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Tasco 15TE/10TE clock drive motor specs?

classic equipment mount refractor accessories eq
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#1 ccwemyss

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Posted 14 July 2019 - 09:11 PM

One of my students is refurbishing a 76.2mm Tasco that may be a 15TE or a 10TE with the add-on clock drive. It came missing the serial number plate (along with most everything else but the OTA, mount, and tripod, and a very beat up wood case that had enough of the wood inserts remaining to imply that it was before the switch to styrofoam), but has the bracket and large gear for mounting a drive motor, as seen in this thread:

 

https://www.cloudyni...case/?p=8547814

 

I've done quite a bit of searching and reading of prior threads, and although I have found a bunch about the history, and the different models of drive, I haven't found the actual specs that could be used to source a replacement motor, beyond it being a 60Hz, 110VAC synchronous motor. 

 

Does anyone know the RPM rating, whether it is CW or CCW, the diameter and tooth-count of the spur gear? Seems like we should have that documented somewhere.

 

Or even a pointer to a source for an equivalent motor?

 

Thanks,

 

Chip W. 



#2 Compressorguy

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Posted 15 July 2019 - 06:00 AM

Hi Chip, the short answer is the motor is 1/10 RPM, CCW rotation. I came up with a motor solution years ago for my Tasco 10TE-5 that I still have today and is still working fine. Here’s a link to that post detailing a lot of the info you seek. Good luck with the project. 

 

https://www.cloudyni...hl= tasco 10te


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#3 ccwemyss

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Posted 15 July 2019 - 12:15 PM

Thanks Scott, but I see that you were working on a direct drive system, coupling the motor directly to the shaft. This mount has the 144 tooth gear as in the post linked above, like that for the 15TE drive.

 

So, if the goal is to get 1/10RPM CCW into the shaft, then I take it one would need a 1.2RPM CW motor driving a 12-tooth gear against the 144-tooth main gear. 

 

Perhaps someone who has an older 15TE could confirm that?

 

Chip W. 



#4 Compressorguy

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Posted 15 July 2019 - 03:56 PM

Ahh, didn’t see that before and didn’t realize there was another gear driven version (older?) of the drive for these. I’ve only ever seen the direct coupled/clutch version. Learn something new every day.


Edited by Compressorguy, 15 July 2019 - 05:22 PM.


#5 ccwemyss

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Posted 15 July 2019 - 05:01 PM

In one of the photos that Russel posted in that thread, there is a photo of the shaft side of the motor. It's not clear enough to count every tooth, but looks like it may be 16 teeth. That would imply a 0.9 RPM CW motor.

 

Again, if someone still has one of these, it would be great to get confirmation, as well as the diameter of the spur gear on the shaft. 

 

Chip W. 



#6 Larrythebrewer

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Posted 15 July 2019 - 07:05 PM

these are off of a Tasco 15TEA, hopefully they'll be of help

 

15 teeth on spur gear

fat (teeth part) of spur gear:  13/64" (.2")  5.15mm

thin (shaft part) of spur gear:  10/64"  (.159") 4.04mm

 

 

 

 

 

Attached Thumbnails

  • motor on mount.jpg
  • large gear measurement.jpg
  • 15 teeth spur gear motor back.JPG
  • fat part spur gear measurement.jpg
  • side spur gear.jpg
  • thin part spur measurement.jpg
  • large gear.JPG


#7 ccwemyss

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Posted 15 July 2019 - 08:18 PM

That's really interesting. Your main gear has 150 teeth instead of the 144 I've seen quoted elsewhere! So with a 15 tooth spur gear, if the motor runs at 1RPM, it generates 1/10 RPM to the worm shaft. 

 

Now I'll have to ask the student to actually count the teeth on the gear. 

 

Thanks!

Chip W. 



#8 DAVIDG

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Posted 15 July 2019 - 08:36 PM

 The gear that has 144 teeth is behind the RA setting circle and inside the black housing.  There are 1440 minutes in a solar day so 144/1440 = 1/10 rpm  needed to make the telescope turn once per day. So the worm that drives the 144 tooth gear needs to rotate at 1/10 rpm.  You can buy a 1/10 rpm motor that can be directly coupled to the worm shaft as what Compressorguy did or use a motor with a  faster RPM and use  a combination of two gears to achieve the needed 1/10 rpm. So for the other example of the motor with 15 teeth on the spur, the motor is most likely a 1 rpm and the gear on the worm shaft is has 150 teeth to achieve the 1/10 rpm needed to drive  the 144 tooth gear. 

You also need to make sure that the either the motor by itself or the motor and gears combination results in the correct direction of rotation.   When you use two gears the final direction is the opposite of that of the motor. 

  A third option is too use a stepper motor and controller board. You can easily control the stepper with handful lines of code and Arduino microcontroller to achieve the needed 1/10 rpm.

 

                    - Dave 


Edited by DAVIDG, 16 July 2019 - 11:21 AM.

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