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Royal Astro R74/Tasco 10TE - how to disassemble the mount?

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#1 LukaszLu

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Posted 13 December 2020 - 05:50 PM

Hello, I'm stuck at this point. Will anyone suggest what to do next? Do I correctly suspect that it will be necessary to tear off and destroy the felt lining the clamp? How do I remove the brass worm wheel and the worm?

Thanks!

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#2 CharlieB

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Posted 13 December 2020 - 05:57 PM

You have to loosen all four of the grub screws that lock the eccentric bearings quite a bit, then the bearings can be pulled out.  Once that happens, you can remove the worm and then the wheel can be removed.  Take photos of each step so you know where all those reddish gaskets go.

 

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#3 CharlieB

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Posted 13 December 2020 - 06:03 PM

I think that on this version of the mount, you have to remove the dec assembly before you can get to two of those grub screws.

 

Charlie


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#4 Bomber Bob

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Posted 13 December 2020 - 07:10 PM

Three Illustrated Threads on servicing these EQs....

 

Preston Smith (2008):   https://www.cloudyni...sco-3-eq-mount/

 

Bomber Bob's (2014):   https://www.cloudyni...em-restoration/

 

Tasco 10TE (2019) - Volvonium:   https://www.cloudyni...co-10te-5-find/


Edited by Bomber Bob, 13 December 2020 - 07:13 PM.

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#5 LukaszLu

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Posted 13 December 2020 - 07:14 PM

Thanks a lot! I've also found the next topic showing all the steps here: https://www.cloudyni...mount-overhaul/ - great reference material...


Edited by LukaszLu, 13 December 2020 - 07:20 PM.


#6 Kokatha man

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Posted 13 December 2020 - 07:33 PM

Thanks a lot! I've also found the next topic showing all the steps here: https://www.cloudyni...mount-overhaul/ - great reference material...

...was going to suggest the thread you found Lukasz - the last contributor in it (Graham, aka Blue Gumby) recently sold his restored scope & mount for a song here in Oz!


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#7 LukaszLu

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Posted 13 December 2020 - 07:48 PM

...was going to suggest the thread you found Lukasz - the last contributor in it (Graham, aka Blue Gumby) recently sold his restored scope & mount for a song here in Oz!

Looks like I'll be spending my long winter nights cleaning off the old grease :-)


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#8 Kokatha man

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Posted 13 December 2020 - 10:00 PM

I'm sure you'll be rewarded when you finish bro - they have a fine reputation...I thought long & hard about buying Graham's unit but I have too many scopes as it is! lol.gif


Edited by Kokatha man, 13 December 2020 - 10:00 PM.

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#9 Bomber Bob

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Posted 13 December 2020 - 11:15 PM

Removing the Pine Sap Grease & replacing it with modern lube is worth the effort:  MUCH smoother motions at all magnifications.


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#10 Kokatha man

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Posted 14 December 2020 - 01:55 AM

Removing the Pine Sap Grease & replacing it with modern lube is worth the effort:  MUCH smoother motions at all magnifications.

...might be my own memory bells chiming here Bob - did I read something sometime here about WW2 pine sap grease (in lieu of hard-to-obtain petrochemicals at that time) being used from left-over stocks in some of these Japanese "classic" mounts..? 


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#11 LukaszLu

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Posted 14 December 2020 - 04:57 AM

My first goal is not so much to improve comfort as to avoid damage. The mount moves hard, unevenly, and the previous owner destroyed the focuser gear by forcefully turning the knob, even though it was blocked with a displaced sliding washer. I am afraid not to lead to similar damage here.



#12 LukaszLu

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Posted 15 December 2020 - 06:35 PM

slow forward :-)

 

20201215_195245(0).jpg

 

20201215_232227.jpg

 

20201215_232842.jpg


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#13 LukaszLu

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Posted 19 December 2020 - 06:56 AM

The next small step:

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#14 Piggyback

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Posted 20 December 2020 - 12:52 AM

Nice cleaning job! Did you check for cracks, metal fatigue? I am curious as I won bid for a 10TE, yesterday. 120 Euro! Total gamble. Hope it turns out serviceable. 3 hour drive to sellers location. Been looking for one of these for years. 


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#15 LukaszLu

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Posted 21 December 2020 - 06:25 AM

Great bargain, congratulations! I've bought mine in Germany also, but gave much, much more for the scope. However, I do not have a special choice - at the time when this equipment was produced, it did not reach Poland and you can hardly find it here.

 

I did not find any cracks in the metal castings, but some elements, such as screws or declination circle, are bent, and the worst I have found so far is the focuser with damaged gears. I am afraid that it cannot be repaired, only the replacement remains...


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#16 LukaszLu

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Posted 21 December 2020 - 08:09 AM

Well... That's it! The entire mount is disassembled into parts, cleaned, polished and prepared for greasing.

 

Cleaning agents: white spirit, isopropanol, regular cooking oil, warm water and soap.

