Official Luthiers Forum!

Matt Mustapick (a very nice guy) told me it is fine to share any information that I glean from him. I noticed in one of the photos on his site that he cuts his sound port holes before he bends the sides. (He said he cuts them big enough to get it over an oscillating spindle sander, and that is where he gets his final size, as well as smooth edges.)

I'm going to try ports, and I'm just about ready to bend sides. So, can I ask those of you that have cut side ports, do you cut them before bending, after bending but before assembly, or after the box is assembled? Any additional info that you're willing to divulge about your methods would be appreciated. (Like, what do you cut the hole with, do you heat bend a patch for the inside, etc.)

Thanks in advance!

Dennis

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Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia

I cut my soundports when the box is closed. I protect the top and the side using thick cardboard.

Prebend to 20 years new builds I cut prebend but I have a 20 year old Alvarez I cup a port in and I have done the same for a client or two. Be sure to add a back up plate inside with the grain going perpendicular to the sides grain or you are asking go a crack to develop.

If you care to see how I do it, check Here for my little tutorial of how I make ports (scroll way down).
But the short answer is that I cut them before bending.

After the third coat of finish is on the sound box. This allows me to tune the port volume to the sound box volume. It also prevents a lot of finsh from building up around the port opening(s).

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tim...
http://www.mcknightguitars.com

Thanks, Sam, Michael, Paul and Tim!

Excellent food for thought. Now, as long as I'm not going to bind the soundhole, it looks like there are reasons for doing it either way.

Paul, do you use Titebond III when binding the port, knowing it will get wet and hot in bending? You're right, I can't even imagine how hard it would be to bind the sound port after bending.

I do kinda like the thought of gluing a couple of layers of different colors of veneer as a patch behind the port, allowing their edges to form fake binding.


Thanks again!

Dennis

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Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia

I have only done one, but I found it easy this way. I bend the sides and attach the top but not the back. At that point I can have big piece of cedar, shaped from a 4x4, that fits the curve of the bout exactly fit inside snug against the side. This provides good support and prevents and allows for a nice clean cut.

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David White, Toronto

"All my favourite singers can't sing."

[QUOTE=DennisLeahy] ....as long as I'm not going to bind the soundport, it looks like there are reasons for doing it either way......[/QUOTE] You can bind the soundport hole if you cut after the box is assembled.
BTW - I bind the sound hole on every guitar I make. I

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"An adventure is only an inconvenience rightly considered. An inconvenience is an adventure wrongly considered." G. K. Chesterton.

Thanks, Dave and Steve.

Again, and as usual, there are a wide variety of ways to excise the epithelial tissues of a feline.

I had imagined that a cylinder of binding material, rather than .25" of binding material, was the way to bind ports after the fact. Now, I have seen it done. Thanks, Steve.

-Dennis

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Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia

Steve, when and how do you sand the extra binding from the inside? I did one this way and was about ready to got nuts by the time I was done. Thus the reason I bind prior to bending.
And Dennis, I use TB 1. I had one try to pull away a bit at the edge so I make a little plug that fits in and keeps everything tight while bending.

Paul,
Yep, it can drive you nuts, but my new method works pretty good.
I sand with 80 grit wrap around my finger. It goes pretty fast if I sand perpendicular to the binding. When it gets close I change to finer grits and start sanding parallel to the binding.

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"An adventure is only an inconvenience rightly considered. An inconvenience is an adventure wrongly considered." G. K. Chesterton.

Thanks Paul, I picked up on the trick to use Titebond III for binding with attached purfling veneers, as they are less likely to fall apart in the (heat blanket) bender.

I'll be interested to hear Steve's answer, but suspect it is a convex sanding block.

I'm sort of frozen in my tracks, as I have visualized (or looked at photos) of each method. Each has merits; each has (apparent) drawbacks. I'm concerned that a pre-drilled hole will weaken the side and lead to at least some species, or some wood figures just not being able to keep from cracking. The pre-glued in patch should keep the success ratio higher, but (depending on the thickness of the patch material and the side wood species, it is just hard to wrap my head around the fact that the intended body curve/shape can be maintained without a telltale bump at the leading and trailing edges of the patch.

Cutting the hole (and even patching the inside) after the bending is done avoids misplacement/misalignment, weakening the wood to be bent, having to cut a hole in a non-flat surface without chipping out the interior face (though Dave covered that aspect), and finish buildup during spraying.

Cutting the hole before bending makes the initial hole cutting very safe, and using Paul's method, could make binding the sound port easier.

Decisions, decisions...

I'm about to try this on Cocobolo, Granadillo, figured Katalox, and Ziricote. (Obviously, one at a time, so I'll have some personal experience to base the 2nd, 3rd, and 4th on.) Wish me clarity to choose a method. Then wish me luck!

Dennis

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Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia