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Hi All, First time posting. I'm building my third acoustic and am trying to decide on a side sound port. I have successfully, at least so far, done a nice Florentine cutaway. I was worried about that challenge but so far so good. This is an OM and I want to put a small port on the upper bout. I'm thinking a oval 1 1/4 x 1 3/4. This side is about 3/32 thick at that point, claro walnut. I was wondering if I put a side support on either side of that it if that will keep things from cracking down the line. My engineering mind thinks it will be fine. I don't really want to do a lamination if I don't have to. I'm building this for myself. The other 2 guitars were d28's and came out real nice. The local repair luthier agreed. Any opinions about my plan for a sound port will be greatly appriciated. Perry

Welcome Perry. I reinforce it by gluing in a patch a bit bigger than the intended hole - using offcuts of back or side material, and orientating the grain at right angles to the side. It is very easy to bend it on a hot pipe and just glue it in, as long as you haven’t closed the box yet. Even if the box is closed it would be easy to reach it through the sound hole.

If you have a double thickness of side when you cut it out it will be very stable. Also looks better than a hole through a single thickness. If you laminate in a piece of contrasting veneer you can get an accent strip in the cut face which might complement your binding and purfling (e.g maple if it is a rosewood sandwich, or whatever). Another nice way to trim it is to glue in a soundhole binding, matching the binding for the rest of the body. A double thickness cut face makes a good surface to glue a binding strip to.

My own feeling are that side supports either side may prevent any cracks originating from the sound port propagating along the side, but don't see how they would prevent any cracks at the port itself.

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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.

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Thanks for the input. I just wondering if it's worth the effort. I have some curly maple and black fiber I can use. The binding will be curly maple. The top and back are not yet built.

We use three layers (and very occasionally four) of standard 0.022"-0.025" veneer, with the two layers next to the side running cross-grain (across the side), and the final layer aligned with the side grain and of closely matching material. The outside mold may be used as an outer caul, but it is easy enough to make up a purpose-built set of cauls which are 5-6 layers of 3/4"/18mm ply. We seldom use ports on other than the small jumbo (SJ) body, so the time spent making up the caul set is not too onerous a chore.

Prior to lamination, a layer of very thin vinyl transfer tape is added to the sides to define the edges of the reinforcement, as well as an adhesive barrier...the edge of that film also provides a nice guide for trimming the laminates after glue-up. After lamination, the ends of the laminate edges are squared with knife and file, and a tapered 3/4" wide ramp is is added at each end of the reinforcement (the ramp runs across the grain of the side for easier shaping) using the same transfer tape trick to minimize the labor necessary to prep the sides for further work. Cloth side tapes are added, to include two slightly wider ones over the ramps, and linings are applied as usual after final profiling. The port is milled out after the body is bound and blocked level.

The contrasting end grain of the (usually) lighter or darker center laminates is sufficiently decorative in nature to give the soundhole a finished look where the wood chosen for the sides is interesting enough to carry it off, but the thickness of the total lamination - usually between 0.160" - 0.185" - is more than enough to handle either an incised purfling line (similar to bowed instrument edge treatments) or dedicated purfling and binding (there is long grain on all sides of the raw port, so a good gluing surface).

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For the times they are a changin'

- Bob Dylan

Thank you Woodie. Good info. I will be doing something similar and will not be binding the hole. The concept for this guitar is the walnut maple contrast. I will put a piece of black fiber between the two layers.

This one is Walnut sides with maple veneer backed up with a piece of rosewood.

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Steve Smith
"Music is what feelings sound like"

That looks nice, Steve!

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Thanks Brad, that was my first sound port. Since then I've done several that are similar, it's a bit more work than the usual oblong hole but I like the look.

_________________
Steve Smith
"Music is what feelings sound like"

Tagging along on Mr. Smith's beautiful work...through some trial and error, we arrived at the size and location shown on the SJ. There are more complex, treatments, but if you have what it takes to make simple work, it just works (aka, the Little Black Dress effect).

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For the times they are a changin'

- Bob Dylan

Very nice both. I hope my oval looks half that good. Just roughed out the hole with a coping saw. Backed up the walnut with a layer of black fiber then the maple. So far so good. Thanks for the input.

I'm a bit late to join this thread, but I'll share my experience in any case, as I've put a sound port in a half dozen or so builds.

After the sides are shaped, but before attaching either the back or the soundboard, I measure the profile of the upper bout area when I want the port and then carefully shape a block of mahogany or walnut (around 3" x 3" x 1") to fit that shape, with the grain of the block running parallel to the side. I drill a hole, the size of the port that I want (typically ~1.5" across) almost through the block, using a Forstner bit, just letting the tip of the bit penetrate the block fully. Then I glue the block in place, using the cut-off from the block as a caul. After the glue sets, I use the small hole in the block to drill a pilot hole through the upper bout from the inside. Then, using that pilot hole, I can drill with the Fortstner bit from the outside and get a smooth port through the guitar side and the block. A bit of sanding, using a conical sanding block (the neck of a bottle works), results in a port that is sturdy and doesn't have a fragile look. Per Woodie's picture, a layer of veneer between the side and the block would be attractive. I'll be doing that, going forward.