 

Black varnish tolerated all of them well. I cleaned the printed scales with soap and isopropanol, the print turned out to be resistant to such treatments. I washed the bubble level surface with water only, afraid of damaging the little red circle. Finally, the paintwork was polished with Tempo car body polish. The metal friction elements were polished with a "aluminum, inox & chrome" type agent.

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Edited by LukaszLu, 21 December 2020 - 08:13 AM.

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#17 LukaszLu

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Posted 22 December 2020 - 12:14 PM

And now something different. Cleaning the optics and ... What an unpleasant surprise! It turned out that there are two small dents on the edge of the inner lens. Micro-shards of glass from them shattered in the space between the lenses. It became apparent only after cleaning the outer surfaces and strong direct lighting. Why did this have to happen to me? Will disassembling the lens end up scratching the lenses with these sharp particles?

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#18 LukaszLu

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Posted 22 December 2020 - 12:16 PM

I decided to try. I unscrewed the metal ring with the calipers, placed the toilet roll on the inner lens, and set them upside down. I picked up the cell casing and ... and the second unpleasant surprise! The outer lens remained in it, dropping only a few millimeters down.

 

How do I put the lenses back together now? Fortunately, on the side of the lenses there was an engraved mark made of three lines (you can see it on the first picture below) - I think it was made just with the idea of reassembling the lens in mind. A very good idea worth using even where the lenses can be easily removed from the housing!

 

I've cleaned the surfaces of glass dust and assembled the lenses according to the marker. At least now, I won't worry if the glass debris is sliding between the lenses, scratching the surface!

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Edited by LukaszLu, 22 December 2020 - 03:59 PM.

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#19 Kokatha man

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Posted 23 December 2020 - 05:58 AM

If you've removed those glass particles, cleaned the lenses & put them back in the correct orientation I don't think you have anything to worry about - I presume you are talking about "clamshell chips" on the edge of a lens...I cannot see any in your piks & the lenses now look very clean & clear - so I don't think that they'd impact on the performance! waytogo.gif


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#20 LukaszLu

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Posted 23 December 2020 - 06:55 AM

I do not know the exact age of this telescope, but I assume it may be from the early 1960's judging by the condition of the rubber foam that protects the edges in the transport box. It's almost petrified, even though it was once soft and supple...

 

Taking this into account, I think that the condition of the optics is quite decent anyway - especially since the previous owner was clearly not a connoisseur and treated this equipment like a cheap "family" telescope from a supermarket. In the case of equipment of this age, there are almost always such surprises related to optics - for example, fungus, which even after cleaning, leaves clear defects on the old anti-reflective layers. Here the main lens were clean, although I found traces of a fungus on the lenses inside the finder.



#21 Garyth64

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Posted 23 December 2020 - 09:19 AM

"How do I put the lenses back together now?"

 

This link shows a very good way to remove and replace lenses in a cell:

 

 

https://www.cloudyni...-restore/page-2

 

#21


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#22 LukaszLu

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Posted 23 December 2020 - 11:25 AM

Thank you very much for the hint! I have already disassembled air spaced achro lenses several times and the structure of the cell has always let me freely remove both lenses after removing the tightening ring, preserving their mutual position and then applying a marker. In this case however, one of the lenses unexpectedly becomes stuck in the cell, so without the previously engraved marker (probably by factory?), it would be impossible to restore the original position of the lenses.


Edited by LukaszLu, 23 December 2020 - 12:35 PM.

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#23 photiost

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Posted 23 December 2020 - 01:02 PM

In old telescopes, I have noticed when left sitting in the same position for a long time sometimes the spacers will leave very faint "traces" on the glass surfaces so with a little effort it may be possible to find the factory orientation. 

 

Before  cleaning, try holding both elements up to a bright light source, like  a window, if the "traces" are still visible mark their positions, then after cleaning there are only 3 possible combinations to test for best results.    


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#24 LukaszLu

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Posted 23 December 2020 - 02:03 PM

Valuable advice! Fortunately in my case i've found this mark and used it to align both lenses:

 

 

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#25 Kokatha man

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Posted 23 December 2020 - 07:21 PM

In old telescopes, I have noticed when left sitting in the same position for a long time sometimes the spacers will leave very faint "traces" on the glass surfaces so with a little effort it may be possible to find the factory orientation. 

 

Before  cleaning, try holding both elements up to a bright light source, like  a window, if the "traces" are still visible mark their positions, then after cleaning there are only 3 possible combinations to test for best results.    

This has been my experience also - Lucasz, what exactly are we seeing in your pikky above...are these markings/etchings on the edges of each lens of the doublet objective, or the shadows of these on the metal cell..?

 

Is that a clamshell chip you spoke about on the far bottom right just above the foil spacers? - if so, it is minuscule! waytogo.gif


Edited by Kokatha man, 23 December 2020 - 07:21 PM.

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