HD28 Kit - First Build

[tippie53]

Rick got it right , the rise off the mold allows you a small amount of compression to the set . This helps the wood to conform to the mold and secures the wood to the mold. Martin uses this same set up . I used to use 4 spreaders , upper bout , waist , lower bout and then the blocks .
This method does the same job without all that needless work. It don't take much to get things locked into the mold. Did you see this vid link ? It will help explain it visually.
http://www.youtube.com/results?search_q ... guitars+be
We are here to help . Ken pointed out that I stated 1/8 off the tail on setting up the geometry and it should be 1/4 inch off the tail .

[MuddyFox]

Thanks Rick and John!

I have 3 spreaders all ready to go but I guess I'll give the 1 spreader method a try.

[tippie53]

feel free to call me .

[nkwak]

Good luck with your build, Rick. It looks like you've got lots of good advisers to draw from here.

FWIW you're making good progress regardless. I started my first last August and you just passed me by!

Thanks Neil. What kit are you building?

I'm not building a kit, but I'm at the same stage with my first that you're at though and I'm taking notes. Figuring out the geometry has been hard for me to wrap my mind around. I need to build one of those sanding table thingies.

[deadedith]

I think of it this way: see pic attached. The explanatory page on Ken's KMG site is worth reading 20 times or until the 'aha' moment arrives! Once you grasp it, it becomes so much easier in practice.

[Rick S]

feel free to call me .

Thanks John. I will give you a call. Is there a particular time of day that's best for you? Normal business hours?

[tippie53]

I am on the east coast , If I am here I pick up the phone , or at least trip over the cats while running for it

[Rick S]

I think of it this way: see pic attached. The explanatory page on Ken's KMG site is worth reading 20 times or until the 'aha' moment arrives! Once you grasp it, it becomes so much easier in practice.

Thanks Dave. A picture is worth a thousand words. I think I have the basics of the neck angle / complementary angle down. Adding the domed top component at certain locations complicates it for me that I'm having a tough time factoring that into the overall geometry.

[nkwak]

Makes sense to me - at least on the upper bout where the fingerboard makes contact with the soundboard. OTOH I would think that a radius on the lower bout creates a dome that is structurally sound enough to counter the string tension.

Om my build I'm following some pretty detailed plans for the Official Luthier's Forum's medium jumbo and the luthier who drew them up made it abundantly clear that there was to be a 1.5º angle at the neck joint - which was further applied with a neck block extension that runs beneath the fingerboard extension up to the upper transverse brace. He also specified a 28' radius for the top though, so what I was going to do was to use a 28' dish to apply the radius, then go back with a flat sanding stick across the upper bout.

[deadedith]

Is it clear that the radius dish is used to add a little angle to the sides and kerfing to make a good mating surface to glue to the top ?

That has nothing to do with the slope of the rims from the soundhole to the neck block.

I use a 40' radius top, which is so close to flat that I do not have to use a radius dish, for instance.

But the slope of the rims is the same each and every time, regardless of the radius of the top.

Get your slope right first, then if you need to radius the rims to provide a good mating surface with the top, then go ahead.

The dome need not trouble you. With proper rim preparation, it will fit nicely.

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