1st scratch build (Walnut OM)

[kencierp]

Trim off the edge along a straight grain line be it the wide or narrow pattern. While backs joined on the wavy edge etc. usually have an attractive symmetrical pattern and look good without a center strip. To most of us tops with a near invisible center joint looks best. Its not likely there is an acoustic advantage one way or the other.

[Darryl Young]

Like John said, old school Martin had the wide grain at the center seam so it's no big deal either way. FYI, tight grain is not necessarily an inindicator of a stiff top or even a great top.......though it could be both.

I would see if you could join that top on the opposite side and have the wavy region located outside the waist area that gets trimmed away. Not sure where it's located top to bottom so not sure if this is feasible or not.

[Coach]

I've sanded the back to .095. The front is sanded to between .090 and .100. May have gone too far, but it is what it is now. Haven't done any fine sanding. It makes that metallic whomp, whomp sound when firmly shakin, so it may not be too thin yet.

My next step is to radius the braces. The plans call for 15' back and 25' front radius. So I presume the way to radius the braces is to tie a pencil at the end of a 15' (and 25' foot) piece of string that's held at the other end, then draw the arc on a template, or directly on the brace. Correct?

[Kevin Sjostrand]

Yep Coach, that's the laymans way of doing. The way I did it and I still use those templates I made.

Kevin

[Coach]

Thanks Kevin.
My problem is that it arcs a great deal more than it shows on the plans. Am wondering if the plans are messed up.

[darren]

there are some pdfs floating around the old interweb that have radii on them already. here is one, needs to be printed full size of course. Maybe compare this to your plans and the string method.

[Jim_H]

I have radius guides that I've acquired from various places, and found they there are some discrepancies in them. By that I mean that (for example) a 28' radius guide from one source has a slightly different curve than one from another source, and neither matches my 28' radius dishes. The differences are rather small, but they are noticeable if you check them closely. It's probably not enough of a difference to have any effect on a guitar.

[Darryl Young]

You are using feet for the measurement aren't you (not inches)? 28 foot radius and 15 foot radius. there are other ways to create the arc instead of using a string. There is an old boat building technique that's call ________ compass and I can't recall the name where I put the bland. It will come to me and I'll post an update. Also, you can buy templates that hae the correct radius cut into them. Not sure but Ken may offer these (on this forum).

[Coach]

Those radii templates Darren posted will work fine. The plans specify a 15' back radius, but the plans template matches a 28' radius ??. I think I'll go with the 15', unless someone here suggests otherwise.

Now, it'll be fairly easy to radius the back braces, as they are perpendicular across the back. Seems to me not so easy doing the top braces. So how do you guys get the correct radius on the X braces if they are at an angle from one end of the guitar to the other?

[johnnparchem]

Those radii templates Darren posted will work fine. The plans specify a 15' back radius, but the plans template matches a 28' radius ??. I think I'll go with the 15', unless someone here suggests otherwise.

Now, it'll be fairly easy to radius the back braces, as they are perpendicular across the back. Seems to me not so easy doing the top braces. So how do you guys get the correct radius on the X braces if they are at an angle from one end of the guitar to the other?

Just put the 28' radius on the X braces your really in a dome so it is the same angle.