first back carve update

[Greg Martin]

Ive been working on the back this week.The outside carve is done and the inside is rouged to 1/4" ,but with mixed satisfaction . The carve from the waste up to the heel including the cutaway came out the way I had envisioned. From the waste down not so much, I had a hard time with the longitudinal doming of the arch as it came down from the bridge to the end block. it is flatter than I had hoped for not terrible, but not what I wanted . Im not sure exactly what I did or didn't do right yet. I wish I had had some topo carving templates but did not. I think Ill need to have templates before I attempt the spruce top . Has anyone here in the forum made arching templates in pdf or downloadable format that I could purchase?? Id be grateful. My build is a pretty standard L-5 17" so Benedetto type templates could be a good place to start. I suppose there is a way to layout the arch and then the templates but I dont know what it is yet. Much to learn about arch tops !!

[Dave Stewart]

Bob Benedetto's book (which you should have) has templates which you can use.
Alternately, you can generate cycloid templates in pdf using this program
http://www.cgl.uwaterloo.ca/~smann/ccycloid/

[Michael Lewis]

Greg, can you put up a pic or tow of your arch? The back arching is mostly cosmetic, but the top is also structural besides being cosmetic. A shot from the side would be the most important.

[Greg McKnight]

I haven't been able to quite wrap my mind around the technique for making the different hole depths on the drilled outlines Benedetto suggests in his book. He says to use the arch templates in the back of the book to make that map but I'm not sure how to do that. Any tips besides computer programs?

Sorry to hijack the thread btw.

[Michael Lewis]

Do you have a drill press?

[Dave Stewart]

FWIW, I never used a drillpress.
My method was to start with the longitudinal template & reduce the centerline down to match the template with gouges / fingerplanes etc. (I flattened the template recurve so it would bottom at the correct arch height ... recurves come later). Then mark the stations & do the same thing with those station templates. You're left with a blank having a long groove & several lateral grooves. Mark the bottom of the grooves with a heavy pencil line & then go ahead & remove the rest of the material to fair the arching to the bottom of the grooves. (I should say that getting the perimeter lip down close to final thickness before carving is helpful.)

[Greg Martin]

Im not very good with software and Bobs arching templates were not helpful. I think my topo spacing was to far apart in the lower bout area from bridge to tail. giving a flatter profile.Ive completed the inside carve successfully without issue. If anyone has generated topo templates Id be grateful to get a drawing or pdf just to get my thoughts in line I want my top to be perfect..

[Barry Daniels]

What is the problem you are having with Bob's templates. They worked for me.

[Michael Lewis]

I suppose you can carve the inside first but I get the outside surface "perfect" before removing anything from the inside. I use a drill press with the quill adjusted as a stop for setting the thickness by drilling from the inside and carving to the bottom of the holes. It doesn't take too many times through the process to smooth out procedural wrinkles and find a better and more efficient approach.

The big drawback I see if carving the inside before the outside is done is that you risk making thin areas. You may well have better luck than I had doing it that way.

[Dave Stewart]

Im not very good with software and Bobs arching templates were not helpful. I think my topo spacing was to far apart in the lower bout area from bridge to tail. giving a flatter profile.Ive completed the inside carve successfully without issue. If anyone has generated topo templates Id be grateful to get a drawing or pdf just to get my thoughts in line I want my top to be perfect..

I agree with Barry .... if Bob's templates weren't helpful, you're not using them right. (Whether you like the arch they produce is entirely a different subject)

Generate your own "topo" maps during carving by chucking a pencil in a drillpress & pushing the blank into the pencil every inch or so. Raise the pencil a bit & repeat ... join the dots ... check your progress/ symmetry & adjust carving 'till spacings are even.

My suggestion is make up a practice piece in pine 'till you know what you're doing.

[Greg McKnight]

Benedetto has in his book a small depiction of a top with some drilled holes and lines circling around. My understanding is that you start with a 1" thick piece of wood, and the outer rim is 1/4". That would leave 8 steps of 3/32" to amount to 1". Do I have this right?

[Greg Martin]

well this is what i got,its ok . opps no pics uploaded.

[Greg Martin]

Ive stared at this pic for days and it finally clicked,i dont know why I couldnt understand what was shown.thanks to who ever posted this pic,really thanks alot.I saw the rule square and pen as props,but finally realised what was being shown was the transfer of the arch height for each section from one view to another, I guess im alot slow when it comes to reading blue prints.

[Barry Daniels]

What helped me the first time was making poster board templates of the inside of the arches and creating a 3D spine model to visualize the desired finished surface. The reverse of these templates can be used during the wood carving process to get you close.