# Bow clamps



## Rebelwork (Jan 15, 2012)

Anybody actually made authentic/lookalike Bowclamps? Based on the original design?


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## woodnthings (Jan 24, 2009)

Rebelwork said:


> Anybody actually made authematic/lookalike Bowclamps? Based on the original design?


Is this what you are asking about?


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## Rebelwork (Jan 15, 2012)

i think most are familiar.. if you need to know what Bowclamp is , you haven’t actually made Bowclamp…

I don’t know why we need the videos..


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## Jim Frye (Aug 24, 2016)

I use regular straight cauls with multiple clamps using the width of the caul to spread the pressure over the area being clamped. There's an old adage that says clamp pressure is spread at a 45 degree angle on each side of the clamp. The wider ( or height) of the caul the greater the spread of the pressure.


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## B Coll (Nov 2, 2019)

I always called them cauls. Learned a new term.


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## Rebelwork (Jan 15, 2012)

B Coll said:


> I always called them cauls. Learned a new term.


”BowClamp” was his brand name.

He offered me a set of these for free on Woodnet years ago, Guess I should have taken him up on the offer..

In the mood this winter to do shop projects I guess


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## woodnthings (Jan 24, 2009)

Rebelwork said:


> i think most are familiar.. if you need to know what Bowclamp is , you haven’t actually made Bowclamp…
> 
> I don’t know why we need the videos..


Because not every one is familiar!
Furthermore, they are NOT clamps, but curved cauls.
They are named by/after the guy who invented them which is not widely known.
The videos explain to others who may not have heard of them.
I never claimed to have made one, but I have used cauls many times.
I have aluminum sweeps or curves in various radii to make the curves on the cauls.
They were used in designing the surfaces on automobiles, not specifically for woodworking.
The curves must be symmetrical or the pressure won't be even.
How did you intend to make the curves?


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## Rebelwork (Jan 15, 2012)

If they are not familiar, they wouldn’t know..

read the post “Bowclamp”

The guy was a frequent member of Woodnet..


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## Rebelwork (Jan 15, 2012)

Back to the original question…

”Anybody actually made authentic/lookalike Bowclamps? Based on the original design?”


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## Rebelwork (Jan 15, 2012)

B Coll said:


> I always called them cauls. Learned a new term.


They’re cauls, but they’re a bit different. You can add a clamp to hold them down.. It has a groove for a clamp..


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## Dave McCann (Jun 21, 2020)

Rebelwork said:


> Anybody actually made authenotice/lookalike Bowclamps? Based on the original design?


Yes, to your 1st question.
Unsure how to answer your 2nd question. The full design was never disclosed. It was just described as
the "perfect arc".

We made a short "production run" of around 10 or 12 sets for some of the guys in the shop to take home for personal use.


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## Rebelwork (Jan 15, 2012)

Curious what materials they used to make their” Bowclamps”. Thinking I might laminate something to get some flex…


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## Dave McCann (Jun 21, 2020)

Rebelwork said:


> Curious what materials they used to make their” Bowclamps”. Thinking I might laminate something to get some flex…


According to their sales ads;
Bowclamp® developed a process that creates a true curve on quartersawn hard maple blanks to ensure perfectly even distribution of clamping pressure across a clamped surface.


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## Rebelwork (Jan 15, 2012)

I’m not sure how much hard maple I have, but plenty of hickory…


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## Dave McCann (Jun 21, 2020)

Rebelwork said:


> I’m not sure how much hard maple I have, but plenty of hickory…


When we made the production run, the engineers in the shop choose NOT to use Maple. These engineers were also the guys who wanted the bow clamps. Myself and a couple other machinist, simply machined their chosen material, to their engineering specs, to produce the completed bow clamps.


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## kwoodhands (May 1, 2020)

Rebelwork said:


> Anybody actually made authenotice/lookalike Bowclamps? Based on the original design?


I buy my inexpensive bow clamps at the lumber yard. I just grab 2x3"s , everyone is bowed.
mike


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## B Coll (Nov 2, 2019)

Rebelwork said:


> Back to the original question…
> 
> ”Anybody actually made authentic/lookalike Bowclamps? Based on the original design?”


Interesting. Most of my cauls are Honduran mahogany. I put a slight bow on them with a plane when I make them, but never any science to it. They are all the same though. I have used them in the fashion described, never had an issue. Calculating spring tension for equal pressure distribution is out of my league.


