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Help identifying Edmunds mount

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35 replies to this topic

#26 Garyth64

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Posted 01 April 2020 - 08:11 AM

I just realized this thread has diverged from the title and my original intent, which was to identify the thing I'd been given.  It's pretty clear it's a bit of a mongrel.  Would the moderator or anyone else prefer that I restart this topic, which is now more in the line of a restoration, in another forum, or under a different title, or anything else?  I'm very grateful for the interest and assistance offered so far by this community, and prefer to leave it here in the absence of objections.

Thanks,

MPW

Keep it here.

 

This is CN.  There will always be a lot of divergence on any topic.

 

It is the nature of the beast, and no guarantee that a new post will stay on topic.



#27 apfever

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Posted 01 April 2020 - 10:19 AM

Mike,

 

The strips are Teflon 1/32".

 

It is hard to tell where you might want to go with mods even simple ones if you intend to pass this on soon. Many are simple hind sight engineering that require little or no additional input during assembly. The previously listed link to my restoration of this mount has been out of sight and mind, like myself - out of my sight and....

That thread is another unfinished one of mine and is lacking 1 or maybe 2 hundred photos I found still on my comp.  These are a couple. You might find it very convenient to remove the entire cap and mount assembly from the pier for transportation or departure. The altitude pin was never meant to be a disconnect. I suggest Teflon tape on the pier threads. Tighten the cap ONLY to a light stop so it is correctly positioned over a leg (your photo in entry #20 is correct). This allows some movement each way for polar alignment. Otherwise you have to kick the legs around and god luck with that. I wanted two lock points so I added the hole with the tap (slight offset intentional). The location for the extra bolt was chosen for a thicker part of the cap and easy access in use. I placed a soft plug in each hole that will form to the threads and keep the bolts from damaging the pipe. I also have a tendency to put a friendly face on a lot of my bolts. More often than not, there is no need for a holding bolt to crater the item it grabs. The extra bolt isn't really necessary when the threads are anywhere close to nesting, including the loose side.

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Edited by apfever, 01 April 2020 - 10:25 AM.


#28 apfever

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Posted 01 April 2020 - 10:36 AM

Excellent, thanks for the photo and offer, apfever.  I just did some more careful measuring and concluded I need to do several of the operations I named above, or mill the slot between the yoke arms very deeply, because of the much-extended RA housing lug.  Evidently that's the difference between the D-2088 and D-2089 castings!

 

You can very probably address my next question, then.  I prepared to remove the declination shaft from the RA housing, in order to facilitate setting it up for precise measuring and machining.  A plastic sleeve bearing can be seen in the attached photo.  I pressed the shaft out a short distance and can see the same kind of bearing at the other end as well.  I'm very concerned about being able to reinstall the shaft.  Even though I can arrange some kind of guide sleeve for the sleeve when entering the larger end of the housing, it could expand after being pressed through the first journal and be unable to enter the second one.

 

Have you, or any others reading, removed and reinstalled the declination shaft in the RA housing?  Any tips or tricks?

 

If I can resolve my concern here, I'll be very happy to take you up on your offer to swap the housings, and cover any shipping costs.

MPW

pm sent. Look for the red flag by the envelope in the upper right corner, top of the page. 


Edited by apfever, 01 April 2020 - 10:38 AM.


#29 mweir2

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Posted 01 April 2020 - 09:24 PM

Replied to PM.

 

I'm always impressed by your clear photos.  After feeling the clearance with the cap screwed onto the column with grease lubrication, I think I'm going to switch over to Teflon tape as you advise.  I, too, would add some pad between the lockscrews and the pipe threads.  And regarding disassembly and transport, I fully intend to take the legs off and remove the cap w/mount from the column.  In fact, I noted in some other forums the contributors talking about the formidable task of climbing up on ladders and screwing the cap on, I assume with a large/heavy telescope installed.

