Hello!
I have a student who needs to sand MICRO cuts in plastic - specifically taillight plastic - I’m wondering if you guys have any ideas on tools that might work to get into the groves.
He has a Dremel but it’s melting the plastic he needs to go in and finish some of the cuts before a clearcoat spray.
Wondering if something like this might work or if you guys know of anything I’m not thinking of:
If they are melting the plastic, any aggressive sanding tool is going to have the same effect. They need to slow the tool down.
If the plastic is already grooved and all they are trying to do is polish it, wet sanding with fine sandpaper is a potential option. if the grooves are so small that sandpaper isn’t an option (and micro implies this) then fine abrasive paste like rouge or toothpaste with a tooth pick or popsicle stick, possibly with some water may be an option. Power tools aren’t always a better choice. If the grooves are that fine and the plastic has such a low melting temp, handwork is probably the order of the day.
I’d recommend radial bristle discs. Typically used by jewelers you can use them on a Dremel or equivalent. Riogrande carries them in a wide variety of grits. He’ll want something about 7/8" diameter. Depending on how coarse his stuff is … he can start with something like 220 grit and work up a very high grit like 1600.
Note that the price is for a 12-pack.
People typically mount several discs on the mandrel at one time but that will depend on the width of his grooves.
He will also need to buy a mandrel to hold the discs. The disc has a 1/16" hole, so he needs either this nickel-plated mandrel or this stainless steel one. Note that the price on these is for a 6-pack.
This is a good choice, but they will still need to go slow.
I have found that the best way to polish acrylic is a combination of progressive micro mesh hand sanding and a multi-stage polish like novus 3 stage polish. Micro mesh sanding pads start at like 800 grit and go to 12k or so. Powered sanding of flat acrylic surfaces is hard to manage with high speed tools like dremels . Marlowe of dead on with her recommendations but the best outcome will be from hand sanding with micromesh and a final polish . By the way, I have done this in vintage tail lights and it works well. For deeper scratches you may need to start with a lower grit than micromesh and work up to the micromesh range . You at looking for a uniform dull finish that blends out the scratches before you start the progressive polishing with micromesh. Final polish can be with. Soft foam pad and a hand drill or polisher .
@keoliver is spot on that hand polishing with successive micromesh grits is the only good way to get any large/flat areas smooth and polished. I’m recommending the radial bristle discs for the grooves or micro areas.
Depending on what he needs to do … an old electric (rotary) toothbrush with toothpaste and then baking soda might give him a real good start.