Primarily Petroliana Shop Talk Forums Shop Talk Petroliana Forums General Petroliana Discussion "Trimming" lenses....?

Hello All....
I have a Marathon Diesel 2 lens notched for a glass body. My problem is the lens was not properly trimmed at the factory and has a small area that sticks out too much for the lens to be mounted to a body. If one were to try it would undoubtedly crack from the pressure of the uneven border point. I am not handy with glass so do not plan to attempt anything myself. My only thought is to take it to a local glass company and see what they can safely do to it.
Has anyone else ever had this issue and how did you handle it, or any suggestions I should give the glass folks or am I thinking this is a bigger deal to fix than it really is, lol?
Thanks for any suggestions,
Darin

have a pair of flying A 15" & one is as you describe-
haven't done anything with mine as you only have one
chance with glass...

I haven't had that problem with globe glass but had the problem with an ad glass that was purchased. The place I got it from was very helpful and told me to trim with a pair of nipper pliers. It works really well if you take your time. I know your glass is curved and may be a different scenario. Hope this helped, Tim

I've heard a water jet is good for cutting glass. I don't have any first hand experience though.

My mother had some glass ground down once at a glass shop. The guy used a special grinder similar to a knife sharping wheel. Dave

ive had it done--my glass shop use a commerical wet belt sander

but one wrong move and it breaks-- and it has happen at my expense

My local glass shop makes all of my window door glass for pumps for me. When he has to radius the corners on them he marks and scores the radius and the breaks it off around the corner on the score line. This usually gets ragged as it goes and then he sands the radius smooth on a belt sander. I'm not sure what grit the belt is or if it's a special glass dressing grit but it can bring down a pretty good irregularity in the edge of the glass. I tried it once making up a special ad glass I needed a radius corner on, using my belt sander with 100 grit in it. I cracked the glass.....I think I might take the lens to a glass shop and see what they say. I wouldn't think they would try to fix it if they didn't think they could, but you never know I guess.....GB

Thanks for the suggestions so far everyone. I got your message when I returned home tonight Neil, I will call you tomorrow.
I realize this lens isn't super attractive, but it's not a globe you see every day either. I could always be super safe and only display one of the pair, but would like both lenses on the body if possible.
Darin

I also had a set of 15" lenses that were slightly out of round. They had 2 spots that stuck out about 1/8", preventing them from fitting into a metal globe body (probably why they were never used). I ended up shaving them down on my bench sander. I went slow and easy to keep the heat down. Probably one of the most nerve wracking hours I've had in a while. But it worked! Now, 15" lenses are thicker than 13.5" so risk may be increased with the thinner lenses.

Darin, I retired after 39 years from a plant that made glass grinding/cutting equipment. Modern machines use glass coolant solution while grinding. However, glass can be sanded down by hand with NO coolant if you use a lot of patience. HEAT is what breaks the glass. I've sanded imperfections down many times by hand with a belt sander & simply with a sanding block. Sanding block by hand is the safest way; you won't generate heat. Just take your time & those rough edges will disappear. Funny story: when I was still working at the plant, one of the employees wanted a piece of 1/8" window glass for his garage door. He gave us the dimension & we cut it exactly to his measurements. However, when he got home, he realized that the measurement was 1/16" too large on one side. This was on a week-end. Following Monday he comes in & tells us what happened. He made the glass fit by rubbing it on a cement sidewalk stone all week end long to get the size down!!

I use to do stained glass as a hobby. Had a wet grinder that worked great. Basically a router with a diamond covered bit and a water pump.
he other way is to sand it down. Just don't let it get too hot.

...this is the part where DB would ask how much beer that took

Thanks for the additional comments.....Sam, sounds like a pretty safe plan there just slowly sanding it. Any certain grit of paper to use? Like Griffin's, this area is about 1/8" out at the widest point by about 1/2 and inch long. You can see the original score line on the back of the lens under the frit by the way.
Darin

Darin, you can use #100 or #120 grit paper. No matter what, the glass will wear down the paper. fasten the paper to a sanding block to make it easier. With some patience, you'll get it!

Darin, I'm kinda thinking that you should bring your lens 12 miles north of you and drop off at the garage to keep my single lens company.
Roger