Physopto

Thanks Mike,

Friends Huh?

And thanks Damian. I tried opening two instances of I.E. Side by side, earlier on today, didn't help much. Ah wus still puzzled. Maybe it's an age thing!

I'll try again when on the main computer. This iPad is rubbish.

Keep trucking.

Just remember Progress.......

Derek

Nope don't use that word,try progress!!!

Got to be honest Damian, I'm finding it difficult to see what the Progress is. Untrained eye ya know.

Hope you are right and Galloway is great Damian. Although I have to temper that as I'm going to Kielder first. I need the time to get some imaging in. S Shields where I live is diabolical for light pollution. I really am jealous of all the lads and lasses with darker skies and especially with observatories. Working towards it when I move, but Hey Ho.

Looked at quickly it does not seam a lot 2 to 1 micron but I suppose 100 % bigger., wow!

Whiskey maybe and of course our scintillating whit.............Ok then, just the whiskey!

Mike and I are still trying to fathom out what we are going to charge for entry tickets to the big event. Pie and peas  cost money you know!

Derek

Damian,

There is no rush to answer this, I know you are somewhat pushed for time. I'm just filling in mine waiting for gear to arrive for imaging. I'm in the middle of thought experiments. At times very boring others my brain hurts.

Just how much are you trying to remove, maybe a difficult question I know. It is a question possibly answered in time or microns. From the bit of the process that I have watched and seen on other videos, it seems that as mirror makers you try for a slice of a circle first then change this into a parabola by using a different stroke type. ( if all goes well). As everything I have seem so far suggests, it is more of an art with careful thought than an scientific exercise. I know that the bit removed will be small but by what amount? You told me that the solution you use is made up from the powder you buy. You also mentioned the grade was not as fine, sorry wrong wording there, but cheaper than that used by another mirror  maker. Would it make sense  in the last bit to use the finer cerium for the very last few laps, thus saving money?

Can't help wondering. Goodness........ so many questions!

Just keep going got to finish before Galloway you know........

Derek

Hi Damian,

In that video of John Dobson he talked about the sound changing to squeaking when it became time to replenish the cerium polishing solution. I noticed he just spread a bit cerium by spoon on the surface and wet it. Then used his finger to spread it about. From what you have said you make a solution. So I guess you think that is better. Is it because of consistency of mix?

Derek

Yes Derek behave or you'll be sentenced to 18 months mirror making!

What? You mean I can exchange the Dog House for a life of Chip and Grind?

Ohh the fun! Could it get any better?

Gents, I know it's just a bit of banter but let's keep it on track and family friendly [emoji2]

Cheers

Stu

My fault, as you say banter, just trying to keep spirits up. 

A day or so ago I detailed the lack of response to my emails over the last 12 days from Optec in the USA.

I thought it only fair to add an update to the saga.

Today after still no reply to my third email, I decided to telephone them. I used Skype as it is the cheapest method and after some preliminary hick ups with a none functioning microphone on the headset, I got through to Tina, the wife of Jeff Dickerman ( owner and CEO). She was very pleasant and was at a loss as to why my emails had not been acknowledged. Jeff was  on other business at that time, but she assured me she would pass on the message to him as soon as possible. We also exchanged blank  emails to ensure the system was working.

Sure enough a short while later I received a very nice email from Jeff answering my original email. He apologised for the delay and then went on to suggest ways to accomplish what I wanted. Over the day we have exchanged several emails until it would seem we have a solution. I have now received the formal quotation and accepted it. It now depends upon if VISA do what they often do and decline the order stating that it may be a fraudulent attempt on my account. (This happens about 3-5 times a year). Once past that hurdle I am assured that the items should be with me in the next week or so. Time will tell.

If all goes well I will post a note here. The way it has been handled today suggests it has been a glitch in the system, I hope so, as they have been very helpful and pleasant to deal with.

Derek

Yup, we all guessed it, actually wrong words we KNOW IT

The silicone is going off so it's looking good but the rubber smell is not exactly the best thing in the world! 

Well now we know you aren't into S&M.

I'd thought of something similar Derek with the bonding although it was going to be silicone as I had it in stock  drilling the flag again to allow the slurry drainage was another thought (great minds and all that). Plastic would be better as metal anywhere near the glass at this stage fills me with dread. Upvc with a stanley is probably an option and I've just remembered I've got some square drain pipe somewhere 

Use an angle grinder with a stone disc. Being one or two fingers short might inhibit your grinding technique a bit.  Seeing a red moon is one thing but just stained .... well not quite the same is it?

 On a serious point though, upvc  does not bond very well with anything. Not silicon or Soudal.  That is why I suggested Aluminium with a rubber edge cover. You know the type fitted over car door edges to hide the metal to the interior. It fits over the edge well and is not damaged by a knife or a knock. You could also bond that on. I use Metal Supermarkets for my supplier for aluminium. You can get 2" wide by 4 mm thick in lengths.