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## Rebelwork (Jan 15, 2012)

I’m use to just grabbing random 8/4 Ash at the shop, get done and throw them back on the pile. I want dedicated Bowclamps in my shop.. I’ll take the time and make the grooves, etc..


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## Rebelwork (Jan 15, 2012)

I considered laminating these for spring back. I may have to trial/error these..

It would be nice tomhave them ready for my shuffle board table..


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## Rick Christopherson (Jun 27, 2016)

Dave McCann said:


> According to their sales ads;
> Bowclamp® developed a process that creates a true curve on quartersawn hard maple blanks to ensure perfectly even distribution of clamping pressure across a clamped surface.


This is ironic as hell, because the guy didn't have a technical bone in his body. He and I used to go round and round on the most basic of engineering/physics principles.


Rebelwork said:


> I considered laminating these for spring back. I may have to trial/error these..


Just FYI for you as you consider your chosen curve and spring-back; once you have applied enough clamping force to the two ends of the caul to flatten them out (i.e. touch the surface), no new force will be applied to the center, no matter how much harder you tighten those two clamps. This was one of the main principles I could not get him (forgotten his name) to understand. (Oh, now I remember his name: _Craig Feuerzeig_.)

This was the major failing of his marketing campaign, because he kept claiming the clamps would apply more force to the center of the caul than physically possible.


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## Rebelwork (Jan 15, 2012)

Rick Christopherson said:


> This is ironic as hell, because the guy didn't have a technical bone in his body. He and I used to go round and round on the most basic of engineering/physics principles.
> 
> Just FYI for you as you consider your chosen curve and spring-back; once you have applied enough clamping force to the two ends of the caul to flatten them out (i.e. touch the surface), no new force will be applied to the center, no matter how much harder you tighten those two clamps. This was one of the main principles I could not get him (forgotten his name) to understand. (Oh, now I remember his name: _Craig Feuerzeig_.)
> 
> This was the major failing of his marketing campaign, because he kept claiming the clamps would apply more force to the center of the caul than physically possible.


Sorry , but I understand how they work.

Sorry , but Rick your arrogant..


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## Rick Christopherson (Jun 27, 2016)

Rebelwork said:


> Sorry , but I understand how they work.


I wasn't being snarky. Most woodworkers didn't (don't) understand them, especially because Craig repeatedly mistated the information.


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## Rick Christopherson (Jun 27, 2016)

Rick Christopherson said:


> I wasn't being snarky. Most woodworkers didn't (don't) understand them, especially because Craig repeatedly mistated the information.


Actually, and more importantly, Craig refused to state the caul's clamp-force rating, nor even measure it. That is to say; each caul has a specified clamping force based on its length and curvature, and that caul cannot apply any greater force beyond just a flat stick of wood.


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## Rebelwork (Jan 15, 2012)

I’ll look through my stock later today and decide how I want to make my “BowClamps” should be fun..

I’ll have to see what router bits I have And check my clamps to the bit.


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## Half Fast Eddie (Jan 12, 2022)

woodnthings said:


> Because not every one is familiar!
> .
> They are named after the guy who invented them which is not widely known.


Agree with #1. 
#2 … was his name Bow? or Caul?


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## Rebelwork (Jan 15, 2012)

Half Fast Eddie said:


> Agree with #1.
> #2 … was his name Bow? or Caul?


#1 is meaning less.

“Anybody actually made authentic/lookalike Bowclamps? Based on the original design?”

If you didn’t know what it was, you couldn’t have made them based on the original design.

looking at the question, there has been no answers so far,.


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## Rick Christopherson (Jun 27, 2016)

Rebelwork said:


> Sorry , but I understand how they work.
> 
> Sorry , but Rick your arrogant..


Whoa, I didn't see your edit until now. Who pissed in your cornflakes this morning? And by the way, if you're going to try to insult me, at least get your grammar correct: it's "you're arrogant" not "your arrogant". 🤣


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## Rebelwork (Jan 15, 2012)

Move on..


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## Rebelwork (Jan 15, 2012)

This topic is dead, close it..


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## Rick Christopherson (Jun 27, 2016)

Rebelwork said:


> Move on..


I got no problem with you, but apparently you are harboring some sort of long lost grudge like a teenage girl. I have the memory of a goldfish when it comes to past grudges; so if you can't get over yours, just keep it to yourself.


