Category: +How-To

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Questions: Custom CNC Orders

Questions: Custom CNC Orders

by Dana Bourgeois

Originally published in American Lutherie #74, 2003 and Big Red Book of American Lutherie Volume Seven, 2015

 

Greg Pacetti of Fairbanks, Alaska asks:

Do you know of a CNC machining company that could take a custom neck order of as little as thirty in quantity?


Dana Bourgeois of Brunswick, Maine answers:

Small runs are nice in theory, but one-time engineering, programming, and setup costs can kill you. For example, I just had a run of twenty-five pyramid bridges made by Maverick Precision Wood Products (207-225-5043; maverick@exploremaine.com). The one-time costs came to about $500, after which bridges cost $12 each. If I never make any more than twenty-five, the overall cost of each bridge (including setup, and so on) is $32. If I had wanted only one, Maverick would have made just one, but it would have cost $512. In reality, I will probably use five hundred of them over the next ten years and my cost will eventually come down to $13 each.

Also remember that I supplied the CAD drawing, which meant that I got exactly the bridge I asked for. The engineering cost would have been much higher if I had given Maverick a bridge from which to generate their own drawing.

The bottom line is to try not to make runs that are either too small or too large. A small builder might use up to twenty-five pyramid bridges over a three-to-five year period. At that rate, a cost of $32/bridge is realistic. ◆

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Questions: Freezing Hide Glue

Questions: Freezing Hide Glue

by Frank Ford

Originally published in American Lutherie #79, 2004 and Big Red Book of American Lutherie Volume Seven, 2015

 

Peter from cyberspace asks:

At one of the discussion groups on-line I read about making a batch of hide glue, freezing it in ice cube trays, then microwaving it to thaw each cube as needed. Doesn’t freezing it change the texture, and therefore how well it will work? Likewise, doesn’t microwaving it change it molecularly? Has anybody done any testing?


Frank Ford of Palo Alto, California responds:

It’s long been standard procedure to mix up hide glue and keep it in the refrigerator for future use, but I don’t know anyone who freezes it routinely. For general interest I recently froze a batch and I saw no difference in its working properties once it was melted in the microwave. But I won’t be likely to freeze glue in the future as it’s more difficult to judge its progress as it melts. Sure, it does mold over with time because it’s food, but it lasts a couple of weeks and I’m happy with that.

I have been microwaving hide glue as my only method of heating it for about fifteen years. It’s a good way to avoid the mess of a glue pot. By heating the glue just before use, there’s no chance to overcook it and reduce the molecular strength as I might if I left it day after day in a glue pot. I just heat 1/2 oz. of glue in a “portion cup” (the kind that hot sauce comes in at the local taco stand) until it melts. Then, I float the cup in a regular coffee cup filled with boiling water to carry over to my bench for use. After I use the glue, I toss the excess. The “experts” I’ve talked to agree that my method is the most conservative and the most unlikely to result in degradation of the glue.

We’re taught to keep the temperature under 150°F, but it’s clear from the literature that the temperature is far less significant if the time under heat is reduced. And I do get great results with my hide glue! ◆

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Questions: Glued Vs Floating Bridge

Questions: Glued Vs Floating Bridge

by R.M. Mottola

Originally published in American Lutherie #74, 2003 and Big Red Book of American Lutherie Volume Seven, 2015



Greg Pacetti of Fairbanks, Alaska asks:

Why is it that most all flattop guitars have a glued-on bridge rather than a floating variety, as in the archtop guitar. I know that historically many have been produced this way, but the standard is still towards the fixed, glued-on bridge. I build a particular model in this configuration with good results.


R.M. Mottola of Newtonville, Massachusetts answers:

The short answer, to borrow a phrase from Fiddler on the Roof, is tradition. We like, or at least we have become accustomed to, the tone of instruments with glued-on bridges. The long answer (at least my long answer) is, well, longer, and much more speculative.

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