Question on making a template out of plexiglass

[Neil K Walk]

Last night at Yamaha Junkie's I tried to undertake the process of making a template out of plexiglass and met with my first failure of what are sure to be many.

As I stated in my other thread in this section, I purchased the blueprints for the Official Luthier's Forum medium jumbo and last night I carefully traced them on a thin sheet (about 1/8" or maybe less) of plexiglass. Tracing it was tricky enough: I used a lot of green tape to hold things steady and despite the offering to use a French curve I mostly made use of my freehand skills and a straight edge. Once I traced the outlines and bridge plate position and bracing pattern/scalloping I moved on to trying to score the outline with a razor blade in the hope that the plexiglass would break cleanly.

Long story short: it did not and there are a couple of areas where the deviation from the curve were significant enough that the whole thing warrant a "do over."

As I think this over I can't help but wonder: is scoring the plexiglass and bending/breaking it by hand really the best method? Would a jeweler's saw make a good alternative?

[runamuck]

Originally Posted by kwakatak

Last night at Yamaha Junkie's I tried to undertake the process of making a template out of plexiglass and met with my first failure of what are sure to be many.

As I stated in my other thread in this section, I purchased the blueprints for the Official Luthier's Forum medium jumbo and last night I carefully traced them on a thin sheet (about 1/8" or maybe less) of plexiglass. Tracing it was tricky enough: I used a lot of green tape to hold things steady and despite the offering to use a French curve I mostly made use of my freehand skills and a straight edge. Once I traced the outlines and bridge plate position and bracing pattern/scalloping I moved on to trying to score the outline with a razor blade in the hope that the plexiglass would break cleanly.

Long story short: it did not and there are a couple of areas where the deviation from the curve were significant enough that the whole thing warrant a "do over."

As I think this over I can't help but wonder: is scoring the plexiglass and bending/breaking it by hand really the best method? Would a jeweler's saw make a good alternative?

I would recommend that you first make a template out of something like 1/4"
MDF and then flush cut the acrylic to it with a router.

But the only reason one would need to be using something as durable as acrylic is
because you plan to make many guitars off it, - over and over and over again.

Jim McCarthy

[Neil K Walk]

Originally I was just going to use a piece of cardboard but YJ suggested I use the plexiglass. I may just yet use the cardboard, if only just to have an outline to transfer to the MDF mold we're in the midst of making. Still, I can't think of an easier way to transfer the bracing pattern to the top.

[Kitchen Guitars]

The superglue held, You have a template.
The reason we used Plexyglass is I have a bunch of old ad frames that are shot so the Plexyglass is lying around/free. Cardboard works, I like seeing through though.

[arie]

Scoring and cracking plexiglass isn't the best way and you will wind up with cracks, chips, and misery etc... on the back side.

Runamucks idea is ok but now you have to cut 2 templates instead of one.

Try instead:

-A jigsaw equipped with a fine pitch metal cutting blade. Whatever the material thickness is try to get at least 2 teeth into the cut. Finish up with some light drum sanding with a Dremel or equiv. I do this at home.

or,
-A bandsaw with a fine pitch blade. Again, whatever the material thickness is try to get at least 2 teeth into the cut.

or,
-A Haas VF2 vertical machining center, doubleback tape, and a 2 flute carbide endmill. Design your template in Solidworks, program the part in Camworks, and you have a perfect template. (it could happen) I do this at work.

[Neil K Walk]

Originally Posted by Yamaha Junkie

The superglue held, You have a template.
The reason we used Plexyglass is I have a bunch of old ad frames that are shot so the Plexyglass is lying around/free. Cardboard works, I like seeing through though.

Really? That's great! So we have a smooth enough outline to transfer to the MDF mold?

Don't laugh but I taped the plans to my kitchen floor and was trying to replicate what I'd done the other night with wax paper and a Sharpie. I used a pair of very neglected 30 pound dumbbells as paperweight but the wax paper kept shifting. When I flipped it over everything was off. *grumble*

At this point I'm just concerned about symmetry so that I can get the top done. I still think I may try John Hall's method for transferring the bracing pattern to the underside of the joined top though.

[SMan]

Spiral cutting bits work well with plexiglas.

And regarding plexiglas templates....they are great when trying to determine how to crop a top or back when cutting them out. You just position the clear template on the book matched set and mark out the perfect area that highlights your favorite grain.

[BlackHeart]

Just use paperboard from art supply store. You cut out the brace pattern after you trace it with tracing paper, with exacto knife. You make triangle cut outs at the corners/ends of the braces. Kinkeads book shows this.

[SteveS]

I hate Plexiglas and I hope to never use it for anything. Lexan (polycarbonate) is so much easier to work with and will not shater like Plexiglas. I use thin plywood or Masonite for my templates.

[SMan]

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[Neil K Walk]

Originally Posted by SMan

Waiting for a Mod to make this spam man go poof......................................

As the OP I felt it my civic duty to report it. Besides, Armani is way too gaudy for me and doesn't really go with sawdust.