The Mapstar Scope build

[stonemonkeylives]

Soupy wishes, lol.

Sent from my GT-I9505 using Tapatalk

[mapstar]

Would I be correct in assuming that "Soupy" is the end user ;-0

Ian

No Paul is the chairman of our society and a great friend also a 200pds user but unlike me make's full photographic use of the scope ;-)

[Soupy]

Would I be correct in assuming that "Soupy" is the end user ;-0

Ian

I wish as well... But I have seen most of the progress and you all won't be disappointed with the end result, it's well worth the wait

[wookie1965]

The spider set up looks impressive.

[Daniel-K]

The secondary holder is a neat design but with the weight of the size of the secondary i would like a little more surface area for the silicone to stick too. 

[mapstar]

The secondary holder is a neat design but with the weight of the size of the secondary i would like a little more surface area for the silicone to stick too.

The ally plate is 100mm so well on the large side for the silicone

[Daniel-K]

ahh i get you now i thought you was using that ally plate as a template. very cook design though well done so far.

[mapstar]

ahh i get you now i thought you was using that ally plate as a template. very cook design though well done so far.

No worries Daniel its always hard to describe things so people know what you're angling at.

And thanks I'll post some more bits later on

[crashtestdummy]

despite having seen all the peaces in the flesh im glad you got round to putting it into words and pictures fella.ive loved blogging my mirror so glad you are enjoying blogging your build.when you have finished with the scope build part if its ok I will link this to my mirror blog when its all finished

[mapstar]

No problem's Crash and looking forward to seeing John again tomorrow ;-)

[jamespels]

Absolutely superb thread. Many thanks for posting this - it looks like a wonderful bit of engineering.

Hats off all round.

James.

[faulksy]

any more pics today ?

[mapstar]

Mirror making seminar today folks and a long day. My 22" grind is going in the right direction thankfully

Thanks for the compliment James

Sorry for no updates will post some tomorrow

Damian

[Uplooker]

Mirror making seminar today folks and a long day. My 22" grind is going in the right direction thankfully

Thanks for the compliment James

Sorry for no updates will post some tomorrow

Damian

So how did the testing of your mirror turn out??

Ian

[mapstar]

It's in the first stage of polish Ian but roughly spherical which is good.

Looking at the Ronchi image it is under polished in the centre so need's more.

More polishing and set up the testing gear.

Damian

[crashtestdummy]

no quite as underpolished in the centre as mine!!

[mapstar]

After thinking on the truss pole arrangement I decided that I wanted the truss poles to remain together and have machined ends.After testing some ally I opted for 22mm 16gauge poles. so at the same time I bought some 22mm aluminium round bar so I could machine ends for them and get them welded on.

Another very long session at the machine shop (2 days) I had 48 truss ends machined ready for welding onto the truss poles when the length was determined.

Got to admit that if I was ever going to do it again I'd take a CAD drawing to a CNC shop and have them machine them as it was so repetitive I never thought I'd finish.

Next up was the way they would attach to the LOA (mirror box). I wanted the box to be like the rest of the scope a bit different so went for an octagonal box. Working out the UTA would be 650mm ID and a 750mm OD the truss attachment needed to fall inside these two circles. I went back to the CAD program and drew them out to work out the optimal size of box with 18mm ply and the corner attachments.

More engineering drawings to the laser cutters and a lot more machine shop time and I'd got a plate to attach to the box (first pic) with two dowels (fitted later) for locating the lower truss pole assembly (second pic) that slotted over the dowels and locked down with an 8mm locking knob. Again cut from 1/2" aircraft grade ally

(Apologies for the poor pics)

My original thought was to have an allen cap bolt (as shown) and nut on the other side (where the thread is) to tighten the truss poles once assembled (meaning 2 tools?). A change of mind and I made some inserts from the same ally, so they were captive rectangular nuts thus needing only a T bar allen key to tighten the poles once assembled.

I could've just tapped the things but like my machinist friend said "at least if you strip the threads you can just replace the inserts instead of the whole bracket". Sometimes things just evolve.I also counter bored the allen cap bolt into the side of the bracket so that it would tighten onto the truss end.

Here's the lower truss assembly when I finalised it.

I know there are truss arrangements made by manufacturers out there but as with the rest of the scope just something a bit different and my own design.

When the truss pole length was worked out, I made up a Jig so I could have the ends welded on parallel and square

And finally when they were welded up and fitted to the truss lower mounts

More thinking and cups of Tea!

