Thread: Plastic Oil Window Repair

Bryan,
a question about the glass you are trying to fix. Is it hard and brittle or can it be marked by gripping the edge with a pair of pliers etc.
If it is hard it is probably acrylic (polymethyl methacrylate) if it is deformable it is probably polycarbonate or polysulfone. Polysulfone is listed in one of my reference books as suitable for sight glasses, it is expensive and may be difficult to obtain in the quantity you need. Clear polysulfone has a honey coloured tinge to it which your glass appears to have.

If you want to use CA adhesive on clear plastics Loctite make a 'non blooming' formula which is numbered 406 if I remember correctly.
Regards, Mm.

Is plastic really worth persevering with? Real glass is cheap and durable, and with a nice metal frame for it should make an interesting project.

Jordan

To plug one of the forum supporters.
I used these to polish my pens
Soft Touch Pad 3" x 4" Micro-Mesh&reg Kit | The Sandpaper Man
with a final polish with Brasso

They also sell these that you could use
Polishing Swab 2.25" Variety pack | The Sandpaper Man

The plastic guy I use sells Acrylic and polycarbonate rod, but he doesnt open until the 10th. I'll be going in there to buy polycarbonate for the front of my VSD box, so if you havent got it sorted by then we'll work something out.

Stuart

Polycarbonate stress cracks in touch with oil based products.

Originally Posted by Big Shed

Polycarbonate stress cracks in touch with oil based products.

Um, what would welding helmet lenses be made from? Don't tell me... polycarbonate.

Originally Posted by Big Shed

Polycarbonate stress cracks in touch with oil based products.

I'm going to have to remember that.
Thanks
Stuart

I've done some Googling and the technical sites I'm seeing are saying resistance of polycarbonates to mineral oils is anywhere from 'fair' to 'excellent'. None of the three or four I've looked at has said 'poor'. I'm not saying Fred is wrong, I'm sure he has some valid experience or knowledge, but since I've done the repair it seems like it might be worth at least seeing what happens. If it reacts or leaks it'll be obvious and I can deal with it then. I've kind of learned how to do it now and it'll be easier a second time. (Not that it was hard the first time.)

BTW, that's not the finished paint job on the oil tank. I was just trying out Forest Green.

OK, should have been more specific.

Oils ain't oils

I was talking about the resistance of polycarbonate to petroleum based products, such as solvents and oils derived from a petroleum base.

My experience with polycarbonate has been in the paint industry, especially with reference to signwriters who are using it for backlit signs.
If you use paints using Mineral Turps, it will stress crack before your eyes. The same enamel paint using White Spirits as the solvent works fine.

The difference between Mineral Turps and White Spirits is in the %-age of aromatics, White Spirits has almost zero hydrocarbons, Mineral Turps has quite a high aromatics %-age.

So, if the oil you are using is petroleum based and has a reasonably high aromatic content, your polycarbonate will stress crack, otherwise you'll be OK.

Thanks Big shed but I'm not sure that helped
To come at it from a different angle. Would acrylic be better with oils?(or some other clear plastic like material that I dont know of)
Stuart

Originally Posted by Stustoys

Thanks Big shed but I'm not sure that helped
To come at it from a different angle. Would acrylic be better with oils?(or some other clear plastic like material that I dont know of)
Stuart

Be careful what you wish for.................

In a word, yes.

A clear thermosetting resin would be the most resistant, PR-polyester resin and casting grade epoxy resin spring to mind.

Originally Posted by Bryan

Master Splinter, acrylic or perspex you say? Superglue? I think we're getting somewhere. Fred, do you want to argue against these choices? If the choice of glue is too problematic, could you use a sealant instead, and make the fit sufficient to hold it in place? Like I said, there's no pressure.

Superglue is nasty stuff for perspex.

You can get a tube of perspex bonding glue for ~ $13 from a perspex supplier, dries clear.

I'm not sure how it would react with the plug if its not perspex.

{edit: opps missed the 2nd page)

Bryan

this is what I was thinking of
as you can see the glass is removable from the body ..I just dont know what the thread size..its some where around 3/4

Eskimo, thanks. That looks like a quality fitting and would look good in the right place. But I would have to fit it inside my existing plastic 2" window, which I think would look like a bodge. So thanks anyway, I'll see how my existing repair goes.

On that note, I've got a scrap piece of the polycarb I used with chain & b... h^h^h slideway oil sitting on it. No visible reaction after a few days. Will monitor for a couple of weeks before assembly.

Thanks to all respondents.

Perhaps it may take time.
machine a front and rear mold (polished) with a 10mm ledge to silicon them to the front and rear of the oil tank,(use magnets to help keep them in the right position).
drill small holes on top of the molds, one to fill the resin using a syringe, its full when the other overflows.
the air escape or resin overflow hole would not need to be drilled, just file a small groove on the attaching ledge, without getting silicone into it, (preferably do this to the front mold as its easy to sand out the slight excess, for a better finished look).

place something the same diameter as the drilled injection hole into that hole, until the resin is cured (makes for easy removal).
may need to use some type of mold release agent on the molds and tank, (especially the threads) for easy removal.