# Make your own panel cauls.



## derek willis (Jan 21, 2009)

here is an idea that was given to me and which I made.
I found them very useful indeeed!
Adjustable Panel Cauls, Derek.


When gluing up a solid-wood panel, one of the challenges is keeping it flat while the clamps are tightened down. For a long time, my solution to this problem was to clamp cauls across the panel. But on too many occasions this "jury rig" method turned out to be awkward and generally unsatisfactory. So I determined to come up with an improvement. 

The result is the set of adjustable panel cauls you see at work in the photo above. The construction details are shown in the drawings below. Each caul consists of two hardwood "beams" that sandwich the panel. A slot running down the middle of each beam accommodates the adjustable clamping mechanism that connects the two beams. This is simply a carriage bolt that passes through a foot and is tightened down with a large, plastic wing nut.


----------



## xplorx4 (Dec 1, 2008)

That is a good idea, do you use something to keep your cauls from getting glued by squeezed out glue? I can't seem t see it in the pic.


----------



## derek willis (Jan 21, 2009)

I keep some cling film in the workshop and use that when ever there is a chance of sticking to some other product.
Derek.


----------



## harrysin (Jan 15, 2007)

A first class idea Derek, one that I could have used on countless occasions in my younger furniture making days.


----------



## gregW (Mar 14, 2007)

Thanks Derek, that's a great idea...Its funny how a lot of times the simplest jigs and fixtures turn out to be the most useful!


----------



## bobj3 (Jan 17, 2006)

Hi derek

That's neat  how about a snapshot of yours ? ?

===



derek willis said:


> here is an idea that was given to me and which I made.
> I found them very useful indeeed!
> Adjustable Panel Cauls, Derek.
> 
> ...


----------



## waynoe (Sep 29, 2004)

Hey guys
The easiest way to stop the glue from sticking is in the kitchen. Steal the wife's wax paper. I have been doing it for years and she still hasn't figured it out.


----------



## a1tomo (Dec 3, 2008)

Good idea Derek thanks for sharing, and Wayne, shame on you!


----------



## derek willis (Jan 21, 2009)

I'll take a pic.and post it, maybe tomorrow.
Derek.


----------



## downhill (Nov 21, 2008)

Great idea! Thanks for sharing.


----------



## derek willis (Jan 21, 2009)

*cauls*

Here is a picture of my cauls.
Derek.


----------



## jw2170 (Jan 24, 2008)

Hi Derek,

just one question...

Are the cauls flat or tapered slightly?

James


----------



## derek willis (Jan 21, 2009)

J W 2170.
The answer is FLAT!
Derek.


----------



## harrysin (Jan 15, 2007)

Bj, does Derek get an apology from you for the implication that HE hadn't actually made one?


----------



## derek willis (Jan 21, 2009)

Good on ya Harry, that's what I thought.
Derek.


----------



## Mike (Nov 22, 2004)

Tomorrow I am thawing the garage, it has been around 20ºF inside but with the heaters running it will be short sleeves and a cold drink time. I think this is an item I will see about building, with a slight modification. A strip of UHMW on the inside edges of the cauls would eliminate any worry about glue sticking. I will make provision for these to be added later. This should make gluing panels a bit easier.


----------



## Gene Howe (Jul 10, 2007)

For panel cauls, I use paired pieces of Uni-Strut. By using Uni-Strut's spring loaded nuts and purchased bolts, There are no clamps needed. Uni-Strut is extremely rigid and does not bend or bow making it ideal for cauls. Plus, Uni-Strut is powder coated and glue won't stick to them. The down side is their weight.


----------



## harrysin (Jan 15, 2007)

I await the results with baited breath Mike.


----------



## mailee (Nov 11, 2005)

I use a set of cauls made out of box section mdf and stop them sticking with a strip of gaffa or duct tape. I just remove the tape afterwards and renew it for a fresh face again.


----------



## derek willis (Jan 21, 2009)

A lot of good ideas and modifications for these, I passed the idea on to a mate of mine, he made some out of box section steel which turned out to be very good, as long as he protects the timber from the steel, especially Oak, turns black.
Derek.


