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Nothing that special, but knocked this up to fit a plastic binding strip at the tail because it has to be pretty nigh perfect for depth control, and hand tools were a challenge with the wood involved.
Pretty self explanatory, rectangular 1/2" birch ply halves connected by 4" x 1.5" of 1/2"" birch ply strips (to clear bolt slots) glued underneath at front and back.
2 pieces of 2 1/2" high x 2" wide pine bars underneath to grip guitar (cut out to clear the 1/2" birch ply connecting strips), with 2 1/2" square x 1/8" cork pads at the gripping ends underneath.
Held in place with cam clamps.
The slots are 1 mm wider than the 1/4" coach bolts diameter to allow "floating" adjustment for lining up, uses a 20 mm guide bush in the router.
Line up was set with an acrylic strip 20mm wide with centre line scribed on it, checked with a 1/4" pointed rod in the router, cut with 6 mm 2 flute straight bit and a fine depth adjustment in small steps.

I also use a similar set-up for routing an oval soundport, using a 6 mm mdf plate with an oval cut in it, and can vary guide bush sizes to change hole size (cut with a spiral downcut bit)

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Nice Colin, great jig! This is way easier than what I used to do free hand with an engineer's scale as a guide.

Thanks for posting this!

Thanks for sharing, Colin! I always have lots of scrap ply kicking around, so I'll be making one soon!

Alex

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"Indecision is the key to flexibility" .... Bumper sticker

Some more pics, better than a description - End and side views, note the amended dimensions in first post.

Excuse the CA everywhere, I'll maybe pretty it up and nicely round the corners later.


Worked fine

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Yes, used to do it the same way, but last guitar I made with this wood was pretty tough to cut and chisel without chipping out and needed some filling, so wanted to avoid that.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Colin

Simple and eloquent - the best kind of jig. Why not permantely fasten one of the 2 X 's to ensure that the cut is square to the body?

Ed

Hi Ed. You could if you want.
But with the 1/8" cork to prevent marking the guitar, it will compress (it also takes up some of the curve of top and back), any difference in clamping pressure side to side, the actual areas of contact of the cork on each side , or compressability of the cork itself will misalign it.
Also this flexibility allows for any slight variation you may actually want to make in the end strip alignment, due to top/back plates being slightly misaligned, lining up with centre strips in the back for example, or a noticeable pattern in the top plate.
This variation may be less noticeable than a slight misalignment of center strip and tail end strip.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Colin

I get it - good call

Ed