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mapstar

The 22" mapstar mirror

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Thanks Guys.

I hope it comes to fruition soon but these things do take a while and when it does it will all be worth it. The mirror will take as long as it does.

I have just returned home after a pleasant few days of mirror work and astronomy talk so it is time to relax for tonight.

I will update the thread a little more tomorrow.

Damian

Edited by mapstar
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Ah I see wonder how you were removing the glass.

Obviously as the first part of the thread describes I did it all by hand and have to admit I will never go that way again. It definitely gives you an appreciation of why machines are used.

It was only the 25 that came with (some of) a curve already in it. Both my 20" and 18" were done by hand just like your one although I do have a powered spinning table and I wouldn't want to make a mirror without it. I really don't want to hog out the 30" by hand as it's going to need an 18mm sagitta!

Anyway keep it up as it's awesome viewing with a large mirror you have made yourself !!!!!!!

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Hi all just so this is on each page,

John Nichol is hoping to hold another one day seminar if there is sufficient interest.

The previous two editions have been limited to mirror making, this time it will include aspects of telescope making. This is because some people would like to make their own telescope without making their own optics. As a result the day will be about 50% mirror making and 50% telescope making. Details of the day are...

Date: 22nd November 2015

Time: 10am til 4pm.

Location: BIllingham, Teesside. (Easy access from the A19)

The day will feature a talk from SGL's Mapstar (Damian).

More details to follow as the timetable is firmed up.

This is not a profit making event, But There will be a charge for this seminar, sufficient only to cover costs of

the facility, and materials etc.

If you would like to register an interest in attending the day please send me a PM

Damian.

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Hi all,

It's been quite a while since I last updated the thread and posted a few images. 

So here is what has happened and where it stands at present

I spent a total of five days working with John on the mirror using one of the machines he has in the workshop. The mirror looked like it had a depressed ring zone in the middle as well as the slight turn on the edge but as many know who have made mirrors it's difficult to really know how deep the centre was.

Using an 8 inch lap on the 70% zone for several hours gradually pulled the edge back and resolved the edge issue and try to bring the centre up. The lap was then set gradually further in to work on the depressed ring zone. As I posted a couple of weeks ago it eventually came back to an oblate sphere.

Here is an image as it progressed getting back to a sphere . There is still a slight turn evident but this was sorted a few hours later.

post-28847-0-38210200-1445201616_thumb.j 

It was so enlightening to watch how John (through many years of experience) knew instinctively where to place the lap and I probably annoyed the hell out of him with the constant school boy type questions! although you have to remember he is used to working solo. He did an excellent job of explaining the process and the thinking behind it though.

The mirror took three days of work to get it something like then it was onto the parabolising. This as John had said would be a case of working through the centre to deepen it, but alternating back to the edge so as to gently push the parabola out with smooth curves and no zoning. Things don't always go as easy as said and sometimes it is a case of the glass just doesn't behave the way intended. This is what takes the time and why it requires lots of patience. 

Here is the mirror as the curves developed

Inside ROC

post-28847-0-53271100-1445202849_thumb.j

Outside ROC

post-28847-0-20765900-1445202853_thumb.j

As can be seen quite a few zones developed which I have seen before the outside ROC image showing the kink developing at around the 70-80% zone.  The lap would be moved back to the outer zone to work this and smooth it.

So back and forth with the lap and the centre was gradually deepened. 

Inside ROC

post-28847-0-80430600-1445202861_thumb.j

Outside ROC

post-28847-0-71041000-1445202864_thumb.j

It still has some zones on it to smooth out but is on it's way.

So finally after a discussion with John at the end of my time up there, I agreed that it was about time it was finished and that I should concentrate my efforts on getting back into my comfort zone which was progressing the shell of the scope.  After all it is about out there and viewing the heavens fingers crossed with some of you guys.

Reluctantly the mirror now resides with John who has been carrying on with it and updating me regularly, I'm hoping to get back up there sometime this week to see it and help out (hinder more like) with a few bits but in the meantime I will try to post more updates of the progress.

Thanks for reading and sticking with the thread and me all this time guys

Damian 

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Thanks for the update buddy! It's nearing the end, you'll soon be up and running with a monster mapstar scope! :)

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Thank you for the update. It's getting there. Hope you enjoy putting your craftwork into the build, and you are going to create a beautiful scope. You'll soon be taking in those breathtaking views your scope is going to give :)

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Looking good Damian it will soon be done and I'm sure the views will be super.

Mark

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It's been an exciting, and pleasurable experience tracking you through your Mammoth task Damian.

I so wished I could have spent some time in your presence to encourage, and perhaps offer some on site advice, but

I know deep down this mirror making job is an extremely personal journey.

You've shown a great deal of patience, and may I say restraint too, as there must have been times when the pressure Cooker valve

got very near blowing off. However, I'm sure you accepted Johns experience had to be tapped into, and there is nothing wrong with that at all,

in fact I would call it a  common sense move.

Congratulations on your fortitude and stickability my friend, you certainly have plenty of it, and in due course,

I look forward to your experiences as you gaze out into the magical universe, and drink in the beauty of those magnificent

Deep Sky gems that only a Big Eye like that 22" will deliver.

Smaller apertures are never to be mocked of course, and I would never do so, but there is no substitute for 

huge light collectors, and I hope one day I get a looksee through the Mapstar Monster.

Well done  :icon_salut:  :icon_salut:.

Ron.

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Many thanks for the comments along the way Ron.

It was a difficult and heartfelt decision to make accepting John's help but that I have and do feel it is the right decision. John has been more than generous with his time and hospitality and I really can't thank him enough.

For someone such as myself who never really gives up on a project I will master the making of a mirror one day, just not this one. The experience gained along the way will make a huge difference.

