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Hello,

I'm already wincing at the idea that side port is not the right term for this and I'm about to get flamed for it.... but here it goes.


I have an idea to route a side port on my next guitar. I asked my resident artist (aka Wife) to make a shape for it that would be the outline of the logo I use on headstocks. I then proceeded to print out the image on printer paper, glue to a test panel with a kids glue stick, then route it out with a .062 end mill in a dremel on the SM router base.

Some observations and questions:

1) A smaller bit might be in order here. I ordered a couple of the smallest end mill that bqtool carries. Any other ideas on ways to route this out that will produce better results? Setting aside CNC for now.

2) The paper fuzzed up as the router was moving. This made it hard to see where I was going and also caused the router base to drag. I wonder if hitting it with shellac would help? Other ideas? Different paper type maybe? Thicker or thinner than plain printer paper?

3) The cheapo set of needle files performed like cheapo needle files. Any suggestions on files, sanding sticks, etc... that you've had success with in tight spaces like this?

4) Doing .010, .020, .010 sandwich of veneer. Is that enough to reinforce or should I go all .020? Or even thicker?

5) Is Robbie Obrien correct that just cutting a dang hole in the side of the guitar is the right way to start putting side ports in? Or do I really need to "do the math" and compensate at the sound hole right off the bat?

Here is a pic:


Long, loooong way to go before I'll feel good about doing it on a set of bent sides, but the PoC is sound. The pucker factor will be high on this one.

Brad


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Another way you could do it would be to cut an oval side port and bind it in a contrasting wood to form the "C", and then cut the guitar/ "B" line out and add it to the opening. It might make the reiteration of your logo even more obvious.

What I did for mine was make a copy of the shape I wanted that was just slightly larger than I wanted the final size to be (the amount depends on your bit cutting diameter and shank diameter difference) which I glued to a 3/16" thick board that was long enough to be my template, meaning it was long enough to brace on the waste curve and extend past the neck block so it could eventually be held onto the side of the guitar and taped/braced securely in place. Then I freehand routed and cleaned up the template until it was as good as I could get it, I think I tried a few times until I was happy. Once done I positioned it on the guitar and used the bit to cut the sound port, the smooth shaft of the bit runs on the template so it is not harmed and the cutter cuts the port. A long bit is needd since the guitar curves away from the template, but the method makes it a lot less tense and so far no mistakes.

One thing I would I would worry about with your design would be the stability of the inner piece. I would be afraid that if someone pushes lightly on the edge of the inner piece it might have enough torque to break it right off. I worry about that with mine also but do cross grain laminations for interior support and since the openings re rather thin most forces would be applied to several parts of the design (I hope).

Hope this makes at lest some sense.

Kent

For the paper fuzzing problem, maybe make a template out of thin flexible plastic so you can trace the outline onto the side and then rout to the line?

I think Clay's suggestion, if I understand it correctly, to make the logo design more obvious is good. To me, the design above is a little too much of an abstraction of your logo. I've always liked your logo and, even so, it wasn't obvious to me at first glance what it was. For someone new to your guitars, I'm thinking they might be wondering what it is, especially when looking at it with the guitar in playing position.

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I also wondered about the possibility of breaking the tab off. We thought about maybe connecting it to the other side with a thin line but it ruins the whole effect. The binding / inlay idea is a good one and I'll experiment some more with that one.


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I use paper for my patterns and use thinned Titebond or fish glue to attach. Also brush the top of the paper (basically saturate the paper) with the thinned glue which helps with the fuzziness. Scrape/sand to remove when done.

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Steve Smith
"Music is what feelings sound like"

To prevent the inside of the 'C' from breaking, you could run a narrow piece of ebony or African blackwood across it on the inside. It would be visible, but somewhat inobtrusive.

Pat

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I buy my bits from Drill Bit City (1/32") for cutting the sound port. They have a type that has teeth on the side of the bit the full length that works better than end mills. Also, if you make a cross grain patch (make mine about .054" thick) I believe it will be strong enough to resist breaking.

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Tim Benware
Creedmoor, NC

If you could cut and polish the "binding/ inlay" out of something like nickel silver, brass, or copper sheet it would be resistant to breaking but still look finely made.

We use two or three cross grain layers of veneer (three layers when we want to generate a light/dark/light effect on an unbound port; two otherwise) and an inner layer of the same species as the sides with grain running the same direction. Each layer runs about 0.025" with allowance for glue, so doubles side thickness in the port area. A cross-grain mahogany tapered wedge (think ramp feathered from reinforcement thickness to nothing in about an inch) is installed on each side of the reinforcement to ease lining installation, then a bias tape cover is installed on the ramp (with a bit of overlap on side and the reinforcement). The extra thickness allows a nice radius on unbound ports, and the cross-grain veneer plies provide enough reinforcement to support work such as you've shown.

I like Mr. Foster's notion of a strut or recessed brace to reinforce what can be done beyond added veneer.

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I did extensive reasearch on this topic and was going crazy with the formulas available on the internet for decreasing soundhole size depending on the size of your soundport. It was fellow Colorado Luthier, Randy Reynolds, who told to just cut a "dang" hole in the side of the guitar and move forward. I did that and have never looked back. For those that like formulas, there is plenty of info available on that so knock yourselfves out.

Another way to stop the paper fuzzing that I use when doing inlay is to score through the outline on the paper pattern with a scalpel blade. Also helps to avoid tear out on the cross grain. Bob