Step by Step OM Guitar Build

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MaineGeezer
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Re: Step by Step OM Guitar Build

Post by MaineGeezer »

Interesting that you don't profile the sides prior to bending and gluing to the end blocks. I cut mine to a template prior to bending...but of course that means you need to know what the final profile is going to be. With your method, you don't. Assuming I'm understanding all this correctly.....
Don't believe everything you know.
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ericschaefer
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Re: Step by Step OM Guitar Build

Post by ericschaefer »

That is correct. In this case the sides were not profiled prior to bending. The profile is set by the height of the end block in relation to the height of the neck block. The maximum depth of the body, then, is at the end block. It then tapers from the end block to the neck block. I believe the end block was something like 100mm and the neck block was in the ballpark of 80mm.

Profiling the sides prior to bending is necessary if you want the profile to peak somewhere between the two blocks.
tippie53
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Re: Step by Step OM Guitar Build

Post by tippie53 »

I will agree that an exact profile at bending is going to be difficult to maintain but you can get it close. I profile all my side before bending , it save so much work at the end. The radius will determine the final shape of the side in the mold. At that is the key , as the side shape sets in the mold the radius if the back will determine the points along that shape . So a side profile of a 000 once complete is slightly different than a 00.
I was trained at Martin and I pretty much use the same system they use, rough in the shape the detail it with the concave dishes.

As long as the end result is what you need, you can do it other way as well.
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John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
MaineGeezer
Posts: 1483
Joined: Wed Aug 13, 2014 12:14 pm

Re: Step by Step OM Guitar Build

Post by MaineGeezer »

Stream-of-consciousness thinking:

So you don't have a spherical radius on the back -- it's a straight taper end to end, and it's flat side to side...at least until you sand it in a radius dish, if you do sand it in a radius dish. But I think I remember seeing that you put a radius on the braces, so that gives you the side-to-side radius, except the sides need to vary in height (by a few hundredths of an inch) according to how far from the centerline they are. But that can be accounted for by sanding. But end-to-end is a straight taper. Until you sand it in a radius dish.....

I tend to agree with tippie -- profiling the sides prior to bending saves a lot of work, once you do the initial up-front work to make a template. Just make a paper pattern off a finished side and cut out a 1/4" thick template to match, then use that with a router and ball bearing straight cut router bit to follow the template and cut the side to the template. Tape the sides together with double-stick tape and cut both of them at once in 5 minutes, and they're a perfect match and require minimal clean-up.

But whatever you're most comfortable doing is the way to do it.
Don't believe everything you know.
Anything is possible if you don't know what you are talking about.
When things are bad, try not to make them any worse, because it is quite likely they are bad enough already. - French Foreign Legion
ericschaefer
Posts: 17
Joined: Sun Aug 09, 2015 5:32 pm

Re: Step by Step OM Guitar Build

Post by ericschaefer »

You are right Mainegeezer. The radius from front to back is spherical in the end, and I probably do spend a little too much time on the radius dish because I don't profile prior to bending. I'm always looking to cut back on unnecessary sanding, so thanks to you and John. I'll try profiling the sides ahead of schedule for the next class. I think it will make a difference. Thanks!
tippie53
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Re: Step by Step OM Guitar Build

Post by tippie53 »

I use the same technique that Martin uses
It does save a lot of time. I can have a side set ready in less than 5 minutes
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
MaineGeezer
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Joined: Wed Aug 13, 2014 12:14 pm

Re: Step by Step OM Guitar Build

Post by MaineGeezer »

On the other hand, for a one-off like my current guitar build, I might have been better off to do it your way and not bother making a template that I will probably never use again.
Don't believe everything you know.
Anything is possible if you don't know what you are talking about.
When things are bad, try not to make them any worse, because it is quite likely they are bad enough already. - French Foreign Legion
Slowpicker
Posts: 35
Joined: Thu Dec 02, 2021 11:07 pm

Re: Step by Step OM Guitar Build

Post by Slowpicker »

Super helpful post, Eric. I really like that waist clamp that you use. And it's nice to see you building in a different order than I have learned thus far, reinforcing that there are many approaches to a good product.
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