Bow clamp clamping cauls

[DaveO]

A while back someone created a thread about Bowclamps. There was a little discussion about them, but the general consensus was that nobody had tried them to give a reliable opinion about them. A reply was posted to that thread by Craig Feuerzeig of Zig Industries, the creator and maker of the Bowclamp system. He offered a set of the clamping cauls to be tested and reviewed by a member of NCwoodworker. D L Ames, took on the task, but due to a very busy work schedule has been unable to make the time to give them a good testing for review. He handed the set off to me to test and give y'all my thoughts and opinions about them. And they follow:


I have to admit that I was a little skeptical about the Bowclamp system. Not about the technique or method of using clamping cauls as it is a time proven method of distributing clamping pressure across a large area. Nor that they were well made items. But about the whole idea of buying curved pieces of wood for between $22-32 a set.
Well, I picked them up from D L on Saturday, and gave them a work over today. My first impression of the cauls as I removed them from the box was that they were definitely hand made, not by a CNC or any other automated process. You could see the tooling marks, a little burn from a router or shaper, and some slight chip-out from shaping. None of these thing affected the usability of the cauls, it just proved that Craig is a one man operation, and made each on himself.
Right off the bat I noticed that each set of cauls had their own unique curvature, definitely not random. I wanted to see if they would bow like they were designed to do so they could provide even pressure across the entire work piece.
Here's a shot of the cauls without clamps showing the curvature:

And with clamps applied closing up the gaps to a straight line:




After doing that I decided to put them to use in a panel glue up. I was making a cat bed, (as something to make that would require the use of the cauls). First I milled up three pieces of Lacewood that were to be the “headboard” of the bed. Normally I would use 3 or 4 Bessy clamps for this glue-up.
Here's a shot of the panels and cauls before clamping:


And after, showing very even (somewhat excessive for illustration purposes) glue squeeze out across the entire joint:




The cauls applied excellent pressure even though only two F-style clamps were being utilized.
The only draw back I found in this application was that I need to make 1/2” spacers to lift the panel so that it was in the center of the caul face to provide parallel pressure.


The next application I tried was a quick lamination of some Red Oak 5/4 stock to make the legs for the bed. Seeing as the panel was still drying in one set of the cauls I had to use my standard method of clamping for one and the cauls for the other.
Here's a 18” lamination using 3 Bessy clamps:


And here's a 26” lamination of the same stock using the 36” Bowclamp cauls:



Excellent glue squeeze out across the entire joint line:




The only issue I had during this application and others was the amount of screw travel to completely close the cauls. It takes almost the entire thread length of my standard F-style clamps...that's a lot of twisting.


I wish that I had a scientific method of testing how much pressure the cauls applied compared to a standard K-body style parallel jaw clamp. But I don't so I tried to break the joint after the glue had cured and the wood broke first...that's enough pressure in my book, it created a solid joint.


My overall impression of the Bowclamp caul system is that they are well designed, do what they are designed to do, and worth the money. A full set of 3 pairs of cauls 24”, 36” & 48” runs about $130. If you bought the wood to make them, about 6 BF of 8/4 hard Maple, you would spend around $36. Then factor in 3-4 hours milling, squaring, dimensioning, routing, cutting sanding and finishing, and you would come out better buying them. If you value your time like I do. I much rather be making something fun than some high tech bowed sticks.
And the savings goes even farther because instead of having a arsenal of expensive parallel jaw clamps you can use many less and cheaper F-style clamps. That is something that I found to be quite advantageous as I have many of the cheaper F-style clamps that I don't use very often due to their tendency to not stay parallel and to mar the work piece with their small area of surface contact.
My biggest complaint is that I don't have 2 sets of any of the sizes to be able to utilize them to help keep a panel glue up flat, something which I think that they would also excel in doing.


I would like to thank Craig for the opportunity to test out his product and commend him on taking something very simple and refining it to perfection for a reasonable cost.
Also thanks to D L for being to busy to test them out...I will find lots of use for them in my shop. If anyone would like to give them a test run themselves, I would be more than happy to let you give them a try providing you post your thoughts also.


Respectfully submitted,
Dave:-)

Bowclamp

[Toddler]

Nice review DaveO.

and seriously. . . cat bed???



PS) PM me your address so I can send that nesting box plan.

[cskipper]

Dave, thanks for a well written review. I think I was one of the first to mention these in thee original dissuasion, so I was especially interested in the results. It was also good to hear that DL is alive and well.

[nelsone]

Good Review Dave! I have also been skeptical about purchaing cauls. You did a good job on the cost breakdown.

[DavidF]

They sound like a good thing that I would find very useful. I have never been able to justify the high cost of K body clamps and their ilk, so I too have many "F" style clamps. I am going to be glueing up a lot of panels for the bedside cabs so perhaps I could borrow the 24" set??

[Splinter]

Dave, thanks for the detailed review. It helps to get a review from a know WW'er not just from the company's web site. I have to put them on my wish list.

[DaveO]

I am going to be glueing up a lot of panels for the bedside cabs so perhaps I could borrow the 24" set??

Certainly, just let me know when you would need them, and I can drop them by Apex when I am in the area.
Dave:-)

[DavidF]

Certainly, just let me know when you would need them, and I can drop them by Apex when I am in the area.
Dave:-)

Starting next week end! how about bringing them to the Apex lunch tomorrow? then everybody could see them and I could take them away

[DaveO]

You bet, I'll write myself a note right now.
Dave:-)

[Sully]

Nice review DaveO.
and seriously. . . cat bed???

Exact same thing I was thinking! Geez-louweez, lacewood and all. The darn bed I sleep on ain't no where near nice as that.

[cpowell]

Very well-written, objective review, Dave.

I agree with you on the value of my time. And if you reckoned you could build a set in 3-4 hours that means it would likely take me a few days!! :lol:

Chuck

[DavidF]

You bet, I'll write myself a note right now.
Dave:-)

Thank you Sir, I appreciate that.

[sapwood]

Well thought out and thorough review Dave
Excellent point about not needing the big Besseys'. Their cost has limited me to mostly F-clamps.

Roger

[DaveO]

My first impression of the cauls as I removed them from the box was that they were definitely hand made, not by a CNC or any other automated process.
Dave:-)

Bowclamp

An amendment to my review. After visiting the SMC Bowclamp forum I realized that CNC technology (Shopbot as a matter of a fact) is used quite heavily in the production of the cauls. In addition to a very cool Drycleaner's conveyor system to automate the finishing process.
YouTube - bowclamp dipping mock-up
That doesn't detract from their usefullness, I just didn't want to be giving out incorrect information...even if it was only my erroneous impressions.
Dave:-)

[John Reeves]

Thanks for the review Dave. It really helps when a trusted source comes forth.