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1978 8" f4.5 Cave Astrola Restoration

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#26 Thaeland

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Posted 31 January 2019 - 10:24 AM

While you're at it, replace the power chord with a grounded chord.

Someone had already done that. The cord is not the original and if you look at the picture you can see the ground wire underneath the other two. It is however in bad shape.

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#27 tim53

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Posted 31 January 2019 - 10:37 AM

Oops!  I should have looked more closely.

 

On the 8" lightweight deluxe I restored a while back, I added a ground plug to it.  I had found a nice, vintage-looking round plug at Ganahl Lumber.  So I bought a standard black grounded chord, cut the plug off and put the round plug on.  Looks about as close to original as I could get, easily, and added the ground safety factor.

 

post-6788-0-76289100-1496522120.jpg


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#28 semiosteve

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Posted 31 January 2019 - 12:22 PM

I finished stripping and painting the pier and legs today. I used a citrus based paint remover I've used on other projects. It works quite well and is better for the environment. I also added two coats of automotive clearcoat.b0f49f2811bf905b1763d040f0dbb461.jpg7b142fa1f567790099b020743edccc38.jpg7430e436119a906c4f4bdfada22ed89f.jpg0c325cdb48cef7bbd39e6d77999e9ee7.jpg

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Its winter - how bad is the CitrusStrip to use in a basement workshop I wonder? I'd love to begin restoring my Cave 8" RFT before the Spring, but its too cold to use the garage to do so....sv


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#29 Thaeland

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Posted 31 January 2019 - 12:28 PM

Its winter - how bad is the CitrusStrip to use in a basement workshop I wonder? I'd love to begin restoring my Cave 8" RFT before the Spring, but its too cold to use the garage to do so....sv

I just read the label and there is no temperature restrictions but I would assume it can't be used in freezing temps. It is labeled safe for indoor use

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#30 Mr Magoo

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Posted 31 January 2019 - 05:55 PM

I really like that color. Very nice so far!


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#31 steve t

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Posted 03 February 2019 - 09:40 PM

Nice restoration job.

I remember seeing a Cave 8" F/4.5, back in 1979, at a telescope store called The Astronomical Unit in North Little Rock, AR. I thought it was the coolest looking scope.

Thanks for sharing your restoration progress and photos.  Looking forward to seeing the end results .

Steve T 


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#32 semiosteve

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Posted 06 February 2019 - 09:50 AM

I had my Cave 8" RFT out the other day to view the Orion nebula with a classic Galoc 16.5mm. Huge field, - got  batwings plus groups of bright start at 11 o'clock and 5 o'clock periphery of FOV. Kind of like the stitched view shown here...

 

http://www.asod.info/?p=7928

 

My question for your restoration is whether you are going to stick with the original helical focuser?

 

It only handles 1.25 EP's and I have given some thought to switching to a 2.0 focuser like the one over at  e Bay "Perfeclan 2-inch 1:10 Dual Speed Reflector Focuser for Newtonian Reflectors".

 

Otherwise, the best 1.25 options might seem to be

 

Panoptic 24mm 1.69 deg
TS Optics Expanse 22mm 1.69 deg
ES 69 Deg series 24mm 1.71 deg
Pentax SMC XW 20mm 1.51 deg (rumored to exist)
APM UltraFlat 24mm 1.71 deg
Baader Hyperion  24mm 1.82 deg
BST Flat Field 19mm 1.33 deg

 

Best

Steve


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#33 tim53

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Posted 06 February 2019 - 09:57 AM

You should also consider Edmund's 28mm RKE, or Brandon's 32mm.

 

-Tim.


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#34 Thaeland

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Posted 06 February 2019 - 04:40 PM

I had my Cave 8" RFT out the other day to view the Orion nebula with a classic Galoc 16.5mm. Huge field, - got  batwings plus groups of bright start at 11 o'clock and 5 o'clock periphery of FOV. Kind of like the stitched view shown here...

 

http://www.asod.info/?p=7928

 

My question for your restoration is whether you are going to stick with the original helical focuser?

 

It only handles 1.25 EP's and I have given some thought to switching to a 2.0 focuser like the one over at  e Bay "Perfeclan 2-inch 1:10 Dual Speed Reflector Focuser for Newtonian Reflectors".

