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Good afternoon,

I'm Rich, and I'm an addict. I've loved all things regarding acoustic guitars for the past 43 years of my life. Finally getting around to building my first, an OM-28 with as many pre-War specs as I can muster.

I've made my cam clamps, thickness sander, and a spindle sander. I'm gathering wood orders online, and while they are en route, I'd like to get some plans printed so that I can start building my form.

Would anyone know first-hand who offers, for online purchase, the most accurate plans for an OM?

Thank you,

Rich
Go Army!

I don't know if you'd be interested, but in this forum, John Hall has photographed and measured an actual 1931 Martin OM top, if you're inclined to draw your own plans. This is the basis for all of my OM's. I've given you the link below. You'll find additional info in the posts below the photos.

viewtopic.php?f=54&t=5424

There are good plans here. I would compare any prewar OM plans to the top we have here on the forum.

https://www.grellier.fr/en/downloads

the most accurate ones are from Cadguitar plans

Thank you kindly, Diane and John.

I was staring at the neck of my HD-28 yesterday, thinking I could draw that neck and import the OM tracing/plan you mention in Autocad, and make my own plans. The only thing I would have to interpolate are the body depths, using the dimensions written on that plan. This is my backup plan.

I will check out the Cad plans John mentions.

Thank you again!

Rich

Even if you use bought plans, you can still copy your HD neck, if you like the profile (or any profile neck).

Use some malleable wire, or buy plastic that can be heated and molded. If using wire, gently bend pieces of it around the back of the neck, at various frets, molding the neck profile at that fret. Keep your wires safe, so you can work your neck to fit the wires. Be careful though that you don't inadvertently mark your HD neck!

If using moldable plastic, just model the back of the neck. Personally, I like the plastic. You can buy beads or sheets on Amazon.

Thank you kindly, Diane. Great suggestion!

Rich

Diane Kauffmds wrote: ↑Wed Jun 29, 2022 1:30 pm
Use some malleable wire, or buy plastic that can be heated and molded. If using wire, gently bend pieces of it around the back of the neck, at various frets, molding the neck profile at that fret. Keep your wires safe, so you can work your neck to fit the wires. Be careful though that you don't inadvertently mark your HD neck!

Pay attention to this! It can happen. (Guess how I know...)

I believe you, MaineGeezer. I've given this technique thought, and, if I use it, I'll initially try using solder of various diameters. What I'll try first is my old stand-by, which is a contour gauge.

For me, the more daunting aspect will be fretboard/fret measurement. I would want this, of course, to be precise. I realize there is a mathematical solution for scales/fret spacing, so that will likely be my solution. My local Woodworkers' Guild may have a spreadsheet with these numbers.

Trying to measure each distance with calipers may compound an error. Another advantage of using the math would be the option of making a 000 neck. I do like both scales.

Rich
Go Army!

There is also this link https://www.maurysmusic.com/maury_s_blo ... eck_shapes
which may be more useful than attempting to copy a neck contour with wire.
From the parameters given you can draw a profile -- close enough, I think, for practical purposes.

Using a CAD program I drew the "modified low oval"contour, interpolating for the 5th fret shape, transferred it into Vectric's VCarve program, generated CNC g-code, and cut out a template on my CNC router.

When I tested it on one of my freehand-shaped guitar necks, it was a pretty good match, so much so that I'm not sure it''s worth the effort to have templates once you have done a few. For your first neck, it probably is. The first neck I carved I kept thinking I was taking off way too much, and the fellow teaching me had to keep telling me to take off more. A template would have helped me see that.