Quote:
Originally posted by BraenDead
Some tips I thought I would share after drilling lots of small holes in my 75g (8mm holes drilling slots for an external overflow).
- Using a drill press is easiest, but if this does not work, I recommend using a cordless drill. I haven't found a corded drill which offers good enough speed control.
- Do not drill at fast speeds, use slow. I used 600 rpm on the drill press and use a cheap cordless drill (6.8V) that does not go very fast either. Using a corded drill was hard to control the speed and went WAY too fast and did not produce a good smooth cut.
- My technique:
1. The best way to start a hole without any slippage is to make a guide for the hole. I use a small piece of acrylic with a hole drilled the same size as the drill bit. I recommend not using the same bit as you may wear-out some of the diamond dust from the bits. Use this guide to drill your hole by either clamping it in place, or if you can not clamp it, you can put a small amount of plumbers putty to form a thin sheet on the acrylic to keep it in place on the glass. You only need to use the guide for a little bit until you have cut away enough for the bit to fit in without sliding around.
2. I tried dozens of methods trying to eliminate any glass knicks and shards from happening while the bits goes through the back side. Using duct tape on the back side works alright, but you will still get some knicks and shards. The best way to eliminate this is to start drilling one side as described above in #1. Once you have gone a little bit, remvoe the guide and do the same process on the back side of the glass. Make sure to line the guide up so it lines up with the front side where you started to drill and do the same process. Drill at least 1/16" deep on the back so that there will be no shards or pieces that break away once you finish the hole. I have found that I did not need a water dam by keeping the drill bit wet with a spray bottle every 5-10 seconds (drill for 5-10 seconds, stop drilling to spray off bit, then drill another 5-10 seconds). 1/16" shouldn't take too long to drill.
3. After drilling the back I recommend putting a piece of duct tape to keep the piece of glass from falling. More importantly, I found that occasionally the drill bit would get loose in my cheap cordless drill. If the bit is loose, you dont want it coming out and falling through the hole.
4. After drilling the back, finish with the front. Initially, I used water dams to hold a lot of water but I found that I did not need a lot of water to keep it cool. This added a lot of time and was a mess to do (especially with the 70+ holes I drilled). I found all I needed to do was keep a small puddle of water where I was drilling the hole. Monitor the bit while you are cutting by feeling the bit and the glass to make sure they are not hot. If they are noticeably hot, you need more water or maybe you should just use a water dam (my holes were much smaller than what others may be).
Hopefully these tips will help out.
Bob
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I drilled 3 holes in my 75. After I got done I figured one way to keep the glass from "splintering",would be to clamp a piece of glass on the back side of the hole you are drilling to keep the bit from "busting" through... Just a thought....also i rounded all the edges of all 3 holes with sandpaper, made for a very nicely finished hole with no sharp edges.