Polar mount plastic bushings: What moves?

[archive10]

I'm reviving this old Triax polar mount.



The mount swivels on a set of plastic bushings.
(Nylon, probably. Reminds me of roller-skate wheels.)



I'm trying to figure out two things:
a) how to treat the ageing plastic parts so they become weather resistant
b) how to lubricate the mechanism properly going forward

So the first question is:

What to do to the plastic bushing to make them last another 10 years?
Soak them in oil?
Cover in Vaseline?
Automotive lubricant?

As for what to lubricate, I can't figure out the swivelling mechanism.
What parts move, and what parts don't?

The axis is a threaded bolt.
On the axis there's a washer, and then a big-diameter rusty washer.
Then there's a metal tube, which seems to have a thread inside it (so it doesn't move).
Around the metal tube, the two halves of plastic bushings are fitted.
The metal flap of the swivelling bracket fit in between the plastic bushings.



My current gues is that the evertying including the plastic bearing are kept stationary, and the metal flap of the moving bracket glides within the plastic bearings.

Any thoughts on what to lubricate, and with what?

 

[RimaNTSS]

I would try to apply some copper-grease or maybe even WD40. And, of course, all the nuts&bolts change to INOX.

 

[blademedia]

You could always replace them with something like this
50pcs thrust needle bearing AXK0619 + 2AS washer for 6mm shaft-in Shafts from Home Improvement on Aliexpress.com | Alibaba Group

 

[archive10]

I would try to apply some copper-grease or maybe even WD40. And, of course, all the nuts&bolts change to INOX.

Hmm, trawling the net last night brings up people discussing how anything oil/petroleum based will kill plastic & rubber.
Even WD40.
Most spray-driven materials also seem to have solvents in them that are no good.
I get most people saying "just use silicon paste".
Maybe that's the answer?

 

[RimaNTSS]

Maybe that's the answer?

Maybe. But OTOH, if WD40 kills plastic you can replace broken parts by new ones, anyway existing parts look ugly

 

[jeallen01]

@st1 /@bm
From the photos of the mount, it appears that you would need one of the larger-bore sizes of bearings (but a very useful sort of component anyway).
@st1
"Silicone" - not "silicon" - I think.

 

[archive10]

Maybe. But OTOH, if WD40 kills plastic you can replace broken parts by new ones, anyway existing parts look ugly

Probably right, you are.
I will give them a go with Silicone (happen to have some in atube here).
If this not work I will try rougher stuff, if still not work I must replace with steel or copper variants.

 

[Channel Hopper]

That is a Lenson Heath polarmount and I have about five clients still using them, 80cm solid and mesh, 1m solid and one person with a Prodelin 1.2 offset reflector.

All I do is tighten the bolts of the 'bearings' once a year and rise the elevation angle a smidgen to make up for the wear.

I was thinking of drilling new holes for the retaining screw at 90 degree angles to the original, and rotate but so far nobody has complained about loss of service with the routine in place.

 

[archive10]

@st1"Silicone" - not "silicon" - I think.

Sorry, bloody auto-correct feature of web-browser plug-in.
How embarrasing, actually, it is one of my hobby-horses when using computer lingo.

UK: Silicone == DK: Silikone (the plastic stuff)
UK: Silicon == DK: Silicium (the semi-conductor materail).

 

[jeallen01]

BTW: I would have thought that using those needle roller bearings would reduce the friction, and thus the load on the motor and so the mount might turn a little more easily &/or quicker.

OTOH: if CH offered that mod to his customers then he might lose the repeat business

 

[archive10]

Ok. thanks for the suggestions.

Trying to dislodge the plastic parts from metal ones demonstrated that the plastic parts are quite brittle.
I've given up trying to pry them apart, and will just lube them up as much as I can.

Found this in a local builder's market:



From the blurb it says it's specifically made for lubricating plastic and rubber parts.
Nevertheless, it contains petroleum, which some websites claim is bad for plastic and rubber.
Well - time to try it out...