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Intes MK63. I don't NEED another scope!

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#76 tim53

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Posted 13 October 2019 - 04:18 PM

I'm back to work on fixing this mirror today.  Been quite a while, but not as long as my last post about it.  Reason being, I made the figure a lot worse before I started making it better.  I can claim it's "part of the plan" so I can gain experience before tackling the C-14 or the Mak 16".

 

-tim.



#77 tim53

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Posted 01 December 2019 - 04:48 PM

Almost there. I have a sphere with a bit of a tde and a hill around the perforation. Worse, my sphere is rough. So today I’m softening my pitch with some olive oil. 
 

 

Attached Thumbnails

  • E26B84EE-BE60-4643-AF16-78EA9C8F6751.jpeg


#78 tim53

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Posted 01 December 2019 - 08:27 PM

Well phooey.  I spent most of the afternoon trying to whip the lap into shape.  These fast mirrors are a pain to press, IMHO, because the pitch wants to form a level surface in the toaster oven, but the mirror needs it to be mounded up in the center.  I got almost there, but with a low spot off center (wish it were on-center where the hole in the mirror lives), when I just had to put it away for the day.  Don't know when I'll get back to it now. 

 

-Tim.


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#79 G-Tower

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Posted 01 December 2019 - 11:33 PM

Have you tried the Emeril pitch lap maker?


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#80 tim53

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Posted 01 December 2019 - 11:54 PM

Have you tried the Emeril pitch lap maker?

Mine's more better, because it was free!  wink.gif


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#81 Terra Nova

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Posted 02 December 2019 - 10:15 AM

Mine's more better, because it was free!  wink.gif

It’s hard to beat FREE! 



#82 tim53

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Posted 20 March 2020 - 11:08 AM

So I have been slowly working on this refigure for several months of acopious spare time now.  My pitch lap has been on a 3/4" plywood disk, shellacked (so-so sealed).  Hot pressing was always a challenge the several times I've re-formed the lap, because of the steep curve of the primary mirror.  I can quickly get it pressed to about halfway to the center of the mirror, then it's cooled enough that going any further takes lots of time, weight, and repeated tweaks with a heat gun.  And still I never got it pressed quite to the perforation.  

 

Then, even using typical strokes to spherize, I keep getting a TDE and hill around the perforation.  Even thinning the pitch to soften it didn't seem to help any.

 

So now, I ordered some dental stone and poured a new tool that has the primary's shape and perforation.  So when I pour and press the new lap, it should have a uniform thickness throughout.  And hopefully getting to a perfect sphere will be straightforward!  

 

Family portrait:

 

Mirror_newtool.jpg



#83 G-Tower

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Posted 20 March 2020 - 03:26 PM

The problem may be your stroke and pressure.



#84 tim53

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Posted 21 March 2020 - 10:12 AM

Perhaps.  I've tried pretty much everything I could think of.  But the lap on the plywood disk is about twice as thick in the center as at the edge, and has to be affecting the way the pitch adjusts to the figure.

 

In any case, I still have the lap and could go back to it if necessary.

 

-Tim.



#85 Augustus

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Posted 21 March 2020 - 04:28 PM

I would plug the hole in the primary with hard pitch, personally. 



#86 davidc135

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Posted 21 March 2020 - 05:00 PM

Very likely a stupid idea but could wrapping a tube packed with salt or calcium chloride/ice around the edge during polishing help with the tde? Just a remote chance. Ensuring an even thickness of pitch sounds right.  David


Edited by davidc135, 21 March 2020 - 05:00 PM.

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#87 tim53

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Posted 29 March 2020 - 03:15 PM

Made a new lap yesterday, but only just started using it.  Still some pressing to do. It's amazing how hard it is to squeeze down the outer edges with a fast mirror.  makes me wish I'd been paying attention when Gerry Logan described how he pours pitch on a surface (wax paper?) and transfers it to the tool before it's too hard.  With terpentine on the tool to help it stick.  That would give a uniform thickness of pitch draped over the tool.  But I couldn't figure out how to make the dam to contain the pitch that way.

 

-Tim.



#88 davidc135

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Posted 29 March 2020 - 04:32 PM

Could plywood be used for the dam? If it's finished smooth and coated with cerox.Could be made in two halves which pull apart.  David


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#89 tim53

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Posted 25 April 2020 - 03:25 PM

I'm almost there!  i "perfected" my dpac rig:  https://www.cloudyni...ter/?p=10140005.

