Angle SIdes - 15" Back on Weissendborn

[Kim Strode]

I am currently building a Weissenborn. I have the back almost finished, which is curved to a 15" radius, braced and almost ready to glue to the sides. I now need to angle the sides to match the 15' radius of the back....any suggestions for an effective technique. I don't believe I can use a radius dish with sandpaper as the back is only curved around the bottom and sides and not at the neck extension. Suggestions welcome.

[Bob Connor]

I'm not sure what you do there Kim.

I build mine with a flat back mainly because I couldn't figure out a way to radius the sides with the dishes that I have. So a flat back is much simpler. I do a flat top as well.

If it were me I'd chisel the braces off make it a flat back and save yourself a lot of head scratching It may just be the quicker and simpler way to go.

Regards

[Dave White]

Kim,

Use the old chalk technique. Cut the inlets for the brace ends in the linings then mark around the edge of the back with chalk to see where it touches the linings. Keep removing where there are chalk marks on the linings and deepening the brace inlets if necessary. Repeat until it fits.

[Kamusur]

Hope i have understood the question you asked Kim .....are you trying to change the bottom plate contour from 15 feet (not inches) dished radius across the neck joins body area (in side profile/side elevation that is) to flat as the sides diminish to the headstock area ,or are you after some sort of radius in the profile either cylindrical or spherical continuation but in the different plane?

Steve

[Kim Strode]

Hi Steve, I'm looking for a method of sanding or planing the sides where they join to the radius back, to ensure there is a good side-to-back join.

[jeffhigh]

I built mine with flat backs across but in your situation I would probably use a 12 thick 100mm wide sanding board, deformed to approximately 15' radius by a central screw into a thicker beam and packing at the ends.

[Trevor Gore]

A dome is a dome is dome. Which is the great thing about domes.

So as I see it (I hope I'm understanding this) you have two options:

1) Dome the rims over their whole length (butt to headstock) with the high point of the dome towards the top of the upper bout. This will, of course, narrow the depth of the rim quite a bit at the butt and the head. To get the profile, sit your 15 foot dish on the rims, one edge of the dish flush with the butt, with a packer (probably about 10-15mm thick) between the rims and the dish at the base of the neck. Then use the mechanical-pencil-through-a-scrap-of-wood-trick (see pics) to scribe a line around the rims. Leave the packer where it is, shift the dish to the neck end and repeat. Block plane close to the line and finish up with the dish with sandpaper glued to it. This should blend everything (because a dome is a dome is a dome) and the dish should "fit" everywhere (and hopefully your linings are deep enough)

2) Do as above for the "body" of the guitar, but at the neck, come off the dome as a straight line tangent and keep the neck flat. Sand the body using the dish with sandpaper glued to it and sand the neck with a flat sanding block.

Of course, the real recommendation is to plan a head a bit, choose your back panel profile, mark/plane/sand your rims to suit, then glue your linings in and trim up. And only then notch for the back braces.

Here's the mechanical-pencil-through-a-scrap-of-wood-trick:

Pencil.jpg (100.27 KiB) Viewed 10845 times

Scribing.jpg (57.34 KiB) Viewed 10845 times

In this pic, the dish is on the top and I'm scribing around the sides, keeping the bit of wood in contact with the dish all the way around. In your case, the scrap of wood will need to be the other way up (pencil at the far side from the dish), because it has to bridge the gap between packer and the rims.

[Nick]

Paddle stick sander with the appropriate packing under the handle of the paddle to set the sanding face at the correct angle? The angle would change slightly of course as the handle bridges the various different length of rest points(the opposite side) but it would get it close that you could then sit the sides in your dish with the neck section hanging over as you've done with your back, & spin it back and forth on an axis (I think John Hall refers to it as "steering the bus" ) to finish it off. Maybe put some thin cardboard over the neck section so that you dont undercut the neck with the dish?

[Kim Strode]

Thank you all for your suggestions and ideas...I'm sure a combination of these ideas will work well.