Forum Replies Created
-
Posts
-
hello Frank
I am pleased that you did a beautiful job of fine mechanics in the service of a Dobsonian “any land” I would say with robust military.The advantage of having a lathe and know how to use may be seen in the details of your work.
Really congratulations.
Question: How have you found with the use of the Turbo Cad XT5?
I make it hard having worked since the early 80s in the factory with various Autocad, Now the XT5 free sando they are instinctive controls who might have the same syntax, but different procedures. And the trouble is that not using it every day, for each shot I take me time to re-acclimate…..Cause even advancing age and has already arrived to overcome 70P.S. The deserts are my passion. What desert locations (or which areas), are seen in the background of your images certainly not Italian?
On the Roddier my knowledge is only theoretical, and I believe that its possible use parallel to other tests underway “scratching” can be a great thing. In fact, the cross-use of multiple complementary tests is a source of security not otherwise obtainable.
Hi guys,—– I have dedicated this last period to review all the processing phases and the grattavetro has played the lion's share!
My goal is to produce diameters between 30 and 50cm with focal lengths from f4 to f5 knowing all the difficulties of the case ,I gave myself a time of 2 years even if the way I think and that I have always had is "never finished learning"
The thought I have right now is the control system , the person I know uses the focault with its coudè mask, however, I felt that the null test is more immediate and more precise .
I have already requested to equip myself with a flat mirror to use the control system in autocollimation .
Tell me what you think
He believed I will learn a lot here
Thank you
MarcoHi Marco and welcome also from me.
As for my knowledge as a non-professional scratcher, albeit supported by passion and study of foreign stuff for my own business (given the absence of Italian books also due to the scarcity of interested parties that the subject encounters in Italy) I am sure that the autocollimation control method is the one that is the most popular at a professional level, and well suited to the range of diameters and focal lengths you have in mind.Method that I know so alone “academic” , having never applied it due to the prohibitive expense to equip themselves with a lambda / 16 flat mirror with a diameter at least equal to the maximum diameter that you want to produce. Expenditure that includes a test case, and it is justifiable if its amortization is foreseen to be spread on a certain number of mirrors to be put up for sale.
(the flatness a 1/16 of lambda is necessary for those who plan to work mirrors with focal ratios not lower than F4, since the focal ratio is part of the formula that determines the tolerance of the autocollimated measurement).
Americans like Parker say the sensitivity of the method is excellent while using it “poor” Ronchi lattices from 5 lines millimeter, than we Italians used to 10 lines, they are at least strange.
The Foucault test in my opinion (that I am a staunch supporter of it) despite its intrinsic objectivity (given by having to judge by eye whether two shadows are of equal intensity) it is invaluable help, and it is the only test “quantity”, that is, it allows to know “how many nanometers” glass I have to remove, or I have exaggerated to remove, and it would be advisable if you want to achieve a certain quality.
I also understand that craftsmen dodge it because now they are done “the Eye” to corrections with Ronchi…But it is useless for them to go around telling stories, because no one is able to judge nanometers by eye, who are the ones that Foucault tells you (albeit subjectively), and they are also the ones who make the lambdas / two digits.Which Ronchi or autocollimation do not say, providing only an image of the location of any defect, which with its curves suggests the quality of the optics, but that does not help with numbers to understand how deep it is and how consequently the scratching actions suitable to correct it must be long over time.
While the Roddier test cannot be used when making the mirror, because it is applicable only to the finished optics and does not allow you to see what happens on the parabolic profile of the surface being processed.
All new commitments represent new ones “go up” which are a little more tiring at first, but the trick to succeed is not to make simplifying inventions right away, but trust the techniques in use, only learned well which are certainly carried out excellent customizations.
…Lots of chatter, but I hope you will find yourself well here.
Ciao
GiulioHello Charles and welcome from my.
With all those ladies readings, parts definitely “vaccinated” and benefited
Careful Louis that a marble plaque, or any other material having a crystalline structure, It would present a non-uniform surface hardness, and workmanship, the hardest veins that are found in all natural materials, cause of “ribs” relief, that make it difficult to achieve the precision of abrasion 68,75 millionths of a millimeter (nanometers high.), which characterizes the minimum quality of a so-called mirror lambda / 4.
The metals have a less varied texture of materials narurali. They are more pure marble, and in fact they have been used before 1858, when Foucault showed that the parabolic mirrors could be manufactured in glass, in the manner that still today we adopt amateur homebuilders.
The fact glass is the only amorphous material useful, ie devoid of crystal structure so as to be considered a liquid with infinite viscosity at room temperature. When not hardened, but it is annealed, It is uniform in its volume, and this is the premise that guarantees the possibility, with a good workmanship, to obtain the best optical quality.
In regard to the degree of gloss that is necessary to reach in the processing, You can also read just the short sentence “practical” by title “SHORT NOTES ON THE DEGREE OF TRANSPARENCY REQUIRED FOR OPTICAL MIRRORS”, in the article at the following link
The only affordable cost is the purchase of two discs up to 300mm in diameter, in normal glass (calcium-soda) 19mm thickness, at industrial glassworks, namely those that provide glasses for walkable floors and other uses in the building industry.
The last two records I paid them 100 totaling EUR, cut and crimped on 4 circumferential edges, leaving the remaining edge of rough cut.Interesting. Thank you!!
The problem, however,, at least the time of purchase of the blank of my 250, It was that calciosodici tool were provided only for the purchase of a blank.
Hi Alessandro. Welcome.
We'll try to help you certainly, as part of our knowledge no professional punctual…ma “quasi”.
If you want to, Meanwhile, can you tell us something about your RC “reanimate”.
The new problems are always challenging for teamwork !
Hi Stefano.
I am also on holiday without computers. Looking at the CAD design are parties can immediately find out if I was wrong to attach a dimension line.
I think it is easier that the error is mine, crafts, compared to the professional response of Atmos.Uno zoom 8-24 It is a good choice because it will be useful in a future when you have maybe a telescope 250F5 suitcase travel.
The focuser nice but too expensive.
Because crayford are simple, robust, and a life on the market, I think there will be much of differenza..se technology is not the production costs of living produttori..quindi countries GSO crayford low profile in China costs about 160 euro.
My top is a 90mm Intes Crayfotd (russo) of 2″ and flat base, that in 2002 Pagai 125 euro.
Today there are many brands, Also the low profile high half of my. with demoltiplica 1:10 (that it did not, and of which I have never felt the need).The run of mine is 40mm, and with the trellis cut to bring into focus the eyepiece which requires the insertion of the most fok, They are going to focus even more eye of different brands 10vecchi, including the three I always use, which are from Explore Scientific 14, from 8,8 e 4,7mm e 82 degrees, and which they are mutually parfocal (that is, change them without the need to refocus)., More 2 Former curious microscope, with grid, requiring a longer barrel to stay behind.
The board on the eye and then take the series and sressa Parfocal.
The other helical focusers (stepwise advancement screw 3 two or three principles, for advancement 6 or 9mm lap), weight of 31,7mm 40 grams, I did turning on my design from solid black nylon, for small telescopes travel, have 40mm stroke.
Bear in mind, however, that I am not a
expert…esolo but a curious fact that few times “roads” of which describe the transit impressions.
For which I am one that normally is technically outclassed by those who have accompanied for those brief initial stretches of road that I know, because already trails. And this is the thing I like best.
