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Equipment Discussions >> Classic Telescopes

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actionhac
Post Laureate
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Reged: 08/09/08

Loc: Seattle
Re: Mr. Edmund gets a Drive new [Re: actionhac]
      #5851865 - 05/10/13 11:49 AM Attachment (18 downloads)

Here it is mounted to the gear. I have no part number and cannot find it in any Edmund catalog.

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DAVIDG
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Reged: 12/02/04

Loc: Hockessin, De
Re: Mr. Edmund gets a Drive new [Re: actionhac]
      #5851885 - 05/10/13 11:59 AM

Do you know what that kit is for ?
- Dave


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actionhac
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Reged: 08/09/08

Loc: Seattle
Re: Mr. Edmund gets a Drive new [Re: DAVIDG]
      #5851894 - 05/10/13 12:09 PM

To make it possible for the RA circle to move with the clock rather than being fixed to the mount. The Plexiglas pointer also is fixed to the polar shaft.
I'm hoping you know the benefits of doing this way Dave!

Robert


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DAVIDG
Post Laureate
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Reged: 12/02/04

Loc: Hockessin, De
Re: Mr. Edmund gets a Drive new [Re: actionhac]
      #5851961 - 05/10/13 12:56 PM

Quote:

To make it possible for the RA circle to move with the clock rather than being fixed to the mount. The Plexiglas pointer also is fixed to the polar shaft.
I'm hoping you know the benefits of doing this way Dave!

Robert




Sure do ! Just wondering how many how others know about this and why it is a benefit. I find it interesting that only few classic scope had this feature. I also wonder how many classic scope owner even know how to use setting circles ? I have never seen this kit as well or Edmund scope that had one attached.

- Dave


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chuck52
sage
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Reged: 12/03/09

Loc: Quartz Hill,California
Re: Mr. Edmund gets a Drive new [Re: DAVIDG]
      #5851999 - 05/10/13 01:14 PM

I could use two of those kits.Looks like the parts could be made without too much difficulty.The installed kit does show up in some Sam Brown illustrations in his books.

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tim53
Postmaster
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Reged: 12/17/04

Loc: Highland Park, CA
Re: Mr. Edmund gets a Drive new [Re: chuck52]
      #5852055 - 05/10/13 01:37 PM

My Optical Craftsmen mounts have driven RA circles.

Thankfully, so does the 12.5" Cave Model D Transportable Observatory (complete with 10" circles!!), though my other Cave mounts don't.

I don't think the Meade Newtonians ever had driven RA circles either.

Wonder why not? Granted, they're harder to make, but ever use one that's not driven? What a pain!

-Tim.


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rdandrea
Carpal Tunnel
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Reged: 06/13/10

Loc: Colorado, USA DM59ra
Re: Mr. Edmund gets a Drive new [Re: tim53]
      #5852063 - 05/10/13 01:43 PM

Quote:

I don't think the Meade Newtonians ever had driven RA circles either




I think the RA circle on my 645 turns with the clock. It's loosely friction fit so that you can reset it.


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terraclarke
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Reged: 05/29/12

Loc: Just South of the Mason-Dixon ...
Re: Mr. Edmund gets a Drive new [Re: rdandrea]
      #5852086 - 05/10/13 02:00 PM

Very interesting thread Robert. I have really enjoyed reading about your restoration of the trusty Edmund 4 inch refractor. Very cool. I love the old mount. I hope I can find mine now. Since things of late are re-emerging from the blackhole they disappeared into years ago, I have high hopes.

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DAVIDG
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Reged: 12/02/04

Loc: Hockessin, De
Re: Mr. Edmund gets a Drive new [Re: terraclarke]
      #5852119 - 05/10/13 02:17 PM

Robert,
Maybe you can measure up the hubs and post details so other i.e. me can reproduce it ? I'll have to check my copies of All About Telescopes and see what I can find out about the kit.
By the way how are you powering the drive ? I use an inexpensive DC/AC inverter and 12 volt "battery boost" to provide the DC power for the inverter. I dug inside the inverter an adjust the output frequency so it makes these drive track at sidereal rate vs solar rate. The inverter and battery boost makes for a nice compact package and I don't have to drag out 30' of extension cord.

- Dave


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john gabriel
sage
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Reged: 12/13/11

Loc: Southern California
Re: Mr. Edmund gets a Drive new [Re: starman876]
      #5852141 - 05/10/13 02:33 PM

Hi Robert. Thank you for posting this interesting material! - I'm just catching up, and I have a question about the drive. I have the same one on Edmund's 6" newt, and I get a good deal of slop on the polar axis.

I initially tried what you suggested on first page of this thread - "adjust the eccentric studs A to remove slop from the slo-mo cam". I squeezed the studs together fairly tightly on the cam and cinched down their cap screws, but the cam pin itelf seems to have quite a lot of slop in the housing it rides in.

