What I'm talking about is a clamp like this:
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| How do you fix a non-tightening wood F clamp http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10101&t=19011 |
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| Author: | Paul Burner [ Wed Oct 01, 2008 2:33 pm ] |
| Post subject: | How do you fix a non-tightening wood F clamp |
I have a few 6" wood F-clamps that just don't want to tighten down. Is there anything I can do to them to fix this issue? These are not old - just probably not very well built. Thanks in advance. |
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| Author: | Michael Dale Payne [ Wed Oct 01, 2008 2:43 pm ] |
| Post subject: | Re: How do you fix a non-tightening wood F clamp |
I assume you mean a Kelsma type clamp. Typically the problem is the two apposing brass pins that make the movable jaw wedge against the bar are worn to the point that it can not wedge and lock the jaw position. When you tighten the cam the jaw just moves up the bar. is this the issue you are having? |
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| Author: | Paul Burner [ Wed Oct 01, 2008 2:47 pm ] |
| Post subject: | Re: How do you fix a non-tightening wood F clamp |
Michael, I've not looked closely at the problem. Here's what I know. They don't tighten down much at all. I've only used the clamps about 2 or 3 times in the less than 4 months I've had them. They weren't good from new. I'm wondering if there is a fix - or if I should contact the manufacturer to see if they will replace. I'd just as soon repair if possible - as long it only requires duct tape, chewing gum and bailing wire. |
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| Author: | JRE Productions [ Wed Oct 01, 2008 2:51 pm ] |
| Post subject: | Re: How do you fix a non-tightening wood F clamp |
If these are anything like "clam clamps" or "bar clamps": we have seen the same issues at my shop as well as my dads. We remedy this issue with a small triangle file. We filed very small grooves/knotchs on the edge of the bar that engages the "locking" feature. This caused the moveable jaw to lock in place when presure was applied. We did this recently to a pistol grip clamp an it probably increase its holding presure by two-fold. Good luck. |
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| Author: | Michael Dale Payne [ Wed Oct 01, 2008 2:57 pm ] |
| Post subject: | Re: How do you fix a non-tightening wood F clamp |
Two things that might help is to first knurl the inside and outside edge of the bar. This will give the pins something to gab on. Sometimes just taking a bastard file and removing round over on the edges will help. Maybe the pins were placed with too much clearance between the pins and the bar when they were made. Second look at the flex tong to see if has good rigidity and you may want to make a very slightly oversized cam lever. |
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| Author: | Paul Burner [ Wed Oct 01, 2008 2:59 pm ] |
| Post subject: | Re: How do you fix a non-tightening wood F clamp |
What I'm talking about is a clamp like this:
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| Author: | JRE Productions [ Wed Oct 01, 2008 3:13 pm ] |
| Post subject: | Re: How do you fix a non-tightening wood F clamp |
Yep. the moving part of the clamp is no longer grabbing the bar. There is a pin on both sides of the bar that need to catch the bar to lock in place the moving piece. If you rough up the inside edge of the bar, it will grab the pin and hold it better. J |
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| Author: | Michael Dale Payne [ Wed Oct 01, 2008 3:14 pm ] |
| Post subject: | Re: How do you fix a non-tightening wood F clamp |
Yep we are speaking of the same type of clamp. the brass pins next to the bar are the mechanism that holds the jaw in place. The inside pin at the top side of the movable jaw and the outside pin on the bottom side of the movable jaw wedges against the bar when pressure is applied. These are the pins I suspect have worn. |
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| Author: | Howard Klepper [ Thu Oct 02, 2008 2:13 am ] |
| Post subject: | Re: How do you fix a non-tightening wood F clamp |
Nope, the problem is not the pins that engage the bar, or the bar itself. It's the cam lever, which is not properly shaped. I bought a few of those Shop Fox clamps from Grizzly a few years ago; it was a waste of money. You might be able to knock the pin out of the cam lever and replace it with one shaped properly. I've just set the three I have aside and use them only when I want a very gentle pressure. |
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| Author: | Mark Groza [ Thu Oct 02, 2008 8:33 am ] |
| Post subject: | Re: How do you fix a non-tightening wood F clamp |
I found that it pays to get the good german made klemmsia cam clamps as most others aren't of the quality for a good working clamp.Cam clamps hve to be made with the correct angles to work well,and those cheap china ones are worthless as far as i'm concerned on this type of clamp. |
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| Author: | Brook Moore [ Thu Oct 02, 2008 2:24 pm ] |
| Post subject: | Re: How do you fix a non-tightening wood F clamp |
A few years back I bought a dozen of these Shop Fox cam clamps. The first time I used them, 7 clamps cracked as soon as I swung the cam lever up. Sent them back. |
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| Author: | Paul Burner [ Thu Oct 02, 2008 2:30 pm ] |
| Post subject: | Re: How do you fix a non-tightening wood F clamp |
BrookM wrote: A few years back I bought a dozen of these Shop Fox cam clamps. The first time I used them, 7 clamps cracked as soon as I swung the cam lever up. Sent them back. That's so reassuring! DANG! |
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| Author: | Howard Klepper [ Fri Oct 03, 2008 1:30 pm ] |
| Post subject: | Re: How do you fix a non-tightening wood F clamp |
BTW, the clamps from Garrett Wade are IMO superior to Klemmsia and can generate more pressure. |
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| Author: | WaddyThomson [ Fri Oct 03, 2008 2:03 pm ] |
| Post subject: | Re: How do you fix a non-tightening wood F clamp |
And, for what it's worth, Garrett Wade is having a special on them, currently. They are all 4 1/4" deep, but the 12" ones are only $8.95 each vs the regular price of $12.75. |
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