MTFCA Forum

Does anyone know what the procedure is for drilling a hole in safety glass to install a through the windshield spotlight? Can it be done without taking the glass out of the frame? Should I take it to a glass shop?

If it is tempered, it cannot be drilled. You can have laminated glass drilled

Allan from down under.

I believe the trick is to mask off and sandblast all the way through. I’ve had success with diamond hole saws made for ceramic and glass, but I didn’t try it on my expensive windshield….
Id take the whole windshield frame to a local glass shop and ask. Same as a hole for a handle in a shower door, but they will know how to treat the safety glass. I had a handle added to the new glass for a sliding window in a truck cab and I that’s how they did that job.
Good luck with the installation and please post some pics! I have always like those “Clymer” style lights with the pistol grip.
-Chris, in Boulder

There was an installation tool for those lights. It is a drill turned tool that clamped to the glass and worked with a single-use packet of grinding compound that essentially ground a proper sized round hole in the glass.

There was a collector near me about 20 years ago that had one of the tools and a few of the grinding packets but they are gone now.

Here it is:
https://www.mtfca.com/discus/messages/8 ... 1261769535

gary80005 wrote: ↑

Wed Oct 01, 2025 1:55 am

Does anyone know what the procedure is for drilling a hole in safety glass to install a through the windshield spotlight? Can it be done without taking the glass out of the frame? Should I take it to a glass shop?

Take it to someone that knows how to do it. Time is money & so is the windshield.
https://www.trueviewglass.com/locations ... s-company/

Glass won't drill like metal. You have to grind a hole in it, and you don't want to get in a hurry and generate much heat.

At the risk of repeating myself, there are two.o distinct types of safety glass. One is the tempered variety which shatters into a million tiny bits on impact thus avoiding large shards like plate glass.
Then there is laminated glass. It can be drilled and cut to size/shape. Try that with tempered glass.

Allan from down under

As others commented, take your windshield and go to a good glass shop for installing that lamp.

Had local Lee&Cates make laminated safety glass windwings and drilled holes for the mounts.

This year I hit one and accidentally cracked the glass across a hole (weak link)


But they made a new one and drilled holes for the mounts.

Is tempered glass used in windshields? Is it even legal to do so?

TXGOAT2 wrote: ↑

Thu Oct 02, 2025 9:27 am

Is tempered glass used in windshields? Is it even legal to do so?

Nope

Tempered glass may no longer be legal, but that does not mean you are dealing with laminated glass. If you can get to a raw edge that would help to ascertain if you have laminated glass.
Tempered glass will have a dimple or two on the edge where the glass was gripped when passed through the furnace.

Allan from down under.

Couple of things to consider here, obviously whether you can drill a hole depends on the glass type. As Allan points out tempered glass can not be drilled, laminated can. The spotlights in their day were being added to plate glass as the other types were not usually available then. If the glass is laminated the hole can be drilled, if tempered order a new piece with a hole to be added before tempering or go for laminated.

Tempered glass would be the prefered type for some old wood bodied cars than can twist a lot and the windscreen frame may mean laminated glass will just crack as Dan shows in his photo, as side windows in vehicles still use tempered glass Dan should have been able have it used for his windwings, having seen police try to break side windows on cars you can see how good it is . A friend had a depot hack, large windscreen in a wooden frame, could not stop it cracking with laminated glass. Changed to tempered glass problem solved, another brass framed windscreen vehicle, suffered the same problem until tempered glass was installed.

My Town Car has a wooden framed large one piece glass windscreen, it can be slid up and back to then sit overhead. It could crack easily if not tempered. I think inspectors would be checking for plate glass on Model T Fords and would probably not reject tempered glass, especially if it was pointed out that there was a high risk twisting of body or frame would crack the glass.

Where I am here toughened glass has to have a sandblasted mark to identify it (if it is for a windscreen, on older vehicles its original so it should be OK so why wouldn't it be acceptable on even earlier vehicles) If tempered glass is ordered for other uses such as furnature table tops or shelving etc it does not need the mark. So ask for tempered glass, state its for a coffee table and its OK.

This I did on my Lamsteed Kamper. On the TC the mark was sandblasted on and I just put a registration label over it. On the small windows in the back the glass company put small printed wording at the edge, the wood frame recess covers the mark.

In 2011, I installed a Fyrac spotlight through the windshield of my 1926 coupe which had laminated safety glass. No one ever told me it couldn’t be done, or discouraged me so, in my ignorance, I went ahead and successfully embarked on the job. I took pictures and detailed the process for the MTFCA members which can be seen in the following thread: Www.mtfca.com/discus/messages/179374/211340.html.

Go slow and good luck. Jim Patrick

It's a grinding process. You have to go slowly with light, even pressure. You could probably do it with valve grinding compound and a worn out hole saw.

You are fortunate Jim. The results would have been different if you had tempered glass.
Allan from down under.

Automotive tempered glass is odd stuff. It can be very difficult to break. I locked my keys in a 2004 GMC pickup, and used a 24" pipe wrench to attempt to break the passenger door window with no success. I swung the wrench at the window several times, which left marks on the glass but did not break it. The commotion attracted a kid, who was willing to give me a ride home to get a spare key. (50 mile round trip). However, a tiny chip in the edge of a piece of tempered glass can cause it to shatter into tiny fragments with an explosive pop. A light tap on the edge of a sheet of tempered glass is liable to cause it to shatter. A hardened steel point, like a center punch, can be used to break tempered glass fairly easily. Once in a while, a tempered glass window will shatter all by itself. There is a new type of glass appearing in some vehicles, which is called acoustic glass. It is supposed to block noise transmission to a substantial degree. It is a laminated glass that cracks in a different pattern than typical safety glass. I noticed peculiar cracks in a late model pickup door glass, with cracks running crazily like bug tracks. It was laminated acoustic glass.

If you drive your later model car into a body of water, do not assume that you can break a window to get out. It can be very difficult, and often impossible, to break a window in a car with tempered glass, especially if the car is full of water.
Breaking the windshield and clearing an escape path can be near-impossible, too.