Bowclamp problem

[bruegf]

Hi,

I just bought some bowclamps intending to use them to glue veneer edging on plywood panels I'm using to build kitchen cabinets, seems like a perfect use for a bowclamp.

The problem is that even though I tighten my f-clamps as tight as I can, I can't get all the bow out of the bowclamp and there's so little pressure at the end of the clamp that I can easily move the panel up and down between the bowclamp pair.

First I thought it might be that the cheap f-clamps I bought from harbor freight don't work quite as well so I pulled out the Joregensen f-clamps and tried those, no difference.

Next I thought some oil on the clamp threads would allow me to tighten them more, a little better but not enough to clamp well.

Last thing I tried was to use a straight board on the back edge that I'm not gluing veneer to and only use a bowclamp on the front edge, thinking that more force gets applied to the bowclamp rather than trying to straighten out a bowclamp on the front and the back edge.  Still not any better.

These things can't be that hard to use - maybe I just haven't eaten enough wheaties lately, but I'll be darned if I can figure out a way to make them work.

Only thing I can think to try yet is to use pipe clamps but I don't own any of those and haven't ever needed any, so hate to buy them just for the bowclamp.

Any thoughts as to why I can't get the bowclamps to apply enough pressure at the ends?

Thanks

Fred

 

[semenza]

For anyone looking for info on Bow Clamps .... tons of it here http://www.talkfestool.com/vb/bowclamp/index2.html  [thumbs up]

Seth

 

[PeterK]

Guess I don't understand. I have never had any problem compressing the Bowclamp cauls with either the Bessey F clamps - not the light duty ones - or the Bessey cabinet clamps. What length cauls were you using?

 

[bruegf]

I'm using 24" at the moment.  I tried just clamping the 2 24" bowclamps back to back to see if I could straighten them out and the best I can get is about 1/16" gap at both ends.  I just can't tighten my f-clamps past that point.

Fred

 

[Deansocial]

Surely bow clamps over clamp in the middle and under clamp on the ends?

 

[peter halle]

Surely bow clamps over clamp in the middle and under clamp on the ends?

Dean,

Actually that is the beauty of them - they don't.  Years and years or prototypes and whatever other magic happened produced a way for them to be produced such.

That is where their value lies.

Peter

 

[mouppe]

Fred,

I often have this problem. It's because you are running out of thread before the bowclamp fully closes. I start tightening the f-clamps, then use an extra parallel clamp to hold the bowclamps in place temporarily, readjust the f-clamps and then fully close them. The parallel clamps also help me do any final adjustments before cinching the bowclamps up.

Dean, they really do work very well. Panel glue-ups in particular.

 

[nclemmons]

Reach out to Craig Feuerzeig who is the owner of Bowclamps.  He's a terrific guy and stands behind his product.

Drop him a note at sales@bowclamp.com and explain your issue.  I'm sure he can help you out.

neil

 

[bruegf]

Fred,

I often have this problem. It's because you are running out of thread before the bowclamp fully closes. I start tightening the f-clamps, then use an extra parallel clamp to hold the bowclamps in place temporarily, readjust the f-clamps and then fully close them. The parallel clamps also help me do any final adjustments before cinching the bowclamps up.

Dean, they really do work very well. Panel glue-ups in particular.

That's not it either, with the 24" bow clamps the amount of travel needed on the clamp screw is minimal.  But it does give me another idea to try and that is to use a second clamp to see if I can get some more pressure on the end.

If that doesn't work, I'll contact Craig this coming week as Neil suggested.

Thanks

Fred

 

[Michael Kellough]

The 2 foot Bowclamp is the stiffest. While it is about a 1/4" thinner in section than the 4 foot version the radius is a little smaller so it does take more force to bring the ends down all the way.

I usually use two clamps to get an end down all the way. I usually start with a Quick-Grip (about 1-1/2" from the end) because it's easy to get everything in position. When the Quick-Grip maxes out I finish with a more powerful clamp. Sometimes I can't get a good enough grip on the Bessy's small wooden handles. Nitrile gloves help but the add=on rubber grips are better.

Another reason the seemingly powerful Bessey clamp doesn't always work is the relatively steep ramp of it's Acme thread screw. Sometimes the fine thread of a little Pony clamp does better.

 

[pugilato]

I read somewhere that cauls should have 1/32" deflection at each end for one that is 18". Look it up, and if confirmed, you might want to bring the middle down with your RO 90.

 

[craig feuerzeig]

Hi guys.  Something to keep in mind... The curve is continuous, extending past the point of contact with the clamp.  If you are seating your f-clamps fully into the channel, then the point of contact with the caul will be 2 1/2" in from the end... and you will in fact have a small gap at the end.  Make sure that the point at which the clamp makes contact with the Bowclamp is at the end of the work-piece.  In other words don't stick the head of the clamp all the way in, just grab the end.  And as you said, a couple drops of oil on the threads goes a long way.  And let me know how it goes!