Refurbing classic Charles Frank mount advice

[badhex]

Hi all

I've posted before about my old Charles Frank mount I inherited, but I'm ever closer to finally getting round to cleaning it up and refurbishing it. As I see it there are a number of things to be done, and I'd love to hear anyone else's experiences and advice on such a task (methods, materials, cleaning products used, gotchas etc.). Please see photos below.

The list of things I'd really like to achieve:

- Clean up all gear/worms and regrease (should I risk removing them completely to clean? What to use to regrease?)

- De-rust the areas that need it (Liquid rust remover? Dremel?)

- Perhaps strip the peeling paint and repaint legs/tripod (Hammerite?)

- Touchup or strip/repaint the mount itself (de-rust, a bit of sanding and touch up maybe a better option perhaps?)

- Re-felt the rings (should be fairly straightforward)

- Create a new motor bracket to replace the makeshift one someone has created (this will definitely need to be a custom job. Need to find a welder, methinks!)

- Devise some sort of leg spreader/stabiliser

Things I've already done:

- Clean up the motor, re-cable etc.

- Attached a temporary chain to the legs as a 'spreader'/stabiliser

Additionally I'd really like to paint the OTA which I believe is made of either plastic or fibreglass but I'm not sure which. I'm thinking carpaint, but again I'm not sure!

If anyone has undertaken a task such as this before I'd be most grateful for tips, although I'm fairly handy with DIY/practical stuff I'm really not sure where to start!

TIA

Joe

     

[Bizibilder]

I would dismantle it carefully, taking pictures and making notes as you go - put all associated parts in boxes (plastic tubs) so you don't lose them.  The gears are almost certainly steel and the worms will be Phosphor-bronze.  They should be cleaned in something like white spirit or petrol (Be careful and do this outside, use rubber gloves etc.) followed by Meths (alcohol).  Allow to dry in air.  An old toothbrush is a useful cleaning tool.  Get everything spotless and check for damage and obvious wear - there shouldn't be any - most telescope mounts do less then a few hundred revolutions in their entire lives!!

Be wary of paints as some will remove the original paint - try a small test area first.  Hammerite is notorious for removing or damaging old paint.  Japlac: http://www.amazon.co.uk/International-Japlac-Gloss-Enamel-Paint/dp/B00HYUNOKC/ref=pd_cp_diy_0  is good and is close to the original paint used (if not the same).

You could strip the paint if you wish and de-rust with a brass wire brush - in an electric drill is easier than by hand.  http://www.halfords.com/motoring/paints-body-repairs/specialist-decorative-paints/nitromors-all-purpose-paint-varnish-remover-375ml  is a good paint remover.  The weights are steel so a coat of Jenolite rust preventer before you paint them will keep the rust at bay.  The mount itself is cast "alloy" - almost certainly some sort of aluminium alloy, this means it is quite "soft" and should be treated with due care as it will dent and scratch comparatively easily.

There is no reason that, with a bit of care, you could get the mount back to more or less "as new" condition.

As this is a mount from the 60's or 70's all the threads will be imperial inch threads.

[badhex]

Wow, Roger thanks!

Fantastically detailed reply! I'm no stranger to stripping electronics down as I work in IT support, but much more nervous about old mechanical stuff. Your insights are invaluable, I'm indebted! I'd really love to get it back up and running and looking the part. I know CF scopes were not all that, especially by today's standards, but from the little history I know of it (apparently it was once upon a time cemented into the ground at Chesterfield Observatory), would be a shame to let it go to rust.

A few purchases methinks, and onto the cleaning!

[Zakalwe]

I really wouldn't recommend using petrol to clean anything. Petrol is highly volatile and the fumes are explosive and heavier than air. They will "soak" into clothing, creating a potentially dangerous combination. 99 times out of 100 nothing will happen. On the 100th time you could end up like the brother of a workmate years ago. He was cleaning carbs on his car and the fumes that had soaked into his clothes ignited. His family managed to extinguish the flames but he was unconscious.  He later died in hospital. It just isn't worth risking messing about with petrol.

Use paraffin to clean stuff. It's a lot kinder to seals and plastic than plastic (modern petrol contains ethanol which can dissolve some plastics) , won't give off flammable fumes and is a heck of a lot cheaper than petrol. You can get it in just about any garden centre or larger petrol station.

[badhex]

Thanks Zakalwe, I've seen/heard of too many instances of irreparable damage to self and property to be touching petrol - it wouldn't be an easy get for me anyway as I don't own a car. I have white spirit already so that would be the logical option. Top safety tip though!

While we're at it, Bizi could you explain the logic behind using meths on the gears and worms? Is this to help 'dry' them off cleanly? Also, what to use to re-grease?

Thanks!

[Bizibilder]

Oops!  Sorry - I meant paraffin or White spirit!  I agree Petrol is too nasty!

The idea if the meths as a second solvent is that the first solvent (White spirit or Paraffin) will, as you say, be slow to evaporate and may leave an oily residue behind.  The Meths should clean this away for you.  The Meths may also shift some of the muck that the other solvent wont shift - each solvent has its own properties.  To re-grease you can use something like Vasaline Petroleum Jelly - you only need a touch of it on the gear teeth where they mesh.  Bearings should be oiled, something like "3 in 1" - again just a touch, not a flood.  The biggest problem with greasing/oiling something like a telescope mount is trying to stop grit and dust adhering to the grease and getting into places where it shouldn't be!!  So go easy with it.