I’ve experimented a bit with cutting the focus/centering tube off of an incan Maglite reflector (scrap part). I used a rotary tool with a cutting disk. Made quite a mess and ended up with a lot of fragments on the reflector surface…
Anyway, I was hoping someone could share with me their method? Have you tried widening the opening of the reflector (Smaller end near light source)? Any known method of accomplishing that?
I had in mind to try a red-hot wire, but I only have a few more scrap reflectors that I can practice on and I really don’t want to mess up a brand new rebel reflector.
I’ve seen some modder(s) use miniature slitting saws / cutting discs put into drill press chucks. Set the quill at the correct height, spin and cut. Burrs would presumably need to be razor’d off after the cut, or a chamfer tool could be used, also in the drill chuck. (I’d use a single fluter chamfer tool) A rotary tool or hand drill could be used similarly if they were mounted reliably.
I’ve cut the stem off a few, just used a junior hacksaw. Not the prettiest from the underside, but the reflector part is ok. If you cut the stem off right at the top, it will slightly increase the opening of the reflector. But I had issues with getting it to focus nicely after that, not sure why. These were old incan reflectors.
As they are plastic, I’d have thought a rotary tool spins too quickly and is likely to melt the plastic while cutting, due to heat. I’d guess cutting it slowly would be preference.
I usually cut reflectors with a hacksaw. High speeds make plastic melt, so hand work is better for plastic. After cutting, I use sandpaper on a bench top and run the reflector across that, to get it smoother and level again. For the inside, an exacto knife, or roll up some fine sandpaper and use it like a tube and go inside up and down, to sand the inside edge.
When I need to bore out from the inside, I like to use drill bits by hand. Not in a drill, just bare in hand. I keep the reflector pointing up so that debris tends to fall down away from the reflector. I take as small a step as possible and move up one bit at a time. When done, I use one of those air puffer thingies (see below) to gently blow out any debris that stuck to the reflective surface.
EDIT: I wish I could remember who originally recommended the above product. I prefer it over compressed air as seems to pose less risk of damaging the reflector. Compressed air is much stronger though and will clean of debris better. So I keep a can handy just in case some stubborn debris refuses to leave with the above..
I just chuck the plastic cam part in the lathe and run it very very slow with a parting tool. You could to the same in a drill or drill press if the chuck is big enough. You could use a hacksaw instead of a parting tool.
Old lumens is correct, hand work or very slow speeds work better on plastics, or if you have to use a rotary tool, get a diamond cutoff wheel, and cut it under water. Preferably a tool with a long shank
For those without a lathe I would reccomend doing a rough cut with a hacksaw or similar leaving about 1/16” of extra material. I would finish the piece by putting sandpaper on a flat surface and work it in a figure 8 pattern down to the final dimension ad this will greatly reduce the accumulation of burrs or rough edges.
hack saw and nail clipper. The hacksaw does the initial cut away from the hole (so no dust would get in) and the nail clipper removes the remaining bits of plastic till it’s right up to the ‘dome’ of the reflector. If you want to fuss, use the hacksaw together with a vacuum (to collect the dust immediately.)
Get a drill press. Watch Harbor Freight’s sale flyers, you can pick one up for around $60.
Cutting plastic reflectors is super easy on a drill press. Use the lowest speed, use a diamond coated disc. They’re cheap. Slide the reflector around on the table by hand, not a problem with low spindle speeds and just plastic. The burrs left after cutting peel/flake off easily with a small knife or even a fingernail.
I can’t say anything bad about the harbor freight drill presses. I’ve abused several over the years and they seem to really hold up well for the price. IMO if you get one pay a couple bucks more for the model with the keyless chuck as I find the keyed chuck to be less than desirable.
My only knock on harbor freight would be their battery powered stuff. They’re weak and burn out quickly.
Another tip… paint the inside of the reflector with Elmer’s glue (very very delicate brush, or a cotton ball). Let it dry, do your messy cutting stuff, then soak in hot water to dissolve the glue.
I appreciate the responses very much! For now by hand sounds like the best option for me. Though that $60 drill press sounds like something I need to keep an eye out for.
i use yellow handles sheet metal sheers, and it works great, i cut along the edge of the cam, spiraling down to the lip of reflector opening, no dust, no damaged reflective coating. very easy and fast.
