Best way to cut circles from shower door glass?

I want to make some semi-circular shelves from 1/4" thick shower door glass. Anyone have a special technique for this ?

Thanks,

TMD

more likely then not shower door glass is tempered for safety which means it will most likely shatter if you try to cut it...

I know laser and water jet would both do a nice job, but wish there were something I could jury rig to keep costs down.

TMD

TMD,

How about something like this: Wire Saw Blade?
Depending on how big your shelves will be, and how many you want to cut, I'm sure the wire saw might be a bit tedious, but cheaper than buying a waterjet! I think I've seen these in versions with a ring on each end, so you don't need a saw frame, but this is what I found with a quick Google. Perhaps a more diligent search will turn up something better.

RAS

hate to say it, but when i have specialty glass work to be done, i take it to my local glass shop. I have cut countless panes of glass, and special shapes. Time vs. loss vs. ease vs cost. Most glass shops for cutting are not as expensive as you may think. That, or I live in an awful inexpensive neck of the woods.

Probably the wrong thing to say, but the truth. Take it to a glass shop.

Doc,
Building codes require the glass in shower doors to be tempered. It'll fly into a million pieces if you try to cut it. Most shelves are cut from plate, 1/4 or thicker depending on the application. My brother in law is in the glass business, and I've seen them hand cut circles. Its a matter of scoring the circle and then scoring radial lines outward to the edge, and then getting the segments to break into but not across the circle. From what I've seen, even the guys who do it for a living are a long way from a 100% success rate when cutting circles. If you try it, the first thing you need is a good oil-fed glass cutter. They make a nice line whereas the hardware store variety basically crushes out chips in a somewhat linear manner

If it's tempered, yer screwed...

If not, it's relatively easy to do. You will end up with sharp edges though.

Get yourself an oil fed toyo glass cutter, draw the line with a perm marker then score it. You will want to get some running pliers, they make the job lots easier. Running pliers are pliers with a concave and convex jaw, they are made to "bend" the glass and cause it to break at the score. After you start the score, use a small screw driver and tappity tap tap on the score all the way down. Some of the time it will help if you run lines off from the center of the circle and do it in sections.

After you do all this, find a diamond grinding bit, the larger the better, and touch up the edges to smooth everything.

Make sense?

What is the size of the radius btw?

If the glass is textured it will make it more difficult, but still doable.

I did stained glass for a few years, cutting circles is easy, cutting holes is not

-Jacob

No lie about tempered glass. A friend of mine had a fair-sized piece of tempered, it was an old solar panel.

He managed to just nick off a corner handling it. Really small damage, less than a 1/16" triangle knocked off.

That piece was cracking for the next 4 hours. It immediately got a loose spiderweb of cracks all over it, inside of 10 seconds.

Then, while we were sitting around thinking of other things to do, that piece was going "tink" , plink", "clink-clink".....one little crack at a time. By the time it was done, it was cracked into pieces averaging about 5/16 square.

No way can you cut it.

Unless the shower door is really old, it will be tempered. Bascially, building codes require all large glass surfaces (like doors) to be "safety" glass, which means tempered or laminated. It's not a coincidence that tempered glass shatters into little pieces when it is broken -- that's exactly the characteristic that makes it safe.

Tempered glass can never be cut. Each piece is tempered in the exact size and shape you order. The tempering process is to heat the glass and rapidly cool the surfaces, then when the hot center cools slowly it shrinks the surfaces (including edges) The result is a like a sandwich in which the surface is in compression at about 10000 psi. Same principle as a pre-stressed beam if you know how that works. But all the forces are in balance, and as soon as you violate any part of the exterior envelope, the stresses become highly unbalanced and put some part of the glass in tension, which glass cannot resist, it yields, and sets up a chain reaction, soon reducing the pieces into pea-sized chunks.

Tempered is also ~3 times stronger than regular glass because of the pre-stressing of the surfaces in compression.

The easiest way is to bring a cardboard template to a glass shop where they will cut the glass, polish the edges and send it out to be tempered.

If you already have the shower door glass and you want to do this on the cheap...er...um...I mean frugal, you might try sandblasting. That's how I cut holes in glass taillights to install blue dot lenses.

A double layer of duct tape covering the glass that you want to use would likely be suficient to protect it. Laying an appropriately shaped piece of steel along the edge might give you a crisper edge. I used a big old flat washer when doing the taillights. I blasted through the ID.

I guess with all that advice, I had better leave the job to those who know what they are doing or get the glass shop involved. When I am thoroughly convinced that I cannot find somewhere in the open market the kind of thing I want I will either give up or have someone experienced do it for me. I don't want a shower of glass from a "shower" door.

Thanks to all for their advice.

TMD

As a slightly off topic divergence: A drunk girl (roomates girlfriend) kicked the front glass door in when I was in college. It was NOT tempered and her leg was cut all up and down. The cuts were 4 inches deep and 18 to 30 inches long. I had never seen blood squirt, but it does. We caught her on the way down as she was feinting, held her up, wrapped her leg tight, and called 911. She was fine, after lots of stitches and plastic surgery.
I would make sure your houshold doors are tempered.
Sorry but I had to add that.

You generally don't want to have shelves and similar items with exposed edges tempered. Edges and corners of tempered glass are very fragile, as as JTiers said, the least chip or crack at the edge will result in the glass self destructing. Most shelves with exposed edges are just plate glass with polished edges, because untempered plate can stand a bump on the edge that will kill a piece of tempered. If the edges were enclosed, then tempering would be okay.

Nuff said. Shower doors will get used in back for hothouse, uncut.

Thanks for all the replies.

TMD

With all respect to J.Michaels(absolutely love his stories).........years ago was in biz with this ole geeze,E.D.Stinnette.He was the head pattern maker during WW2 in a big Phil. foundry(would regail me for hours on particular setups),but he "always wanted to be a builder".So it was sorta kismit that we got hooked up for a decent "run"(10 or so years).We were workin the Blue Blood crowd,tolerating interior designers,architects,you name it.As luck would have it we found ourselves down at the then local hardware joint.It was an early 19th cent. 4 story brick affair complete with hand operated elevator,wood floors,big beams,ect.I knew every corner of that old Hdwre joint.Have many an obscure tool from there.Anyway,we'd visit that place at LEAST 5 times weekly.After a cpl years of digging in dusty ole corners looking for anything remotely interesting,there had to be sumthin else.Yeah,yeah studyed to the UMPTEETH degree the makings of a "proper" 18th cent. riverside comercial building(big honkin river jack foundations and all the hows and whys),principals/concepts to this day that still affect my structures.To include taking binoculars and studying the finest of brickwork way up in places unreachable by the public.But there had to be more?Across the street was a well known glass shop.Just as old....just as dingy....a proshop if you will.So when the "ole man" was wearin out the same ole sh*t ad infinum at that old hdwre joint I was across the street at the glass shop.Heres the point.If you need ANY special glasswork,its time to see a pro.They've seen it,done it all, and got the cuts and scraps to prove it.Have a wonderful evening,BW.