When I got the telescope it didn't have the original cave focuser on it.  It has a 2 inch Crayford instead but it appears to be from around the same 1978 time frame as the scope.   I have torn apart the focuser, cleaned, lubricated and reassembled it.   While it works much butter I still think I will use a modern two speed one instead. I bought one online but it turns out it was meant for a scope much bigger than mine as it won't fit the diameter of the tube so I am just going sell it on ebay..


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#35 mic1970

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Posted 06 February 2019 - 04:58 PM

I finished stripping and painting the pier and legs today. I used a citrus based paint remover I've used on other projects. It works quite well and is better for the environment. I also added two coats of automotive clearcoat.sent from my Moto Z (2) using Tapatalk

Already said, but nice job.


Edited by mic1970, 06 February 2019 - 04:59 PM.

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#36 tim53

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Posted 06 February 2019 - 05:45 PM

When I got the telescope it didn't have the original cave focuser on it.  It has a 2 inch Crayford instead but it appears to be from around the same 1978 time frame as the scope.   I have torn apart the focuser, cleaned, lubricated and reassembled it.   While it works much butter I still think I will use a modern two speed one instead. I bought one online but it turns out it was meant for a scope much bigger than mine as it won't fit the diameter of the tube so I am just going sell it on ebay..

I'd just suggest you list it on CN classifieds instead (or maybe in addition to).  I've had great results here.  Your potential buyers are all TNs like yourself, so it will likely go quickly.

 

-Tim.


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#37 Thaeland

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Posted 06 February 2019 - 06:38 PM

I'd just suggest you list it on CN classifieds instead (or maybe in addition to). I've had great results here. Your potential buyers are all TNs like yourself, so it will likely go quickly.

-Tim.

Yes this thing is huge. Thanks I think I will try there....
b70e0884bf5ad25a5aea353c8fb1d081.jpg

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#38 tim53

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Posted 06 February 2019 - 07:21 PM

That's a nice looking focuser, actually.

 

If it weren't for the fact that it's a classic Cave we're tallking about, I might suggest you do something like I did for a 3" f/6 Edmund I built a few years back.  I wanted to put a Lumicon helical low profile focuser on it, but it was designed for a bigger tube.  So I cut a square hole for the focuser, leaving enough "meat" for the mounting screws, but allowing the sides of the focuser to sit flush with the surface of the tube.  I'll see if I can scare up an image.  

 

Another thing you might try is putting washers under the focuser where the screws go through.  That would raise it up some so that it might clear the tube in the center.

 

-Tim.


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#39 tim53

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Posted 07 February 2019 - 10:42 AM

Here's my Edmund 3" f/6 with the Lumicon focuser.  I couldn't find the pics of the scope while I was building it that would show the square hole I cut into the PVC tube to accommodate the bigger profile the focuser was expecting, but if you look closely, you can see that the top of the focuser base is flush with the surface of the tube where I cut the flat sides of the hole to let the focuser sit in there and be fully supported at the mount points.  Like I said before, you might be able to accomplish the same thing by putting washers under the mounting screws of your focuser:

 

post-6788-0-95586900-1442097033.jpg


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#40 Thaeland

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Posted 07 February 2019 - 11:13 AM



Another thing you might try is putting washers under the focuser where the screws go through. That would raise it up some so that it might clear the tube in the center.

-Tim.


I thought about doing that but it would take quite a few washers. I did a calculation on the radius and it's meant for a 12 inch tube.

Jon

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#41 Thaeland

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Posted 07 February 2019 - 11:26 AM



Here's my Edmund 3" f/6 with the Lumicon focuser. I couldn't find the pics of the scope while I was building it that would show the square hole I cut into the PVC tube to accommodate the bigger profile the focuser was expecting, but if you look closely, you can see that the top of the focuser base is flush with the surface of the tube where I cut the flat sides of the hole to let the focuser sit in there and be fully supported at the mount points. Like I said before, you might be able to accomplish the same thing by putting washers under the mounting screws of your focuser:


Yes, I can see where you cut into.it. It looks really professional. My tube has been adulterated many times before but I'm hesitant to cut any hole to allow this beast to fit. I plan to hang on to the original focuser so if someone decides they want it back to as close to original I can always slap it back on. Then again I may be dead before that happens... ;)

There's a patched hole where I think someone at one time had mounted a camera and several other holes for other mountings. While the patching itself is not too bad they apparently used the wrong paint and it has turned yellow on all the spots. So I have got to decide how I'm going to handle restoring the tube.

Jon

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#42 tim53

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Posted 07 February 2019 - 01:27 PM

An even crazier thing to do would be to mount the focuser from the inside of the tube, with the base inside and the body projecting up through the hole in the tube.  This would also lower the profile quite a bit, but the drawtube would project into the light path more.