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## Rebelwork (Jan 15, 2012)

Move on Rick… You’ve already killed the topic..


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## Dave McCann (Jun 21, 2020)

Dave McCann said:


> Yes, to your 1st question.





Rebelwork said:


> looking at the question, there has been no answers so far,.


??? did you miss post #11?


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## Rebelwork (Jan 15, 2012)

Dave McCann said:


> ??? did you miss post #11?


What were the results Dave?


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## woodnthings (Jan 24, 2009)

Rick Christopherson said:


> This was the major failing of his marketing campaign, because he kept claiming the clamps would apply more force to the center of the caul than physically possible.


Once the ends touch the surface and caul has been bent flat, that's the end of the clamping pressure, it's maxed out.
The "grooves" as Rebelworks calls them, are actually "T" slots which make the caul more flexible, and less resistant to bending because material has been removed from the section.
You can't have a meaningful discussion with someone who has their mind made up ... "not the fact that I am right' .....
They are not looking for answers here, clearly.


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## Rebelwork (Jan 15, 2012)

I’m not looking to force a board straight. Just keep thing aligned..


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## Dave McCann (Jun 21, 2020)

Rebelwork said:


> What were the results Dave?


The results were 10 or 12 completed sets of "bow clamps", I don't remember the exact number. What more are you asking? I don't have a copy of the CNC program I wrote to mill the arc.


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## Rebelwork (Jan 15, 2012)

Didn’t care about the program. Did you use maple or something else? You mention if they worked.


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## woodnthings (Jan 24, 2009)

The video explains this, but for those who can't or won't watch it, here's how they need to be used:
Use them in pairs, one on the top the other on the bottom of the surface.
That way the curves oppose each other, You can't use just one because the workpiece may take the shape of the curved caul aka, Bowclamp.
As you tighten the clamps at the ends, the pressure starts at the center then travels outward to the ends, finally being "maxed out".
If you use only one, then as the video explains, you need a workbench stiff enough to clamp on, that will not flex under the pressure.
Straight cauls which are used more commonly, can also be used to keep boards aligned.
Boards that are not flat to start with, need to be saved for other projects, not table tops.
Cauls will NOT flatten a cupped board!


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## Rebelwork (Jan 15, 2012)

We used cauls to straighten bowed boards On large glue ups. Pretty common on 36x144 and large tops..

Even glue wheels have metal cauls..

Even a RF press uses a simulated caul to flatten


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## Half Fast Eddie (Jan 12, 2022)

Rebelwork said:


> #1 is meaning less.
> 
> “Anybody actually made authentic/lookalike Bowclamps? Based on the original design?”
> 
> ...


Why is #1 meaningless? There are at least 2 people here who admit to not recognizing the term bow clamp. 
And you said it was named after the inventor. If it’s called a bow clamp or caul … then his name must have been … ?


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## Rebelwork (Jan 15, 2012)

Half Fast Eddie said:


> Why is #1 meaningless? There are at least 2 people here who admit to not recognizing the term bow clamp.
> And you said it was named after the inventor. If it’s called a bow clamp or caul … then his name must have been … ?


Question #1..
Answer #11


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## Rebelwork (Jan 15, 2012)

Dave McCann said:


> ??? did you miss post #11?


thx Dave for your reply..


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## builtinbkyn2 (3 mo ago)

Cauls do not require the extreme curvature those Bowclamps have, to be effective. There's a ton of info on how to make them on the internet. I've made them in the past from scrap using a hand plane. You just need to take a few shavings off of each end for them to keep a glue-up flat.


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## builtinbkyn2 (3 mo ago)

How to make clamping cauls


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## woodnthings (Jan 24, 2009)

builtinbkyn2 said:


> Cauls do not require the extreme curvature those Bowclamps have, to be effective. There's a ton of info on how to make them on the internet. I've made them in the past from scrap using a hand plane. You just need to take a few shavings off of each end for them to keep a glue-up flat.


Agreed!


builtinbkyn2 said:


> How to make clamping cauls


Great source!

Thanks to the folks who posted useful information and good tips.
No Thanks for all the bickering and blather.


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## Rebelwork (Jan 15, 2012)

Making cauls was not the question..

BowClamp was the question

“Anybody actually made authentic/lookalike Bowclamps? Based on the original design?”

Thx to those who tried to help with BowClamp..


