Guitar plans

[SnowManSnow]

I'm wanting to find a good plan for a 14 fret 000 OM 24.9, but I'm having difficulty locating one. I found one at LMI, but it doesn't appear to have the side shape..? Just looking for one to make some templates out of.
Any direction appreciated.
B



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[charles Tauber]

An alternate approach, instead of pre-profiling the sides prior to bending them, is to bend them un-profiled and then mark and profile them after bending. That way, the sides fit the top and back contours you actually use. It isn't particularly difficult to do but does depend how you go about assembling the guitar.

One you have done so, you can make a template from the profiled sides easily, for use on any subsequent guitar of the same size and depth.

[mirwa]

I precut my sides a little, saves sanding later., but straight taper from one end to the other,nothing more fancy than that.

When I am assembling the body, I sand the sides with a radius dish attached to a convetered pottery wheel, I can control the speed of the pottery wheel with a foot pedal that adjusts my speed.

Steve

[Howard Klepper]

If you want to precut your side to its finished profile (I don't), it's easy enough to make a paper pattern from a guitar. All you will be missing is the last 1-1/8" or so at the top, which is just a continuation of the lines you already have.

[emmsone]

I built my guitar from a Georgia Luthier Supply plan. I found it an excellent base to work from.
Unfortunately I just checked and their 000-14 fret plan is a 25 13/32" scale, but it does have a side template shape.

Not sure if thats helpful information or not though...

David

[Truckjohn]

All the actual plans I have bought include side profile of some sort or another. They either show the whole side profile unwrapped or they show the taper - and you can deduce it with whatever back radius you like.

I generally bend my sides unprofiled - so I just work the shape to my dish after I bend. Thin wood planes pretty fast.

Tracings are a different story. That's just usually an outline with braces marked.

Now... You can make most any body shape into whatever scale you need (within reason) by just shifting the bracing around a bit to accommodate the new bridge position.

The difference in bridge position between a 25.4" and 24.9" scale is about 1/4"... Not really a gigantic change...

I would use the guidelines in Cumpiano and Natleson for drawing out your bracing by starting with the outline and locating your scale length. Draw in your bridge and go from there.

[SnowManSnow]

Originally Posted by Truckjohn

All the actual plans I have bought include side profile of some sort or another. They either show the whole side profile unwrapped or they show the taper - and you can deduce it with whatever back radius you like.



I generally bend my sides unprofiled - so I just work the shape to my dish after I bend. Thin wood planes pretty fast.



Tracings are a different story. That's just usually an outline with braces marked.



Now... You can make most any body shape into whatever scale you need (within reason) by just shifting the bracing around a bit to accommodate the new bridge position.



The difference in bridge position between a 25.4" and 24.9" scale is about 1/4"... Not really a gigantic change...



I would use the guidelines in Cumpiano and Natleson for drawing out your bracing by starting with the outline and locating your scale length. Draw in your bridge and go from there.

I'm quite upset as of late because my boxer ripped this poor book to shreds in the yard....



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[Truckjohn]

Ok... So the short version.

Get a big sheet of Christmas wrapping paper or craft paper.

Trace your guitar template
Get your fretboard template and mark out from the body joint to the nut and then to the listed scale length + saddle compensation.

Now - locate the end of the fretboard and your sound hole.

Draw your bridge. Now locate points where you would like the bracing to overlap the X-brace. Then - you can jigger around with the X brace layout more forward or backward to take up the space between the bridge and soundhole.

Add the rest of the bracing and viola!

[LouieAtienza]

If you are of the mathematical variety, Michael Doolin has a way to figure out the body depth at any given point for any particular body shape. You could probably plug the formula in Excel to make things easier. It involves figuring out where the deepest part of the "dome" is, marking lines that radiate from the center at specific intervals, then measuring each line and use the formula.

The way I've done it, is to tape some oak tag "sides" into my mold, measure the depths I want at the heel and butt, prop it on m radius dish that the depth marks are at same height, and scribe a line around. You can cut it a little big, replace it in the mold, and fine-tune it, and it comes out super accurate. Save a LOT of sanding later on, so much so that I can glue the back linings on, sand and still have a pretty even depth to my linings.

