La Rossa

Just a quick Q. to the ones that went through this before...
I'm reassembling the hard top for my 65 and replaced rubber and hardware along with the back window, now that the window is in I realise it doesn't come predrilled for the upper and lower reindorcements so I was wondering if you guys have any tips, I don't want the lexan to start spidercrack on me as I drill, so..... is there a specific bits for the job or it just like any other hole?
Thanks in advance!

VetteRed1965

Use a step drill bit, They are cheap at harbor freight

Scott Marzahl

Buy a special Lexan bit, they are ground special to prevent cracking. Do not use any type of solvent or loctite on fasteners as it will attack the Lexan.

DUB

I have one and it is needed to prevent any damage.

DUB

68sixspeed

Or take a stone and break the corner on the flute to the tips at the OD of the drill, basically dull it. Helps a bunch. Drill it dry, and make sure the hardware is free of oils. We use lexan for guards at work and if we don't take the oil off the screws or anyone screws up and drills/taps with oil, the lexan will crack a few days after assembly.

ohiovet

Spend a few bucks and buy the correct drill from Glassworks or Auto Entec. It is essential so you don't screw up your plexiglass window.
Cheap insurance.

John S 1961

check out youtube, a dulled drill is the correct method

La Rossa

Thanks guys, I wasn't aware of a specific bit for lexan, a quick look on Ebay and I see they run about $70? WTF? Does it have a gold tip?
Ant way, I guess it's still cheaper than a new window I suppose....
I'll try the dull bit and also the step bit first, I have a handfull of those.
Thanks again!

Sky65

What???? $70?

http://www.eplastics.com/Plexiglass_...tic_Drill_Bits

Tom

La Rossa

Thanks Tom, I guess I overlooked the size and just looked at the $ first!

http://www.ebay.com/itm/drill-bit-for-lucite-plexiglass-acrylic-lexan-15-16-/360200642562?pt=LH_DefaultDomain_0&hash=item53dda1a002

ohiovet

Check Glassworks, $7.00 (seven dollars) plus shipping.

Auto Entec , $5.00 (five dollars) plus shipping.

I'm no machinist but the sharpness has nothing to do with cracking or breaking of the plexiglass window.
The reason they break has to do with the angle at the point of the drill. So invest a few bucks and save a rear window.

Sky65

Thank you. I have some lexan to drill myself and I never thought about needing a special bit. Your thread got me investigating and likely saved me from screwing some stuff up!

Tom

JPB04619

i am doing this now and need the size of the drill bit i need for the rear window...i may have missed the size but i did read thru the excellent article...and yes i know it is an old tread.lol.john b

Rdelvalle

Ohiovet is correct. I just did my 59 complete restoration myself and bought everything from Glassworks including the Lexan drill bit. I was impressed on how great the drill worked, it looked like a factory cut. Do yourself a favor and order the Glasswork Lexan drill bit. Just $7. If you are in a hurry have them shipp next day delivery. I was very hesitant to drill the new rear window but now I can assure you that I would do it again with their drill bit without hesitation.

jerrybramlett

Are you guys sure your hard top windows are made of Lexan? All of them that I've seen were made of Plexiglass. I'm not questioning the need for a special bit, just the actual material you're drilling. There is a big difference in durability and cost between Lexan and Plexiglass.

Roger Walling

The proper shape of the drill causes the drill to scrape the plastic, not cut it.
I do not know just how to grind the drill but was told this by a glass shop.

BLUE1972

I drilled a lot of Lexan when I was boat racing.

Make sure you do not put pressure on the drill bit. Let it drill very slowly.
Use a drill press at low speed, minimal pressure on the bit
Make sure the Lexan is backed up in something firm - like sanded 3/4 plywood or particle board. Under the drill area.
When done Polish the hole with 400 sand paper.
Do not overtighten the screws going through the Lexan.

I drilled holes from 1/16 to 1 1/2'.
I used regular drill bits, If you have a clutch on the drill set it to the lowest setting.

The key - a firm backing to the Lexan - do not wobble the drill bit and do not press on the bit.

JPB04619

appreciate the replies guys but i need to know the size of the bit john b

Rdelvalle

The material is Acrylic not Lexan. The glassworks Acrylic drill bits are :
56-62 Acrylic Drill bit SKU 2301-A 1/8 in diameter
63-67 Acrylic Drill Bit SKU 2301-B Do not know the size.
The drill bit has a very sharp edge triangle shape point. It is very easy to use as the shape and the sharp cutting edge cut like butter. The resulting hole is perfect as I said I was impressed.

R66

I thought that Lexan is a trade name for polycarbonate plastic. A Google search kinda states it that way.
So, I guess the rear windows on all hardtops are Acrylic???