Volume 13, Issue 5 - September/October 2011


Ask The Doctor
pros who know

If It Doesn’t Fill, Drill
by Richard Campfield

I believe drilling is a nec-essary skill for a professional windshield repair technician; it is not optional. I do not know of any legitimate windshield repair manufacturer that does not sell and teach drilling. However, some retail operations have eliminated this fundamental procedure in recent months, creating a large need for re-repairs.

The better you are at drilling and tapping a bullseye, the better a technician you are. The drill is a windshield repair technician’s best friend and will bail you out of anything that can go wrong during a repair. When it comes to speed, why would you want to spend 10 to 15 minutes to maybe fill a break when you can completely fill it in less than 60 seconds by drilling and tapping a bullseye? In windshield repair the rule of thumb should be “if it doesn’t fill, drill.”

How to Drill
Rest the palm of your hand on the glass, and hold the drill like a pencil and drill halfway through the outer-lite with a 170-172 bit (1/36 of an inch). Some folks like to steady the drill with the other hand, too.

Only a few seconds of drilling may be required, as the impact point may be close to halfway through already. Once you’ve drilled the break, place a needle in the hole and tap a mini bullseye. The goal is make access to every part and crack in the break through the tapped bullseye.

This is the reason most do-it-yourself kits don’t work—most breaks require drilling to allow access into the cavity when there is no round bullseye under the impact point. This includes the two most common windshield breaks, the radiating crack and the partial bullseye.

Most direct windshield repair marketers will tell you these two breaks make up more than half their repairs. Those who do not do direct marketing will see these breaks usually as the second or third breaks as many consumers do not think these small breaks are serious enough to take the time to get them repaired.

The Science
Glass breaks on the opposite side of impact. The break or cavity is on the backside of the outer-lite against the PVB interlayer.

Filling a cavity in dentistry is comparable to completing a windshield chip repair. The dentist drills a small hole from the top of the tooth into the cavity to fill it with a methacrylic to save the tooth, while a windshield repair technician drills a small hole from the top of the glass to fill the cavity with a methacrylic to save the windshield. In both cases, the tooth and the windshield already are damaged.

Many of us have been re-repairing disgraceful repairs for decades and we have become very good at it. All it takes is the required skill of drilling to gain access and re-repair those breaks into which no resin has been placed. You must drill into the void and fill it with a resin that bonds to glass and acrylic.

Richard Campfield is the founder and president of Ultra Bond Inc. in Grand Junction, Colo.

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