[SnowManSnow]

So ...
I'm probably not thinking correctly here but ..
Let's consider a 000 14 fret OM
The side can be cut at say 32". The bottom would be 4.25" and the top at 3.25". Or maybe 3 I don't remember.
Anyway...
The top will be strait for now.
The back... about 14 " in starts tapering off to the 3.25. Then I have the shape? Right? Put it in the mold and use my radius dishes to get the radius right.



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[charles Tauber]

The concept is simple, the geometry is not.

You want the sides to be the contour that matches whatever shape your top and back will have. For example, assume the back is a segment of sphere of, say, 20' radius. Assume that the top is a segment of a sphere of, say, 15' radius.

Suspend the top and back in space. If you want the space between them to be, say, 3" apart at the heel and, say, 4" apart at the butt, the top and back are not parallel.

The sides are some form of "S" curve as given by your desired guitar shape. The "S" shaped sides will intersect the spherical top and back. The further you are from the longitudinal centerline of the instrument, the closer the top and back get towards each other, due to the curvature of the top and back. That means, the "wider" the sides are from the centerline, the narrower - less tall - they become. Superimpose on that the change in height from heel to butt. That's your geometry.

You can physically get that geometry in a variety of ways. One way is to approximate it in the unbent sides, bend the sides and then refine the shape to fit top and back. Another way is, as others have suggested, is copy the side contour of an existing guitar that is the shape and curvature you want. Another way is to bend the un-contoured sides, then cut, plane or chisel and sand to match the curvature of your back and top. (That's what I prefer and it is easy to do.)

To throw more wrenches into the works, some purposely do not match the side contour to the shape of the top and back and then force the top or back to conform to the side contour.

I don't use a spherical curvature on back or top, making the side contour different than one would obtain with spherical plates.

[Halcyon/Tinker]

Lol...your dog ate your homework...

[SnowManSnow]

Originally Posted by Halcyon/Tinker

Lol...your dog ate your homework...

Shuuup!


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[SnowManSnow]

Originally Posted by charles Tauber

The concept is simple, the geometry is not.



You want the sides to be the contour that matches whatever shape your top and back will have. For example, assume the back is a segment of sphere of, say, 20' radius. Assume that the top is a segment of a sphere of, say, 15' radius.



Suspend the top and back in space. If you want the space between them to be, say, 3" apart at the heel and, say, 4" apart at the butt, the top and back are not parallel.



The sides are some form of "S" curve as given by your desired guitar shape. The "S" shaped sides will intersect the spherical top and back. The further you are from the longitudinal centerline of the instrument, the closer the top and back get towards each other, due to the curvature of the top and back. That means, the "wider" the sides are from the centerline, the narrower - less tall - they become. Superimpose on that the change in height from heel to butt. That's your geometry.



You can physically get that geometry in a variety of ways. One way is to approximate it in the unbent sides, bend the sides and then refine the shape to fit top and back. Another way is, as others have suggested, is copy the side contour of an existing guitar that is the shape and curvature you want. Another way is to bend the un-contoured sides, then cut, plane or chisel and sand to match the curvature of your back and top. (That's what I prefer and it is easy to do.)



To throw more wrenches into the works, some purposely do not match the side contour to the shape of the top and back and then force the top or back to conform to the side contour.



I don't use a spherical curvature on back or top, making the side contour different than one would obtain with spherical plates.

But isn't this what my radius disks accomplish ?
Then I use a clamp deck and contoured braces to conform the top and back to the radius


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[charles Tauber]

Originally Posted by SnowManSnow

But isn't this what my radius disks accomplish ?
Then I use a clamp deck and contoured braces to conform the top and back to the radius

You are asking about contouring the sides before they are bent. You are trying to figure out what shape the flat sides should be prior to bending such that when bent, they will provide the correct shape to conform to the domed top and back.

You aren't asking how to make the top and back domed.

Is that not correct?