Cauls, curved or straight?

I have several panels to glue up on the project I just started (YES, I am woodworking again!!!! ) so I decided it was time to finally make a few sets of cauls. I plan to use them as clamping cauls as well as for holding a panel flat when gluing them up.

I am trying to decide if there is any disadvantage to cutting a bow or slight curve in them for flat panel glue ups? I can't see one but I have never used them except for once or twice to solve some problem and then I just what ever scrap I could find.

I prefer to have the cauls taper from the center to the ends. I use a hand plane and cut the ends about 1/64 to 1/32 thinner than the center. The longer the caul, the more taper I use.

i tend to agree with tom and craig(bow clamp) that curved cauls are more usefull, but again.......it all depends what you`re doin`...

I am leaning toward curve/tapered. It makes more sense mechanically to me. But I also know enough to know I could be wrong.

Just taking the clamps off some I glued up. Going to joint the backsides (or is that top side?) and will probably plane a few down tonight. First I need to have a sharpening session. All my planes need touching up.

I finally got tired of looking for scraps a and stuff I could make a quick caul from and finally broke down and made a decent set. Best move I've made in a while. A decent set of cauls are one of those things that just always get put on the back burner and when you finally make a set you slap your self in the forehead and say "why didn't I do this a long time ago".

I made a set of 8 out of some 8/4 ash sitting around. I made them 2" X 2 1/2" X 30" figuring I'd use the cauls mostly for casework which is generally 24" wide and I'd still have an extra 3" on each side for off size stuff. I used the planner and a sled to taper them by shimming one end about 1/8". Make a pencil mark down the entire length and mark the center line to tell when you have 1/2 tapered, then flip them end for end and run them through again to taper the other end. A hand plane would work also, but I'm lazy and the sled did the job quick and they were all uniform. A 1/4" round over on all the edges helps eliminate scars from bumps and drops and makes them easier to handle. I also ran a 1/4" deep datto/groove down the center of the top the width of a bessey clamp head to help keep the clamp centered on the caul and making them easier to use. The groove makes them easier to work with, especially working alone. A good coat of paste wax keeps them from sticking to your project, DAMHIK

Mike

I got two set of 4 each glued up. a set of 36" and a set of 24". I finished the 36" set. I am wondering if I made a mistake though. I planned both ends and left a small flat in the center. Probably around 4" wide. I would think it would pull down just fine but then I have gotten to that point I am starting to wonder??

I rounded over the edges and waxed them. I was debating on cutting a dado but you just convinced me to do that. Tomorrow I will do the 24" set. By the time I got the blades sharpened and the cauls planned I was tired ad hungry. But I bet it didn't take two hours to make them. Add another hour tomorrow for the 24" set. I think it will be time well spent.

I just started the first Christmas present. I am building my sister the Chef, a wine (liquor) cabinet. It has 6 raised panels and I have to glue up each panel. The sides are frame and panel so that another glue up. I could see really quickly that it was time for some cauls!

Jeff,

The small flat in the center, will bow back the other way when tightend flat on the ends. This may or may not matter in your glue-up. It depends whether or not you need pressure everywhere along the length, or just some pressure in spots. Also don't add too much taper... if you can't flatten them against your workpiece using the available threads on your clamps (not as much as you might think )... they're basically firewood. Keep us posted.

Craig Feuerzeig said:

The small flat in the center, will bow back the other way when tightend flat on the ends. .......

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That was sort of what I was thinking might happen. Will clamp down a set tomorrow and see what happens.

... if you can't flatten them against your workpiece using the available threads on your clamps ... they're basically firewood.

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Naa, just hit them the No 5 a few times till they work.

Craig Feuerzeig said:

Jeff,

The small flat in the center, will bow back the other way when tightend flat on the ends. ....

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Your right (as if you didn't already know this ). I tried it with a piece of paper and it just slipped out of the center. So I planed them, waxed them and they are ready for some panel glue up today. I also decided to plane the back sides flat. That way they are two sided and I can use the flats for small holding small panels flat during glue ups.

Photos later. Anxious to try them and see what I want to do different. Like a dado in the ends or not?

Jeff Horton said:

I planned both ends and left a small flat in the center. Probably around 4" wide

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Jeff, I left about a 1 1/2" 2" or so in the middle also and tweaked them with the ROS. I placed 1" strips under them every 3" or so in the middle 12-18" or so and clamped them to the bench to test. If the paper pulled out I just hit it very lightly with the ROS in the center area until I had them right. Kinda PITA but it really didn't take that long, well worth the effort though. I cut the groove in the back of mine after I figured out the flat side didn't distribute pressure like the tapered sides. Try the strip of paper trick and you'll see what I mean.
Mike