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ATCO 80 x 1200 restore

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#1 Garyth64

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Posted 19 November 2020 - 01:47 PM

I recently picked up a APL 80mm x 1200mm by ATCO.  I was in parts and the lens has a large clam.

 

I've started the process of fixing this scope up and get it usable again, despite the damaged lens.  It is not a complete kit.  There isn't a finder or bracket, there are no eyepieces, no accessories, and no wood box.

 

Here is a file photo of a complete scope in excellent condition:

 

777136-2.jpg

-this is what it's suppose to look like.

 

That is my goal.

 

The tube is scuffed and has a couple small dents.  The dew shield is dented, but it can be straightened.  The mount was totally disassembled, and some of the paint is scuffed. The wood tripod is in good shape and will be refinished, and all the hardware will be repainted.

 

ATCO 80 mount 2.jpg

 

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Edited by Garyth64, 19 November 2020 - 02:01 PM.

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#2 Garyth64

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Posted 19 November 2020 - 01:56 PM

Here's the clam in the lens: frown.gif

 

ATCO 80 lens clam.jpg

 

 

This scope is a big brother to my APL Shrine Manon 60mm x 700mm.  Their focusers are similar and their color matches.  Their labels are patterned the same.

 

ATCO 80 focuser 2.jpg

ATCO 80 focuser 3.jpg

 

Like the smaller Manon, the ATCO focuser is threaded to accept the vixen-style 1-1/4" VB.

 

ATCO 80 focuser 1.jpg

 

Since the ATCO focuser doesn't have the long skinny draw tube like my Sears 6339a, or my Tasco 10TE, I was wondering why.  The ATCO tube does look longer than the Sears and Tasco tubes, and in measuring them, the ATCO tube is about 4" longer.  The ATCO is about 35-3/4", and the Tasco is about 31-3/4".  I wish the Sears and Tasco tubes were longer.

 

So I will be working on this scope, along with my Swift 831, until they are both finished.

 

Does anyone have a finder or bracket like in the file photo in post #1?


Edited by Garyth64, 19 November 2020 - 02:13 PM.

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#3 Kasmos

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Posted 19 November 2020 - 02:12 PM

I didn't know that the APL scopes ever had a large pinion cover on the focuser. I thought they were only on the HOC versions. Reading this forum, You learn something all the time!

 

What are you going to do about the giant clam...use it or replace?


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#4 Garyth64

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Posted 19 November 2020 - 02:18 PM

I'm thinking that I will not be able to find a replacement lens for this scope.

 

I spent a lot of time yesterday trying to the lens retainer ring loose so I can take the lens apart.  After some initial attempts, I noticed a small set screw was holding the ring in place.  I think that is not a common thing to find.

Once I do get the lens out, I will clean it and probably blacken the area of the clam.  I should ask Robert what he does with his clams.

 

I believe that even with the blackened out clam, the lens should be pretty good.


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#5 Bomber Bob

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Posted 19 November 2020 - 04:28 PM

My Triple Nickle 5" F5 has a larger clam than this ATCO, and it still gives a near-perfect star test, and is good up to almost 200x on lunar / planetary.  It's on the middle of 3 elements, and a previous owner not only blackened the clam, but also the back & front of the 1st element to match that size & shape...  I hadn't seen anyone do that before, but it seems to work...


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#6 Garyth64

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Posted 19 November 2020 - 07:38 PM

I finally got the retainer ring out.  I cannot get the lens out.  It will move about 1/4", but once it comes in contact with the retainer threads it stops.

 

I think that whatever cause the dew shield to become dented and made the clam in the lens, may have been hard enough to distort the lens cell itself.

 

Right now it is in the freezer.  So will that contract the cell and tighten on the lens? Or will it make the lens looser?  I guess I will find out.



#7 jelloptic

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Posted 19 November 2020 - 07:56 PM

Yes, the freezer will contract the cell and tighten on the lens.   Apply heat.


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#8 Red Giant

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Posted 19 November 2020 - 08:20 PM

Sounds like a good project...how did you come across this telescope?


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#9 clamchip

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Posted 19 November 2020 - 08:56 PM

I'm thinking that I will not be able to find a replacement lens for this scope.

 

I spent a lot of time yesterday trying to the lens retainer ring loose so I can take the lens apart.  After some initial attempts, I noticed a small set screw was holding the ring in place.  I think that is not a common thing to find.

Once I do get the lens out, I will clean it and probably blacken the area of the clam.  I should ask Robert what he does with his clams.