 

And now, this result.  I still have a few minutes to go to be perfect, but I'm waiting for Dave's comments to do the next run.  I've still got a couple IPAs to tide me over until then.

 

msg-6788-0-99409700-1587845832_thumb.jpg


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#90 starman876

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Posted 25 April 2020 - 06:01 PM

I'm almost there!  i "perfected" my dpac rig:  https://www.cloudyni...ter/?p=10140005.

 

And now, this result.  I still have a few minutes to go to be perfect, but I'm waiting for Dave's comments to do the next run.  I've still got a couple IPAs to tide me over until then.

 

msg-6788-0-99409700-1587845832_thumb.jpg

How does it look on the other side of focus?



#91 tim53

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Posted 25 April 2020 - 06:12 PM

Here's how it looks now.  I'm waiting for Dave to tell me whether to go ahead for 2 more rounds around the mirror.

 

inside focus:

msg-6788-0-65226300-1587855759.jpg

 

 

and outside focus:

msg-6788-0-21518800-1587855775.jpg


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#92 Terra Nova

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Posted 25 April 2020 - 06:20 PM

Jail bar straight Tim. Good job, I'm impressed! waytogo.gif waytogo.gif



#93 starman876

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Posted 25 April 2020 - 06:58 PM

That looks really good Tim.  Great job. waytogo.gif



#94 tim53

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Posted 26 April 2020 - 09:39 AM

Dave suggest, and I agree, that it needs about 2 more times around.  Very slightly undercorrected still.  You can tell by comparing the inside to outside.  Look closely - the inside lines bow inward ever so slightly, and outward in the outside focus image.  Gotta paint some more in the attic today, but this afternoon, I hope to knock this one out.

 

-Tim.



#95 DAVIDG

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Posted 26 April 2020 - 10:31 AM

Tim is really close to having  extremely good optics. Right now they are better then 97% of the commercial SCT and Maks I have tested over the years.  If he stopped  here the image would be excellent . Go back to message number 38 in this thread to see the test images of were they started out. Pretty poor.   As I keep saying you have to test your optics and can't assume their quality. I'm sure this scope sold new for over $1000 and the expectation was that it had at least 1/8 wave optics.  The good new is that with some  pitch, optical polish and a bit of  email coaching he fixed them . He'll now have a big Mak that will live up to all the hype of their planetary performance. 

 

               - Dave 


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#96 tim53

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Posted 26 April 2020 - 10:43 AM

...I got a reprieve!  My wife and I are both sore from painting the ceiling for 4 hours yesterday, craning our necks and balancing on scaffold and step stools.  I managed to paint most of it from standing on the floor, but that meant I had to stretch my arm more to paint.  

 

So, once I get off the computer and changed into my optical grubbies, I'm going to FINISH this guy!!  Dave has been a tremendous help, everybody knows it.  grin.gif   We just need to figure out how to revive the Delmarva mirror class using Zoom or some such.

 

-Tim.


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#97 davidc135

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Posted 26 April 2020 - 10:47 AM

Excellent work, well done.  David



#98 DAVIDG

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Posted 26 April 2020 - 11:14 AM

"We just need to figure out how to revive the Delmarva mirror class using Zoom or some such." I wonder if Cloudy Nights would consider hosting some type Zoom video meeting to discuss certain topics ? My astronomy club has been having it's usual Tuesday evening telescope workshop meeting via Zoom since the virus problem started. 

 

             - Dave 


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#99 starman876

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Posted 26 April 2020 - 11:25 AM

Dave suggest, and I agree, that it needs about 2 more times around.  Very slightly undercorrected still.  You can tell by comparing the inside to outside.  Look closely - the inside lines bow inward ever so slightly, and outward in the outside focus image.  Gotta paint some more in the attic today, but this afternoon, I hope to knock this one out.

 

-Tim.

I saw that Tim. However, the work you have done is excellent.   You have far more patience than I have figuring optics.  I congratulate your efforts and results.



#100 tim53

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Posted 26 April 2020 - 11:37 AM

The reprieve was temporary. I now have a project to complete first. I need to replace some siding on the side of the stairs up to the veranda on the side of the house. Not a huge deal, but I need to get to my table saw, which means I need to charge the battery in the model a, and make a run to the gas station for some gas to fire it up. 




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