The next project to hit SGL will hopefully progress be a little quicker and be more successful from me so to say. The scope build.

Fingers crossed you guys will stick with it like you have on this one. It should be an interesting read.

Many thanks to everyone for reading, commenting, helping and encouraging along the way. I know it has posed some serious questions about mirror making and given many different thoughts on the techniques to use.

More updates to come and it would be a pleasure to share the views in person and with a first light report when they finally appear.

Damian

Edited by mapstar
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Courageous choice. You've avoided the 'owe it to our lads' fallacy!

Keep up the updates!

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Evening all.

Thanks for the comments again guys.

Tomorrow I have a trip up to see John and take a look at the progress he's been making on the mirror. Through emails I know he has been putting in quite a few hours.

I'm looking forward to it.

The scope is progressing and I'm in the process of documenting it all in photos for when I start the thread. Although I'm sure I will stop at building a rocket to put it in orbit.

I will post another update after tomorrow's trip, John also has some real interesting glass at the workshop at present so that will be a bonus.

Clear skies

Damian

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Very excited about the rest of the build. Have learned a lot about my own scope and the optics behind it through following this thread - looking forward to what I'll learn from the other half. Good luck with the rest and I look forward to the first light report!

Sent from my iPhone using Tapatalk

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Very excited about the rest of the build. Have learned a lot about my own scope and the optics behind it through following this thread - looking forward to what I'll learn from the other half. Good luck with the rest and I look forward to the first light report!

Sent from my iPhone using Tapatalk

Thanks Pdols, hope you find the next thread as interesting.

Damian

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  • Look forward to seeing next lot of pics. 

eric

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Any updates on the mirror?

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Hi all,

I have been rather busy of late with the scope build so not had chance to post the progress.

I'll try my best to get one on this week and start a build thread over the coming weeks too.

Thanks

Damian

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Hi all,

It's been a long time in the creation and the update is a little late so after apologies here it is.

As I left the thread last the mirror was in the hands of John and he informed me every day of the progress with regular updates and photo's.

John works with the Auto collimation test rig but does test with Ronchi too, when he said it was completed I took my own test rig to keep the photos in the same style as the rest have been.

Working from the inside ROC the images were taken at 2mm steps moving to the outside ROC. Incidentally there was some thermals about in the room at the time of taking the images but they seem to have come out ok

post-28847-0-96279600-1448730566_thumb.j

post-28847-0-94781900-1448730570_thumb.j

post-28847-0-66677800-1448730574_thumb.j

post-28847-0-35823200-1448730578_thumb.j

post-28847-0-20933900-1448730582_thumb.j

post-28847-0-94228300-1448730585_thumb.j

The matched Ronchi images generated were a very close match and the focal length was finally measured at 1907mm so F3.4. I was going to have John make me the 130mm flat I needed but he had helped me enough and he had other mirrors to be going on with which were a little behind due to all the work he had put in on mine.  So I decided to pick a 130mm flat up from Orion optics when I dropped the mirror off for coating.

So Sunday the  8th of November I travelled north again to be as ever greeted by a warm welcome from John and a cuppa whilst the final Ronchi tests were conducted. The mirror was then boxed up and after a farewell I took it home.

The next day I took the mirror to Orion optics for the HiLux coatings and returned home with a 130mm flat in my possession.  Orion turned the mirror around in a week and I picked it up the following Monday so great service.

Here's the Mirror after coating with the flat. Apologies to all as a can of beans was unavailable so my other favourite thinking vessel compliments the thing for scale. All it needs is a centre spot 

post-28847-0-62799500-1448731276_thumb.j

All in all a lovely Job and many thanks to John for his helping hand to get me to the finish line.

Next up to put the scope build thread together and adorn the pages of SGL with that. It wont take as long as the mirror though as it is well on its way  :grin:.

Thanks to everyone  that has popped in along the way and followed the thread offering advice and support. Hope you have enjoyed the trials and tribulations but I will say it may be the first but it won't be the last as I will try again.

Clear skies 

Damian

Edited by mapstar
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Not ashamed to admit I got very excited when I got the notification about the update - great to see you're getting so near to the end of the project. Congrats and good on you for all the hard work

Sent from my iPhone using Tapatalk

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Damian,

I am in envy now, get it all together so we can here of those great night views through the beast, can't wait for your first light.

Congrates my friend.

Rick M

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Damian,

I am in envy now, get it all together so we can here of those great night views through the beast, can't wait for your first light.

Congrates my friend.

Rick M

Thanks Rick and all,

First light isn't too far away as the scope is in the final stages of build with lots of photos to put on a thread.

The mirror is under wraps for now but I'm looking forward to the day it gets placed in the cell to finally View the heavens.

Hopefully your 20" is getting there and with the help on here I'm pretty sure you'll complete the challenge. Will enjoy reading your updates.

Damian

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My heartiest congratulations Damian, on the completion of your mirror.

You must be relived to reach the end of the journey at last.

I'm pleased you decided to buy a flat for it, I think you have done enough battling with the 22".

It's of no detriment buying the Secondary, making one may have been in your mind, but flats are not

an easy task either, there is flat, and then there is flat, not easy to make at all.

I think the telescopes first light will be the moment all the hard work you have devoted to this project will

overwhelm your emotions, when those distant photons hit your retina, and flood your mind

with extreme satisfaction. Almost as good as you know what, perhaps better even.

We have accompanied you most of the way on this labour of love, and we all very much look 

to the report of the christening of this instrument, and the writing of the final page.

Well done young man, you are a credit to yourself, and this forum.

:icon_salut: :icon_salut: :icon_salut: .

Ron. 

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