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## Dave McCann (Jun 21, 2020)

I concluded once before, that it wasn't worth anyone's effort to even respond to Rebelwork. This thread has confirmed that it's a wasted effort.


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## Rebelwork (Jan 15, 2012)

Gotta stay on track.


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## Rebelwork (Jan 15, 2012)

Dave McCann said:


> I concluded once before, that it wasn't worth anyone's effort to even respond to Rebelwork. This thread has confirmed that it's a wasted effort.


“Didn’t care about the program. Did you use maple or something else? You mention if they worked?”

Dave had no reply..

No facts..

”Anybody actually made authentic/lookalike Bowclamps? Based on the original design?”

A lot of dancing around the question without answers..


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## Rick Christopherson (Jun 27, 2016)

Rebelwork said:


> *Making cauls was not the question*..
> 
> BowClamp was the question
> 
> “*Anybody actually made* authe...


If you don't know what you want, how the heck do you expect anyone else to know either?


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## Rebelwork (Jan 15, 2012)

“Anybody actually made authentic/lookalike Bowclamps? Based on the original design?”


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## Rick Christopherson (Jun 27, 2016)

Rebelwork said:


> “Anybody actually made authentic/lookalike Bowclamps? Based on the original *design*?”


Design? There was no design. If you missed it, the very first thing I said in this thread is that Craig didn't have a technical bone in his body. He didn't design anything. They weren't magical. They were curved cauls with a T-slot (as Woodenthings described).


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## Rebelwork (Jan 15, 2012)

“Anybody actually made authentic/lookalike Bowclamps? Based on the original design?”


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## woodnthings (Jan 24, 2009)

Dave McCann said:


> I concluded once before, that it wasn't worth anyone's effort to even respond to Rebelwork. This thread has confirmed that it's a wasted effort.


Yep.
A closed mind is like a closed book, there's no information transferred. If you already have all the answers, why ask the question?
A forum is a means to exchange ideas and opinions, and ask questions. It should be "an open exchange".


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## Rebelwork (Jan 15, 2012)

“Anybody actually made authentic/lookalike Bowclamps? Based on the original design?”


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## Half Fast Eddie (Jan 12, 2022)

Rebelwork said:


> “Anybody actually made authentic/lookalike Bowclamps? Based on the original design?”


You are really determined to make an ass of yourself, aren't you.


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## Half Fast Eddie (Jan 12, 2022)

Half Fast Eddie said:


> You are really determined to make an ass of yourself, aren't you.


Here … i’ll save you the effort …
“Anybody actually made authentic/lookalike Bowclamps? Based on the original design?”


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## Rick Christopherson (Jun 27, 2016)

My shocked face...









🤣 🤣 🤣 🤣


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## Rebelwork (Jan 15, 2012)

You can choose to argue, but you’ll have to do it with each other..

Nothing here to learn..


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## Biotec (Mar 14, 2021)

@Rebelwork asked this question in june 18 2021 also








Bowclamp


Didn't the guy who created the Bowclamps use to come on this forum?




www.woodworkingtalk.com










BowClamp Review


BowClamp Review



www.festoolownersgroup.com




from 2013
The Bowclamps are made of solid maple and are CNCed to have the perfect curvature

I have had the Bowclamp Master Set for about a week now and have become pretty familiar with them. In order to review them I have built a standard wall cabinet. I found them helpful in carcass assembly, FF to carcass assembly, and edge banding. I will go over all of these procedures in this review. There are other things that the Bowclamp can do, such as gluing up panels and laminations. In the next week i will be posting about using the MFT, shims and Bowclamps to clamp, without clamps. I will also post back on some more complicated glue ups.

The Bowclamp Master Set comes with two 2', two 3', and two 4' cauls and can be found at http://www.bowclamp.com/
You can also buy single cauls or pairs. The Bowclamp has a leather strap which makes it great for hanging from the wall and doesnt take up much space. The Master Set would suffice for all the procedures i will go over, although I can already tell that for some complicated FF to carcass assemblies more would be better. Specifically if your project had mid rails where more then two pieces of the same size caul would be needed.

