mapstar

I'm sure you would've heard about them before if I had.I did manage another 2 hours today just working the centre but it's going to take a while yet till it starts to reduce

Afternoon all I managed a couple of foucault type images which gives an indication of the hill I am dealing with just for interest. I have tried to put it together with a couple of Ronchi images to show how the lines bend according to the actual visual. Easiest way I can describe the foucault image for those that aren't familiar is like shining a light from the left across the mirror surface which picks up the front slope and casts into shadow the rear slope of any height changes. Ronchi inside Ronchi outside It's a fair old lump but after the edge work it is going to take a while to work and then blend. I obviously didn't clean the mirror up well as my finger prints are all over it showing just how sensitive a test it is Damian

It does rather, and cheers guys.Like a few of the other scopes (swamp things, SimonfromSussex) above, the build thread is still about (Mapstar scope build) and the pic with me puts it into perspective. Quite funny Hope to get the next build thread on later Damian

It's locked up in a garage somewhere in Huddersfield although I think the owner is having it motorisedI look forward to seeing it again probably at Kelling heath later this year where hopefully it will share the skies with its smaller sibling (if I ever get this mirror finished!)

I've no pics of the next build but here's a couple of the 24" from last time Next one will be appearing in autumn and be very similar just 22" Damian

Hi all I managed four half an hour sessions working just on the centre with a slight change evident. I have some more work planned today so hopefully I'll get a meaningful update on soon. I have recut the channels in the lap and also gave it as good a clean as possible. Also been in touch with John and I'm going to have another trip up to see him for his experienced eye to give it the once over. Damian

Some nice scopes there guys, hopefully I'll add my very own soon Damian

Cheers for the replies and encouragement guys. Hopefully I'll get the centre sorted this week but as I did that much edge work it will take a lot of time to get back. I also Must try to get my foucault test rig sorted so I can get some images of that. Another trip to see John soon too so he can take a good look on his own test gear. Damian

Hi Guys, Been a while since an update so your all probably wondering where I've got to. I'm still here pushing glass molecules about and at present I am trying to get rid of the hill I made in the middle whilst working on the edge. Here's a few Ronchigrams of the mirror how it stands working from inside centre of curvature to the outside. Not sure why but my camera just didn't want to play ball today so the images are a bit blurry. The inside show the middle bands curving in and the last few outside show the bands curving out indicating a central hill. The images I took previous to this session did look better but the mirror had cooled overnight. I have been working through the centre with minimal overhang but now I've moved to just working in the centre to bring the hill down. Hard to tell whether the turned edge is still there but I suspect I will end up going back to it once I've sorted the middle out although it may help the edge with the varied central strokes I've also tried to capture a few Focault images but can't remember how I did it last time and they turned out very poor so I've not added them to the post. I will fingers crossed get some more time on it wednesday and will try my best to remove the central hill Damian

Hiya DerekI've been struggling this week for time on it and only managed 5hours of work on it last week. I have more work planned this aft so will update with the progress images later today for definite Damian

Hello RickNice to hear your well enough to continue and fingers crossed for you that the wrist doesn't give you any more trouble. I am getting closer although still working through the centre to get rid of the hill I have. It may help with the slight turned edge I suspect I still have which I may have to go back to. Will be good to see another update on your thread soon and I shall be posting one on mine sometime this week I just need to get some time on the glass again. Damian

Thanks Sam, it's a fair way off being finished but steadily getting there.It tests the best of patience and motivation as you have probably read. I have a way to go but will get there and agree first light will be something else especially in a scope built by me too

Cheers Calvin. Crash is still on with his and having his own battle of a different nature. I've not checked in with him for a couple of weeks now so I'll have to get in touch and see how he's getting on

Hi Ron, I'm still here battling away with the glass molecules this weekend after a week away last week. Things are progressing, although not at the pace I would like.It is a long Journey but good things do take time and an update will follow soon. Thanks for watching Damian

Thanks for the replies guys and the agreements in opinions as they are appreciated and valued. I've looked at both sides of image's and it is very difficult to see any turned edge inside the centre of curvature where as outside is different. Raymond is bang on with the correction being added to the outside as I work through the centre so make's it difficult to judge. And modest too after creating such a well crafted piece of glass so please keep up with the replies . John has said it is still there but through centre work could help it but I may end up alternating between edge and centre work. My main concern at present is the central hill which is still there I'm on holiday for a week at present so a bit of a break which will do me good. I'll get back to it when I return and thanks for looking at the image's Damian

Thanks guys

Still a turned edge and with a week's holiday from tomorrow It will now have to wait till I return for more and will be raring to continue Damian

Hi all, Well a busy couple of days have passed although I've not managed much on the mirror since the weekend when I did about 6 hours on it. I think I have now managed to get through at least a quarter of my music collection up to now although it's quite therapeutic so no big problem So onto the updated images and after a bit more edge work I went onto straight through the centre with little to no overhang. I've lined up a series of images so yet again everyone can see how the surface changes over time. The centre is a hill and get's smaller as the image's progress. Images left are inside the centre of curvature and the right outside the centre of curvature Moving through from approx 5mm inside centre of curvature to 20mm outside is quite interesting to see how the banding changes

Hi all I have spent the last couple of days with a little more edge work then 4 hours through the centre which has cleaned up quite a lot. TDE is still present so I will continue tomorrow with the centre through strokes to see how things progress. I'll up date with some images tomorrow after some more work Onwards and upwards Damian

No problem David. It didn't bother me to be fair, I try my best to encourage people to have a go at anything (some here don't have that same attitude though) I shall try to pick up your thread when you put it on the forum and read it with interest Damian

He he Excellent, best post so far Richard As the sketch says I certainly will tomorrow Damian

Thanks Guys I suppose the table comments just ran away tas I did ask out of interest if it was going to be powered. It's the 25 years in industry dealing with motors and drives from 0.25kw up to 4500kw that make's me curious I guess. Anyway back to the mirror making Damian

Nice short answer there Derek thank you proving there is more than one way to crack a nut and doesn't need a huge irrelevant explanation to get there.

Looks like someone has 25years of experience in the industry

Thanks for replying David It will be nice to see your progress on the table build and mirror so I hope you will be documenting it on here if not whilst your doing it then later when you've completed it. On the right RPM, fitting an inverter would give you infinitely variable speed control and you wouldn't need to be accurate with pulleys. Grinding the faces flat does take a while but I'm sure if I can do it anyone can. Damian