Tal 2m Mount rebuild

[rawhead]

Hi Folks.

Bit of a longshot this one.... I have some wobble in the RA arm on my Tal2m. I have found some instructions on dismantling and have got this far. (In green)

I can't remove the 'round nut' When I grab it and twist the whole thing moves. Can anyone help?

Cheers

Jon.

TAL-2M RA ARM DISASSEMBLY

There are two screws in the "arm assembly" near the RA setting circle on opposite sides. You unscrew these all the way (don't screw them inward), they are actually cap or grub screws and serve as covers. Deeper underneath you will see two more screws, loosen these about 3 turns. Then stick a screwdriver through one of the holes in the RA plate to stop it rotating and turn the arm assy CCW (unscrew). Just keep right on unscrewing until it comes off. You will then see the end of the RA shaft. Surrounding it is a cover held on by 3 screws. Remove. Then you will see a round nut with two perimeter holes. Unscrew that. If you don't have a spanner you can just grab the nut with a pair of channel locks or other large pliers. At this point the RA shaft can be pushed out of the motor housing through the back. Drift the bearings out with a wooden dowel or brass punch. The inner bearing is sealed so I just left it alone except for application of a bit of thin gear grease. The outer bearing is the one that collects all the metal chunks despite the cover. It is the most exposed except for the lower Dec bearing which collects everything else that gets loose inside the arm assy. The round nut supplies the pre-load, on reassembly it should be tightened snug only. If you can't pull or push any play in the RA shaft that's tight enough.

(click to enlarge)

(click to enlarge)

[AndyH]

Hi Jon.

Been there.

What you need to do is 'tap' the nut loose with a centre punch or a bit of rod or a drill bit. Once it's loosened, you'll be able to unscrew it with your finger.

Does this help?

Andy.

[rawhead]

Hi Jon.

Been there.

What you need to do is 'tap' the nut loose with a centre punch or a bit of rod or a drill bit. Once it's loosened, you'll be able to unscrew it with your finger.

Does this help?

Andy.

Thanks Andy,

I was hoping you’d see my plea for help. I’ll take your advice and give it a whack!

I assume positioning the punch just inside one of the two holes would be the best bet?

I’m going to clean the bearings and re-grease. Do you think petroleum jelly will be up to the task?

Cheers

Jon

[AndyH]

Hi.

Yes, just inside the hole. The big brass gear and shaft should then easily pull out. My bearing was a snug fit and I had to give it a bit of a dunt from behind to remove it from the housing. Try to use a bit of wood or such in front of the hammer, to avoid harming the bearing. As for cleaning, I used a tupperware container filled with white spirit in which I dunked the bearing in and whirred it round to clean out the russian gunk. An old toothbrush or someones you dislike would be a help to remove stubborn bits. Before you re lube it, check that it turns smoothly. Mine was a bit rough, so I got a new one from a bearing shop. BSL or something like that. Hopefully yours will be okay.

I used just a standard grease(lithium?) from halfords to relube mine.

Have you taken out the worm shaft yet? It has a bearing on either side. Both on mine were quite rough, so I changed these too.

Cheers,

Andy. :wave:

[AndyH]

A quick update for those that may have any interest.

Whilst waiting for a new reduction gearbox for my tal motor, I stripped my mount down too. It may seem daunting, but it's relatively straight forward and lets you understand how the head works.

Here is the RA shaft, with hefty bearings and the big brass gear.

(click to enlarge)

After giving the brass gear and surrounding parts a good clean, I checked the bearings. The rear one was fine and smooth, but the smaller front one was as rough as a badgers bottom after a night out ! The damn thing was only put in a few years back. Either I got a dodgy one or perhaps this one takes the brunt of the weight carried on the mount.

(click to enlarge)

No matter, I got a replacement, re-fitted the shaft after a hefty greasing and WOW. What a difference. After adjusting the clutch, balancing the scope, snugging the worm to the gear etc, I was rather pleased by the smoothness when the slow mo wheels were turned. Much, much better.Now I have to endure the long wait for the replacement gearbox. As can be seen below, mine is well and truly gubbed.

(click to enlarge)

Thanks goes to Jon for pointing me in the direction of OVL who had spares in a darkened corner somewhere !!

Cheers,

Andy.

[rawhead]

Hi Andy,

After following your excellent advice, my mount is also now reassembled and soooo smooth

Putting the motor back I managed to short out the transformer on the metal casing

A guy at a work replaced a resistor (which blew before the fuse?) and I've also got a natty yellow LED (prolly kna**er my night vision )

All working fine. Now where can I get a Vega....................

Changing the subject, I assume at some point in the past you swapped your Tal2 for a 200K. How do the scopes compare?

Cheers

Jon

[AndyH]

Glad to hear you're all fixed. :hello1:

I still have the 6"F8 newt. It's lying in it's coffin, in the loft. Haven't used it for years !! When Daz put the 200K up for sale on here, back in November, I couldn't resist the temptation . I've always been fascinated by the Klevtsov after reading reviews and all the talk on the Talscopes yahoo group. Up til I got the 200K, I had been using my 100RS and my wee Ylena 85 mak. The jump to the 8" was and still is, a nice improvement. So I've no idea how the newt and the Klev compares. I guess the extra 2" will improve views and will compensate for the Klevs bigger central obstuction.

The 2M mount is a star though, as long as you don't mind tinkering. Good old fashioned engineering. It carries my heavy 200K with ease. In fact, it was with this mount, carrying the 100rs, that I got my best ever views of Saturn, years ago.

Cheers,

Andy.

[AndyH]

I thought I'd post an update on the 2M mount.

My gearbox arrived from OVL . As you can see from the pics, it came with the motor too.

While I was waiting for the motor/gearbox to arrive, I ordered some new setscrews for various parts of the mount.

These ones hold the motor plate in place. As you can see, they fit an allen key, which is better than my chewed up old flat screwdriver ones. Size= m3x10 countersunk head (x3 needed)

New motor in place

I also replaced the x4(per side) m4x16 c/sunk setscrews that hold the worm bearings in place. Again, my original ones were badly chewed.

Everything's working rather nicely now. :hello1:

Just need to wait till my 56* north skies darken in a few months time, before I can give it a true workout.

Cheers,

Andy.

[rawhead]

Excellent stuff Andy

Glad you got sorted...

[SteelRat]

Yup, good stuff mate 8)