----------



## Mike (Nov 22, 2004)

Well the temperature finally got back into the 40's yesterday and the annual garage clean up is under way. I built a pair of the clamping cauls from aspen with poplar spacers and feet. I would suggest changing one thing on the plan, it calls for 5" carriage bolts and this barely allows for 1" materials to be inserted. I am replacing mine with 6" carriage bolts to allow for easier set ups. I used fender washers and knobs from Rockler. I still plan to add the UHMW strips later so glue won't stick to them. Here is a photo of one of them with some pen blanks inside since I didn't have anything cut to glue. My cost to build was about $20 for the pair.


----------



## petersenj20 (Aug 6, 2006)

Hey derrick. I'm enjoying watching this post. I observe you bring a lot to the table (May ruffle a few feather here). I've seen the jigs you been postin and will make a few on the tool making list.

You're avatar picture looks just like my neighbor (But I won't hold that against you, Oxfordshire is English for Douglasville)


----------



## derek willis (Jan 21, 2009)

Peterson,
I'm pleased you like the jigs, I have more and will post as and when I can.
Derek.


----------



## harrysin (Jan 15, 2007)

Well Mike, it took 10 days for the weather to warm up and now that it has don't stop with the cauls, keep going, there are heaps of projects in your pipeline and don't forget the pictures.


----------



## Mike (Nov 22, 2004)

The clamping cauls are really useful when working with items that have critical alignment like the walnut image that BJ made with his CompuCarve of Sue and I. The wood split down the center and the irregular thickness of the piece would have been very difficult to align with out the caul. I use wax paper secured with push pins to prevent the glue from sticking to the cauls. Now I have to do some fine touch up with a rotary tool to remove the glue squeeze out.


----------



## dutchman 46 (May 23, 2007)

Great set-up! I like it. My Father used to cut His own beef . He has been gone for 40 years, but I found a bunch of wax paper, Works well also. and i can normaly reuse it for smaller glue-ups! As much as I got, It should last for 30 more!


----------



## prgl7 (Jun 26, 2011)

I am new to using cauls, but in the past I have seen some with a slight curve to the side that clamps to the wood. Is that just a preference or is there a reason for it? Does the flat perform better? how do you keep from bending the cauls accidentally by over tightening?
George


----------



## Mike (Nov 22, 2004)

George, the single biggest mistake people make when gluing and clamping is to over tighten the clamps. The theory behind the curved cauls is that there is increased pressure in the center where no clamp is applying pressure and it works very well. I use these cauls for alignment and there is no need for increased pressure. In the photo below I used the cut offs from the rockers as cauls to clamp the glue ups.


----------



## Roger Leclercq (Jan 28, 2009)

xplorx4 said:


> That is a good idea, do you use something to keep your cauls from getting glued by squeezed out glue? I can't seem t see it in the pic.


I would wax the cauls that should keep them from sticking


----------



## bobj3 (Jan 17, 2006)

Hi

I made my set out of Baltic Plywood and put on some edge banding on them, it's easy to wipe it right off with a wet rag,most glues will not stick to plastic/vinyl edge banding ..the plywood is much stronger than the normal wood if you use on edge..( 3" wide plywood by 3ft long.). and I use threaded rod and knobs and tee nuts) in that way no router slots are needed..and it's easy to store them when I don't need them..

===


----------



## Mosti (May 17, 2011)

cant they be removed once the clamps are in place or not? it will help remove the glue problem and they can be shifted to the next job no??


----------



## Mike (Nov 22, 2004)

Joesph, you are better off leaving them on the project until the glue is dry. That way you know the wood won't shift.


----------



## bobj3 (Jan 17, 2006)

For Mike
Sorry I don't have the picture anymore but here are some files.

see files below

Dang server will not take my file will try later 
===


----------



## douce1949 (Oct 7, 2011)

Good idea. I will try it my self. Thanks


----------



## GulfcoastGuy (Feb 27, 2012)

Mike said:


> George, the single biggest mistake people make when gluing and clamping is to over tighten the clamps. The theory behind the curved cauls is that there is increased pressure in the center where no clamp is applying pressure and it works very well. I use these cauls for alignment and there is no need for increased pressure. In the photo below I used the cut offs from the rockers as cauls to clamp the glue ups.


