Telementor 2: service and restoration

[markse68]

Thanks @Stu, I bought a Baader low profile 1.25” T2 adapter a little while back for this lens and a diagonal.

it proved to be not much cop for visual- a lot of CA and it wouldn’t reach focus with the diagonal so I plan to use them with this scope. I baullked at the price of the Baader m44 to T2 adapter 😳 so have ordered a sh Miranda to female T2 and a cheap Chinese T2-T2 male adapter which hopefully will do the same job. Won’t be here for a while though so my neck and back are getting a lot of extreme stretching!

 

Edited May 3, 2020 by markse68

[estwing]

10 hours ago, markse68 said:

? Mine had a tiny little dab of varnish to lock it but it span out really easily

Not sure how much was on mine but my its solid

[markse68]

All the stuff needed to sort the slo-mo controls arrived so here we go.

The problem- a broken missing spring housing on one axis and both the slo-mo knob thread inserts stripped and unusable

inside the mechanism

The stub of the broken spring housing came out quite easily

It should look like this

Inside 2 very stiff compression springs and a brass plunger

I hadn't realised there were 2 which means one was lost when the housing was broken

Found another spring- its not as stiff and smaller diameter but it should do- might order a correct one

The original threaded inserts for the slo-mo knob are PTFE- nice and low friction but no wonder they strip out so commonly- it's so soft.

The replacements will be delrin- at least that's what I ordered but it didn't smell like it when being cut...

Tricky to get the old ones out- they'e secured with a little grub screw but had seized in place after all these years- screwdriver in slot wasn't going to work

No option but to drill them out! 1mm steps starting at 6mm- they both unscrewed when I got to 8mm

Measure up the old/existing parts

The die I bought was a very cheap one so I started with the new delrin thread inserts figuring there was a good chance it'd get ruined doing the spring housing 

I didn't slot the inserts- just installed them with an M6 screw- the knobs have standard M6x1 threads. Lock them in place with the grub then unscrew the screw

New spring housing in stainless- the original was chrome plated steel. They don't match but close enough. I sand blasted the finished item to try and match the look a bit better

All assembled back together with fresh grease on the sliding surfaces and it seems to work as intended! Should be a bit less frustrating to use now

Edited May 7, 2020 by markse68

[DaveL59]

no pics Mark? 😛 

[markse68]

You're too fast lol

[DaveL59]

figured you were post-editing, just it appeared in recents so I took a peek and just text lol.

Nice job though, well done sir! Handy to have a good workshop to be able to turn the required bits too, I'd have been stuck on that side of things. I do wonder why they used non-metal for those parts, the TAL's all seem to be threaded metal components and kept greased they work for a long time. Guess in a school environment they figured no maintenance would be done and went the PTFE route to prevent them seizing up, perhaps.

[markse68]

Thanks Dave- yes my work workshop comes in handy

Good question though- the Tal ones are much more robust- these are a bit dainty by comparison. It does have a nice feel with the plastic inserts- maybe they figured they'd get damaged regularly and offered repair kits to keep them going- knobs and inserts?

[DaveL59]

no clue on that, was just a thought given they were I think intended for school use at the outset, so perhaps spares were available back then. I'd imagine the action is silky smooth though in your setup with those nice new inserts. Might almost be worth turning replacements in bronze next time around though different thermal properties might be a bind in very cold nights