Hi Col,
I have bought a bit of it from "Cut to Size Plastics" which is an industrial plastics supplier. They have an office and warehouse in Sydney and Brisbane. You can go to the warehouse and buy over the counter, or mail order. They have PTFE in every shape and size you could hope for and will also cut it for you as required.
https://www.cuttosize.com.au/engineering-plastics/#3
Last time I bought some I bought several thicknesses and widths and got them to cut it to the widths I needed so that I only had to cut the pieces to length. I spent <$30 and got enough PTFE for about 10 telescopes. That was over 10 years ago and I still have some left.
Commercial PTFE doesn't glue all that well as it isn't "acid etched". 98% of what you will be able to source, wont be acid etched. Acid etched PTFE glues reasonably well with contact adhesive, but is very hard to source. Personally I haven't needed to use acid etched. The Pads I have glued on or screwed on have never come off.
I contacted all of the Australian Glue companies about 20 years ago and asked them "how do you glue non acid etched PTFE". Apart from one company which was "Loctite" they all said, "with great difficulty and not very successfully".
The Plastics engineer that I spoke to at Loctite had other ideas. He said we have a special primer you can glue it very well with. Use Loctite 770 Primer on the PTFE face only and Loctite 406 Adhesive, which is a cyanoacrylate adhesive, on the other face. You put the primer on the PTFE, let it dry which only takes a few minutes then apply glue on the other face and push together. He was 100% correct, if you follow the instructions properly. You can buy the primer and the glue on ebay, or special order from industrial suppliers.
I am assuming its for the 12" Lightbridge ?
If so and you plan to glue it, I would recommend using 3mm thickness for the ground board and 2mm thickness for the altitude bearings.
You can also attach it with 4 gauge countersunk stainless screws, which works very well. If you plan to attach with that method I would recommend 3mm for the altitude bearings and 4mm for the groundboard, which just gives you a little more meat to countersink the heads. It does make it a bit more difficult to bend the 3mm around the radius of the altitude bearings, as opposed to 2mm, but It worked fine on my 10" dob which has smaller diameter bearings than your 12" lightbridge. I have used both fastening methods and neither have ever come adrift.
Cheers
John B
