Thread: Plastic Oil Window Repair

Bryan, that looks almost identical to the oil window on my DM45 mill. It was also supplied with a spare.

If you could give me some sizes I could compare it to mine, if it is the same it may be worth a phone call to Tom Standing at Standaco (03 9873 1066) to see whether he can supply a replacement.

Failing that I could cast you a blank rod of clear PR (polyester resin) and you could make a new one from scratch. Once you turn clear PR, you then wet sand 400-2000 grit, then polish with fibreglass or car polish and it will be very clear and glossy.

Fred, thanks, that's very helpful. The thread size I believe is 52 x 1.5. I say believe because it actually measures 51.5 but the threads are well rounded, so 52 is my best guess. The pitch is certainly 1.5 so it's not imperial. I keep seeing sizes up to 48, then a jump to 60.

The snag with turning one up from scratch - I should have mentioned this - is that I can't turn metric threads.

Can you turn 17 tpi, that will be 1.494 mm pitch which, given the number of threads involved and the deformability of the plastic, would be close enough probably.

Wow, photos can be deceiving! Whilst it looks virually identical to mine, mine is only 26.5mm OD on the thread, so a fair bit smaller. The OD of the window part is 35.8mm.

There is another way of doing this, but it would involve making a mould out of silicone rubber from the existing one, then cast the PR in to this mould so you could turn the rest of the thing.

Bit of mucking around and not too cheap, smallest quantity of silicone rubber is 500 gr and costs about $35.

Gavin, I did think of that, and no I can't. 16 or 18.

Fred that sounds messy. Would my idea of gluing in a new piece not work?

Originally Posted by Bryan

Gavin, I did think of that, and no I can't. 16 or 18.

Fred that sounds messy. Would my idea of gluing in a new piece not work?

Probably would, but without knowing exactly what the thing is made off it is hard to determine what glue to use. Looking at mine it is probably acrylic, you can the joins in the die still in it.

If that is the case, the acetone would probably do the trick as a glue BUT it would probably make your problem worse as it works as a glue by attacking the plastic!

Which is why I suggested starting from scratch in PR that way it will be clear all through and no remnants of your existing discolouration will remain.

Take the discoloured face off cleanly on the lathe, and then glue on a piece of 4-5mm acrylic or perspex with one of the solvent adhesives used for plastic model making, or even superglue. If you cover the actual window area with a layer of masking tape (soak off with water later) it should stop the clear plastic getting fumed by the superglue.

i think someone asked the same question not long ago on PM .....i think you can buy them somewhere

Bryan

If you can't source a spare and you have some time one day when you are up in the big smoke we could turn it up on my lathe.

Rgds - Gavin

Bryan
if you cant find anything let me know

I could try a compressor re-manufacturer to see if I can get one off of a Manuroupe or Copeland etc Refrigeration Compressor that is to be scrapped.

these are a piece of glass bonded and embeded into a threaded plug and can withstand pressures as used in refigeration sytems...can with stand pressures of 150psig.

unfortunately I dont know what the thread size would be...but dia would be in the order of 1inch...it would also depend on where the comp was made ie Manuroupe would be metric as they are made in europe while copeland would be imp as they are made in USA

I will have a look later to see if I have an old inline liquid sightglass that had a removable glass...these can withstand pressures of up to 800psig (depending upon which one)....I removed one from a job last month as the gasket was leaking...but that is while its under 300psig and higher...the glass itself and seating area was ok...I usually keep that type of stuff as its brass/copper and goes into the scrap bin for when i get enough to take to metal recyclers.

I just looked up a trade catalogue and also available are replacement glasses for some inline sightglasses ... approx $30 but again, I dont know what size thread they are.

just found these...they should be available from my suppliers

Heldon Quality Products - New Product Available: Rotalock Sight Glasses

Patrick, I know you can buy them, I just can't find one that fits my thread. Or do you mean a simple lense? I think that's what came up in that PM thread, though I can't seem to find it now. I haven't come across these in my searches. If you know of a local source I'm interested.

Gavin, that's a very kind offer, I will keep that in mind.

Eskimo, I think the tube type would be vulnerable and ugly, not to mention a hassle to fit. The Heldon ones are imperial threads, so would have to be fitted inside the existing one. The compressor ones you mentioned are smaller than mine so the same applies. That would likely work, but again I think it's an inelegant solution. I do appreciate your offer though. BTW temp and pressure shouldn't really be issues here. It's only a reservoir.

The simplest, neatest, most original looking outcome (aside from a direct replacement) would be a new insert in the existing window. IF I can figure out how to make that likely to work, that is my first preference at this stage.

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.

I'm not concerned about discolouration because I think most if not all can be removed, and anyway, it's really the face that matters not the edges.

Hi Bryan
How thick is what's left of the face?
Cant you just bore out the discolored material and re polish?

Failing that you could bore it right through and make a plug with a shoulder on it to push fit from the back. Then you could use a sealant rather than a glue. Of course then the "glass" would be(hard to tell from the pictures) about an inch thick? If you felt that was to thick you could counterbore it but that would make polishing harder.

Stuart

Quick tips on working with acrylic/perspex - http://www.abplastics.com.au/hintsan...crylictips.php

The stuff is fun to work with aside from the fact that the sawdust gets a static charge and clings everywhere. Normal woodworking or metalworking tools are fine, just don't cut too fast with fine tooth metalworking saws otherwise the stuff tends to glue itself back together from the heat of cutting.

A cheap source for your needs might be the nearest $2 store - walk around and find a rigid plastic thing to cannibalise, although this will give you plastic of an unknown variety, mostly the hard plastics glue quite well.

Perspex has been used to make sight windows/entire oil catch cans for show cars for ages.