Drilling holes in glass
Not sure where else to put this question, so...
I've recently started making glass wheels for kaleidoscopes. You basically cut a circle of Bullseye clear, then mark the center and use a drill press and a glass bit to drill a hole in the center of the disc. Then you fuse the disc with colored glass, frit, etc. to make the wheels. The first set of about 12 discs I drilled went just fine. I know to keep the glass under water and proceed slooooowly when drilling the center hole. I cracked the first one or two, figured out the proper pace and the went smooth as silk. After a several week period, I had another chance to work on some more discs. Side Note: Cutting the circles is a bitch, even using a Silberschitt circle cutter! I've never fused or done stained glass, so cutting sheet glass is a whole new experience for me, and cutting circles is HARD! I'm hoping it will get easier the more I practice... So I get my discs cut after much cussing and several wasted bits of glass. Take them in to use the drill press to drill the center holes. EVERY.FREAKING.ONE of the discs broke!!! Cracked roughly in half - EVERY DAMN ONE! ](*,) I did it the exact same way as the first time, so what the heck went wrong? The glass bit is brand new, only used to cut approx. 12 discs (my first attempt that went well). So what did I do wrong this time? Any ideas? Suggestions? |
How good are your glass bits? when I was drilling sea glass I would only get 5 pieces before my cheap bit was blunt. It might be worth trying to drill after you've fused, I have more luck drilling a double thickness (6mm) than single (3mm).
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Is it the same sheet of glass?
Maybe while you're figuring it out, drill first, then cut the circle so you aren't so frustrated if it breaks? I don't make my lenses with a hole, but have drilled holes for wind chimes, etc. and I wonder what you have them sitting on. Any chance the surface has a bump, bit of glass, etc. that is getting pressure when you drill & causing the break? |
Also, how hard are you pressing when cutting the circles? Many beginners think you have to press very hard to score the glass. When you do that (if you do) you chip the edge of the glass which can make it break nearly anywhere along the score.
If you are using a Silberschitt cutter try changing the wheel to a new position. Also, practice on some window glass. Many stores will give or sell cheap scraps so you can practice cutting circles. |
http://www.system96.com/pages/circledemo/circle1.html
This is how I learned to cut circles. I use a piece of neoprene or a clean self-healing cutting mat. Clean well and brush off chips between each circle. What are you using to support your circles for drilling? A piece of styrofoam always worked well for me, but it floats so I affixed it in a shallow container with silicone and let it sit overnight before adding water and drilling. Chips either got pushed in or brushed off and lasted a long time. I was partial to Triple Ripple bits from Kingsley North...I don't know how big your holes have to be but if they're not big enough, I'd go to core bits. http://www.kingsleynorth.com/skshop/...702&catID=1031 |
If you don't have neoprene a couple layers of foam packing sheet under the glass works.
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Your bit is probably dulled after 12 sheets - if it's a sintered bit, you will need to expose more diamonds with a dressing stick. If it's not sintered, you probably need a new bit.
If it was cheap, it's not sintered, it's resin bonded. They wear out fast. |
Just to clarify, I use the neoprene or cutting mat to run the score, not to drill.
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Oh my gosh, you guys are great! So much good information here for me to try!!
OK first to clarify - I am cutting small circles using the circle cutter - they are only 2 1/2 " round. I have only used one half sheet of the Bullseye glass to cut all the circles so far, so it's all the same sheet. I then drilled the first dozen circles in the middle - the hole needs to be just a tad bigger than 3/32" to accommodate the brass fittings and then fit through a 3/32" brass mandrel that holds the wheels on the kaleidoscope body. After reading some of your comments and suggestions, it sounds like it might actually be the bit is already worn?? That sucks to think I will have to buy a new bit every time I drill a dozen or so wheels!! I think my first try will be what Fiona suggested since I WAS able to successfully re-drill the center of about 5 of the fused wheels that slumped too much and the center hole closed in on itself. Those drilled fine. It was when I went to drill the plain circles of Bullseye (before I added the additional glass and fused them) that the discs kept breaking. Also, I will try checking as Eileen and I think a few others suggested to make sure there were no bits of glass on the surface of the drill press shelf. I don't think there were, but who knows? I am going very very slowly and barely pressing at all when drilling the holes in the discs, so I don't "think" that is the problem. I know when I first tried it, I did go too fast and applied too much pressure and the discs broke. And Deb, thanks for the suggestion to practice on some window glass! I never thought of that, and was cringing at all the expensive Bullseye I wasted learning to use the circle cutter (which is still a work in progress!). I think part of my difficulty with the circle cutter - other than the fact that I just need to PPP, is that I have it set to the smallest possible circumference since I need small circles for the kaleidoscope wheels. So it's fairly tricky getting the circle cut cleanly. So I will check out the link you provided on cutting circles, Rebecca - thanks!! And I also went to Kingsley North and ordered some new diamond bits from the link you provided as well! Thank all of you for offering such great advice. I love this place!! Everyone is so helpful when someone has an "issue", lol! |
Rebecca, I was talking about putting something with give under the glass when drilling. It helps the glass from moving and gives the bit a "soft" place to land when you finally get through. You are correct that it helps to put something under the glass when cutting also.
