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Servicing a Tal 100 RSM mount


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I have recently joined SGL after deciding to get my Tal out of storage from the garage and back in working order again. Before I could do so it needed a good service. After finding Asto_Baby's Tal 1 Restoration/ Strip Down and Rebuild guide (http://www.astro-baby.com/TAL%20Telescope%20Rebuild/TAL%20EQ%20Mount%20Strip%20Down%20Guide.htm) along with some old documents I had saved, and help from her and AndyH, I am pleased to say it is now back working again.

To help anyone else who may be be thinking of doing the same thing I thought I would post some infomation.

The Tal

My Tal 100 RSM: I bought it some time back in 2001, it has a 2" focuser, the 'lighter' of the motorised Tal mounts (MT-1C), a wooden tripod, a Vega drive corrector, and also the original wooden pine box.

One problem I had was removing the declination setting circle. It would rotate but could not be removed from the shaft. After some messages and help from Astro_Baby and AndyH, I finally managed to remove it. I cleaned out the screw thread on the axis again!, put some new grease on the thread, some penetrating oil above the setting circle around the shaft and then pulled down and rotated the setting circle back and forth. It seems the secret was to make sure that when I pulled down, it was perfectly square with thread on the shaft, plus lots of lubricant. Inside, the setting circle was quite gummed up with some very hard Russian grease and dirt, making the fit exceedingly tight and difficult to pull over the thread on the shaft.

Clutch adjustment and screw settings

When I adjusted the main clutch, I found it was easiest to remove the motor first. This gave access to the worm drive which I could adjust, and then tackle the motor clutch adjustment on the side of the RA drive.

After tightening the 3 screws on RA clutch until they were snug, they needed to unscrewed 1 complete turn to be properly adusted. The motor clutch adjustment screws needed to unscrewed 2 1/2 turns.

It was rather trial and error to get the clutches properly balanced but these adjustments are fine for my setup. I did discover that the motor clutch adjustment screw adjustmenst are quite sensitive. Once adjusted properly, just a slight loosening of the screws (less than 1/8 turn) has a significant affect on the tracking accuracy. I found also that when the worm drive and clutches were properly adjusted the motor was much quieter than previously and could hardly be heard.

PDF file

I have included a copy of an old pdf file I had saved regarding adjusting the clutches that other users may find useful, I think it came from Talscopes (Canada? I seem to recall) that was around some years back. I have some other images too regarding servicing that I will try to post later.


Other adustments

Another thing that needed attention was to make sure that the 3 screws underneath the mounting cup on top of the tripod were tightened.

Later I intend to replace all the small black screws in the tripod mount with something a bit larger, especially as several have become slightly loose.

One thing I would like to do is to change the way the mount is held on the tripod and not have to use the 3 retaining bolts. Has anyone done this?

If anyone wishes to ask anything further, please feel free to ask.



Edited by rokkerz
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Nice report.

Regarding the three thumbscrews on the tripods 'cup'. I've got a Tal tripod, earlier version, I think and it has a different way of holding the mount on.

My 2M mount(MT-2C) came with a threaded adapter plate screwed to its base....4817514177_d8955fbe99.jpg

My Tal tripod....


The large knurled hand bolt...


I've always found this method of attaching various Tal mounts to the tripod, very secure.


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Years back, I shimmed up the tripod cup, in a similar way, as described later on in the above pdf. I found that it does help the stability when using one of my heavier Tal mounts. Perhaps not really necessary with smaller loads, but it defo improved with heavier mounts and scopes.


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