Is there a rule of thumb for the amount of curve?

GCG


----------



## GulfcoastGuy (Feb 27, 2012)

GulfcoastGuy said:


> Is there a rule of thumb for the amount of curve?
> 
> GCG


 Found an answer on the Fine Woodworking site.










GCG


----------



## olwudwurker (Mar 16, 2011)

Thanks Derek. Great idea. Roy


----------



## Matador58 (Jan 28, 2012)

Hi Derek ,

Thanks for sharing the home made jig .
Very simple jig that will make jobs easier .
When I get time I will try to make one .

Cheers Graham .


----------



## jlk103144 (Mar 26, 2012)

I'm glad I located this thread. Last week I was contemplating how I was going to make a veneer press, instead of going whole hog on a vacuum press. And while surfing around, looking for answers, I came across the BowClamp. I had seen these a few years ago, but forgot about them. 

Like all self-respecting do-it-yourselfers I began thinking of how to make a set out of regular lumber, and put only some time into it. I realized that to get a good and even pressure, I would have to find a way to make the curve as smooth as possible. But unfortunately I don't have anything like a computerized machine like the BowClamp people do. 

The best solution I could come up with was to make a cut as accurate as humanly possible, and then use a metal strip to act as a smooth guide for passing a router along the curve. 

I went to Lowes, looking for a long section of thin steel, about 1/2" wide. But there wasn't any there that was longer than four feet, so I had to settle for aluminum. I also picked up a new 1" Bosch 'flush trim' bit with the bearing on top. Also, four premium grade 2"x4" boards went with the purchase. 

After taking them home, O found a spare piece of 3/4" plywood, and ripped it down to something like 3.5". The length of the plywood was 51" in order to allow for some place to screw down the metal strip. By placing screws into the plywood, I was able to make the curve I wanted. Then I just took a pencil and marked the entire length of the outer curve. 



Then to the detail part. Back in the late 70s I used to be in commercial construction management, and had been exposed to the reverse tooth jig saw blade. And since then that's all I ever use anymore. With the reverse tooth blade, I was able to make a pretty close cut along the pencil line. When finished I just passed a belt sander to rough out any glaring mistakes. I used fine sandpaper and only made a couple of quick passes. 





Then I cut the metal down to the 51 inches and drilled a countersink hole into the aluminum. When I placed the aluminum around the hand drilled curve, and screwed it down, I had about as good a curve possible. Then I just used the plywood template on top and ran the router along the template. I had to be careful because the wood was easy to tear out if I went too fast. 







My mistake was that I only used a 1" trim bit, when a 1 1/2" bit would have allowed me to make just one pass per board. But Lowes did not have one available, and I didn't want to wait for it to come in the mail. 

On the picture above, the left board was the trial shot, and next I did six cauls. For the picture I forgot to go retrieve the sixth one from the back deck. Sorry about that. 

Even with a trim bit, it is virtually impossible to make a cut, and then use that cut as the template, and have them both come out perfect. So I had to sightly sand off any imperfections. 

Then I changed out my table saw blade for a dado set and cut a 3/4" dado, 1/2" deep, which was centered on the board. My metal wood clamps fit neatly into the dado cut. After doing that, I just lightly sanded off any loose shavings, and applied a pair to a sample, just to see if the cauls could evenly clamp it and not explode on me. And they didn't. Here is a pair of them clamped down.





Today I released the first two cauls and tried a second pair. They also worked, but there was a knot at the top of one, and it split. However, other than the small split, it is still hanging in there. 




But now that I have seen this alternate caul, I have already been thinking about how to incorporate both systems into one and have an even better one to boot. I am so happy to have found this thread, that I just had to give my recent experience, and do my best to come up with bringing in the best of both alternatives. And I believe I can get a set up and running when I get back from visiting my daughter this weekend. I also have a big job I need to have finished by next Thursday, but I'll try to make a combination caul as soon as possible.

What do you all think? Is it worth it? 

Thanks for your time, and sorry about the poor quality of pictures, but I was in a bit of a hurry and didn't use my tripod. Shame on me.


Oh, I almost forgot: Before running the dado cuts I cut off one inch from the height of the cauls. That made it a bit easier to tighten down.