 

I believe that even with the blackened out clam, the lens should be pretty good.

What I do with the clamchips is try them out on the sky.

I usually don't do anything to the injured lens except clean it.

Sometimes a clamchip will not effect the lens and othertimes it can.

These vintage lenses can be so extraordinarily good that you can

live with the clamchip.

Clamchips are mysterious.

I once thought a primary mirror with a big chip on the back was nothing to worry about.

Until Dave brought up the fact it can introduce stress during the temperature adjustment

period, and really the primary is always in a state of temperature adjustment !

I think a refractive objective is less affected by a chip. Providing the chip does not send

stray light through the element, these are very harmful and easily noticed when observing

bright objects.

 

Robert


Edited by clamchip, 19 November 2020 - 09:06 PM.

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#10 Garyth64

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Posted 19 November 2020 - 10:14 PM

Yes, the freezer will contract the cell and tighten on the lens.   Apply heat.

Freezer didn't work, the heat did, eventually.  The lens cell wasn't perfectly round, probably from an impact that damaged the lens.

After working on it for two hours, the lens finally came out, but it will never go back in.  It is just too tight of a fit.  I tried my best but I ended up putting a clam on the crown. 

I discovered which way the cell was oval, and applied a clamp on the wide part.  The flint came out first, and then I had to coax the crown.

 

I was thinking I could line up the two clams, but no, I'm not even going to try and put it back in.

 

Without the lens, there's no point in continuing.


Edited by Garyth64, 19 November 2020 - 10:20 PM.


#11 Garyth64

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Posted 19 November 2020 - 10:17 PM

Sounds like a good project...how did you come across this telescope?

The scope was advertised here on CN a couple of weeks ago.  The guy wanted to part it out, but I asked him to sell it all to me.



#12 CharlieB

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Posted 19 November 2020 - 10:21 PM

What is the actual diameter of the objective?  Would a 76mm lens fit?  Or you could just slap a 76/1200mm objective and cell onto the OTA. 


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#13 Garyth64

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Posted 19 November 2020 - 10:27 PM

I did think of that, but I don't have an extra 76 mm lens around.  The ID of the cell is 82mm.

 

What I have thought of doing, since I like the longer tube, would be to see of the Sears or Tasco lens cell would screw onto the ATCO tube. 

 

And even if it did, in thinking to myself, what would I be trying to do.  Both the Sears and Tasco scopes work great as is.

 

Now if I did have an extra 76mm RAO lens around, I'm sure I could get the lens to work in the ATCO cell with a little shimming.  And being smaller, the out of round cell may not even matter.  It's just a hair off of being a perfect circle.  Maybe like 1/4 or 1/2 of a mm.


Edited by Garyth64, 19 November 2020 - 10:30 PM.


#14 Kasmos

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Posted 20 November 2020 - 01:24 AM

Gary,

Sorry to hear of these developments. Maybe you can just keep an eye out for another 80mm. They do turn up

 

Scopehed semi-recently sold one including the cell

 

https://www.cloudyni...to-choose-from/

 

Or.... lightly sand or grind the tight spot with a Dremel and try puttting the lenses back with clams aligned and both blackened. Nothing to lose but a little time and effort.


Edited by Kasmos, 20 November 2020 - 01:25 AM.

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#15 TSSClay

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Posted 20 November 2020 - 07:39 AM

I did think of that, but I don't have an extra 76 mm lens around.  The ID of the cell is 82mm.

 

What I have thought of doing, since I like the longer tube, would be to see of the Sears or Tasco lens cell would screw onto the ATCO tube. 

 

And even if it did, in thinking to myself, what would I be trying to do.  Both the Sears and Tasco scopes work great as is.

 

Now if I did have an extra 76mm RAO lens around, I'm sure I could get the lens to work in the ATCO cell with a little shimming.  And being smaller, the out of round cell may not even matter.  It's just a hair off of being a perfect circle.  Maybe like 1/4 or 1/2 of a mm.

Gary,

 

I have a 3" f15 objective that I have not built into a telescope yet.  I believe it is an Edmund lens (in a cell).  You would be welcome to borrow it and try it out if you wish.  A spacer to fit it into the cell would be pretty simple to make.

 

Clay



#16 Garyth64

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Posted 20 November 2020 - 08:12 AM

Hi Clay,

 

Thank you for the offer, but I just don't know at this time.  Because the lens cell is out of round, it won't even screw back into it's other section.

