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Thread: Make Your Own Curved Clamping Cauls

  1. #1
    Join Date
    Mar 2008
    Oakland, CA

    Make Your Own Curved Clamping Cauls

    I had an upcoming job requiring almost 30 slab doors, " panels, ⅜" solid edge banding, four sides. I needed curved cauls of several different lengths of for the glue up. Two issue presented themselves. How to get the ideal curve for each length, and how to produce a bunch of them quickly. The methods involving hand planes, bandsaws, jointers, and sanders did not appeal to me, to much futzing. I wanted a setup that was repeatable and didn't involve a lot of individual handy work.

    Steve Elliott describes how he bends and marks the stock for the curve, but he then shapes it by hand. Good on the curve but not the shaping. Wes Grass, post #10, cuts his while still bent. Now we're getting somewhere. {On Wood Central - Moderator}

    In my shop, jigs are made from scrap, cobbled together with staples and sheet rock screws. If glue is involved, it's hot glue. They are made for a specific task and are pretty much a temporary fixture. After it's used, it gets cut up and trashed. Rare is a jig that makes it on the wall.

    This is the jig I came up with to repeatedly cut curved cauls on a tablesaw. The "sled" is " ply with a " ply support stapled to the underside.

    The "clamp body" is a bock of scrap with a hole, screwed to the sled. The "clamp screw" is a " carriage bolt with the head cut off, heated and bent. The bend continually straighten. Bigger would be better, or a better bolt.

    Drill a hole in the middle of the stock, put a spacer at each end of the blank and tighten the "clamp" until the stock just touches the side of the sled. Notice the stock lifting off the " base.

    More scrap and a screw makes it sit back down.

    Set the tablesaw fence for the narrowest width of the sled and stock (measured by the clamp), and run it through the saw. To be sure the blade trims the entire edge, scribble a pencil in the middle. If the pencil mark is still there, nudge the fence over and take another pass.

    This is what the curve on one of my cauls. This method gave me the most even clamping pressure of all the other methods I experimented with. Another reason I like this is you can rework the same blank. For a 54" caul, I started with ⅛" spacers and work my way up to a ", using the same blank. I made two other lengths using different spacers. For 40" I used 3/16, and 28" was a fat ⅛", 4/5 oak. Your milage will vary depending on wood and size.

    After the jig was made and the stock prepped, it took less than 2 minutes to shape each (virtually identical) caul. No, This jig is not hanging on the wall.

    This is my first post here. I have used this site as a reference many times over the years. Just paying it backwards. Hope this is of help to someone.
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    Last edited by Jim Becker; 06-14-2016 at 9:02 PM. Reason: Direct links to another forum are not permitted.

  2. #2
    Join Date
    Aug 2008
    Los Chavez, New Mexico
    Blog Entries
    Welcome to the Creek! That's a well thought out idea.. Thank you, I'll be using it. I think I even have an L bolt that would be perfect...

  3. #3
    Join Date
    Apr 2008
    East Virginia
    Awesome first post and very neat idea. Thank you for posting it up. This thread is getting saved!

  4. #4
    Good idea! Thanks for posting.

    Go into the world and do well. But more importantly, go into the world and do good.

  5. #5
    Great idea. Thank you very much.

  6. #6
    That looks like a really good way to make a caul that has even clamping pressure along it's entire length. I may have to make a few.
    Universal M-300 (35 Watt CO2)
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    Glass With Class, Cameron, Wisconsin

  7. #7
    Welcome to the Creek !!

    Great way to make the cauls, it sure beats the way I have done it.
    This will give me something to do in the shop this weekend.

  8. #8
    Join Date
    Nov 2004
    Belden, Mississippi
    Now that's a feller usin' his head.
    Well done.
    Note to self:
    Why the heck didn't I think of that?
    On the other hand, I still have five fingers.

  9. #9
    Join Date
    Aug 2007
    Greenville, SC

    Now just to add the dado and rabbet so that you clamp can be captively held in the ends...


  10. #10
    Join Date
    Mar 2006
    Cool idea. I template route mine but, your idea actually deals with the caul under stress and takes the individual characteristic into account.
    I am familiar with modern idioms but they are outside the vocabulary of what I want to say.

    - George Dyson (composer)

  11. #11
    Join Date
    Mar 2008
    Oakland, CA

    Caul Jig v2.0

    In the past, the length of time a glue-up was in the clamps, and the number of clamps I had, was kind of self monitoring. Run out of clamps and the first glue-up was ready to come out freeing up clamps. Using cauls, I need only 2 clamps per door and the glue-up goes faster too. I run out of cauls before running out of clamps. I NEEDED MORE CAULS!

    Version 1.0 has long been "re-purposed". It had a tendency to try and tilt the blank. v2.0 has corrected that. I think I would be able to cut a 2x4. I'd try but there are none laying around the shop right now.

    The flat side of the cutout was a plunge cut on the tablesaw. That flat area and the back of the upper piece need to be flush. Don't worry about the front side being aligned, running the whole jig it through the tablesaw will true it up. This blank was 66" x 1-7/8", 5/4 oak. When tightened in the jig, the bottom is not in contact with the table surface. It cut fine.

    This time it has a full length, 1-1/2" high face.

    The clamp is 5/16" all thread with an 1/8" hole drilled through it.

    The base is cut out to allow tightening the nut. A ratcheting box end wrench is real handy.

    One hole for the all thread, one for the retainer pin (a drill bit).




  12. #12
    Very nice!

    The only improvement I can suggest would be to have a method to tension the caul to the average tension of the clamps you're going to use rather than using a fixed displacement. That way you know that when you tighten down the clamps it'll give even pressure across the whole surface.

  13. #13

    Thanks, Mike

    Reviving an old thread...

    I am gluing up a 72" countertop of about 23 x 2" sapelle slats.

    The curved cauls have made gluing up a real joy. I made mine from 2x4 scraps. I found it easiest to work in 24-36" sections, and to clamp the cauls in the middle temporarily while I attach pipe clamps at the ends. This stabilizes the cauls during tightening, and also evens the gap before tightening so you don't have to muscle one side to close a huge gap.

    Thanks, Mike!
    Attached Images Attached Images

  14. #14
    Join Date
    May 2013
    Northern Virginia
    I had a bunch of 48" cauls to make for a 11' dining table and remembered reading this thread. My version used a washer head spax screw instead of a threaded rod. It worked great and took no time.


  15. #15
    Join Date
    Mar 2006
    San Diego area
    Could someone post some pics of these curved cauls in use? I don't understand using them on flat stock.

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