 Derek

Over the last 10 days or so I have been waiting for a response to two emails sent to Optec Inc in America. The first was sent to Mr Jeff Dickerman on the 21/3/2015 asking for information on adapters for the 3" Pyxis Rotator and the rotator itself. I explained that I was interested in purchasing the rotator for my setup. I explained exactly where in the optical train I wanted to place it and the reasons for that decision. There was no reply at all. I sent a second email to the same firm two days ago with the same result. Tonight 1/4/2015 I have sent a third email, this time stating that I have not received an answer to my queries.

If a firm wants business from us why do they not respond. The item concerned is not cheap it retails at $1950 plus each adapter is in the order of $95, ( I need two). Then there is about a charge of $80-100 for postage and on top of all that UK import Tax of 4.2%. Next the dreaded VAT is placed on at 20%. To cap it all the delivery company here in the UK will charge us anything from about £15 to £40, for the privilege of releasing it to us as they fill in a form and pay the import tax etc., on our behalf to the relevant department. ( there is no other way to import an item unless you are a bona fidi importer).

No Astronomy Shop  advertises these actual items here in the UK.

One or two actually advertise the smaller types, but at vastly inflated rates compared to the actual prices in the USA.

 Derek

Hi Damian,

You could try bonding some plastic sheet around the edge of the flag, raised edge 1/2". Then drill a hole or two through the flag to let the slurry out though a bonded in pipe (15 mm copper or plastic). just put a bucket underneath to catch it all. I use Soudal Fixall bonding for loads of things, it is very strong and slightly flexible. Most importantly unlike silicon you can just cut it off and re-bond on top again if necessary. Can't do that with silicon.

Can't use polythene as it won't bond may get away with upvc as used in flat type guttering and it's cheap, just cut with a grinder. Better still some aluminium strip. Stronger and you could fit a rubber edge over the upright edge for safety. It would last a lot longer.

Derek

Rough ain't quite the word I would have used  but fun to watch!

Hi again Damian,

Well if you haven't see it go look it is a real eye opener.

Telescope Building with John Dobson (1:28:30)  in SGL.

You were annoyed at a small chip on the edge of your mirror, well NUTS is all I can say!

He proves you don't even need a sledge hammer.  Forget all this rubbish about Ronchi and Foucault tests. Ordinary tap water will do. Mind you, you will probably need to move to America for the sun shine to do it.  Hummmm maybe not such a daft idea!

Regards,

Derek

Ay a gin and tonic,

Well maybe more than one. Looking good Damian.

How long does the pressing take and what temperature do you warm the lap to? Guess work? Or specific temp?

Derek

Well!!!

I aint going to put myself in the position of any comment on a ladies weight  I value my life too much! I learned the hard way, married and poor you know.

Derek

Aye,

You have put yersell unda da spotlight a bit haven't you.

Glad it's no me

Gina,

 Just out of interest, have you tested the printed parts for strength in any way. I'm afraid I look at them with some suspicion. The printed parts are usually well fused in the x-y plane but because of the necessary time taken to return to the same position in the next layer the fusion strength is not the same. I.e. the bond strength is less in the z axis. Over a period of time the strength may deteriorate and basically the layers could possibly split apart. The cold weather may also hasten the process! The material could be very brittle in our climes especially at low temperatures when being subjected to shear stresses.

It would be a great shame as the amount of effort you are putting is something to behold.

I speak as an ex engineer.

Regards,

Derek

Mike shame on you!

Corruption tut tut.

Whiskey is the Water of Life!

Well now there's a thought!

Been at a loss for something to annoy the wife for a while. Maybe a mirror on the newly finished dinning room oak floor. Better still in the middle of the living room. That should put a stop to Coroation Street.

I'm sure she would be right behind me on that. Probably with an iron poker!

Once I start, all ...you know what I mean.., breaks loose.

Last good idea ( instigated by wife, hasten to add) to keep me occupied was astronomy, now several shekels poorer.

Me, very happy, wife Err well.

Derek

Hi Damian,

You may think me nuts but here goes, please don't shoot me for this. Your pictures are great showing the mirror. Also the Ronchi test results are very interesting to see.

But !!!

How about a short video of you actually figuring/grinding the mirror. It is not for me, although that would be informative. It is just a thought that as you seem to be getting a bit disheartened or fed up with things not panning out. Maybe John could see a possible problem with the method you are using, I.e. Stroke shape. As I say don't shoot me, it took me some time to understand what a "W" stroke was. It is just a possibility as time has passed, that you have slipped into a slight methodical error. (if that is the correct word). I have done the same in other endeavours in the past without realising it. It may, may just save you pulling out some hair.

I'm receding so I wouldn't want that for me

Derek

I have done about another 2 hours during the day, I think I may have a beer now as I think I deserve one 

I would vote for a good malt, it's the Scottish side of me I guess.

Well hi all,

Thanks for you input.

 Just spent a productive half hour or so on this website.

http://www.atm-workshop.com/ronchi-test.html

Very informative. So now I understand what you are doing a bit better. It is a test based on reflected light/shadows through  a grating from a pinhole or a grating parallel to the one being viewed through. Nice idea. The Foucault test is a bit different. Not sure as yet what the knife edge does. I'll figure it out.

I did see the effects of diffraction ( producing a double image in the Ronchi test). My original optical and atomic physics was more to do with lasers, so this is all new to me. It's nice to learn something new. What a really great hobby this is!   

Derek