108 replies to this topic

[mstatti]

  How many teeth are on the main gear ?  Count the number of teeth on that gear and divided it by 1440. If the number of teeth is 144/1440 then that is 1/10 so that is the speed of the motor. This is what many of the Criterion scopes used 

   Some manufactures would use a 1 rpm that had 10 tooth gear on it. That drove a 144 tooth gear on the worm gear and that drove a the main gear that had 100 teeth and that ratios resulted in 1 revolution in 1440 minutes. So by doing some counting and little a math will give you the answer of what speed motor you need. One other thing you need to pay attention to is the which way the motor turns  That direction will depend if the motor is directly driving the main gear or if there is additional gears. 

 

                  - Dave 

I didn't even need to count, it was already marked! It is indeed 144 teeth, and there is a 10 tooth gear on the motor itself. So if I were to get a 1/10 rpm motor, what gear do I use to mesh with the main gear, do I just reuse the 10 teeth gear on the dead 1 rpm motor? Also, the dead motor turns counter-clockwise (when the gear and shaft is facing towards me).

[apfever]

Pictures Pictures Pictures.

 

It will be difficult to know exactly what arrangement you have without drive pictures. There are different configurations from Criterion in just the Dynascope series not to mention the RV series. A thousand words can be written and not convey a picture. What you describe on your 8" seems different than the 6" or 10".

 

The first picture of 3 motors is the 6" configuration and also what I have on my factory drive Dynascope 4.25".   This motor is 1/10 rpm, has no gear, and directly drives the worm at 1/10 rpm. The worm drives a standard 144 tooth gear on the RA shaft. 

 

The second picture is my Dynascope 10".  This is totally different with a small gear on the motor and a large gear on the worm. This might be what you have on the 8" but the rest of the mount is obviously different looking. 

 

IF you have a 1 rpm motor with a 10 tooth gear on it, then that has to mesh with a 100 tooth gear attached to the worm, and the worm drives a 144 tooth final gear on the RA shaft. 

If you have a 1/10 rpm motor with a 10 tooth gear, then that has to mesh to another 10 tooth gear attached to the worm, and the worm drives a 144 tooth final gear on the RA shaft.

 

Changing motor speeds will require changing gear sizes and that won't be fun. Well it might be fun if your into it but most wouldn't consider that route. 

WHAT are the shaft diameters of your mount? I will open my 10" Dynascope drive if you have 1.5" diameter shafts. I think we will have the same drive with the same diameter shafts. Unfortunately the 8" Dynascope is where I fall through the cracks. I never had an 8". 

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[mstatti]

I took some pictures of a rough assembly, what I didn't properly mention is that the gear attached to the worm is the one with 144 teeth, and I counted 100 teeth on the large shaft gear. Does that mean I need to get a 1rpm motor? The shaft itself is 1.5", so it seems very similar to the Dynascope 10.

 

 

Thanks,

Matteo

[apfever]

BINGO! Now you are getting it.  Yes, you need a 1 rpm motor assembly. The 10 tooth gear may or may not be included. You need to get the right motor shaft size if you have to use the old gear. 

For the Northern Hemisphere: The motor shaft needs to turn clockwise if you have the shaft facing you, like my picture in entry #102 above. 

For you science types oriented with the Right Hand Rule: The large gear that goes on the RA shaft rotates out of the picture, the worm rotates to the left, the motor rotates to the right. 

 

Some of us can not click on your pictures for a better view. This was discussed in pm.  Your pictures are jpg format which is good. It is possible that the source you are posting from messes things up. Do not post directly from an editor like Paint.  Save your edited pictures in a regular file and load them into your entries from that file.  That is a guess, it might not be the problem.  It is convenient to be able to click your pictures and have them 'pop up'. The pop ups are easier to see, save, enlarge, examine, etc.  Clicking your pictures as is now results in a statement "You do not have permission to view this image". 

If any of you have no problem clicking the pictures for the pop up, let us know. I had a mod check and he had the same issue as me - access denied. 

Edited by apfever, 22 November 2024 - 10:59 PM.

[DAVIDG]

 As stated you need a 1 rpm motor. The main gear that drives the telescope has 100 teeth . So the speed that gear needs to turn to make one revolution in 24 hours ( 24hrs x 60 minute in a hour = 1440 minutes)  is 100/ 1440 or 1/14.4 RPM   So now you  have 1 rpm motor with  a 10 tooth gear driving a 144 tooth gear. That ratio is 1 rpm  x 10/144  = 1/14.4 RPM. 

 

                - Dave 

[mstatti]

Ok, I have found a motor that is the same rpm, voltage, Hz, and turns clockwise, but it is only 3 watts instead of 5, would that make any difference?

[mstatti]

I ended up ordering that motor, I will get it soon. As for the next step, I should remove the old paint remaining on the exterior parts as I would like to repaint the telescope. What method should I use to do that?

 

Thanks,

Matteo

[DAVIDG]

 It looks like the mount is painted in black wrinkled paint. If the paint is still attached well, you can wash it with soap and water and brush. Then spray over the finish with  a light coat of gloss black to  freshen up the look. If the paint is coming off  you can repaint it with VHT black wrinkle paint to get the same finish as the original.

 

https://www.autozone...wE&gclsrc=aw.ds

 

   I have used it on a number of telescope parts.

 

                         - Dave 

 

 

Edited by DAVIDG, 02 December 2024 - 08:07 PM.

[YourNotSirius]

 It looks like the mount is painted in black wrinkled paint. If the paint is still attached well, you can wash it with soap and water and brush. Then spray over the finish with  a light coat of gloss black to  freshen up the look. If the paint is coming off  you can repaint it with VHT black wrinkle paint to get the same finish as the original.

 

https://www.autozone...wE&gclsrc=aw.ds

 

   I have used it on a number of telescope parts.

 

                         - Dave 

 

 

R4 finished tripod.jpg

From what I can see in that photo the tripod head is in excellent condition. We would at best give it a simple cleaning with acetone or brake parts cleaner and then let it alone.

 

IF the original paint is still well attached to the piece then a little cleaning with brake parts cleaner and a soft bristle brush will work wonders. (We use CRC red/white can exclusively! The "green" stuff has melted plastic and caused paint damage.) After it is all dry we sometimes shoot some clear coat over it then let it set up for 24 to 48 hours at room temperate so that it cures properly.

 

Our personal experience and that of others who to auto repair have found that the high heat paints do not set up well unless the parts get heated up very well. We have used it on occasion but, parts such as this needed to be put into the oven and baked for several hours to have it set up and harden properly. The words "high heat" in the name pretty much define its intended use like in header pipes, exhaust manifolds and so on.

 

Maybe that will help. Maybe not.

 

Q