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Bowclamp Modern technology used to realize an age-old idea: a perfect bow shaped arc. The Bowclamp's patented design - made possible only with the help of computerized, numerically-controlled cutting technology (CNC) - allows for equal clamping pressure along the entire length of the glue line... with only one clamp at each end!

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Old 08-20-2013, 01:49 AM
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Default How much force to tighten?

Those of you who have used the Bowclamp cauls before, is it hard to tighten up the clamps to close all the way to the end of the cauls? I would like to get some but I'm worried about being able to crank down the clamps with my small hands. I'm figuring to get the desired pressure onto the cauls, they would need to be pretty rigid and hard to tighten.

I think I read that the 4' cauls has a 7/16" crown in it. If you double that when using 2 cauls it adds up to almost 1" of clamping gap to overcome just to flush the caul ends not to mention adding a little more pressure too.

Thanks,
Rob
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Old 08-20-2013, 02:39 AM
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Default Re: How much force to tighten?

That came up once before. It's not an issue. I remember it because that night, in an effort to prove that it was not hard, I had my then 4yo daughter do it. She just smiled. Daddy's helper, you know.
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Old 08-20-2013, 02:42 AM
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Default Re: How much force to tighten?

I've used a few different clamps to flatten out my bowclamps, and they've all been successful. Mainly I use pony bar clamps and Bessey clamps. Once they are down flat, that's it, don't over tighten them as you will reverse the effects and finish up with a gap in the middle.
If you find you run out of clamping thread on the clamps handle before the bowclamps is flat, there's a couple of ways to solve this.
1) put one end down and clamp it (not fully tightened) then push the other end down before placing the clamp on, this will give you more thread on the clamp to get it down.
2) the same as before but use an extra clamp if you run out of thread.
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Old 08-20-2013, 05:11 AM
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Default Re: How much force to tighten?

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Originally Posted by RWeber View Post
That came up once before. It's not an issue. I remember it because that night, in an effort to prove that it was not hard, I had my then 4yo daughter do it. She just smiled. Daddy's helper, you know.
Wow, now if your daughter can do that, then how much pressure is the Bowclamps actually excerpting?
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Old 08-20-2013, 06:07 AM
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Default Re: How much force to tighten?

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Originally Posted by rjwz28 View Post
Wow, now if your daughter can do that, then how much pressure is the Bowclamps actually excerpting?

Here You can see, Craig, the inventor of Bowclamp demonstrating a carcass assembly. You can get a feel for the amount of force needed by watching him.

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Old 08-20-2013, 07:15 AM
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Default Re: How much force to tighten?

I too have small hands, and have never had a problem tightening Bowclamps. I have no idea how much force (or pressure) they exert, but it's plenty for everything I've done - from cabinet panels to chair seats. Get them. They're great!
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Old 08-20-2013, 02:20 PM
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Default Re: How much force to tighten?

The easiest clamps to use are the Pony 3700 series clamps as the jaws fit in the bowclamp channel easily. Clamps that fit in the channels are the key to a fast and easy setup.

The heavier duty clamps willl work, but the jaws do not fit in the channel, making cabinet glue-ups as demonstrated in the video impossible without a second set of hands. That said, I have also used my Jet parallel clamps outside the channels and they pull the clamps down easily.
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Old 08-20-2013, 05:15 PM
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Default Re: How much force to tighten?

Quote:
Originally Posted by rjwz28 View Post

... I think I read that the 4' cauls has a 7/16" crown in it. If you double that when using 2 cauls it adds up to almost 1" of clamping gap to overcome just to flush the caul ends not to mention adding a little more pressure too.
I'm sure Craig Feuerzeig will weigh in here with more info soon.

Hey Rob, to the forum!


.
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Old 08-20-2013, 06:40 PM
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Default Re: How much force to tighten?

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Originally Posted by joraft View Post
I'm sure Craig Feuerzeig will weigh in here with more info soon.

Hey Rob, to the forum!


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Quote:
Originally Posted by rjwz28 View Post
Those of you who have used the Bowclamp cauls before...

Thanks,
Rob

Indeed. Welcome Rob! All info sounds right. F-clamps will give you about an 1 1/8" of thread to work with, and you'll want to avail yourself of all of it by backing the screws out before hand...and as Okami says, pre-stress the bowclamps by squeezing some of the bow out while setting your clamps in place. I think you can see that at a little at about 1:18 in the video. Takes a little practice, but that will save some valuable thread length (also helps hold things in place).

And as for the tension in tightening... a few drops of oil on the threads will go a long way.

And thanks for your interest Rob. And thank you guys for help chiming in. I'm sure Rob would rather hear from you guys.
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Old 08-20-2013, 11:50 PM
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Default Re: How much force to tighten?

Quote:
Originally Posted by rjwz28 View Post
Wow, now if your daughter can do that, then how much pressure is the Bowclamps actually excerpting?
You don't particularly need alot of pressure. Whats great about the bowclamp is it's pressure along the entire length of the clamp rather than single pressure points spaced by however many clamps you have handy.
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