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How Do You Make a Caul??

Total Topics: 25
Total Posts: 151
The SM instructions & video 'skip over' this step for making a caul to clamp up the end block for glueing. What's the best/easiest way to make one? I've heard mention of using bondo, but I'd have to buy a big can for $$'s. I've got one of those belt/disc sanders I'd like to use. Any tips?

PS, as you might guess I've never done much woodworking b4.

Jan 15, 10 | 8:45 pm

Total Topics: 26
Total Posts: 257
I think in the case of gluing up the end block, all a caul is, is a scrap piece of wood to clamp to the outside part of the sides, and the inside part of the end block. Those pieces of wood are just to keep from damaging the parts you are gluing together.
If you look at this topic , you'll see in the first pic where he's put some cauls on both ends of his body to protect the sides and blocks:
There are other cauls too, that can be made for different things also.
In this topic, look at the 5th pic down and see the cauls I use to keep the sides of my guitar braced against the mold:

Jan 15, 10 | 10:09 pm

Total Topics: 25
Total Posts: 151
Thanks Bob.
My SM 000 end block has a slight convex radius. I need to make a complimentary concave radius on one side of my caul.

Jan 16, 10 | 12:15 am
blues creek guitars Authorized Martin Repair Ctr

Total Topics: 52
Total Posts: 1011
You can use more flexible material . I find 1/4 inch lexan perfect for these. I also use UHMW nylon.
john hall

Jan 16, 10 | 3:57 am

Total Topics: 27
Total Posts: 668
Yes, a caul is simply something to back up your clamping pressure - it can be as simple as a piece of scrap wood on your bench or something carefully shaped to fit a particular piece. Usually I make the shaped ones out of scrapes of MDF or press board - I use a router, chisels, rasps and sandpaper to shape them - sometimes I pad them with some thin cork (buy at Lowes or Home Depot). For really wonky shapes you can get that need moldable stuff from StewMac - would be good for things like bridges.

Sometimes making a good caul takes a lot of time but it is worth doing it. A very important one is the inside of the bridge area - make it while the top is off the guitar so you can get it just right.

Here a a couple that I made early in my building days - the two on the right are the inside and outside bridge cauls for a fan braced classical, on the left are the inside and outside bridge cauls for a pyramid bridge, with one for the fretboard extension (the notch clears the truss rod). The back are a couple of simple curved cauls for clamping braces to top and back and a couple of angled ones for things at, well, an angle.

Jan 16, 10 | 8:04 am

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