 

I'd always assumed coupling the tube to the mount was the final step of assembly, especially if it employs a yoke and straps which must permit positioning for balance and viewing convenience.  In mine, the user must make a choice where to penetrate the tube for the mounting bolts, thus constraining it axially and rotationally.  I'd appreciate some comments from readers about choosing the position of the tube on the mount.

 

Here's a further update on the repairs.  I completed the elevation axis shaft today - it fitted the head casting nicely at about half a thousandth over 7/8 inch diameter.  I also sawed out a blank for the tangent arm and profiled it on the mill.  With the shaft now completed, I'll finish boring the arm for a snug fit, then drill and tap for the setscrews.  Will provide photo then.



#30 PawPaw

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Posted 02 April 2020 - 09:02 AM

"I'd always assumed coupling the tube to the mount was the final step of assembly, especially if it employs a yoke and straps which must permit positioning for balance and viewing convenience.  In mine, the user must make a choice where to penetrate the tube for the mounting bolts, thus constraining it axially and rotationally.  I'd appreciate some comments from readers about choosing the position of the tube on the mount."

 

The Edmund mount came with stainless steel straps.  These can still be purchased and are called "T bolt hose clamp stainless steel", they come in different lengths.  You will need to apply felt to both straps and the saddle.  They were Edmund's low cost solution for a rotating tube.  Here are pics of my straps holding the 8 inch reflector.

 

 

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#31 mweir2

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Posted 02 April 2020 - 09:52 AM

Thanks all.  PawPaw, your photos and apfever's (#12) both show a broad cradle with perforated ears at the corners, through which the strap securing screws can pass.  My original photo, apfever's, and others elsewhere at this site show a narrower mounting bar, with holes on its centerline only.  My conclusion is this is actually consistent with my RA and declination housings, which appear to be from a 1 inch "heavy duty mount" rather than the "extra heavy duty" I think is pictured in your present (#30) post.

Still, it looks like I could use large straps to attach a tube to the lighter mount.  I can make these easily, and perhaps a pair of extended yokes to bolt to the mounting bar that would cradle the tube more effectively.  I'd certainly prefer, and I assume the eventual owner would, the tube to be adjustable in the mount.

I think some form of strap attachment will be my eventual choice.



#32 clamchip

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Posted 02 April 2020 - 10:52 AM

You can use Orion rings. Flip them over so you mount the rings with

the small boss:

https://www.telescop...mblies/e/39.uts

It's not the best system but it works.

Put the rings on the tube first, then line up with the holes in the saddle. After attaching

to the saddle then you can loosen the rings to slide the tube around.

Robert

 

post-50896-0-40883900-1512944442_thumb.jpg


Edited by clamchip, 02 April 2020 - 10:55 AM.

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#33 Garyth64

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Posted 02 April 2020 - 11:06 AM

"Put the rings on the tube first, then line up with the holes in the saddle. After attaching to the saddle then you can loosen the rings to slide the tube around."

 

Yes, because otherwise, where the bolts go thru the saddle there is a slight angle. 

If you attached the rings to the saddle, they would be angled to each other and probably wouldn't fit the tube very well.

 

That's why I added in a section of aluminum about 11" long to keep the ring straight on my set ups.

 

Sears on Edmund.jpg

. . . you may be able to see the aluminum in this photo

 

or in this one:

 

Bar for clamps.jpg


Edited by Garyth64, 02 April 2020 - 11:08 AM.

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#34 Terra Nova

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Posted 02 April 2020 - 06:19 PM

Here’s the one that I rebuilt for the 4” F15 Edmund refractor I used to have. I used a set of Stellarvue rings and cut notches into the cast iron cradle with a milling machine and recessed the rings into the notches.

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#35 Terra Nova

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Posted 02 April 2020 - 06:23 PM

Here is a detail of the notch with ring inset.

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#36 mweir2

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Posted 02 April 2020 - 08:19 PM

Thanks, everyone!  Very clear, very helpful.  Rings are the answer.  I think I will have no trouble adapting the mount rail to whatever tube I end up using.  That topic will be coming up soon.


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