Help with first build - making guitar mold

[blnote]

Had access to a ban saw & spindle sander so I thought I'd make my own mold from the pattern I received with the kit (traced half D-18 body on cardboard). The upper bout is off a 1/4" (11 1/4 instead of 11 1/2), waist seems right at 10 1/2, lower bout is off an 1/8 (15 1/2 instead of 15 5/8) lenght is a tad over 20". I'd love to know where I went south but instead wanted opinions on whether I should trash this, fix it, or is it even that critical. Sorry, I did search the forums, and googled this for days. Thanks

[Neil K Walk]

What materials and type of mold are you making? Are you making a solid mold or a semi-solid mold? Are you using birch plywood or MDF?

I'm only a little further ahead of you but went through something similar. My first attempt was a solid mold out of MDF and had to trash it. My second attempt is a semi-solid mold made from birch plywood and things went a bit better.



If you're setting out to make a mold such as this then concentrate on getting one board perfect to the profile and use it as a template for the rest. From what it sounds like, you still have extra material to work from so all's not lost. If you have a template then just place it on the top of the master (with a piece of scrap to support it) and trace the outline on the top of the board.



I didn't have a spindle sander though, so you're one up on me as far as accuracy:



...actually that little jig didn't work out so well so I used a better spindle on my hand drill and a t-square to make sure I kept the cut outline perpendicular to the surface of the board. Just be sure, I checked against the blueprint frequently until I was satisfied:



...then I went about using the master as a template for the rest of the outlines. I made sure to protect my master as best I could but I'm told that a pattern-tracing bit on a router table would be the best tool for the job:


Once I had everything matched up I checked yet again against the plans:


after that it was just a matter of assembling the mold and using pine as spacers and sanding them down to match the outline.

[Kitchen Guitars]

Originally Posted by kwakatak

What materials and type of mold are you making? Are you making a solid mold or a semi-solid mold? Are you using birch plywood or MDF?

I'm only a little further ahead of you but went through something similar. My first attempt was a solid mold out of MDF and had to trash it. My second attempt is a semi-solid mold made from birch plywood and things went a bit better.



If you're setting out to make a mold such as this then concentrate on getting one board perfect to the profile and use it as a template for the rest. From what it sounds like, you still have extra material to work from so all's not lost. If you have a template then just place it on the top of the master (with a piece of scrap to support it) and trace the outline on the top of the board.



I didn't have a spindle sander though, so you're one up on me as far as accuracy:



...actually that little jig didn't work out so well so I used a better spindle on my hand drill and a t-square to make sure I kept the cut outline perpendicular to the surface of the board. Just be sure, I checked against the blueprint frequently until I was satisfied:



...then I went about using the master as a template for the rest of the outlines. I made sure to protect my master as best I could but I'm told that a pattern-tracing bit on a router table would be the best tool for the job:


Once I had everything matched up I checked yet again against the plans:


after that it was just a matter of assembling the mold and using pine as spacers and sanding them down to match the outline.

Neil that turned out great. Looks like it will still be going strong on your 10,000th build

[Neil K Walk]

Originally Posted by Kitchen Guitars

Neil that turned out great. Looks like it will still be going strong on your 10,000th build

As will your L-00 mold, buddy. That thing will outlive our grand kids so long as the Lord's willing and the creek don't rise!

[martinedwards]

the spacers between the top and bottom don't need to be exactly flush with the edges. if they're set inside they won't damage the build any way.

and it's easier.

[blnote]

Thanks for the reply, yours looks great, I think I'm more impressed with your sanding jig. I was heading that way I until by chance I came accross a spindle sander at my in-laws. I pretty much followed the process on LMI's site - http://www.lmii.com/carttwo/davekit/...ldingamold.htm

Looks like I'm going to try this again. Working with just a tracing of half the body on cardboard, I think each step I got a little off. I knew when I started that expereince working with wood doesn't translate into woodworking experience, throwing out plywood is one thing, throwing out rosewood is another. I'm a little more apprehensive than before.

[Brackett Instruments]

Originally Posted by blnote

Had access to a ban saw & spindle sander so I thought I'd make my own mold from the pattern I received with the kit (traced half D-18 body on cardboard). The upper bout is off a 1/4" (11 1/4 instead of 11 1/2), waist seems right at 10 1/2, lower bout is off an 1/8 (15 1/2 instead of 15 5/8) lenght is a tad over 20". I'd love to know where I went south but instead wanted opinions on whether I should trash this, fix it, or is it even that critical. Sorry, I did search the forums, and googled this for days. Thanks

Some builders (including some that build really nice guitars) don't even use a mold. I built my first 4 with no mold. Using the......"imperfect" mold you've made would be OK, but.........(there's always a but) I suspect your kit came with pre bent sides. Clamping the sides into a mold they don't fit could cause problems. I'm not real picky about 1/16th here or there on my molds, but my bending forms are made from the inside pieces cut out when I make the molds. This insures that my sides fit my mold so the guitar isn't assembled under a bunch of stress.

[mercy]

Do it again, do not use the form you did. If you use it you will have no end of headaches. If you cant build a form you cant build a guitar. Try again.

[Guitar Hack]

It's easier just to buy one.

[arie]

i built myself something similar to this:



i used pvc pipe for risers instead of wood and did away with the rubber band hooks. i slotted mine to handle anything from a 3/4 to a jumbo.

[TomDl]

"It's easier just to buy one."

What? The guitar?

If you are just making a couple of guitars with that pattern to start with, it is easier to build without a form. I build classicals were that was always done. I read somewhere that Torres built like about 30 times less guitars than Martin, but he sure didn't waste time on tooling! With classicals there are so many different shapes, that it doesn't make the same sense to build forms. And guess what? It turns out just fine. In the beginning you are either bending your own sides, or using prepared sides, forcing those into a mold isn't as good for the guitar as putting them where they want to be if that is 1/32" fair curve somewhere else. And if your sides are dead nuts perfect, then you really don't need a mold.

Of course if you are just building the first of 100 identical guitars, you need a mold. But to start with I would spend my efforts/$ on bending tooling like a real hot pipe, or a Fox bender.

I am certainly not saying you shouldn't build a mold, but you don't have to.

When I build a mold I use a bandsaw, and a drill press spindle sander, and it is all pretty easy to do. If I didn't have a spindle sander, I would fair up a thin piece of ply and use it as a pattern to rout from.

[arie]

one good thing about a uni mold is that you can stack up 10 templates in the space of one mold vs. stacking ten molds around your shop.