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1978 8" f4.5 Cave Astrola Restoration

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#51 TOM KIEHL

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Posted 09 February 2019 - 10:55 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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REPAINT ! ? Are you sure you have , or want to do that ?



#52 Thaeland

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Posted 09 February 2019 - 11:20 PM

REPAINT ! ? Are you sure you have , or want to do that ?

Well look at these spots. Most of the tube is good but here are some of the spots on it where they patched it after removing old equipment. Looks like they used some type of paint that yellowed over time. The last pic is where the primary mounts and the paint is coming off....


a1df073cc911dd6e1f76595af207cc8a.jpg061fa2ca20da966b8e406f51cd74e315.jpg0dbd8d4d7caf65a12dd7e4c6ae70f890.jpg

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Edited by Thaeland, 09 February 2019 - 11:22 PM.

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#53 TOM KIEHL

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Posted 10 February 2019 - 08:07 AM

Agreed , The patch spot is hideous ! I just thought if there was someway to save the original Gel Coat , that would be the better option . The gel coat usually cleans up rather well with polishing compound and wax . I have worked with this 2 part epoxy in the past , with great success . It is white in color and cures super hard and smooth  ... Smooth On M13 ...  https://www.smooth-o...products/mt-13/  .  Other than redoing the patch spot that will still look like a patch spot when done . A coverup is a option .... maybe a nice NASA decal or some appropriate space themed sticker / decal just to cover  ?  I had the same problem with my " Barn Fresh Cave Restoration " ......    https://www.cloudyni...on/?p=6265087   I did the repairs as stated in the link and did all the prep work for the auto body repair shop to spray in a booth a 2 part auto finish on . It came out better than the original finish waytogo.gif . Here is a shot  of my tube prior to going to the body shop for paint .

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  • BARN-FRESH-Fin.-PREP-002.jpg
  • CAVE-FIN.-019.jpg

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#54 steve t

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Posted 10 February 2019 - 08:27 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

Hi Steve,

For me I`d consider a few things:

 

- How large of an exit pupil do you like. My dark adapted eyes open up to about 5mm, so l tend to like an exit pupil of 3mm or less,.

- Does the 1.25" focuser cut into  the light cone.

- Do you plan to use a coma corrector? 

 

Take care

Steve T 


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#55 CHASLX200

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Posted 10 February 2019 - 09:40 AM

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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If it was made in 1978 then it is not a Parks tube. I am almost betting it is a Meade Fiberlite tube as Cave had a hard time getting parts in the late 70's before they went belly up.  I can't use spray cans worth a hoot and a body shop could charge 150 to $300 to paint it. I used to have a body shop paint my tubes years ago whenever they did a white car they used what was left to spray my tubes.   Someone like Chuck Hards does great work with spray cans, but all i get is blotches and shiny area's.


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#56 Thaeland

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Posted 10 February 2019 - 10:49 AM



I did the repairs as stated in the link and did all the prep work for the auto body repair shop to spray in a booth a 2 part auto finish on . It came out better than the original finish.


Wow, that came out really nice... Thanks for the links. I will take a look.

Jon


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#57 tim53

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Posted 10 February 2019 - 12:01 PM

I had to repaint a fiberglass Parks tube for my 6" Kludge Classic several years ago.  It had an f/9.5 mirror in it with a big chip and a bad figure, so I replaced it with an f/10.3 mirror from ClearVue Optics (I think it was).  That meant I needed to drill a new focuser hole and patch the original.  I used Bondoglass to attach the patch "hole" I cut for the new position, and filled and sanded the rest, plus some other holes in the tube.  I couldn't save the beautiful pale grey gel coat, so I painted it with a satin finish white rattle can.  I did it before I figured out how to put the tube on a PVC pipe between two saw horses for a "rotisserie".  I just stood the tube up on end.  I was worried the finish wouldn't be uniform, so I avoided gloss.  It still looks good today!

 

https://www.cloudyni...= kludge tim53


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#58 mic1970

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Posted 11 February 2019 - 09:18 AM

Agree with above... that looks really cool.