 

ATCO 80 lens cell.jpg

 

I can't get the threads to even start to mesh, and I don't want to force it and risk cross threading them.  So now it's another deterrent even if I got any lens in there.

 

I have thought about you lately, because I have the 5" Apogee refractor that you have seen, and I recently purchased a 127x1200 Wollensak lens.  I'm thinking of having an adjustable cell made and marrying everything together.  I'll send a PM later.

 

Thanks again for the offer.


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#17 Garyth64

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Posted 20 November 2020 - 08:19 AM

Here's what the scope looks like set up at this point:

 

ATCO 80 mock up.jpg

 

The lens is not in the scope, but everything else is back together and working properly.

 

 


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#18 Garyth64

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Posted 20 November 2020 - 08:28 AM

I do like the tripod legs on this ATCO.  They seem more robust that what are on the 3" sears and tasco scopes.

 

ATCO 80 tripod leg.jpg

 

The center section is about 1-1/2" wide, and with its concave curves, it fits nicely with the other two sections that are convex.


Edited by Garyth64, 20 November 2020 - 08:29 AM.

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#19 apfever

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Posted 21 November 2020 - 10:24 AM

I'd put the cell in a vice or press, record the stopping point when squeezed, and keep going further till it stays round - IF the cell is more oval shaped now. Use rags or curved blocks to help protect the contact points.

 

The short diameter that is squeezing may be more from a dent than being evenly oval shaped. The dent would be localized while the rest of the cell would still be basically round. Determining this could take some close examination.  For a dent, I'd mark my best guess on the cell for each end of the dent.  Cut a curve in a block of wood that is slightly smaller than the cell size, very slightly undersized cut. The undersizing will let the wood block concentrate on the dent. You might crush the block to 100% contact and still not move the dent. Then add tape or spacers to the blocks to increase the contact where you need it.  It might take a hefty clamp.

 

click the following link and go to entry #5 and #8.  

 

dent fix link

 

 

Your blocks would be smaller for a slight dent. The green areas are where you'd shim for more contact. Very small areas like a dimple can be tapped out while firmly holding a tube on a towel on a hard surface - firm support with some cushion to let the dimple move. At some point you're in your own playground with experimenting. I've found most issues like this can be fixed, fewer not so much. Metal can be brittle, you might shatter it, usually it's malleable enough to work. The lens cell will be thicker than a dew shield - play with good horse sense.  

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#20 Garyth64

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Posted 22 November 2020 - 10:43 AM

I just found out that the Sears and Tasco lens cells will screw on to the ATCO 80 tube perfectly!

 

So, maybe I will be able to find, another ATCO lens in it's cell, or just the cell,  or a Sears/Tasco lens and cell, and this scope will be able to live on.

 

Terra made a suggestion to have the inside of the ATCO cell machined round on a lathe, that is a good idea.

 

As it is now, the lens will not fit back into it's cell, and I'm not even going to try and "make" it fit.  The threads of the two part cell won't mesh, and I thought maybe eliminating the treads, and securing them together with set screws, I would be able to use the original cell.

 

I just wanted to clean the lens, as it was dirty between the elements.  I should have just left it alone.  But in looking back on the clam I made in the crown, it is in the same position that the flint has it's clam.  It may have had micro fractures in the lens, and I just completed the job that the impact started.

 

And another thought . . . I've had several lenses that I have taken out of their cells over the years, and this is the first time I made a clam.  In seeing all these different lenses, why aren't they chamfered?  It seems like if they were, the chances of clams would be reduced a lot.  Anyone have any thoughts on that?


Edited by Garyth64, 22 November 2020 - 10:47 AM.

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#21 PawPaw

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Posted 22 November 2020 - 11:36 AM

And another thought . . . I've had several lenses that I have taken out of their cells over the years, and this is the first time I made a clam.  In seeing all these different lenses, why aren't they chamfered?  It seems like if they were, the chances of clams would be reduced a lot.  Anyone have any thoughts on that?

 

I agree that a chamfered edge would reduce chips/clams.  Of the lens that I have removed from the cells I have found the following ones have chamfered edges:

 

My Edmund 3 and 4 inch have the edges chamfered on both sides of the flint and the crown.

 

I have inspected 3 unitron 4 inch objectives and two of them have chamfered edges on both flint and crown.  The oldest Unitron 4 inch objective I own has a metal band on both the flint and crown facing the cell.   One of the bands stayed in the cell in the pic below and the one on the crown was stuck so I left it as is. Look closely and you can see the chamfered edge of the flint facing the crown.  

 

 

 

 

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