Rene, I forgot to mention that when cutting circles you should cut one complete round with the cutter without stopping AND do NOT cross over your score. In other words when you get to the end of the score, STOP, don't keep cutting. It does not help a score to go over it more than once. Any extra hesitations or moving back and forth only hurt your score. |
I don't use a circle cutter, made up my own method, and they aren't too bad. I do have a grinder though for any little jags, plus the fusing smooths them a bit too.
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Small circles are way harder for me to cut than larger ones.
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I wrecked so many pieces of sheet trying to cut 7" rounds that I eventually just ordered them cut that way.
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Look for a nalgene wash bottle I get better bit life when drilling bottles.
Forcing extra water into the hole helps force out the grim. |
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Go to Glasscraft, Warner-Crivellaro. You can buy those circles with the brass already in it. They come in a kit. I think I still have a couple around here.
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I have a couple of ways, depending on my glass & size circle (I'm really thrifty with glass). I'll try to draw a diagram & take a picture of it.
They are not perfect, have a few bits I have to grind off if I'm not putting the glass in a full fuse. If I am, they are good enough for me, because the glass pulls in pretty good. Of course, I also have 2 layers, so that wouldn't really do the same for you :( I don't know if you can see well enough, but there are a few places that aren't perfect. But being that they are up in my skylight, they work OK, but it's a layer of clear fused to a layer of color with a steel loop between. I'll have to go do one with some scrap & see if I can take pictures or something. |
Eileen, I love your mobile.
Rene, I am sure you don't want to buy another tool, but this is what I use for small circles. My big cutter is great for cutting large circles and super for cutting the rims I use on large bowls ( though they are still hard to break out) this is my go-to for little circles: http://www.delphiglass.com/glass-cut...ut-lens-cutter If you intend to cut lots of little circles it works great. Oil the cutter for every circle. |
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Thank you for the link! And Eileen, the mobile is so pretty, and the circles look great! |
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I used to really struggle with cutting small circles ... then it hit me ... uh, duh, don't cut them, get a core drill!
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Eileen, that mobile is awesome!
You might use the same method I do. I cut imperfect circles by drawing a circle on glass with a sharpie in a square the size of the circle, making multiple cuts (like the red line below), and then grinding the nubs off. Works best for larger circles. |
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http://www.amazon.com/VGCE-LG401156-...ut+lens+cutter |
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And yes to who suggested it, glass from old photo frames or cheap window glass is great for practicing! Oh, and thank you those who said they liked the mobile. I've made some much smaller ones now as gifts, and done some with a mixture of rectangles and squares, & they're nice too. |
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Seriously, I think this will be perfect for the tiny circles I am cutting for the scopes. I am so excited that I ordered it right away and it ships prime - and then I realized I will be out of town when it's delivered!! Luckily, my son and SD will be here to receive the package, and I will be raring to try it out as soon as we return! |
This is where I get my drill bits. http://www.lopacki.com/drills/
And I put a piece of wood under the glass that I'm drilling. It floats a bit, I just hold it down under the water with the piece of glass on top. |
Is there anything Amazon doesn't have!? Great find, Squid! Glad you're getting a new tool, Rene.
Remember, this type of tool doesn't have a way to oil the cutter so you need to coat it for every circle. I place some cutting oil on a cotton ball in an old lid. You don't need to soak the wheel, just a light coat of oil. Too much oil keeps the blade from making good contact with the glass. Palm the ball in your dominant hand and hold the glass with your other. Rotate your hand, making one complete circle stopping when you get to the beginning of your score. You need about 1/2" of glass all around the circle to enable better breaking out of it. Use Eileen's method above to break out the circle. Practice on window glass and remember just like beads, PPP! |
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