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#43 mic1970

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Posted 07 February 2019 - 02:33 PM

Here's my Edmund 3" f/6 with the Lumicon focuser.  I couldn't find the pics of the scope while I was building it that would show the square hole I cut into the PVC tube to accommodate the bigger profile the focuser was expecting, but if you look closely, you can see that the top of the focuser base is flush with the surface of the tube where I cut the flat sides of the hole to let the focuser sit in there and be fully supported at the mount points.  Like I said before, you might be able to accomplish the same thing by putting washers under the mounting screws of your focuser:

 

post-6788-0-95586900-1442097033.jpg

Man... I love that.  Can you provide the specs on it (primary, secondary, F/L, f/r, tube length.  What do you mount it on? 



#44 clamchip

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Posted 07 February 2019 - 05:27 PM

An even crazier thing to do would be to mount the focuser from the inside of the tube, with the base inside and the body projecting up through the hole in the tube.  This would also lower the profile quite a bit, but the drawtube would project into the light path more.

My Robert Plath telescope has the focuser mounted inside:

 

post-50896-0-34544700-1491443684_thumb.jpg


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#45 tim53

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Posted 07 February 2019 - 06:26 PM

Man... I love that.  Can you provide the specs on it (primary, secondary, F/L, f/r, tube length.  What do you mount it on? 

This was to be the guide scope on my 8" f/9 "Delmarvascopics" scope I built a couple years ago.  I've used this scope before, even experimented with imaging with it and a Meade dis pro camera. It takes good pics.

 

Stats.

Edmund 3" f/6 mirror and cell. 3/4" secondary I bought from Ed Beck about 25 years ago, mounted to a dowel and plumbers tape curved spider. Lumicon 1 1/4" Focuser. Tube and end rings are PVC.  End rings are painted metallic gold and the tube is painted Model A Ford engine green.  

 

-Tim.


Edited by tim53, 07 February 2019 - 06:28 PM.

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#46 mic1970

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Posted 07 February 2019 - 07:29 PM

This was to be the guide scope on my 8" f/9 "Delmarvascopics" scope I built a couple years ago.  I've used this scope before, even experimented with imaging with it and a Meade dis pro camera. It takes good pics.

 

Stats.

Edmund 3" f/6 mirror and cell. 3/4" secondary I bought from Ed Beck about 25 years ago, mounted to a dowel and plumbers tape curved spider. Lumicon 1 1/4" Focuser. Tube and end rings are PVC.  End rings are painted metallic gold and the tube is painted Model A Ford engine green.  

 

-Tim.

Thanks... Again, a sweet little small scope.  I have some bigger ones, but I'm really starting to appreciate these smaller guys.  


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#47 Thaeland

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Posted 08 February 2019 - 04:42 PM

New bearings arrived today.d3a6a9823f67af53f4d69efe5d61a57e.jpg

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#48 Thaeland

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Posted 08 February 2019 - 09:44 PM

Turns out when removing the polar axis rod I flared out the the end and damaged the beginning threads of the hex bolt hole. To fix the problem I gently grounded down the edge and re-tapped the hole. This will be hidden when everything is reassembled but I will still give it a fine finish up when I polish the rest of the rod.
b05cc97364896c621f7e9f86c2da9df8.jpg


Edited by Thaeland, 08 February 2019 - 09:50 PM.

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#49 Thaeland

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Posted 09 February 2019 - 08:25 PM

New bearings in place. Decided to put them in before painting. Wasn't sure how hard they would be putting in since taking the smaller ones out were a bear and I didn't want to mess up the paint job.

I couldn't get a good grip on the smaller pin bearings to get them out so I cut the edge with a dremel, pryed the tabs off, removed the pins, and then used a chisel I made in 7th grade shop class (2 years before those scope was made by the way) to beat the cylinder out.

Last picture are the new installed bearings

Jon055e23583150e925eb41f0d6e19f08af.jpg44ad90a25f11f7ddc4aa14ce549056ac.jpg9b71d9fe6b10c694b01f7960a880d876.jpg

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#50 Thaeland

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Posted 09 February 2019 - 08:38 PM

So what's is the best way to repaint my tube? It appears to be a sonotube as I can see the spiral on the inside but the outside it's smooth and no seam is visible.

Jon

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Edited by Thaeland, 09 February 2019 - 11:00 PM.



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