350 newt project

[FraserClarke]

Hi Paul,

Sorry to hear you had to go back to 600 -- probably the quickest route in the end though. The initial ronchi-grams look good. Agree with John about the slight turned edge and centre. The middle picture maybe shows a high zone between ~30-60%?? pretty tough to say though, and it certainly all looks good for an initial polish. No sign of any astigmatism, so your technique is working very well on that front

[paul11]

Hi Paul,

Sorry to hear you had to go back to 600 -- probably the quickest route in the end though. The initial ronchi-grams look good. Agree with John about the slight turned edge and centre. The middle picture maybe shows a high zone between ~30-60%?? pretty tough to say though, and it certainly all looks good for an initial polish. No sign of any astigmatism, so your technique is working very well on that front

Thanks for your comments and i'm glad you think my technique is working ok, i will shorten the stroke a bit and i hope the next ronchi-grams will look better.

[paul11]

Hi all I have gone back to the 600 and all looks very good, I started to polish again but it started to polish the middle of the mirror before the outside, so I am going to do a warm press indoors. The lap is warming up on the radiator, when it is warm through I will put the mirror and weights on it and leave it overnight. John I was leaving this in the workshop overnight and it was very cold out there so it may well be the reason for the scratches, I am thinking about setting up indoors to finish the mirror where I can control the temperature a lot better.

[paul11]

John, your comments are invaluable.

Paul - keep up the great work, and kudos for your determination. You'll get there in the end - as we meet more than enough challenges with our guitar building, eh?

Thanks for the encouragement Sam as soon as we iron out these small problems we can move forward and finish this mirror and then it’s your turn.

[Beulah]

and then it’s your turn.

:eek:

[Glasspusher]

Paul, I think you are making the right move going indoors, a very cold lap may well have been the cause of the problem. If you are not getting a uniform polish it is probably due to poor lap contact. Look through the back of the mirror when it is sitting on the lap, you will be able to see areas of good and poor contact. If you have poor contact warm the lap up in hot water and press, keep moving the mirror every so often so that it does not stick.

John

[paul11]

In the first image i am making the half size lap and in the 2nd image i have just finished figuring the mirror, who's turn is it now.

[weareborg]

Excellent work Paul. You must be proud of yourself. I was wondering what was happening to your project as we not had any updates from you all through April. I was beginning to think that something had gone drastically wrong.

Andy

[paul11]

Excellent work Paul. You must be proud of yourself. I was wondering what was happening to your project as we not had any updates from you all through April. I was beginning to think that something had gone drastically wrong.

Andy

I did have a problem with scratches appearing for no real reason. John suggested making a new lap and adding some linseed oil to soften the pitch and it worked. Using a 50% lap for the figuring also worked very well this is a must.

[FraserClarke]

Good job Paul

Any ronchi-grams of the finished mirror to show us??

[paul11]

These images are a couple of hours before it was finished.

[Beulah]

That's excellent, Paul!!!

Can't see anything wrong there....

[weareborg]

Those images look truly beautiful. You must be so proud of them. Well done. So. Whats next?????

[paul11]

Thanks for the comments on the Ronchi images,i will make the C/F tube next and then the mirror cell and when the cell is finished i will get the mirror silvered,,,,Paul.

[weareborg]

how many points are you making for your mirror cell Paul? When I actually get started on my project, I'll be making a 18 point flotation cell. I know you could probably use a 9 point cell, but I thinking because its only a 25mm thick mirror, a 18 point would be better.

Andy

[paul11]

how many points are you making for your mirror cell Paul? When I actually get started on my project, I'll be making a 18 point flotation cell. I know you could probably use a 9 point cell, but I thinking because its only a 25mm thick mirror, a 18 point would be better.

Andy

Yes I will be using an 18 point cell, as you say a 9 point will not give enough support to 25mm mirror.

[kev]

Ive been following this thread, can I just say that im impressed - very impressed with your work and the help that folk have given when needed. Hope you finish off and have a great scope. Im sure that we would all love to see the end result sometime.

[paul11]

Thanks for your kind comments Kev, the reason I have stopped working on this project is because I am having problems with the 200mm newt I made. The 200mm newt takes a great image but I can’t get perfectly round stars and as yet I can’t work out why. When I find the problem and fix it then I will finish the 14” and know it will work very well.

[paul11]

Ok guys I think it’s about time we finished this contract so over the next few weeks I’m going to go all out to do just that. Here is the cardboard tube that I will use to form the CF tube, I have filled all the gaps and over the next few days I will put on a few coats of release agent and 2 coats of polish and then the C/F.

[weareborg]

Hi Paul

I was wondering what was happening with your scope project. Glad to see it continuing. How come your using a solid tube rather than a truss design???? Is your mirror coated and ready to go in yet????

[psjshep]

Ok guys I think it’s about time we finished this contract so over the next few weeks I’m going to go all out to do just that. Here is the cardboard tube that I will use to form the CF tube, I have filled all the gaps and over the next few days I will put on a few coats of release agent and 2 coats of polish and then the C/F.

This looks strangely familiar.... good luck & I hope you do as good a job as you did for me...

Phil

[paul11]

Hi Paul

I was wondering what was happening with your scope project. Glad to see it continuing. How come your using a solid tube rather than a truss design???? Is your mirror coated and ready to go in yet????

The reason for the solid tube is because it's a newt and with tube rings i can mount it on a gem. The mirror will be going in for a coat of paint in a week or so.

[paul11]

This looks strangely familiar.... good luck & I hope you do as good a job as you did for me...

Phil

Thanks Phil, i can't stop thinking that this thing is a bit on the big side,,,Paul.

[psjshep]

that's a good thing isn't it hahaha...

Phil

[paul11]

A few more images, all the layers are on,3 more clear coats of E/P and then cut it back.