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Drill Bits

Posted: July 18th, 2005, 10:59 am
by Glacier Auto Glass
I am having problems with my drill bits. First off, I am only getting about 4-5 holes drilled before I have to replace the bit. Also, When I drill a long crack and then tap it with my probe to make a bullseye, I end up chipping the glass around the edge of the hole. Is my drill bit too small?

Re: Drill Bits

Posted: July 18th, 2005, 11:08 am
by Delta Kits
Which bits are you using?

Re: Drill Bits

Posted: July 18th, 2005, 1:27 pm
by code3wsr
Glacier Auto Glass wrote:I am having problems with my drill bits. First off, I am only getting about 4-5 holes drilled before I have to replace the bit. Also, When I drill a long crack and then tap it with my probe to make a bullseye, I end up chipping the glass around the edge of the hole. Is my drill bit too small?
Make sure you are drilling half way through the top layer of glass. If you don't drill at least half way, the glass will chip insted of making a bullseye.

I think most people get about 5-8 holes from a bit. Try only allowing the drill to touch the glass 1 second at a time to avoid heating it too much. ( the bit that is )

Hope some of this helps.

Re: Drill Bits

Posted: July 18th, 2005, 1:59 pm
by StarQuest
Here's what I've found in the past that shortens life with drill bits.

1. Excessive Heat (which is caused by the following)
a) applying to much pressure
b) using too high a dremel speed
c) extended drilling cycles (i.e., drilling longer than 2-3 seconds between
cooling, 5 seconds or more will develope to much heat!)
2. Drilling to deep and hitting the laminate (it will clog cutting teeth)
3. Drilling into old repairs (cured resin will also clog cutting teeth)

With 2 & 3, normally a good file brush will clean this up allowing you to reuse drill bit;)

If you use a good carbide quality bit and drill properly... it should last you 40-60 repairs. I use a very small tungsten carbide bit and have stretched them as far as 70-90 repairs before tossing them.

As far as you chipping the pit while popping. It could be your probe tip is flattend or what you already stated, your drilled hole is smaller then the size of the probe tip. Whenever I find the need to pop, I'll use a slighter larger drill bit.

Not sure if any of this info helps in your case.

Good Luck

Re: Drill Bits

Posted: July 18th, 2005, 2:02 pm
by zlm_us
I noticed when I drill on my practice glass mine was doing the same thing. I also found out it was one of two reasons. First my probe had a small bur on the side and this was causing the glass to chip. I also discovered that the probe was to big and caused the glass to crack. I then started using sewing needles instead of my probe to pop a bullseye no more problems. I have also been using small music wire sharpened on the end and this also works great for a probe.

Re: Drill Bits

Posted: July 18th, 2005, 5:05 pm
by J.T.Window
I try to put a 45 degree bevel around the drill hole when it looks like the glass might chip from my probe touching the edge of the hole. The probe I use is a straight dental pick with the tip rounded from years of use. The tip can be shaped with a whetstone or a fine file or fine sandpaper. You can find these picks at flea markets and cheapo tool stores.

Re: Drill Bits

Posted: July 18th, 2005, 9:34 pm
by boyd
JT,
How can you look at glass, prior to drilling it, and tell whether or not it will break.

The answer to the man's question is simple: either buy larger drill bits or buy a smaller pick, awe, or whatever you use. It's that simple.

Re: Drill Bits

Posted: July 19th, 2005, 6:56 am
by dragwurm
glacier i wish i could help you on this one but i no longer drill my repairs so no drill hole for me

Re: Drill Bits

Posted: July 19th, 2005, 6:32 pm
by J.T.Window
[quote="boyd"]
JT, How can you look at glass, prior to drilling it, and tell whether or not it will break?

boyd: I'll answer your question.

The surface damage of the chip is either bigger than my #2 round burr or it isn't. If the crater around the spot where I'm drilling is bigger than my burr, then no worry - drill away and pop the bullseye. However, if the drill hole goes straight into the surface of the glass, I bevel the edge of the hole so the glass won't chip away from using my probe.

Re: Drill Bits

Posted: July 20th, 2005, 8:09 pm
by cwrepair
Glacier, Just add a drop of resin every few seconds when drilling to keep the bit cool and they will last a long long time. I add three or four drops during drilling and even push the resin buildup back up the glass to the hole im drilling to help keep the bit cool. Its really not much resin waste in comparison to how long your bits last and the money you save. Chris