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mapstar

The Mapstar 22" build

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mapstar    5,578

Hi all,

As a few are aware I had quite a long running mirror thread which came to completion late last year. A lot has happened since with the construction of the scope which is now nearing completion so I thought it about time I added this to the forum for you all to read.

The first thing was the mirror cell and I made this quite a time before the actual mirror was finished.

It was constructed from 1 1/4" (31.75mm) square section 1.6mm wall aluminium and designed in PLoP for the optimum configuration. The tapped triangle point were made from 1"x 1 1/4" solid bar. The calculation for my mirror thickness showed an error of 1.9 nanometres and calculating in the edge support error this worked out at 2.8nM. All well and good so onto the actual cell which was to be 18 points. Some of these pic's were in my other thread but seeing as I made the cell at the same time it is no different.

Here is the cell cut to form the basic triangle with the two edge support mounts at the bottom before machining and welding.

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The cell would be fixed at the top using a rose joint spherical bearing and then adjust at the two bottom points for collimation. So next I machined the slots out for the wobble bars, drilled the pivot holes for the wiffle tree mounting points, and the threaded holes for the rose joints.

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And so onto welding it all together which I entrusted to a local welding company in sheffield.

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Moving on the design and construction of the wobble bars, triangles and wiffle tree edge support's.:grin:

 

Edited by mapstar
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Paul73    2,497

Oh the temptation......  One of these days a build will go swimmingly and I will be able to resist no longer.....

After the mirror grinding, Damian deserves a smooth build.

Hope that it has / will go well.

Paul

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mapstar    5,578
15 minutes ago, Paul73 said:

Oh the temptation......  One of these days a build will go swimmingly and I will be able to resist no longer.....

After the mirror grinding, Damian deserves a smooth build.

Hope that it has / will go well.

Paul

Cheers Paul

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estwing    4,493
32 minutes ago, Paul73 said:

Oh the temptation......  One of these days a build will go swimmingly and I will be able to resist no longer.....

After the mirror grinding, Damian deserves a smooth build.

Hope that it has / will go well.

Paul

Knowing Damian it will bang on...

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mapstar    5,578

I had the triangle's (trefoil shaped) cut from 6mm ally at a laser cutter. These were then machined (19mm end mill) to accept a spherical bearing in the middle for flexibility which was glued in using Loctite bearing fit

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All the dimension's were spewed out by the PLoP (PLate oPtimisation program)

I also drilled and tapped the 3 contact points on each triangle ready for fitting the 18 nylon pads that the mirror would rest on.

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A screw through from the other side would then hold the triangles onto the wobble bars. I also had the edge support brackets laser cut from 1/2" thick Aerospace ally which were then machined to accept the 4 nylon edge support contact points.

2 posts to hold these completed the main parts of the cell

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18 nylon pads for the contact points (cnc'd by a friend) and four nylon edge support points finish off the cell which is fully constructed below, a polypropylene ring was used to hold the triangles in the correct orientation.

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There was a fair while until the next piece of the scope was constructed as the mirror took up quite a bit of my time!

 

 

Edited by mapstar
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Physopto    1,458

About time you got around to this thread Damian. We have been waiting!!! Mike even went blue at one point!:cwm21:

:p

Derek

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Demon Barber    627

Hi Damian,i don`t know where you get the time to write up your build ,as usual it is very informative,well done that man

Regards

Mike

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Physopto    1,458
3 minutes ago, Demon Barber said:

Hi Damian,i don`t know where you get the time to write up your build ,as usual it is very informative,well done that man

Regards

Mike

Yer sucking up again Mike :evil4:

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mapstar    5,578

Thanks guys,  it takes quite a bit of writing Mike as you point out.

Whilst it's cloudy there's not much chance of doing much else!

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mapstar    5,578
5 minutes ago, swamp thing said:

Looking sweeeeeeeeeeeet :) 

keep em pics coming 

Cheers Steve I'll try my best 

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mapstar    5,578
Just now, estwing said:

is there a max size mirror you can use with a 18 point mate?

 

Depends on the error Calv. There's a graph I saw once up to 30" for 18 point's 

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mapstar    5,578
37 minutes ago, estwing said:

more means less chance of error tho?...correct?

 

Yes, but it's a lot more work which you wouldn't really see any benefit from. 

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mapstar    5,578
6 minutes ago, wookie1965 said:

This scope is going to be awesome pity ere not going Buxton so i could see it and through it.

 

I'm sure there will be another gathering down that way or somewhere close in the future Paul so you will get a look :happy7:

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mapstar    5,578
Just now, wookie1965 said:

Damian I will look forward to that, Cheers mate.

Me too 

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