Official Luthiers Forum!

The recent post about bending form layouts got me wondering about something...
If I have some guitar plans with the body shape that I like, what is the most dependable, accurate way to make a mold from those plans? I was only able to think of buying some of that large carbon transfer tracing paper. Are there any other ways to do it?

Go to Kinkos an get a copy of the plan made. then cut out half and double side tape or glue it to your playwood

What I would do is glue the plans to the material your making your mold from and then cut the mold to the line. Or, you could glue the plans to 1/4" plexiglass or even plywood and cut to the line. This way you'd have a template and a mold. If you need to copy the plans first, try fedex kinkos. I think they have large format copiers.

Edit: Looks like the above guest and I were typing at the same time.

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Don Sharp
Got Brazilian?
http://www.sharpguitars.com

I cut out the plan, spray glue it to a piece of lexan (on the paper, of course). I cut it a little large on the band saw and finish with a drum sander. This gives you a clear half pattern to lay out a mold - and you can see through it for wood selection.

Welcome to the OLF.
If you're anywhere near central PA we are having a get together at:

Blues Creek Guitars
244 Forrest Dr.
Hegins, PA 17938

Saturday at 10am

Steve

All wonderful ideas guys, thanks. I'm sure I won't have to sweat this part that much now!
SoundMan Steve, thanks very much! I would love to attend but I will be away for the next couple of weeks. Hegins would probably be around a 3 hour drive or so. Hopefully in the future!

Another no destructive method is to tape you plans onto the insid of a window pane with a bit of light outside, then tape another sheet of paper over.
You then trace onto the new sheet.

Just go get some carbon paper (office supply), lay under the plans and use some kind of a stylus to transfer. No big deal. Cheap too! Just did my Harp Guitar mold thatta way.

Mike

Also bear in mind that if you glue paper plans to something using a water based glue, the paper will absorb water from the glue and expand significantly, changing the dimensions of the plans. I'm not sure about other glues, since I haven't tried it.

I like some of the transfer ideas described here, esp Todd's, but I have also found it often works well for me to simply redraw the plan onto the material from which I'm making a template, mold, or whatever. That gives me a chance to double check all my measurements and take the time to draw a really accurate outline onto the material that will actually be used to make the guitars. I draw my original plans on vellum (high quality tracing paper I buy in big rolls at Staples), so I can then lay my original drawing on top of my newly drawn outline on the template/mold/form and check that everything is perfect. That's where the double checking comes in, to assure that I've drawn exactly what I intended to draw on both the original drawings and the template/mold/form material.

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Todd Rose
Ithaca, NY

https://www.dreamingrosesecobnb.com/todds-art-music

https://www.facebook.com/ToddRoseGuitars/

Be careful copying plans @ kinkos or the other cheapie office supply places.

Their copiers are often (read... rarely ever) calibrated correctly and they will not be 100% perfect reproductions. I often find that if the width is correct the lengh is off by as much as 3/16"... so keep this in mind.

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Brock Poling
Columbus, Ohio
http://www.polingguitars.com

I get accurate copies made at a local place that supplies architecs called Triangle A&E. Their copies are pretty accurate and their pricing isn't any higher than Kinko's. I also get a discount because my wife works for an architecural firm.

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Dave Rector
Rector Guitars

Does anyone know of a place in the NYC area that could make architecture-grade copies? I don't know exactly what machine I'm looking for so I'm having a hard time.

Two bad things about gluing the pattern to the wood; one the will cause the paper to be stretchable, even spray adhesive if you burnish the paper out in an attempt to get it flat. Two when band sawing the pattern out the paper tears and at a different rate than the wood cuts some times. It can work but you will be much more accurate if you draw the pattern on the wood in pencil or make a traceable pattern from chipboard or acrylic.

I took my plan, laid it on a table, and then put a piece of plexiglass on top of it. I then copied the plan onto the plexiglass with a permanent marker. I also drew a straight hashed line down the center that marks the center line.
I also cut out my mold to the desired shape, and laid it on top of the plexiglass. I had previously altered the body shape of the mold slightly to a shape I liked better. I lined up the center lines, and then drew the mold outline with a sharpie on the plexiglass. The bacing pattern and guitar outline match up perfectly.
Then the best part: I drilled small holes at each corner of the brace lines and soundhole center. They are just big enough that a number 5 mechanical pencil can stick through and make a pinpoint dot.
You can cut the outline out on a bandsaw and clean it up with a drum sander.
I can take this jig and in about one minute make an exact reproduicible layout of my plan on my joined soundboard. Once you have the dots on your wood, you just play connect the dots with a straightedge and it is done. You can make 500 tops with this and the bracing patteren would be identical from first to last.

That's what I did, the only problem is you can't check your drawing directly against the original plans... You can still measure it of course

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Jeremy Douglas

I photograph the plans, then use the picture as background to redraw them accurately in Corel Draw. I use actual dimensions given on the plan, rather than measuring off the plan itself, to adjust my Corel Draw version, ensuring is super accurate (because the copy of the plans sent to me usually is off by quite a bit from the given dimensions). Once I have the plan redrawn, I cut out acrylic or lexan templates directly using my Epilog laser engraver. Voila.

Dave F.

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Cambrian Guitars

"There goes Mister Tic-Tac out the back with some bric-brac from the knick-knack rack"