 

 

Agreed , The patch spot is hideous ! I just thought if there was someway to save the original Gel Coat , that would be the better option . The gel coat usually cleans up rather well with polishing compound and wax . I have worked with this 2 part epoxy in the past , with great success . It is white in color and cures super hard and smooth  ... Smooth On M13 ...  https://www.smooth-o...products/mt-13/  .  Other than redoing the patch spot that will still look like a patch spot when done . A coverup is a option .... maybe a nice NASA decal or some appropriate space themed sticker / decal just to cover  ?  I had the same problem with my " Barn Fresh Cave Restoration " ......    https://www.cloudyni...on/?p=6265087   I did the repairs as stated in the link and did all the prep work for the auto body repair shop to spray in a booth a 2 part auto finish on . It came out better than the original finish waytogo.gif . Here is a shot  of my tube prior to going to the body shop for paint .

 


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#59 semiosteve

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Posted 12 February 2019 - 09:20 AM

Hi Steve,

For me I`d consider a few things:

 

- How large of an exit pupil do you like. My dark adapted eyes open up to about 5mm, so l tend to like an exit pupil of 3mm or less,.

- Does the 1.25" focuser cut into  the light cone.

- Do you plan to use a coma corrector? 

 

Take care

Steve T 

My exit pupil probably like yours.

The existing 1.25 focuser does not appear to cut into the light cone

I do not plan to use a coma corrector.

 

Given the above, I take it you would you keep the 1.25 helical focuser as is, and not bother with going to a 2" focuser. Is that what you are thinking for the Cave RFT?


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#60 steve t

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Posted 12 February 2019 - 06:22 PM

My exit pupil probably like yours.

The existing 1.25 focuser does not appear to cut into the light cone

I do not plan to use a coma corrector.

 

Given the above, I take it you would you keep the 1.25 helical focuser as is, and not bother with going to a 2" focuser. Is that what you are thinking for the Cave RFT?

Hi Steve,

I don't think you can go wrong either way.  

 

If the existing focuser is a Carle, IIRC, it was offered as an upgrade on Cave scopes. As long as its operation is smooth and meets your expectations l would be inclined to keep the scope original. Otherwise I personally wouldn't hesitate upgrading to a 2" dual speed focuser.

 

A few years back, I replaced a so-so 1.25" Kenneth Novak R&P focuser on my 1981 ATM 6" F/8 newtonian with a 2" dual speed focuser and really like it.   

 

Regards 

Steve T 


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#61 Thaeland

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Posted 19 February 2019 - 06:19 PM

The worm gear cleaned up quit nicely. I was going to tear it apart to polish it up but it turns very smoothly and has no slack in it. So I'm going to leave it alone. Just need a recommendation on what I should use to lubricate it. I was thinking just 3-in1 oil for the bushings and then maybe lithium for the worm gear. What do you all recommend?
3aa69c6c083d0f80bbd890dfa98d140a.jpg

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Edited by Thaeland, 19 February 2019 - 06:40 PM.

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#62 TOM KIEHL

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Posted 19 February 2019 - 07:14 PM

I like 3 in 1 and Super Lube https://www.amazon.c...922229188&psc=1


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#63 Thaeland

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Posted 19 February 2019 - 07:39 PM

I like 3 in 1 and Super Lube https://www.amazon.c...922229188&psc=1

I just read online that is what's recommended for most worm gears.... Your awesome, Thanks....

 

Jon


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#64 JoeInMN

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Posted 19 February 2019 - 08:20 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.

I did that with the little low-profile helical focuser on my 6" Dob in the pic below (posted here). The tube diameter is big enough to allow for this without either the legs or the barrel of the focuser intruding. My motivation at the time was an obsession with making the secondary as small as possible in that f/5 scope. Surprisingly for me, I managed to lay it out right the first time, so that all of my eyepieces reached focus specifically for my nearsighted eye, with the limited travel that those focusers have. It worked really well in that scope, but obviously would not be an authentic installation on a classic...

 

post-252462-0-70949300-1510462852.jpg


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#65 steve t

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Posted 19 February 2019 - 09:19 PM

I did that with the little low-profile helical focuser on my 6" Dob in the pic below (posted here). The tube diameter is big enough to allow for this without either the legs or the barrel of the focuser intruding. My motivation at the time was an obsession with making the secondary as small as possible in that f/5 scope. Surprisingly for me, I managed to lay it out right the first time, so that all of my eyepieces reached focus specifically for my nearsighted eye, with the limited travel that those focusers have. It worked really well in that scope, but obviously would not be an authentic installation on a classic...

 

post-252462-0-70949300-1510462852.jpg

Nice scope,  thanks for sharing .

Steve T 


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#66 steve t

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Posted 19 February 2019 - 09:22 PM

I like 3 in 1 and Super Lube https://www.amazon.c...922229188&psc=1

I've had gerat luck using Super Lube on my Losmandy G8 and ATM mount that has Babbet style bearings.

