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Hi guys,I went to look around the site http://www.mdpub.com/scopeworks/blanks/index.html
and I found it very interesting how this gentleman and’ He managed to melt the glass plates with good results .
I would like to know whether there’ someone who has experience(and maybe he describes the) in this sense, and what results has ottenuto.La What intrigues me a bit.maurizio
hello Maurizio, waiting for answers I moved the discussion in “blackboard”, Now I read the article, looks interesting…
hello Maurizio, unfortunately I have no experience with this, and so I can not be very useful.
But I also found this link, which I think is the same author (the dishwasher is the same), which tries to achieve the alveolar mirrors.
here is the link:
http://www.mdpub.com/scopeworks/hexagons/index.htmlhello Maurizio,
I in 2010 I did some tests with the help of a friend who has the oven very similar to the article you mentioned. We have done something with pyrex made from old insulators for power stations. I must say that the result was satisfactory but then we did nothing because, sincerely, the work behind this thing is not trivial and certainly it takes considerable experience.hello Mirco,I had already also seen that type of merger ,but here we go on even more complicated(in my opinion), I'd be happy to know how to do more mergers simple but good quality.
A future project (I'm thinking about for a while’ I do not know if and’ achievable) e’ autocostruirmi to an oven(if costs are acceptable)and try to do some prova.Vedremo…hello astrotecnico,
as you say not’ all easy,one thing and’ certain that if one tries is expected to account
that the first attempts will help you with experience.wow astrotecnico
! Certainly the power stations insulators are not exactly the brico 
I did not know they were made of borosilicate, then I believe that with this type of glass becomes even more difficult due to the higher melting temperatures .
About glassy processing “unconventional”, if you can let us know how it goes or if you complete the RC 1 METRO
you were working , maybe a small photo ( scale 1:1 
)Maurizio you're right ! this is the right spirit dell'autocostruttore, if you do it will be a good challenge, to follow…
In the last 70 years I designed and built a muffle furnace to bake the ceramic according to fire, ie with temperatures around 800 -1000° C.
At that time my wife dabbled in painting on those media, and me, as a good curious / electronic / electro / mechanic I enjoyed the usual way ... DIY.I had a baked a rectangular boccatura from 300x200mm but opened onto its side. The isolation was rockwool, because they had not yet found the best performing white ceramic fiber panels (like the inside of the oven of the links you've posted).
In my own and was using a thermocouple chromel-alumel.
And the resistances wrapped in nickel-chromium wire 80-20 Ø1.6 (I think ... but I still have in the garage and I could measure).
Their design required an interesting focus, because they were proportional to the current density which makes them hot but do not have red-hot that the maximum temperature of the oven, because their temperature added to the ambient temperature which is gradually increasing, It does not reach the 1400 anniversary of their merger.It 'been a good exercise, and I remember that I also made ashtray facemdo sag of the glass sheets on the refractory disks Plibrico. But with no glass hi did nothing more.
I think the number one enemy of the mergers non-vacuum (as always in all fields) are the inclusions of air bubbles trapped in the mass myeloma, that tend to rise very slowly. So it would agree to use as the optical surface facing the bottom of the oven.
Others say I do not know, except that I, constructive to the light of experience of the oven, when I was infected by the syndrome Dobson, I evaluated the merger topic, which in my eyes it was a complication of the disease. Luckily, from that complications are almost immediately went out of danger.
The insulators have them taken by a local material recovery, shredded and then placed in the oven. My friend often melts the glass for artistic purposes, although not in the thickness serving us, so it's still a good experience about. After a few tests we were able to get two blank: one from 21 and one from 31 centimeters thick 40 millimeters approximately. One of the problems is that the bubbles, very common with Pyrex. However, we noticed that they tend to form near a side of the blank. The biggest problem is now the cooling curve that must be carefully studied and proven. There are still several tests to do. If my friend helps me yet, possibly retrying.
The blank from a meter is during polishing. But now I had to temporarily suspend work in order to prepare a more suitable environment in which to do it. I currently too little space, which it is also critical for optical tests. To move it you need a davit
I'm trying to do. It weighs more than 100 Kg, then move it by hand alone is unthinkable, also for the risk of any falls. To put it on the machine I had to get help from other 3 people. When do I take a few photoswhat a show… I can not imagine the feeling of working ( with the certainty of knowing how to do ) a blank from a meter of an RC ( surely with a hyperbolic F <3 !!! )
In fact it is definitely exciting, for me that I have a lot of glass grated, get your hands on a blank from 1 metro ! In any case there are difficulties, all right ! The focal length of the primary is not so much thrust as the thickness is just 57 millimeters, then a super thin. Is’ almost a meniscus. To be able to work properly I had to make a machining cell that presents similar points of support to those who will then be used in the real cell. Glass is a Pyrex 7740 Corning Glass, now no longer in production. The conic constant of the secondary is marked but not impossible. The biggest hurdle will be at the time of obtaining the correct form, which as is known is a hyperbola.
Impressive ! especially compared with the tiles ( 20 cm ?) on the floor
Astrotecnico, then you will do even secondary or finalize “solo” primary ? Obviously I have to do even the secondary, which in practice, with our modest equipment, It is done ” on the primary” . Fortunately, it is not the first time that I do an R / C, although not of this diameter. The processing is not very dissimilar to a Cassegrain. You know the formulina spherical aberration which is on Texerau ? The whole trick is to use that well ………
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