----------



## Trickshot (Apr 13, 2012)

Great jig thanks for posting


----------



## jlk103144 (Mar 26, 2012)

I'm still trying to figure out how to incorporate Derek's example, found in Woodsmith/ShopNotes that can be as inexpensive as the ones I made in the pictures above. So far the difference in cost between poplar and spruce is so little that I would go with poplar and pay the added cost. 

But I was just walking around Lowes the other day, with my head in the clouds, and came across some wide 3/4" panels of spruce/pine that had been pieced together in order to make one large wide countertop. I'm thinking that it may be possible for me to take one and rip them into 2 1/2" - 3" strips and then route a slight curve on one side of the rip. 

If they are glued correctly, they should work just as well as a solid long board, because the glue is stronger than the wood, and under pressure it will not break open. But I haven't done a total cost figure on doing it that way. 

Incidentally, I managed to make the bowclamp knock-offs above work by doing test clamps and leaving them tight for over a week. They work fine, with only one exception. Where a knot appeared on the surface edge of the side that has been dadoed, a crack has appeared in, or around the knot. Two of the cauls have a small crack, but the other four are perfect, as there are no knots on the upper edge. 

I examined them closely, and if a knot is close to the edge, but regular grain, on the edge, is even 1/4", there is no crack. I am thinking that the cauls with the tiny cracks will not be affected enough to either break, or change the pressure being applied to the entire length of the caul. 

Either way, the bowclamp knock-offs are very inexpensive, and cost less than $2 per caul. Of course I didn't factor in time and labor making them. And if you make a bunch at once, making them will go even faster, because the metal faced sample, dado blades, and router are already set up.

But I just like the idea of having adjustable cauls, which will cost a bit more in materials. I just haven't figured how to make them as dirt cheap as the bowclamp knock-offs.


----------



## Roloff (Jan 30, 2009)

Wow! That looks like a good solution, elegant even. THANKS - I'm going to save the suggestion for future use.


----------



## GulfcoastGuy (Feb 27, 2012)

Found this. Looks like it would produce the correct curve shape to distribute pressure properly.










... and the link ...

Making Curved Cauls *PIC*

GCG


----------



## jlk103144 (Mar 26, 2012)

What he is saying is good and makes sense. However, making the proper cut, i.e. planing off the wood to achieve this, needs to be taken one step further.

Once you have drawn the "line parallel to the benchtop across the caul at the height of the top of the shim", you can attach the flexed aluminum strip I picture above, right here. This allows you to take your router, and the appropriate length bit, and evenly trim off the excess wood. 

I have been using a 1" length bit, but intend to go with one that is over 1 1/2" in the future. That way I can make just pass of a 2" x 4". When you have the bit, and the 1/4" aluminum strip, it is quite easy to do, and then its done. 

The real question though is this: just how thick should the shim be, which is used in the center of the board? It looks like a variable judgement call to me, because some people want to put more pressure than others. With more pressure, the curve of the cawl, or the thickness of the cawl make it variable. 

Nothing is perfect, unless each cawl is made specifically for each job, and that really isn't practical unless you have an unlimited wallet, or unlimited time.


----------



## TRN_Diesel (Feb 24, 2009)

jlk103144 said:


> I'm glad I located this thread. Last week I was contemplating how I was going to make a veneer press, instead of going whole hog on a vacuum press. And while surfing around, looking for answers, I came across the BowClamp. I had seen these a few years ago, but forgot about them.
> 
> Like all self-respecting do-it-yourselfers I began thinking of how to make a set out of regular lumber, and put only some time into it. I realized that to get a good and even pressure, I would have to find a way to make the curve as smooth as possible. But unfortunately I don't have anything like a computerized machine like the BowClamp people do.
> 
> ...


Your idea is great to use a metal strip to create your arc but there is an easier way. it is called a "Flaring Stick". The flaring stick is adjustable and easy to make. It allows you to create the arc to your liking.

Here is a link to show you how to make one:

Fairing Stick

P.S.
I still need to make one for myself and when I do I will post the results.


----------



## jlk103144 (Mar 26, 2012)

TRN_Diesel said:


> Your idea is great to use a metal strip to create your arc but there is an easier way. it is called a "Flaring Stick". The flaring stick is adjustable and easy to make. It allows you to create the arc to your liking.
> 
> Here is a link to show you how to make one:
> 
> ...


