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  #61  
Old 01-05-2018, 03:43 PM
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I ordered some Borofloat blanks from Germany and looks like I won't be getting them until July. I wanted to make a start on the primary before then, so I dug up an old school Pyrex blank from my collection and spent several days machining it down to 25mm thickness. Actually I overshot the mark by half a millimetre.
I just have to generate the front radius and I can start pushing glass. I already have a thick Pyrex tool that I made for re-grinding an ODK10 primary.
The radius difference is very small and I will fine tune it with a metal ring tool.
Cool Stefan, Guessing it should be easier to grind than my 10 inch?
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  #62  
Old 01-05-2018, 04:26 PM
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Cool Stefan, Guessing it should be easier to grind than my 10 inch?
My curve will be a lot deeper than yours (f/3), but I don't mind if we have a race, seeing that we both are at the same stage.
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  #63  
Old 01-05-2018, 04:35 PM
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My curve will be a lot deeper than yours (f/3), but I don't mind if we have a race, seeing that we both are at the same stage.
It's on!
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  #64  
Old 03-05-2018, 08:24 PM
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Any news Stefan?
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  #65  
Old 03-05-2018, 09:19 PM
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Any news Stefan?
Yes, Logan, I have bad news for you: "Old age and treachery will always beat youth and exuberance."

My curve is done, but you may be able to catch up with the following stages, as I'm working on many fronts.
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  #66  
Old 03-05-2018, 09:58 PM
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Yes, Logan, I have bad news for you: "Old age and treachery will always beat youth and exuberance."

My curve is done, but you may be able to catch up with the following stages, as I'm working on many fronts.
I havent even STARTED hogging, still working on the back!

ok, you win!
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  #67  
Old 05-05-2018, 05:41 PM
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I 3D printed the secondary baffle using expensive ($90 for 750g) carbon fibre loaded filament. This stuff produces such a nice matt finish that I'm not sure whether it can be improved with black paint. And it weighs 26g.
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  #68  
Old 08-05-2018, 09:25 AM
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Finished the mounting rails.
I opted for system 20 (2080) extrusions, rather than a solid bar - as I see on many commercial instruments. These extrusions have superior stiffness to weight ratio, compared with solid bars. The end caps are 3D printed ABS.
Another advantage is that the dovetail plate can be moved along the long rail for optimum CG, and thus it does not have to be extra long (and heavy).
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  #69  
Old 08-05-2018, 09:29 AM
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Originally Posted by Stefan Buda View Post
I 3D printed the secondary baffle using expensive ($90 for 750g) carbon fibre loaded filament. This stuff produces such a nice matt finish that I'm not sure whether it can be improved with black paint. And it weighs 26g.
I had no idea you could 3D print CF filaments. So how does it work and holds together? Heat? Glue?
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  #70  
Old 08-05-2018, 09:38 AM
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I had no idea you could 3D print CF filaments. So how does it work and holds together? Heat? Glue?
CF filaments contain only up to 20% short strands of CF and print like any other filament, although slower. The result is nowhere near as strong as laminated CF. I'm waiting for graphene reinforced filaments to hit the market, but that may not happen for a while.
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  #71  
Old 11-05-2018, 08:06 PM
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Making the necessary jigs and fixtures is more work than making the actual parts.
For the primary, I made a new wedge error tester, from an old tooling plate, that allows me to also measure the concentricity of the inner diameter.
For making the dovetail plate, I had to make a fixture for cutting the 60 degree angle of the dovetail.
Next I have to figure out a way of setting up the primary on the lathe to cylindrically grind the inner diameter to the required specs.
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  #72  
Old 11-05-2018, 08:46 PM
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Jaw dropping work!
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  #73  
Old 11-05-2018, 08:48 PM
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Cool!
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  #74  
Old 15-05-2018, 10:44 AM
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Jaw dropping work!
Thanks LewisM, and I'm so glad that the five pointed star is not red. I grew up on the other side of the Iron Curtain.
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  #75  
Old 15-05-2018, 10:46 AM
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Just need some optics now.
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  #76  
Old 15-05-2018, 10:48 AM
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Just need some optics now.
That looks the par already. Superb.
Is that a zero magnification scope at this stage?
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  #77  
Old 15-05-2018, 10:56 AM
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That looks the par already. Superb.
Is that a zero magnification scope at this stage?

It hasn't occurred to me, but you are right (more exactly 1x). Maybe I should call it finished.
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  #78  
Old 15-05-2018, 11:09 AM
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It hasn't occurred to me, but you are right (more exactly 1x). Maybe I should call it finished.
Sounds about right. It has a massive corrected imaging circle and no vignetting. What more do you want?
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  #79  
Old 15-05-2018, 11:13 AM
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Awesome Stefan!!! Wish i knew how to make stuff like that!
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  #80  
Old 15-05-2018, 04:42 PM
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Wow, this is intriguing stuff. I think we are all somewhat in awe here. You have some super useful skills.

Perhaps a custom making scope business could eventuate here. Are we looking at an Aussie Roland Christen here?

Greg.
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