The 22" mapstar mirror

[mapstar]

Try some W strokes Damien, traversing across the mirror, but staying within an inch or so from the edge, but varying it slightly. Keep rotating the 6" tool anticlockwise if you walk clockwise around your table.

Take it slowly with these strokes, and just take care with the amplitude. Concentrate the stroke frequency in the central regions of the mirror, but don't dwell too long there, keep the tool moving.

Do this for a few whets, then study any progress being made.

Your aim is to reduce that raised centre without digging a hole.

Good luck buddy, I hope this helps you, I really do.

Ron.

Cheers Ron

I have tried the w type stroke across the hill and quite a few other strokes.

It is probably a case of digging in for the long haul in what will take a while to shift especially when the edge work took so long

Damian

[mapstar]

Can't wait for first light, it's going to be a stunner. Been looking over your shoulder every step of the way. Legend,

Old Nick.

Cheers Nick. We will have to make it another event for looksies after the demise of the P.S.P and I hope to be then putting together some legendary observing reports like yours

[mapstar]

You've gone from a Trebor mint to a polo mint! Keep banging in there buddy remember slowly slowly catchy monkey!

Hope it hasn't developed into a polo mint as I've gone too far 

[Physopto]

Hi Derek

I normally leave the mirror about half an hour at this stage as I have that much materiality remove it doesn't make much difference.

In the later figuring stage (which still seems a long way off!) It will be a case of leaving it a lot longer possibly over night.

I don't have real a means of temperature control in my test area (the lounge) but keep the heating off as thermals distort the images

Hi Damian,

Pity you don't have a walk in fridge then. It would make the final figuring closer to the temp you will be using it at. .

Sorry just had to.........

Derek

[mapstar]

I managed an hour today and now with work calling I shall have to post an update tomorrow 

[Soupy]

Yes less of the polos! it's a dob your making not a

[JRM]

Hi Derek

I normally leave the mirror about half an hour at this stage as I have that much materiality remove it doesn't make much difference.

In the later figuring stage (which still seems a long way off!) It will be a case of leaving it a lot longer possibly over night.

I don't have real a means of temperature control in my test area (the lounge) but keep the heating off as thermals distort the images

Hi Damian,

 Normal wait time for cool down to test with plate glass is around 4-5 hours, 8 for pyrex.

be careful my friend, if you test to early you may grind a hole before you know the hill is gone,

even after a 15 minute session I leave mine on the test stand for 8 hours just to be sure the 

glass has reach thermal equilibrium, I once checked it every so often just to see the changes

and believe me you will be surprise just how much it will change.

best to give it a look the next day before you start,

just my 2 cents, hope it helps.

Rick M

[RAC]

I figured my 18" plate glass mirror with no more than 30min between figuring and testing, most of the time it was closer to 10-15min or a cup of coffee. At this stage there will be no chance of over shooting because of a temp change if you were to give it 15min.

[Vicky050373]

Can't believe how far things have moved along since I last took a look at your thread a couple of weeks ago. Again, a fascinating read whist I have my morning cuppa! You've got some fantastic support from others sharing their experience, and everyone is behind you. Keep plugging at it buddy, it's going to be amazing

[mapstar]

As is usually the case in this thread the opinions are divided and very varied. I appreciate the varied views as it shows what can work.

I had discussed this with John a while ago and he said in the initial stages which aren't as critical then half an hour should be alright. When on with the figuring then much more is needed obviously depending on the size of the mirror.

Today I have a couple more hours planned if I manage it. I will add an update to the saga later on.

Damian

[mapstar]

Can't believe how far things have moved along since I last took a look at your thread a couple of weeks ago. Again, a fascinating read whist I have my morning cuppa! You've got some fantastic support from others sharing their experience, and everyone is behind you. Keep plugging at it buddy, it's going to be amazing

Thanks Vicky and I just don't know what I'll do with my time once this is finished? Oh yeah build the scope to put it in

[Astrobits]

Surely, once the primary is finished you will start on the flat?

Nigel

[Demon Barber]

Damian,do`nt forget you can also LOOK   through your creation.

Regards

Mike

[Soupy]

Damian,do`nt forget you can also LOOK   through your creation.

Regards

Mike

He won't be able to Mike he'll be at the back of the queue behind all of us vying for a gander!

[mapstar]

Surely, once the primary is finished you will start on the flat?

Nigel

I have to finish the primary first!

Joking aside making a flat is a whole different ball game so John tells me. I assume you have made one before Nigel I know the basic process to make one but that's about as far as my limited knowledge on the subject goes.

I think I won't disappoint anyone by saying I will bow out of that task gracefully and have someone with much more experience make it for me in a much shorter space of time.

I would like you to post about it if you have.

Damian

[mapstar]

Damian,do`nt forget you can also LOOK through your creation.

Regards

Mike

Oh yeah if I can get to the front of the que!

[Demon Barber]

Damian,that can be arranged,greaes and palm, spring to mind  ,

Regards

Mike

[Astrobits]

You're right, I have made flats ( but not for many years ). If I get round to making another one I might post about it.

Nigel

[Physopto]

Aye Damian,

Give the flat blank to Mike.

Mike will probably bring it to me and he'll hold it while I use the grinder. Got a really good diamond plate to finish it off with and a bit Brasso.

"Simples" as the Meerkat would say!

[mapstar]

Aye Damian,

Give the flat blank to Mike.

Mike will probably bring it to me and he'll hold it while I use the grinder. Got a really good diamond plate to finish it off with and a bit Brasso.

"Simples" as the Meerkat would say!

I'd better make a good job of this mirror then to follow such finesse.

[Soupy]

You're already making a good job of it Damian, but it seems you are missing the vital ingredient...Brasso!

Can't believe John didn't tell you you needed this

[mapstar]

Hi all,

I have over the last few days done quite a bit more work on the mirror centre but things are not really working the way I want them to. As the days go on the images seem to be getting more confusing to read. With the amount of edge work then the centre should have had a huge hill so was going to take a lot of work to rectify and I have done quite a bit already.

I have a trip loosely planned to see John this week so the mirror is on hold until he takes a look at it and gives me his expert opinion 

Damian

[estwing]

Very wise mate... No better man to see...

[faulksy]

hi damian, after all the work you have done and time spent and got it so close, would it cost much for john to finish it off for you, overwise you could go to far and have to junk your blank. im realy not knocking you mate you realy have tried your best and most people woulld of given up by now. you should of become a doctor, you have loads of patience

mike

[mapstar]

Very wise mate... No better man to see...

Agreed Calvin a true wizard in mirror terms