Off to do a bit of mirror polishing after yesterdays trip to see John, so more updates later with the upper truss fixings and a bit of wood work

Damian

[faulksy]

this is a great post

[mapstar]

Thanks for that Faulksy it took some writing

[swamp thing]

Looking very classy indeed Damien.

Come on man more pics......

[mapstar]

Today I've been polishing again and still to get full contact with the lap so as its pressing a few more pics.

I'd not quite finished the lower truss mounts so after ordering some 8.1mm aluminium round bar I proceeded to make the locating pegs for the lower truss mounts to slide on.They were an interference fit and held in with more loctite retainer.Finally fitted them to the box plates

The upper truss mounts were made from 1" x 1/2" 16gauge box section although they did alter a couple of times and are something I'll re-think slightly at a later date 

Here's the material 

And the upper mount when I'd finally milled, drilled and finished them

The two holes would take the 5mm allen cap screws to lock the truss poles solid. As with the lower mounts I'd originally intended to have a nut behind but instead went for some 1/2" material that spanned both holes which I tapped two M5 holes in. Again only the T bar allen key needed to be used.

The square hole in the middle would be for a retaining nut to stop the M8 mounting screw coming out of the assembly when it was all built up.All glued up with loctite ultimate thread lock.

After ordering some bakerlite knobs I used some 8mm stainless rod to make up the mounts. Heres how the finally turned out when screwed into the insert nut in the UTA

The nut in the square hole was set so when unscrewed there was about 8mm of thread stuck out to locate the insert nut on the UTA making it easier to assemble. It actually locks up on the double nut.

The material I used to make the spider I also used to make the rocker box az pivot  

This would mount from underneath the ground board and have a circular teflon pad for the middle (pic later)

After all the engineering overload it was finally time to start some wood work after yet another cuppa!

Check my lap too!

Damian

[faulksy]

Today I've been polishing again and still to get full contact with the lap so as its pressing a few more pics.

I'd not quite finished the lower truss mounts so after ordering some 8.1mm aluminium round bar I proceeded to make the locating pegs for the lower truss mounts to slide on.They were an interference fit and held in with more loctite retainer.Finally fitted them to the box plates

37 (6).JPG

The upper truss mounts were made from 1" x 1/2" 16gauge box section although they did alter a couple of times and are something I'll re-think slightly at a later date 

Here's the material 

37 (10).JPG

And the upper mount when I'd finally milled, drilled and finished them

37 (4).JPG

The two holes would take the 5mm allen cap screws to lock the truss poles solid. As with the lower mounts I'd originally intended to have a nut behind but instead went for some 1/2" material that spanned both holes which I tapped two M5 holes in. Again only the T bar allen key needed to be used.

The square hole in the middle would be for a retaining nut to stop the M8 mounting screw coming out of the assembly when it was all built up.All glued up with loctite ultimate thread lock.

After ordering some bakerlite knobs I used some 8mm stainless rod to make up the mounts. Heres how the finally turned out when screwed into the insert nut in the UTA

37.JPG

The nut in the square hole was set so when unscrewed there was about 8mm of thread stuck out to locate the insert nut on the UTA making it easier to assemble. It actually locks up on the double nut.

The material I used to make the spider I also used to make the rocker box az pivot  

27.JPG

This would mount from underneath the ground board and have a circular teflon pad for the middle (pic later)

After all the engineering overload it was finally time to start some wood work after yet another cuppa!

Check my lap too!

Damian

that last pic, is it spun from solid, looking good mate very good. only criticism i have is i wish you would upload these pics quicker dying to see it finished   

[mapstar]

We're getting there but it is piece meal sorry to say.

Yes its turned from solid 2" aluminium round bar. Tapped 8mm with three 5mm clearance holes for mounting.

Cheers

Damian

[JRM]

great work there Damian, got me wishing you where my neighbour. you got the planes for that mirror cell btw, looks fantastic

 I like that better then the sling option, I would just need to downsize for my 20" 

Rick M

[mapstar]

Thanks Rick

The cell was all designed with the PLOP program measurements and it was a real head scratcher to work out when I drew it on the lay up board. I don't have the plans as such as the material may be a little different.

PLOP take's some deciphering but once you know it all works on the x and y axis coordinates it is a lot easier. A CAD program helps too.

once you've got your mirror thickness, focal length and diameter in (if I remember correctly) the program spews out the info on the mirror contact and edge support points although it's like I said not exactly easy to work out.

Being your neighbour would probably get me better skies so let me know the next house that goes up for sale ;-D ha ha

I'll be posting a lot more pic's this weekend of the scope build up especially the lower optical assembly so if it looks a bit confusing it Will all become clearer.

Damian