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Easy Restoration of Vintage C14 Fork Mount

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#1 TVG

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Posted 20 November 2012 - 10:36 AM

Greetings all,

I recently purchased a vintage C14 fork mount for my home built newt to live on. The mount seems to track well enough, but has some play in the altitude bearing(Older mount with tangent arm dec motor). The mount also seems a bit stiff when moved manually. I would like to take this beast apart and clean/regrease all bearing/gear surfaces. I have searched and sent a email to Celestron, but can not find anything on which lubricant is best. A couple of people suggested white lithium, but there is all kinds of white lithium to choose from. I am wanting to do this right, so any suggestions or tips would be greatly appreciated.

Thanks,
Todd
PS I am also looking for the hand controller or instructions on how to build one my self. I found the wiring schematic, but I am a novice and need more thorough instructions/part list.

#2 Geo.

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Posted 21 November 2012 - 09:18 PM

Pretty much any heavy grease will do. The speeds encountered in a worm drive are very slow and the loading is relatively high. So you want a grease with lithium to deal with the loading. Most commercial greases will contain lithium. Petroleum jelly will not.

For the handbox you need two double pole double throw momentary push button switches. Figure about $4 a piece.

And one - Cinch-Jones P-302H-CCT - 6 blade connector @ $7: http://www.mouser.co...sd/645/2568.pdf

A couple feet of 6 conductor cable.

A project box to contain the switches. Something like 4*3*1" will do.

Tools: drill & bits, soldering iron, solder, flux and utility knife.

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#3 TVG

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Posted 22 November 2012 - 06:15 PM

Geo,

Awesome, thanks for the response. This is just what I needed. Will this little box be able to control the dec motor as well?
Surely this is not as simple as it sounds, is it?

On a side note celestron responded with my grease question:
Klubertemp -40 to +260 grease
Anybody know where to buy this stuff?

Thanks again,
Todd

#4 Geo.

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Posted 24 November 2012 - 09:23 PM

Looking again the C14 base circuit, I can see there's something amiss. The way the switches are wired only drives the slow speed motors in one direction. Now many RA correctors kill the power to the main drive for "east" correction, but have to speed up the RA to correct to west. Dec is always driven north and south. So I corrected the drawing to provide both clockwise and counter clock wise rotation of both slow speed motors.

However, now I question whether there is a slow speed motor for RA correction. Celestron did use dual motors in the Ultima 2000 to provide fast slewing speeds, but I don't see the utility of an extra RA motor when the corrections invole minor movements.

Generally, AC synchronous motors are controlled by minor changes in the frequency of the current provided to them. This would seem to make more sense than what we see in the circuit drawing. To design this all properly there should be a declutching of the main drive motor to permit the slow speed motor to make its corrections and vise versa. All this mechanical complexity seems unlikely.

Maybe you can get some photos of the C14 base electrics. I believe these mounts used Ed Byers worm gears and the synchronous motors were from Hurst. These motors had a second field coil so they could be reversed. It would make more sense to have the rocker cut power in one position and step up the frequency in the other than what I see in the diagram.

#5 TVG

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Posted 26 November 2012 - 10:45 AM

Okay, thanks for the reconsideration and time spent thus far. My mount is from the 70's and has the tangent arm with two gears for the altitude motor. I will post some pics tonight as soon as I figure out the best way into the base.
I did find a file with another original hand pad, but looks similar to what you accomplished the first time, might help though. Not sure how to post files, but here goes:

Best,
Todd

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#6 tim53

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Posted 26 November 2012 - 11:26 AM

There was a Byers upgrade drive for the fork mounted c14, but the stock Celestron wasn't a Byers.

Tim

#7 Geo.

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Posted 26 November 2012 - 02:02 PM

There was a Byers upgrade drive for the fork mounted c14, but the stock Celestron wasn't a Byers.
Tim


All the early C14s I've worked on have Byers worm gears. C8s didn't get them until the '82 Super C8.

#8 tim53

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Posted 26 November 2012 - 06:36 PM

You must have worked on C-14's with the Byers retrofit, then:

http://articles.adsa...000018.000.html

-Tim.

#9 TVG

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Posted 28 November 2012 - 04:53 PM

Okay here are the photos of my mount slightly dissassembled. I do not know if it has byers gears?
Let me know if you need more photos or better photos of key areas. Thanks again for the help.
Todd
Photo 1 of base

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#10 TVG

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Posted 28 November 2012 - 04:55 PM

Photo 2 of Declination gears/motor and tangent arm.
Try this again

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#11 tim53

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Posted 28 November 2012 - 06:40 PM

I always *thought* that the Celestron worm gears in the early C-14s were not Byers, but I couldn't find any info on the web to be certain of that. I think it's the case, but I'm not 100% sure.

There definitely IS a "Byers retrofit" with a 9" worm gear and a handful of other modifications done to the stock mount, including "Byers retrofit" on the cover plate.

-Tim.

#12 TVG

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Posted 29 November 2012 - 10:16 AM

So if my mount has the Byers retrofit then it would not benefit me to get an original/regular C14 hand pad or a separate drive corrector? Since Byers has already retrofitted a drive corrector for this mount I will pretty much have to figure out the hand pad for myself, via hopefully with your help here on the forum?
I guess it is too much to ask for Byers to still manufacture this retrofit and just happen to have an extra hand pad laying around.
Thanks again,
Todd

#13 tim53

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Posted 29 November 2012 - 11:15 AM

I think it's just another AC synchronous drive, so any AC drive corrector should work.

Byers is still in business. I don't know if he has parts for the retrofit anymore, but it can't hurt to ask. He's a very nice man.

-Tim.

#14 TVG

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Posted 29 November 2012 - 04:18 PM

Is the knob/potentiometer on the front not a drive corrector speed controller of some sort? If this already has its own drive corrector then I am not going to add another one to the mix. I would rather just figure out a simple hand pad.
Geo,
Does the updated photo of your hand pad schematics still apply to my mount now that you have actual photos?

Thanks again,
Todd

#15 TVG

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Posted 29 November 2012 - 04:22 PM

Just got a reply from Byers and he said that those retrofits had not been made in 25 years. The electrical components were developed by an electrical engineer(who is now deceased) from outside the Byers company, so no luck there.

Todd

#16 tim53

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Posted 29 November 2012 - 04:39 PM

They still turn up for sale from time to time, though. Here's a link to an ad from last June (not a complete retrofit, though): http://www.astromart...auction_id=6956

Here's a site with detailed pics of the drive:
http://www.astrophot...14_Retrofit.htm

best,
-Tim.

#17 TVG

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Posted 04 December 2012 - 08:20 PM

Geo,

Hope the pics of my mount cleared things up, but was looking to order the parts from Mouser and could not figure out which bridge rectifier to get?
Please help,
Todd

#18 Geo.

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Posted 05 December 2012 - 11:42 AM

I always *thought* that the Celestron worm gears in the early C-14s were not Byers.


From what I can find there are Byers gears and then there are Byers gears. Ed claims to have produced over 20,000 gear sets as a Celestron OEM, but I get the sense these production gears were were not up to the high standards he liked to make. The upgrade kits were more like the latter.

#19 tim53

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Posted 06 December 2012 - 02:58 PM

I thought that the 20,000 gear sets referred to the late 80s black tube C-8s, not the C-14. But I haven't seen a fork-mounted C-14 up close in a very long time.

-Tim.






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