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unitron 142 eq mount. questions and modifications?

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7 replies to this topic

#1 jcricket

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Posted 06 January 2019 - 11:03 AM

correction - Sorry for the brain fart folks. My mount is the 142 - not the 128 I posted -doh!!!

 

 

Hey Folks,

I just acquired a unitron 142 mount. It is in vg functioning condition, needs a bit of cosmetic love, and some grease and adjusting. That is no big deal to me. I do have some issues and questions about the mount. I hope someone here can help.

First, the saddle or "ring cage" is for an 80mm OD tube. I do not want to use the mount for an 80mm tube. I would much rather have a saddle on it that can take multiple dovetails, or at least rings like parallax makes. The shaft that goes into the current saddle is about 3/4" and is threaded. I haven't actually measured it yet, just an eyeball guess. Does anyone know of a saddle that can mount on here appropriately. I think I could fabricate one if needed. 

 

Second, does anyone know of a place that makes, sell, may have a drive for these old mounts.  

 

And lastly, does anyone have a decent feel for the load capacity on this mount? I am guessing something 12-15lbs if it is a short length ota, maybe under 10 if it is a long focal length refractor. Thoughts?

 

Thanks for the help!!

 

Edit: My dream scope on here would be something like a tv 85, or tv101 - thoughts?

 

Double Edit: I did some searching to find out what the thread is on the counter weight shaft. I found an old archived thread but know definite answers. I have carefully measured and cross referenced to the charts I have. It "appears to be a 12mm course thread, or more specifically, 12 x 1.75 thread. I am going to be at ace later today, I'll see if they have a thread gage or nut to try on this shaft. I'll let you know.


Edited by jcricket, 06 January 2019 - 11:49 AM.

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#2 jcricket

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Posted 06 January 2019 - 11:37 AM

I found this via google

An aftermarket drive system for the unitron mounts

https://astronomy-shoppe.com/


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#3 jcricket

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Posted 06 January 2019 - 04:08 PM

Forum Moderators, can you move this to the classic telescope thread? I think it might be more appropriate over there. Thanks!



#4 starman876

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Posted 07 January 2019 - 07:26 PM

You will to fabricate the shelf yourself to mount different rings.  When you take the current cradle off, you will need to heat the threads because they put glue on the threads before they set the cradle on. On some I have found a set screw that was buried under some filler.   Do not know if the set screw is original.   They are very good mounts and you will enjoy it.  



#5 jcricket

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Posted 08 January 2019 - 10:20 AM

I took the cradle off. It was screwed on as stated. It had two screws, not set screws, but performing the same job as set crews. I have done some careful measuring with calipers. It appears the threads on this mount are actually metric. I used to be a "parts man" in the industrial maintenance trade. So my job was to identify "parts" for equipment including unknown threads. I have found this chart to be most helpful time and again.

 

https://mdmetric.com/tech/tict.htm

 

The counterweight shaft is m12 x 1.75. I think the thread on the cradle is m20x1.00

 

pics will follow later today

 

mark


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#6 starman876

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Posted 08 January 2019 - 11:41 AM

Sometimes the threads were set for whatever the lathe was set for that day.  That is what I have found with some Unitron parts.   I believe there was a lot of cottage industries in Japan after the WWII that were making parts.


Edited by starman876, 08 January 2019 - 11:41 AM.


#7 Dave Trott

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Posted 08 January 2019 - 01:23 PM

I agree with you, Johann. I have seen a large variety of threads on Unitrons. Parts you expect to be identical do not fit.



#8 starman876

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Posted 08 January 2019 - 01:49 PM

I agree with you, Johann. I have seen a large variety of threads on Unitrons. Parts you expect to be identical do not fit.

It is frustrating.  You go and say oh I have an extra one of these to make a mount complete and then you find that a part from the same model mount will not fit another mount.  There are even variances between other parts with differences even though minor are enough for the part not to fit.  Still the quality of the mounts over all the years was still very good.  Even the OTA assemblies quality was always very good.   About the only weak point was the lenses. Over the years the quality varied.  Thickness of the two lens elements did vary over the years so the lens cells were not the same.     


Edited by starman876, 08 January 2019 - 01:50 PM.

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