I do not want to machine a whole new cam pin to fit more closely in the housing, and shimming the housing does not seem very practical either. That seems to leave boring out the housing and fitting a sleeve with closer tolerance on the pin. What's best? Any other ideas on this? Thank you!
John


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DAVIDG
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Reged: 12/02/04

Loc: Hockessin, De
Re: Mr. Edmund gets a Drive new [Re: john gabriel]
      #5852167 - 05/10/13 02:45 PM

Check that you have the single ball bearing still in place that puts pressure on the cam. It is located under the metal strip on the side of the drive. It sounds like it is missing or might have a flat spot worn in it.

- Dave



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john gabriel
sage
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Reged: 12/13/11

Loc: Southern California
Re: Mr. Edmund gets a Drive new [Re: DAVIDG]
      #5852310 - 05/10/13 04:46 PM

Thank you Dave. I did have that apart for cleaning, inspection, and lube when I rescued the scope. I will check again, but the ball bearing looked fine / unworn at the time. The wiggle in the cam pin seems to be as much at the lower end of the housing as at the upper end where the ball is, but I will recheck the ball for wear anyway.

I have no idea if the timing adjust was actually used by prior, original, owner, but in other areas it's apparent that he did not lube the mount. I obviously need to take it apart again and inspect the pin tolerance in the housing more closely.

I just wondered if others who use these had noticed the lash as common / design issue and what, if anything, people had done to reduce the problem


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tim53
Postmaster
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Reged: 12/17/04

Loc: Highland Park, CA
Re: Mr. Edmund gets a Drive new [Re: rdandrea]
      #5852333 - 05/10/13 05:09 PM

Quote:

Quote:

I don't think the Meade Newtonians ever had driven RA circles either




I think the RA circle on my 645 turns with the clock. It's loosely friction fit so that you can reset it.




The pointers are on the dec casting, so they're driven, but the RA circle is on the RA casting and doesn't move except when you turn it manually. If it were driven, it would move with the pointers. Since it doesn't, you have to reset the circle before you leave one object and move to the new target. A driven RA circle only needs setting once at the beginning of an observing run.

-Tim.


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rdandrea
Carpal Tunnel
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Reged: 06/13/10

Loc: Colorado, USA DM59ra
Re: Mr. Edmund gets a Drive new [Re: tim53]
      #5852343 - 05/10/13 05:12 PM

Quote:

the RA circle is on the RA casting and doesn't move except when you turn it manually




Tim, I'll go out to the garage to check it out one of these days.


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john gabriel
sage
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Reged: 12/13/11

Loc: Southern California
Re: Mr. Edmund gets a Drive new [Re: rdandrea]
      #5852381 - 05/10/13 05:36 PM

With this Edmund drive, I put a nice RA circle at the outer end of the polar axis, on the inner clutch plate no less, and will be mounting the pointers (vernier index) to the drive gear. This allows the RA to remain constant while tracking / viewing and then change when slewing to another object.

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actionhac
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Reged: 08/09/08

Loc: Seattle
Re: Mr. Edmund gets a Drive new [Re: john gabriel]
      #5852696 - 05/10/13 08:32 PM Attachment (11 downloads)

Let me know if this is readable. If not I can send by email.

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actionhac
Post Laureate
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Reged: 08/09/08

Loc: Seattle
Re: Mr. Edmund gets a Drive [Re: actionhac]
      #5852704 - 05/10/13 08:41 PM

Dave I have a inverter 12VDC to 115V I use, and most of the time I plug into house current from where I observe on my driveway. Its not the best situation observing from a giant slab of concrete heat sink but otherwise I have hardly any level lawn. I really want to do something about this soon.
John have you checked the gear lash for play? if you have the eccentric slo-motion pin pinched without play try taking up any play in the gear lash. It doesn't seem possible the slo-motion shaft would be worn in the housing since it gets used so little but it should be tight in the housing. Your idea of sleeving the housing would be what I would do before making a new shaft with eccentric pin. If it isn't too bad you can have the shaft plated to increase its diameter.

Robert


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DAVIDG
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Reged: 12/02/04

Loc: Hockessin, De
Re: Mr. Edmund gets a Drive [Re: actionhac]
      #5852910 - 05/10/13 10:38 PM

Robert,
Many thanks for posting the design of the setting circle adapter. I found a few sentences and a drawing of it in All About Telescopes as well. I'll see if I can machine the parts up for my mount.

- Dave


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actionhac
Post Laureate
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Reged: 08/09/08

Loc: Seattle
Re: Mr. Edmund gets a Drive [Re: DAVIDG]
      #5854298 - 05/11/13 07:34 PM Attachment (5 downloads)

I was rooting around in the Edscorp box again today.
This is a brand new 1/4" focal length Ramsden eyepiece. Instructions is Rev. 6/75.


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actionhac
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Reged: 08/09/08

Loc: Seattle
Re: Mr. Edmund gets a Drive [Re: actionhac]
      #5854305 - 05/11/13 07:43 PM Attachment (5 downloads)

Here are a pair of Ramsden, 1/4" focal length and 1/2"fl.
The 1/4" has a problem. I will need to take it apart and look for a flipped element. The tiny little elements in a short fl eyepiece is a very rewarding challenge to take apart and reassemble and not have a coronary.
Notice these do not have the focal length stamped on top, older or newer, anyone know?


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