Need some help with attaching the Lexan windows

I am about to install the rear and side Lexan windows. I found a place that sells special bits for Lexan/Plexiglass. I'm using #8 sheetmetal screws. Does anyone know what size drill bits are needed? I hate to have to buy a large variety if I can narrow it down some.

Thanks

Bill D

Don't use sheet metal screws. Drill the holes, use a bevel bit on the plexiglas, and use something like some 10-32 metal screws with threadserts in the fiberglass. Much better fit and finish, plus, it is removable many times. Just my 0.02 cents.

How were the originals done?

When you say metal screws, do you mean machine type flat head screws?

Thanks
Bill

Yep, flat head machines screws - they have a bevel on the underside of the head. Check www.McMaster.com.

Need a drill bit that can cut the bevel in the plexiglass and there is a thread here about that from Lynn Larsen (llarsen) using a foresterr bit to do that. I haven't serached for it, but I remember it from years ago.

You can then use the little threaded nut serts, or the tiny theads, to put in the fiberglass to screw into. Much more professional looking for sure. I have both around here, but, I cannot remember what the "threads" are called. All they are is a female thread that can be glued into a hole. The nut serts use a tool to install them, but they are sort of like a rivet and rely on compression to stay put. Good stuff, those.

I don't know what the originals used though, but you'll need to remove windows though for open track days. I don't imagine the sheet metal screws would do too well on that account, a few times sure, but beyong that I imagine you wouldn't have much to grab onto with them any longer.

R

Ron Earp said:

You can then use the little threaded nut serts, or the tiny theads, to put in the fiberglass to screw into. Much more professional looking for sure. I have both around here, but, I cannot remember what the "threads" are called. All they are is a female thread that can be glued into a hole. The nut serts use a tool to install them, but they are sort of like a rivet and rely on compression to stay put. Good stuff, those.
R

Click to expand...

Rivnuts
http://www.aircraftspruce.com/catalog/hapages/rivnuts.php

I used #8 stainless button head machine screws a washer and rivnuts. If you really want to do it right place a metal sleeve in the hole so the plex doesn't take the load when the screw is tightened. You can cut these from thin walled tubing. The tapered plex bits are the way to go. McMaster is a good source for the hardware.

What about Nutserts? Do they work well for this?

http://www.aircraftspruce.com/catalog/hapages/nutserts.php

I have the a kit from them and have used them on metal applications, anyone use them or have a preference vs. the rivnuts?

The other thing that was mentioned in other threads was the use a helicoil tapped and glued into the fiberglass. This seems like a lot more work, not sure if worth it.

Sandy

I went with helicoils and countersunk 8-32 internal-hex stainless machine screws. Just the tiniest dab of epoxy on the helicoil. The problem with rivnuts in this application is that the lexan will sit a little bit off the fiberglass due to the thickness of the rivnut head; helicoils allow the lexan to be installed flush against the fiberglass body work.

I agree with the side windows, but IMHO the rear clam plexi doesn't get removed enough to warrant inserts.

Bill...is your small rear window in the cabin glass or plexi?
Considering how cheap/easy it is to have made, I'd go glass.
It's a pain to remove scratches from plexi.

MikeD

Bill - I just finished all my perspex, I made the holes just large enough for the s/s screws to pass thru, the torque when tightening won't crack it this way.

I used new drill bits without any problems in my press for holes, just go slow and have something like a piece of board under for even pressure and not have the bit 'pop' thru.

I used stainless flat-heads, nothing fancy, into the fiberglass. I undersized just slightly for a tight fit that I hope with care, will allow me to take the door windows on and off - and it looks good. Be really careful if you plan to use a cordless to install the screws, lowest speed and torque setting.

Due to the air pressure on your rear window, I'd use a slightly larger screw.

Bulkhead window - glass if you can get it. Fuel from a Weber spit, the heat, noise and fumes behind your head is worth it.

My 2

Chris

Are you guys using tempered glass in the bulkhead window?

I'm going to use these with SSTL button head screws

I like the idea of replacing the bulkhead window with tempered glass. I'll look into that.

I haven't checked yet..but I'm told tempered is readily available for
this application (flat/simple shape). Guess we'll find out !

MikeD

I recently had a piece of tempered glass cut for a Pantera I was putting together. It was flat and much bigger than the GT40 .It cost like $80.

Glass is good but in the UK unless it has the necessary E marks it will not get through the SVA test so we use acrylic.

Ian

Personally, I would just use laminated glass. It would cost probably $10 and any glass shop could cut it for you.