The Bowclamps are made of solid maple and are CNCed to have the perfect curvature. The curvature allows perfect glue squeeze out and maximum force/pressure, so while you could make these on your own, you are not going to be able to achieve that degree of accuracy. There is a groove that will accept light or medium duty F style clamps and that could greatly help the ease of use, but since i didnt have any of those, I will use Jorgenson 3/4 Pony clamps for the entire review. Virtually any clamp can be used with the Bowclamps. The Ponys worked great. Bessey Parallel clamps were significantly fussier to deal with, but I fully blame the clamp and not the cauls. The beauty of the Bowclamps is that you can acheive your clamping goals with less clamps. Now that I have a 4x8 dedicated assembly table, I want to glue as many cabs as i can at once, but I only have so many clamps. In comes the Bowclamps. My favorite procedure they assist with is the FF to carcass assembly. Usually a task that takes every clamp in the shop. With four Bowclamps and eight clamps you can attach most any size FF. Instead of having clamps every six inches you just need one Bowclamp and two clamps and you can achieve the same results over a four foot span. For me the beauty is now i have extra clamps freed up to work on other cabs, which equals less wasted time and more money in your pocket.

For the carcasses, I dominoed everything as normal. The first pic shows all of my parts, clamps, Bowclamps, and glue all readily available. I start with the base panel and work up around the back. The top slides in and then i snugged up the bottom, snugged up the top, checked everything and then cranked it home. The carcass was very square right away. The glue squeeze out is remarkably uniform.


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## FrankC (Aug 24, 2012)

Rebelwork said:


> Anybody actually made authentic/lookalike Bowclamps? Based on the original design?


Seems like a simple yes or no type of question to me.


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## Scurvy (Apr 12, 2013)

FrankC said:


> Seems like a simple yes or no type of question to me.


Answered by Christopherson in the first dozen posts.

Rebelwork: Please quit being so belligerent. Because this is a public forum, the discussions seek out and get a bunch of various answers and the topics will take twists and turns that satisfy OTHER PEOPLE’s interests. This is the part you keep missing. Even though you were the OP, the threads will evolve and expand as we all SHARE in the discussion, so accept that or don’t participate. It is not all about you.

Christopherson did answer your question, he made a dozen or so prototypes. If you are so familiar with cauls and really understand them, then you must grasp that the Bow Clamps are simply cauls with a T-slot, and you can simply fab some up yourself without any guidance because you understand everything about cauls, right? If not, then go buy a set and figure it out for yourself so you can make as many as you want.


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## Rebelwork (Jan 15, 2012)

Didn’t answer any question.He just complained about the product.. One person said they made BowClamps but has no information to add.

As mentioned you either have or haven’t.

FrankC explained it simply..”Seems like a simple yes or no type of question to me.”

I will to make my own BowClamps. At this point I’ll learn the information first hand.


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## Rick Christopherson (Jun 27, 2016)

Rebelwork said:


> He just complained about the product..


Show me where I complained about the product. You have such a huge chip on your shoulder that you immediately get defensive without comprehending what is written. And for the record, it did answer the question(s), because it relates directly to the "design" of the caul.


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## Half Fast Eddie (Jan 12, 2022)

Nice try scurvy. Unfortunately you too failed to meet the goals of the hidden agenda.


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## Scurvy (Apr 12, 2013)

This would need to be confirmed by some of the engineers here, but one of the misleading parts of the infomercial was that a single pair of clamps would be sufficient for clamping (anything). But the physics are pretty basic: Each clamp can develop a certain clamping pressure, which is expressed as PSI (pounds per square inch, which is the screw force spread over the area of the clamp foot), and that force will stay the same, but the pressure goes up or down depending on the area of the foot or caul.

In the case of these cauls, if each Jorgensen clamp can generate ~600psi, then 2 clamps will generate 1,200psi total that gets divided up by the total square inches of the caul surface area that is in contact with the workpiece. If the clamps are spaced 12” apart, then the force at any one square inch of a perfectly, uniformly loaded caul will have 100psi applied to the workpiece. A 4-foot caul will have 25psi.

So, in "saving” the number of needed clamps by using the cauls, what is gained is a uniformly applied pressure that is also uniformly reduced as the clamped area is increased. The question is, “Will that pressure be enough for the task?” The cauls won’t magically create stronger clamping pressures.


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## Jar944_2 (Oct 30, 2020)

No t slot, but since they are made when under tension they should be more uniform than the "bowclamp" you can also adjust make them more or less exert more or less force in the center by adjusting the curve. 

They also only take a minute or so to make so there's that...


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## Rebelwork (Jan 15, 2012)

Hopefully I get the chance to pick out some material for some BowClamps. Think I’m going to have to layer them…

First things first. gotta get the dust collector cleaned out today


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