I am looking for ideas on how to grind down the diameter of a flashlight lens, I broke the lens on my Solarforce skyline I and the size is not very common, its around 44 or 45mm and the regular Chinese vendors don’t seem to carry it, solar force sales wants $8 for the replacement.
I have a coated Mag lens that I am not using that is the correct thickness but need to file around 3mm all around, already tried a rasp with running water, its working but is going pretty slow for my liking, afraid to break it if i use the dremel, is there a faster method to grind it that I don’t know of? Anyone seen this lens size from the Chinese vendors (already tried the 42mm lens and is too small)
I have used normal fine sand paper on a concrete floor to sand off 1 to 2 mm without problems. Doesn’t seem to take as long as you would think either. You do have to be careful with all the small particles. Vacuum them up as soon as your done and throw the sand paper away. You don’t want that fine glass to end up some where that doesn’t feel to good.
If you think there will be some demand for that size lens, you can request such a lens in this thread. We requested a 64mm for our DST’s and they delivered at $3.50/each.
The OD was slightly too big to fit in the flashlight, so I applied tape to the optic surfaces, and ground or sanded the flange with a fancy fingernail file. Soon, the lens dropped into place.
Taping the optics protects from scratches while grinding. I used blue painter’s masking tape. It’s easy to trim and shape, and unlikely to smear gum onto the lens.
The black grit on this salon-style fingernail file (sometimes called a ‘cushion board’) is silicon carbide, the same stuff on most wet-or-dry sandpaper, and is nearly perfect for quickly and safely grinding glass, etc. I think mine came from Sally Beauty Supply, and I have them in several grits (80/100/180/240). Very useful tools.
Well, I wear a contact lenses and always buy them at the same place so they know me well and they are
willing to do that for free but I don’t want to exploit them too often
Draw the new OD with a sharpie, then use clear packing tape on both sides. Protects from the inevitable slip-ups (ask me how I know...) and at the same time keeps the sharpie from wearing off while being handled.
Plain aluminum oxide sandpaper will work, or a diamond file. A lot of cheap lenses aren't polished on the outer edge and that can make cracks or chips much more likely to happen, and smoothing that OD is something I have to do fairly often.
I do my best NOT to have to do that!! BUT... when I do, I use a wet belt on a 2.5" wide expandable drum.... the water does away with the glass dust and if you finish with a 600 or 1200 grit aluminum oxide belt, the edge appears nearly.... I said NEARLY polished. Places like Rio Grande supply in Albuquerque NM keeps the drums belts, all of it. I do wear some cotton gloves because the edge gets sharp. If the lens spins a little.... OUCH!