The reason why I used a metal strip for making the arch was really two fold. With the flaring stick, I could have easily used it to draw my arch. But I couldn't have used it as a means of running an even cut with my router's flush trim bit. By using metal, I made it much easier to repeat with several cuts/cauls. 

After using the metal strip, I had to hand cut the arch with my jig saw, which is never perfect. I'm pretty good with a down stroke blade, but not that good. So after making my template, I then took the metal strip, drilled recessed holes into the strip and screwed it to the template edge. 

Then I just clamped the template to each 2 x 4 and the ran the trim bit across the wood, with the bearing guide rotating along the metal strip. That way there would be no wear and tear on the wooden template. Had I used a wooden strip, it may not have been solid enough to keep the bearing perfect each time I made my pass. 

Do you see what I mean here?


----------



## TRN_Diesel (Feb 24, 2009)

Ok now I see what you mean. You did not want the template to wear so hence the metal strip and not a piece of 1/4" hardboard. 

I use a system called "The Coper" to cut or cope my base boards with my router when finishing, I had the same problem so I used plexi glass so it would not wear for the bearing guide to run along.


----------



## 4aggies (Sep 11, 2010)

Thanks!


----------



## Greg60525 (Jan 9, 2014)

Does it matter much if the cauls are made with a curve or a linear taper? Would the clamping pressure be even with a taper?

Is there a formula to determine the optimal curve?

I'm thinking of building some and using them to clamp up a router table top (2) 3/4" sheets of MDF. Because I don't have a sufficiently large flat work surface to clamp the panels to, I am thinking of putting cauls on the top and bottom to sandwich the panels (maybe 3 or 4 sets across the width).........I saw this on a Woodcraft video of the BowClamp. Do you see anything wrong doing this? I'm concerned that because these will be homemade cauls that the clamping force between the top and bottom or from side to side may not be perfectly uniform and cause a warp or potato chip. 

Thanks,
Greg


----------



## TRN_Diesel (Feb 24, 2009)

Greg60525 said:


> Does it matter much if the cauls are made with a curve or a linear taper? Would the clamping pressure be even with a taper?
> 
> Is there a formula to determine the optimal curve?
> 
> ...


Greg

You stated your using MDF for your router table top. I just finished doing a face frame clamping station on the right side of my table saw. I used 3/4" Baltic Birch plywood and made the top with three sheets for added strength. To join the three layers of plywood I used contact cement. I applied the contact cement using a foam 4" roller. The trick is to make sure you apply two coats to ensure the two pieces stick to one another. It will take about 15 minutes to dry in between coats. Once you have both surfaces covered with contact cement and it is dry to the touch you can join them together. To test it you can use a piece of paper to see if it sticks to the surface, if it does you need to wait a bit more because it should not stick. 

I ended up cutting the top to size and then the second layer I cut oversize by an 1/8". (this will give you a 1/16" reveal) Prior to joining the two pieces place some wooden dowels (4) across the second sheet and then place the top sheet on top of the dowels. Next line up the sheets so you have a 1/16" reveal all the way around. Start at one end and remove the first dowel. As soon as the surfaces touch they will bond so make sure you are lined up correctly. Continue working working your way across the sheet till all the dowels are removed. Use a laminate roller and a wooden block and hammer to ensure you have a good bond (tap the block of wood using the hammer).

Once your satisfied the two sheets are together you can insert a flush bit trim in the router. Reference the bearing on the top sheet you cut to size and the second sheet will be trimmed to match the first sheet. I did this with my top for three sheets and it worked great. I have a router table so I use the flush trim bit on the table.

Using this method you will not require the use of cauls because MDF is very stable and flat. If you follow what I have outlined above you will have no problems. I will post my project sometime this week so you can see how I did it.

Good luck and enjoy your build.!


----------



## Greg60525 (Jan 9, 2014)

Dan,

Thanks for the detailed top construction. I'll have to rethink the yellow glue vs contact cement approach. Because the contact cement is so thin and the bond is instant cauls are not needed to get squeeze-out........nothing to squeeze out!

