Make Your Own Bow-Clamps Out of Scrap Wood for Free

by Dale on April 29, 2013

In a previous blog I explained why you need a dozen or so bowed clamping cauls. Here I am going to give easy instruction for how to make them:MB_one_4png

You will need some scrap 2 x 2 or 1 ½ x 2 or even ¾ x 2 and about 4’ long.  The 4’ width works for most tabletops and for anything smaller than four feet.

After jointing and planing, ripping these boards and cutting them all the same length. I mark the 4 sides. I the center of the length say at 2 feet. Then I mark another one all around at one foot, or ¼ of the length.

Next I decide which side I want to make the bow on and go to the jointer and taper joint it from about the center of the space between the one foot and two foot mark at about 18 inches from the end. Flip the caul and do the same taper cut from the other end. (Set jointer to take about 1/16” off)

Then I taper joint again starting at the 12” mark and off the end, flipping it around and doing the other side.MB_two

Now the last part, I taper joint again at about the 6” mark from the end and off the end, flip and do the other side or the caul. Now you have a rough curve on one side of the caul, but it has flat spots. To fair out the curve you could use a hand plane, but since I have an edge sander I just sand the bow into a nice curve on the sander.

This isn’t a perfect system and there are more accurate ways to achieve this, but for me the time saved by this method is worth the irregularities and I have about 50 of these that I made this way and they have served me well over the years.MB_Untitled-3

Cauls can get lots of glue on them. I kept the surface that touches the glue well waxed for years. Occasionally touching up the surface on the edge sander.

But about a year or two ago I cleaned them all on the edge sander making sure even the wax was sanded off. I put a run of ordinary packing tape on the bowed side.

Now I don’t have to mess with waxing them anymore. The tape lasts a lot better than I thought. It lasts well over a year even with almost daily use.MB_four

Also mark an arrow on the side pointing to the bowed side to make sure you always know which end is up.

Please leave me your comments and/or questions. I look forward to hearing from you.

{ 13 comments… read them below or add one }

Brent June 25, 2013 at 3:54 am

We used the caul’s described in this post as part of a class Dale is teaching for gluing up the top of our nightstands. I’ll be making some caul’s for myself when I get home as they worked great and I got the best glue-up I have ever had on an edge glued top. Thanks for the instruction thru the blog on how to make these! Regards, Brent.

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ben January 13, 2014 at 2:24 am

could I just the bow shape out with the band saw?

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Dale October 29, 2014 at 1:53 am

Ben, yes, you could just cut them on the band saw and then sand them smooth. But you will need to make a pattern to mark them with. My system is faster for me and it works without making a pattern.

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Bob October 24, 2014 at 8:52 pm

Why do they need a side that’s bowed?

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Dale October 29, 2014 at 1:51 am

Bob, The bow is so when you clamp the ends the middle of the caul has pressure to hold everything together without any clamps in the middle. You have to put the cauls on both sides.

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John Carman January 19, 2015 at 2:22 am

I knew there was someone who has made these, Tks for the info it was about what I thought, does it make any difference on what kind of wood to use?

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Dale January 23, 2015 at 12:05 am

Hi John, It doesn’t make any difference on the wood type. I’ve made them out of pine, oak, maple, cherry etc. Good Luck! ~Dale

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Dennis Regan February 17, 2015 at 3:02 pm

Thanks for the great tips.

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Ron March 14, 2015 at 9:43 pm

Dale,
Thanks for the tips. I plan to make a few of different lengths.
How much of a taper do you suggest? In other words. if the caul is 1 1/2″ thick would it taper to 1″ or more or less.
Thanks,
Ron

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Dale March 15, 2015 at 11:39 pm

It really depends on the length. So if it were 2 feet long you only need about 1/4 inch on each end. A 4 foot long one would be 1/2 inch on each end. These are only approximations, just so it exerts pressure along the whole clamp when it is flattened. the bowclamp on the top and bottom of a panel should be close to matching in curvature.

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Dale March 15, 2015 at 10:49 pm

I recently made a video, with craftsy about 7 different shop made essentials and included these bowclamps as one of the must haves. the video shows how to make them and is more extensive than this blog. if you see the craftsy link on this site, and you click it you can purchase it and you will have access to it forever. there is also another video I made with them on Greene and Greene details. if you might be thinking about taking a class with me, but not sure about my teaching style or if we would fit your expectations, just purchase a video (much less than a class) and check it out! Constructive criticism is welcome!

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Fred Virdeh October 12, 2015 at 7:24 am

Thank you for this piece of information that I have just come across online. I think I can use these cauls for routing straight and smooth edges on veneer seems. However, as I understand your article, you are taking three cuts on each end, on the jointer, set at 1/16″. That makes a 3/16th cut at each end of the 4 foot caul, but in your response to a question you suggest a 1/2″ cut. Am I missing something?
Thank you,
Fred

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Dale October 13, 2015 at 2:22 pm

No, Fred, Im missing my math skills. you are right. however, my point is that it doesnt have to be exact. i might take a bit more than 1/16 each time, its just an approximation and i wouldnt go any more than 1/2 altogwther.

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