Steve T 


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#67 Earthbound1

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Posted 19 February 2019 - 09:42 PM

Great job so far! Keep up the good work!
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#68 Thaeland

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Posted 22 February 2019 - 10:39 PM

I completed the tear down and rebuild of the drive. I used some ideas others had done. If you look closely you can see I added blue fibre gasket material to the front plate of the clutch. Springs to the three clutch bolts so they can give a little while moving the scope. The springs are significantly larger than the bolt diameter so I added aluminum spacers and convex sealing washers to keep the springs centered. While I don't have the telescope fully assembled again the clutch already feels smoother.
I used electrical clips to keep the aluminum wires of the motor from touching the copper wires in the new cord. This will prevent the oxidation/corrosion that occurs when the two are touching and possibly becoming a hazard. Now I just need to add the Super Lube I bought....
564a0b9dbf86da48adcb45aa7f64781f.jpgcbc6f4b6556012a6f79064248e4dd449.jpg

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#69 CHASLX200

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Posted 23 February 2019 - 06:42 AM

Looks like new magoo.


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#70 steve t

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Posted 23 February 2019 - 08:45 AM

I completed the tear down and rebuild of the drive. I used some ideas others had done. If you look closely you can see I added blue fibre gasket material to the front plate of the clutch. Springs to the three clutch bolts so they can give a little while moving the scope. The springs are significantly larger than the bolt diameter so I added aluminum spacers and convex sealing washers to keep the springs centered. While I don't have the telescope fully assembled again the clutch already feels smoother.
I used electrical clips to keep the aluminum wires of the motor from touching the copper wires in the new cord. This will prevent the oxidation/corrosion that occurs when the two are touching and possibly becoming a hazard. Now I just need to add the Super Lube I bought....
564a0b9dbf86da48adcb45aa7f64781f.jpgcbc6f4b6556012a6f79064248e4dd449.jpg

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Nice, restoration on the drive, it' almost a shame to hide it under the drive housing cover smile.gif


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#71 TOM KIEHL

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Posted 23 February 2019 - 09:05 AM

I completed the tear down and rebuild of the drive. I used some ideas others had done. If you look closely you can see I added blue fibre gasket material to the front plate of the clutch. Springs to the three clutch bolts so they can give a little while moving the scope. The springs are significantly larger than the bolt diameter so I added aluminum spacers and convex sealing washers to keep the springs centered. While I don't have the telescope fully assembled again the clutch already feels smoother.
I used electrical clips to keep the aluminum wires of the motor from touching the copper wires in the new cord. This will prevent the oxidation/corrosion that occurs when the two are touching and possibly becoming a hazard. Now I just need to add the Super Lube I bought....
564a0b9dbf86da48adcb45aa7f64781f.jpgcbc6f4b6556012a6f79064248e4dd449.jpg

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Love the mods you have done to the  clutch / drive gearing . I like the fact that you painted the interior surface of the drive mounting plate , Nice touch ! Needs a acrylic cover now to show off your efforts . waytogo.gif 


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#72 Earthbound1

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Posted 23 February 2019 - 10:31 AM

Love the mods you have done to the clutch / drive gearing . I like the fact that you painted the interior surface of the drive mounting plate , Nice touch ! Needs a acrylic cover now to show off your efforts . waytogo.gif

Yes! That WOULD be a very nice touch to showcase your improvements and its inner workings to those curious enough to be interested. Great idea Tom! - Chip
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#73 mic1970

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Posted 23 February 2019 - 10:49 AM

Agree... would make for an awesome touch

quote name="Earthbound1" post="9167727" timestamp="1550935909"]

Yes! That WOULD be a very nice touch to showcase your improvements and its inner workings to those curious enough to be interested. Great idea Tom! - Chip[/quote]
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#74 Mr Magoo

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Posted 23 February 2019 - 05:09 PM

What is the blue gasket material that you used?


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#75 Thaeland

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Posted 23 February 2019 - 09:08 PM

What is the blue gasket material that you used?

It's Fel-Pro #3075 I bought at AutoZone. It's only $7.99 a sheet. What I wanted to buy was more of a pure fiber material but I could only find it online for $24.00 for the same size. Of course it's also not available right now unless I buy the $100 sheets. However this seems to work very well after all...37dbd3f31cddf65c829326ac3ab5b182.jpg

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