My TAL 2M Servicing

[JohnF-R]

I've owned my TAL 2M for nearly 7 years buying it from a chap in the Chepstow area and he gave me a load of paperwork with it. Attached I've put the certificate and specification incase you want to know the telescope details

The scope has been fantastic, I've really enjoyed using it and finally getting back into astronomy after a few years break. It's now a little tired and needs a good cleanup, service and... I'm going to try to improve it a little bit. Here's that journey to hopefully a freshened up scope with blacker blacks and crisper views! 

Telescope before clean-up:

As I've got a few days off I've decided to spruce it up as it's been a bit unloved and generally just needs a good clean-up. I've included some pictures of my progress so far.

Today I've disassembled the telescope OTA, removing everything. I bought some Fortress non-reflective black paint (recommended by Altair Astro) and thought I'd have a bit of practice with it on the finderscope mount and dew shield. 

The first target being the finderscope, I cleaned the lenses up, sandpapered the dew shield and mount and repainted them black. I'll take some more pictures on Monday when my work continues! The finder scope still has some black specs in it, as can be seen with my bad phone photo through it, but it's not too bad and the centre circle is nice and crisp. 

 

Finderscope before cleaning...

Cleaning equipment, soapy water, deionised water (milk bottle for pouring), lens pen, wife's hairdryer 😁

After cleaning  

Finderscope disassembled:

Dew shield after sanding:

And after painting:

I've taken the spider out too and given the secondary a clean, as you can see from the pics there's clearly an issue with my deionised water! Think I'll attack it again on Monday once I get some energy to get rid of those rings... The spider vanes I've painted now, again pictures Monday.

Secondary and spider pre-clean:

Post clean, not happy with the water mark left behind...!

The primary is out too but I cleaned that recently and I think it looks OK so not going to clean it again.

The focuser rack and pinion is really quite stiff and needs cleaning and fresh grease applying. Finally the tube itself needs a good clean! It's got a spider living in there, hopefully it's taken the hint to move out otherwise the feather duster will get it! Inside the tube I'm going to clean it and apply the flocking, just purchased from FLO and I hope that arrives Monday. 

A dirty tube...!

 

So Monday's jobs are:

- Perhaps clean primary and secondary mirrors again

- Top up paint if necessary

- Disassemble focuser, clean, regrease

- Clean tube, apply flocking

- Rebuild OTA

- Maybe start looking at the mount...

- Maybe take apart motor drive...

 

For grease, I'm not sure what to use or where to get it from, does anyone have any recommendations? Also the motor will need a good clean and re-greasing so if there's a common product that would be good but if not, a recommendation here too would be appreciated

Finally, the tube has a lot of yellow tape on it which I've started removing but it's leaving glue and/or removing paint so think I may need to sandblast the whole thing and repaint...! 

I'll keep you guys updated with my progress and hopefully haven't bored too many of you! 

 

TAL 2M specs:

Acceptability Certificate, dated November 1993!:

Blackspots on the finderscope still : 

Spider, pre-clean/painting:

 

 

Edited October 24, 2021 by JohnF-R

[JohnF-R]

Since my last post I've done a bit more to the scope, first was the focuser. It was stiff and difficult to find fine focus, but after a good clean out and regreasing I'm pleased to report it's very smooth! 

As disassembled

After cleaning

Zoomed in before and after

Liberal application of automotive grease, lithium based

And successfully back together and working like never before  

 

The paint has dried on the spider which I'm very impressed with the results of. I'm not quite brave enough to paint the mirror back though... May need to get some bravery and steady hands!

 

The motor was next on the list of things to tackle, hopefully the diagram below explains how it works fairly well and the bits of maintenance I've done. 

The motor turns two gears which spins the shaft turning the work gear and working the RA and correcting for the spin of the earth. I realigned the motor gears as they didn't look central, cleaned and lubed. The RA fine adjuster, in cyan, has two bearings supporting it, these support significant bending forces and looked quite dry of grease. They spun entirely freely when removed from the shaft but I imagine once they were loaded up they probably were not going to turn as smoothly as one would like. So liberal application of grease here. It was very fiddly to get these back together! All gears were cleaned and regreased liberally, including the worm drive which was difficult to access without removing the motor. I really didn't want to remove the motor as some of the wires look very close to their last legs, lots of pictures have been taken incase any snap...

