Homemade lenses from cd case or simaler?

[okoshima]

Ok I got a pair of vintage welding goggles on ebay, the problem is the lenses have deteriorated (apparently)  and I was wondering about how to go about making my own lenses? (low budget)

My ideas so far:

-CD cases, i have seen cheap coloured ones (neon/uv reactive)
-Cheap sunglasses
-Cheap welding goggles (flip up lens type a pair of clear and dark lenses for cheap + parts to make something else maybe?)
- plexi or poly sheets (not as cheap)

I have a cheap rotary tool and can maybe get access to some hand tools if required (I would probably use a hot knife or old soldering iron and finish with sandpaper if needed)

Thank you all for any help.

okoshima.

[Alderman Simeon]

I'd go for a CD case; readily available, cheap, easy to work. Heat tends to make it bloom, so I'd probably use a fine saw.

Take care if you opt for polycarbonate as it tends to shatter. Hot acrylic (Perspex, Plexiglass) releases small amounts of cyanide.

[okoshima]

thanks for the info (cutting would have been done outside or in well vented area) and I was thinking of trying a rotary tool with I think its an engraving bit to go gradually deeper until its through

[Spreggo]

I've cut lenses this way with a sharp instrument (tiny little screwdriver, or really sharp tac) and a guide. Luckily I happened to have a metal ring which was very close in size to what I needed. I rubber cemented the guide to the plastic, then taped it down. Then I just pressed firmly and rand the sharp bit around the inside of the ring until I was nearly all the way through, and was able to remove the lens with a pair of clippers. I used the plastic from an ipod casing that they are sold in, it is thicker than cd plastic. Cd case plastic is prone to shatter, but if you have a lot to try it on than it should work fine.
I used fine sandpaper to bring it down to a perfect fit.

[Hydrargyrum]

I tried CD case plastic - I found that it would scratch and crack VERY easily; I lost two lenses just as I started cutting them, and in some cases, just having it lying on the table with the tools was enough to bump it and make a large scratch. If you want clean, clear plastic, you may want to look elsewhere.

[Smaggers]

Wrigleys Extra chewing gum now comes in 60 piece pots that have softish plastic flip lids in clear blue or green.  A couple of the lids would probably make a goodish pair of goggles on their own with some paint applied, but would provide easily worked lens substitute anyhow.  The might scratch, but are soft enough not to break.

(beware the side effects of too much phenylalanine)

[okoshima]

ok apart from that (may pick up a couple of green) any more suggestions?

Thanks again and if all goes well I may make a how to (I would ask permission to use your ideas and give credit of course)

[okoshima]

does anybody know what a cd is made from? I ask this after testing a small "lens" made from it and it being rather robust to shock and repeated beatings with a variety of tools.

many thanks

[Hydrargyrum]

Via wikipedia:
A Compact Disc is made from a 1.2 mm thick disc of almost pure polycarbonate plastic and weighs approximately 16 grams. A thin layer of Aluminium (or rarely gold, used for its data longevity, such as in some limited-edition audiophile CDs) is applied to the surface to make it reflective, and is protected by a film of lacquer. The lacquer is normally printed directly and not with an adhesive label. Common printing methods for compact discs are screen-printing and offset printing.

[okoshima]

Thanks and I had guessed polycarbonate due to my tests, or more so the outcome after 45 minutes of stress testing of force (piece set on duct tape roll beaten with both high impact and high pressure) the damage was a lot of dents, 1 crack and a small chunk removed.

I only stopped due to boredom, all i need now is to wait for my goggles to arrive and hope the lens is small enough to be made from a cd, if not can anybody suggest a different approach (as in materials)?

Thanks again

[Hydrargyrum]

I've heard of CDs coming apart in such a way that would allow you to use the clear piece - Is that what you did, and if so, how'd you get it apart?

[okoshima]

Ok one of 2 ways
number one:
1: Apply duct tape to top of cd (label)
2: rub down lots.
3: remove fast or slow whichever works.
4: repeat if needed.

number two:
1: cut out shape.
2: use method 1.

Hope this helps

o and i use cdr's as they are cheap and plentiful

[Mydnight]

method # 3 -- put in the microwave for 5 seconds

[clockdug]

Ooooh....sparky!

The microwave technique should be tried when authority figures like bosses, parents or wives are not present.

[Alderman Simeon]

At work, I use a dead CDR as a caster for my teas cup, and over time the coating has come off, leaving a clear polycarbonate disc. Perhaps simply immersing it in hot water for a while would work.

[Duncan Hawthorne]

another idea would be to find old camera filters that are the size of the tube you want - look for skylight or polarized for clear/semi-clear respectively, or colored for daytime use.  The old ones will probably be a better fit, and in my experience if you're looking for them, don't tell the seller what you want them for - some old camera buffs understandably hate losing their vintage gear to home engineering. 

Anyway, the filters are measured in mm (25mm is roughly an inch for the fellow Americans), have fairly decent optics, probably won't shatter (?) and are kind of neat looking already.  You can usually find them at flea markets and antique stores or on eBay.  They aren't the cheapest solution, but will be nicer than a scratched up piece of CD case, and aren't super expensive usually.