DrKev
Wholenote
It's just a guitar, it's not rocket science.
Posts: 418
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Post by DrKev on Apr 7, 2023 5:30:40 GMT -5
When reshaping part of a pickguard to fit, what is your preferred approach for the bulk of the material to remove? There are no machine tools available, so it's files, card scraper or blades, or hand sanding. I've always gone needle files and sandpaper on a dowel before but I feel like I should be getting cleaner straight lines. Thanks!
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Post by Peegoo 🏁 on Apr 7, 2023 8:31:02 GMT -5
One of the tricks to forming straight lines on soft materials like plastics, aluminum, etc., using sandpaper is to back the paper with something that is almost as long or wide as the straight area you're working. For example, if you're removing a small dimension from this area, use a sanding block at least 2" square.  If you use something narrower such as a 3/4" wide file, the line can get uneven and you tend to remove too much from the center. |
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DrKev
Wholenote
It's just a guitar, it's not rocket science.
Posts: 418
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Post by DrKev on Apr 7, 2023 10:36:16 GMT -5
That's makes total sense. Thank you!
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Post by funkykikuchiyo on Apr 8, 2023 14:43:01 GMT -5
Yeah, flat blocks with sandpaper are critical, deburring with a razor blade from time to time. Plastic works so strangely under your hands that you can't rely on your eye or feel as much. The way it plugs tools quickly, and has grain that is far less predictable than wood (in the way all materials have "grain" and internal tensions), it is just going to mess with you a lot. Also, having an array of dowels for the rounded parts helps - the closer the radius of the dowel to the rounded part you're chasing the better. Sounds like you got that already, but having multiple sizes can help as the straight parts transition to the flat parts. That is usually where I struggle the most, getting the round part to have a perfect tangent launching into the flat part.
Clamping it to a bench with the part you're sanding hanging over helps, too. It keeps it from vibrating/being floppy, and you might be able to have a fence in place, if nothing else but as a visual reference. So, if you know EXACTLY where that line needs to be, you can clamp a straight piece of wood up to it sort of like a router fence, but use it as a guide for your hand tools. If you munch into your fence with a giant rasp it obviously won't be as effective, but it can still be helpful. I've tried scoring a line to work to before, but it tends not to work as well because an x-acto REALLY wants to wander on plastic, and the way the plastic burrs, it is hard to see the line as you get closer - it isn't like wood where you can see the material change slightly when you hit the line. I might be doing it wrong, though.
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DrKev
Wholenote
It's just a guitar, it's not rocket science.
Posts: 418
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Post by DrKev on Apr 9, 2023 7:56:25 GMT -5
Thank so much guys.
I spent my high school in an engineering shop so I naturally go to files rather than sand paper for something like this. The sand paper *with* flat blocks are what I've been missing.
I was considering the scoring idea, going deep and hard and following with sharpie in the score line, but you are absolutely right that that straight lines with blades on plastic are a very low percentage shot.
I have an original guard as a template and I think I'll sharpie the line from the original and work to that. As most of this work current job is neck pocket fit, I might just screw the guard on and sand with a block till I hit the neck cavity.
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Post by funkykikuchiyo on Apr 9, 2023 11:27:00 GMT -5
If you can fence off well, you can probably get a good scored line, but it would probably mean clamping a steel straight edge down and following it.
I'm not sure how much they help. With wood, if you work to a scored line on joinery, you can see the wood behave differently when you hit the line, or use the line to index a chisel, and I'm not sure you get any of that with plastic... but, maybe you do and I just haven't tried it enough.
If it is a Strat style heel that doesn't have flat spots on the end, you can probably make a flatish curved block, radiused tighter than the curve you want but not as tightly as a dowel. That will keep tool lines much better blended. The flatter you make it, the closer it would have to be to the exact shape of the end of the heel, so keeping it bit rounder lets you work it by eye more.
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DrKev
Wholenote
It's just a guitar, it's not rocket science.
Posts: 418
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Post by DrKev on Apr 9, 2023 15:07:56 GMT -5
If you can fence off well, you can probably get a good scored line, but it would probably mean clamping a steel straight edge down and following it. I've seen blades wander away from a straight edge on plastic. The surface is always harder and slicker than I expect and this conversation is great reminder of that! And like you said, it's not wood. Without a good fixed fence or template, working by eye to a scratched line will be tough, especially if the edge frays and curls and static makes the dust stick in all the wrong places. I'll go with Sharpie for visibility and an appropriate sanding blocks. |
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sirWheat
Wholenote
For a better future, play Stevie Wonder for your children.
Posts: 319
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Post by sirWheat on Apr 9, 2023 17:10:55 GMT -5
For scoring anything like that, a marking knife is best. It has a single bevel and will be less likely to wander, assuming you're using a straight edge or block when scoring the line. As always, go lightly and make a few, or several, light passes rather than trying to do it in one go.
One other thing; if you're using a sanding block, always glue (or use two-sided tape) the paper to the block. No matter how hard you try, if you're just wrapping the paper around whatever block, or dowel, the paper will bulge away from the block and tend to round the edges over.
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