye, they don't grip tightly at all(which certainly defeats the purpose of the tool). Used maple stock for the jaws, and 1/4"x1" oak stock for the bar. Cut my own mortise to slide the bar through, and the sliding jaw slides, but is semi-snug with not much wiggle to it. Could this be the source of my weak clamping power? Still need to tweak the lever a tiny bit, but it does certainly activate the cam. I can post pics at some point, but any advice at all would be appreciated. |
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| Author: | charliewood [ Tue Oct 23, 2012 2:28 pm ] |
| Post subject: | Re: Built my own cam clamps, just won't hold tight! |
jeffrodite I have heard others using wood as bars who have the same problems, and some using oak bars that have no problems!?!?!?! there is alot of difference in strength and deflection from piece to piece (in a single type) where wood is concerned - are your tolerances tight in the sliding jaw? Did you set up the sliding clamp jaw with brass pins as some do? could you show a picture of the clamps potentially? I built a few homemade klemsia clamps out of wood (oak jaws) - I used rock maple for the bars and likewise wasnt confident enough in them to use them on a joint that mattered - like the bridge which was what I specifically built them for - I can relate ....its disappointing especially when you put so much time into construction - Im going to replace the maple bars with either steel barstock, or at least laminate metal on either side of the maple bars with mine - then im sure there will be enough pressure (as there "just" isnt enough now IMO)- Im not sure what you plan to do... but if your not confident in the clamp pressure dont use them until its sorted - it could lead to many headaches down the road... as i said pictures could help sort out the probs.. Cheers charliewood |
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| Author: | Steve Jeffries [ Wed Oct 24, 2012 11:22 am ] |
| Post subject: | Re: Built my own cam clamps, just won't hold tight! |
OK, took out the old lever and cut some new ones and works great. Cut the mortises w/ a drill press and chisel, used dowels and glue to put it all together. Let me know what you think. Making a bunch more tonight. |
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| Author: | cphanna [ Wed Oct 24, 2012 6:38 pm ] |
| Post subject: | Re: Built my own cam clamps, just won't hold tight! |
Steve, I believe you can improve your clamp performance quite a bit by buying some cork gasket material, which is a common hardware store item. It is usually packaged in rolls, about twelve inches wide by about 18 or 24 inches long. Lay it out flat and cut rectangles the size of your clamping jaw faces. Use an ordinary utility knife or an x-acto knife to cut the pieces. Use common white or yellow glue to adhere these cork pads to the faces of your clamp jaws. Their advantage is two-fold: They cushion against dents and mars and they provide a bit of extra grip, too. You might prefer rubber or leather faces, in which case you will scrounge around a little bit, but those materials are not hard to find (old inner tubes, belts with missing buckles that are hanging in your closet, etc.). Then, for future clamps, keep your eyes peeled for aluminum bar stock about 1/8-inch by 3/4 inch. It is not so easy to find any more, as I discovered earlier this year. It's still out there. It's just not commonly stocked at my hardware stores any more. It's very rigid and light weight. It makes a fine bar, over which your upper jaw can slide. Stash away lots of hardwood cut-offs from your various projects, because these will make future clamp jaws for you. I find oak, ash and hickory to be particularly "springy" woods that work well for this purpose, but you might not use those woods as much as I do. Maple, birch and many other species would work very well for this purpose. Make sets with jaws of several lengths, as they will all be useful at some point. You get the idea. It is often said that a woodworker can't own too many clamps, and it's true. Patrick |
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| Author: | Steve Jeffries [ Thu Oct 25, 2012 1:37 pm ] |
| Post subject: | Re: Built my own cam clamps, just won't hold tight! |
Thanks for the info. I already planned on going out and grabbing the cork, just haven't gotten around to it yet. For the clamps, I used oak for the bar and maple for the cam and jaws,using dowels to fasten everything. Once I made a new/larger cam, they worked great. Making a bunch more tonight. |
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