 

 

Finally, if you listen to the motor in the videos in the Youtube links below there's a distinct clicking. I assume this is because it's a "watch drive", however I think this is probably the root cause of the OTA giving the best views when the motor is switched off. May need to investigate replacing the motor or tweaking it. This fills me with dread when looking at how frail all the wiring is. There is a wiring diagram but I'm not sure my local hardware store will have the resistors referenced! 

https://youtu.be/B-ta9RADVHY

https://youtu.be/2mq1jlpeUwo

Tomorrow hopefully the flocking arrives to do the internals of the OTA and then I can reassemble everything

 

Oh just remembered, I cocked up and used de-ionised water to clean the mirrrors and only just remembered it's distilled water that you should use... The secondary needs another clean before going back together! 

Edited October 24, 2021 by JohnF-R

[JohnF-R]

Yesterday was a mildly traumatic day 😁, the tube really did need repaint... It did... It did...! 

So after many hours of paint stripping and then sanding, so much sanding, it was ready for painting. Undercoat on and it looked pretty smart! 

 

I've done the two layers of white paint now but on the second coat it has started to crease or react, looks like I'm in for a lot of work delicately sanding it back to good white paint then polishing it up. I'm properly gutted with the paint reacting after all the hard work and using all the correct products. All I can think of was when applying the second coat this morning the tube was too cold. Anyway, it just means some more work which I can do.

Lessons learnt:

 - When sanding, don't use water, the paint powder just turns back to paint and fills in everything you've just sanded!

 - If you need your thumbprint to get onto your phone, or internet banking, wear gloves! 

 

Whilst waiting between paint coats I made the sheets for the interior of the telescope, hoping all my measurements and calculations are correct. However I have some spare if I'm off a little, if I'm off a lot then maybe not! 

 

On Friday the top coat of paint should be dry so will assess the damage of the white paint not settling right then figure out what to do. Hopefully not too big a job. Also need to get distilled water bought which seems to be impossible to find in Norfolk (everywhere has de-ionised and as I don't own a freezer I can't just make my own!). 

 

So next steps:

- Finish tube paintjob 

- Flock inside of tube

- Clean secondary again

- Rebuild and enjoy the views!

[R26 oldtimer]

Very nice!!

[fate187]

the Tal 2M was my first real scope after a 60mm achro. I got this as a teenager back mid 90s. Oh the memories

[Alan White]

On 22/10/2021 at 19:28, JohnF-R said:

Cleaning equipment, soapy water, deionised water (milk bottle for pouring), lens pen, wife's hairdryer 😁

Oh John , how could you, never post a picture showing you used 'The Wifes' hairdryer or
indeed the dishwasher or sink for any projects......
It will come back to haunt you, I know from experience 😉

The project is looking great, my first look through a scope was a Tal-1 many, many, many Moons ago.
Always wanted one, but never had the money at the time.

Edited November 2, 2021 by Alan White

[Boki Aristarh]

Amazing work done!

This scope really deserves such treatment because it produces one of the best 6" scope performance.

Planet killer!

[Alkaid]

Fantastic project.  I had a TAL-1 and the optics were very good.  The '2' will be brilliant on the Moon.  Look forward to seeing more!

[JohnF-R]

Thanks for all the positive comments, you all really helped motivate me after the paint disaster, so the scope is now done! I apologise for the eternal cloudy nights that I have now summoned!

Here's my progress, enjoy

Can't wait now for first light!

[Astr0Kaz]

Hi JohnF-R

Thank you so much for such a detailed description on how to refurbish the TAL 2M.  I am tempted to try cleaning and possibly flocking mine,  your post has definitely given me more confidence 😊 

Can I please ask how you collimated the scope afterwards? I have seen a few different methods, using a Cheshire or laser collimator, Ocal, and even a webcam version, but I'm not sure which method would be the best choice for this scope? Without breaking the bank that is, I've just noticed a Hyper star laser collimator that sells for over £600 ..Gulp!!  

Thank you 😊

Kaz