Thanks again,

Greg


----------



## BCK (Feb 23, 2014)

I have just started a kitchen reface and will be building doors soon...something like this will be part of this new adventure now...thx for the post...


----------



## jimdouglas (Feb 24, 2014)

Nice shop project. I think i'll need more than one pair. Like clamps, you never have enough. :laugh:


----------



## rrrun (Jun 17, 2014)

Great discussion & post ... but I'm going to be contrary.

I use 8" clamps and a pair of scrap 8/4 oak boards that I've flattened. Put packing tape on the boards to repel the glue ... and I'm done. I have the clamps, I have the boards, and I'm not storing another jig.

Why should I build these cauls again? Why are they better?


----------



## jlk103144 (Mar 26, 2012)

You all will have to pardon me, but last year Webshots, where I kept most of my pictures for use in forums, disappeared. The Webshots folks sold out to someone else, and in the process of reorganizing things, they scrambled everything into a complete mess. Needless to say, all of the pictures I used here were lost. 

I went to my post here, and confirmed it. So I will have to completely move the pictures, rearrange them, and then repost them here. 

If anyone wants me to repost them, just say so, and I will try to get them up and running once more. Or better yet, I'll try to add them to the forum itself.

Sorry for the inconvenience.


----------



## Aquaman (Feb 7, 2015)

Great idea Derek! Could have used those many times in the past....


----------



## Jimwarren (Jan 13, 2015)

Thank you. Derek super I just loved it


----------



## rbs (Jan 6, 2009)

great idea for my kitchen door build in the future. thanks!


----------



## jlk103144 (Mar 26, 2012)

rbs said:


> great idea for my kitchen door build in the future. thanks!


Here's something else. I saw a woodworker on one of the magazine sites, who stated that he uses his bent/warped lumber to make cawls. It really made good sense, and was a whole lot easier than what I had originally done. I still have my original ones, but now have others that are over 60 inches. And I made them from warped lumber. 

If you don't have any warped 1x6 boards, you can take some that are currently straight, and then rip them right down the middle. Chances are that suddenly the straight board will no longer be straight any more. 

They aren't the prettiest things in the world, but they are easy and pretty quick to make. The one on the right has a warp, and that is my fault. I somehow put it together and forgot to have both pieces either facing each other, or facing away, warp wise. But it still works as well as the other two. 

The bolts are 3/8" x 8", and work on glue jobs up to 1 1/2" thick. If the glued product has to be thicker, just substitute the 8" bolts with 10" ones. No special planing required. Just let nature do all the hard work for you.

http://www.routerforums.com/attachment.php?attachmentid=103506&stc=1&d=1427481990


----------



## rbs (Jan 6, 2009)

Good idea, always plenty of warped stock around


----------



## john60 (Aug 30, 2014)

It looks like its time to get rid of the propane tank


----------



## jlk103144 (Mar 26, 2012)

john60 said:


> It looks like its time to get rid of the propane tank


----------



## Zerk (Jun 24, 2014)

Gene Howe said:


> For panel cauls, I use paired pieces of Uni-Strut. By using Uni-Strut's spring loaded nuts and purchased bolts, There are no clamps needed. Uni-Strut is extremely rigid and does not bend or bow making it ideal for cauls. Plus, Uni-Strut is powder coated and glue won't stick to them. The down side is their weight.


Interesting idea. Little more money, but easy.


----------



## Stick486 (Jan 4, 2013)

those I like... A lot...


----------



## vindaloo (May 30, 2009)

So do I, just made a pair and made my first 2 small panels with them. So Easy to use.


----------



## jlk103144 (Mar 26, 2012)

These are not specifically made to be cawls, but they could be used for gluing panels that are not wide. And too, they can be lengthened as the person wished. 

Right now, they are specifically used for keeping reclaimed boards straight. I just place a bunch of 1x4s that are several thick, by several wide, and then bolt down the restraints to keep them from warping on me before I need to use them. I do a lot of reclaiming of pallets, and I have access to all I can use. These things really come in handy. 

I have five of them, and can easily make more if needed. I can also make them longer to suit my taste. And they really do work great. I also have longer threaded bolts that I can use if I can't get enough slats in the clamps.


----------

