Question about position of soundhole on an oval hole mandolin

[Nick Gellie]

Ok. I am experimenting setting up the neck on an oval hole mandolin to join at the 13th fret like a Collings MTO. On my Siminoff A1 drawings this puts the soundhole at the 24th fret instead of just past the 21st fret. Should I move the soundhole closer to the neck or just leave it as shown in the attached photo.



I am open to any ideas. I just prefer having a bit more neck room for the finger for those of you think it is sacrilege to change the timely old Gibson A1 design.

[Nick Gellie]

I would prefer to leave it where it is. Aesthetically it looks better. I haven't decided whether to use a transverse brace or an x-brace yet.

[Tom Haywood]

I just finished designing and building a smaller D hole flat top mandolin. The neck joint is at the 13th fret - didn't know anybody else had tried that. The hole had to be moved probably 2 frets distance from what I thought was the ideal location (based on Gibson Army/Navy measurements) because I wanted to have a brace between the neck block and the hole. I worried about it, but the end result doesn't seem to make any difference in the sound. I also braced around the sound hole. My limited experience with it says looks and good bracing are the biggest concerns.

[Nick Gellie]

Tom

I am thinking of moving it fractionally forward by about 3 mm. I have pencilled in my X-brace lines which pretty much go underneath the feet of the saddle which is what it does on the A-5/A-4 Stewmac plans. The Stewmac plans have the X-bracing 5 mm away from the soundhole at its nearest tangent to the x-brace lines.

Check out my photo.

[Nick Gellie]

Does the Collings MTO have a front brace? Anyone know.

I am planning to have a raised fingerboard like the Collings MTO. It is all systems go if I am on the right track.

[Tom Haywood]

All my round-ish hole building experience has been in flat top instruments, so it will be good to hear from those with A4 experience. Repair-wise, the flat tops can develop cracks running down beside the fret board to the sound hole if there is much space between the neck block and the hole and no bracing around that side of the hole as the neck block tries to rotate . I have not seen that problem on arch tops. I suspect the arch in your top, the top and back thickness, and the hole closeness to the neck block, if you stick close to the plan, give plenty of support. I think your x-brace location should give plenty of support on that side of the oval. I don't know the scale length on that plan, but a shorter scale length reduces the string tension so there would be less pressure on that area.

[jim simpson]

My project will be an F-4 hybrid so I positioned the fingerboard ext. over the sound-hole to fine the best location for it. I am also locating my rosette joints under the extension.

[Nick Gellie]

Have you worked out at what fret on the fret board extension lines up with the edge of the sound hole closest to the neck. I presume you are joining the neck at the 15th fret.

[Nick Gellie]

I am going to shorten the fretboard over the soundhole to make it look like an A4. It will extend over the soundhole about the same as an A4.

[jim simpson]

I haven't sorted out which fret but it sounds like your plan makes sense.

[Nick Gellie]

Thanks Jim

I am just canvassing options until I do the deed. Any other input is welcome.