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Cow!…Only I am not able to take good pictures with that hell of a microscope!!
However Bravo Maurizio!
I see for example from the beautiful photo 130844, that the majority of the craters in that area are one hundredth of a mm in diameter, ( that means 10 microns, size on average equivalent to the grain 800 or 1000.
The Pit as big as a notch and a half (all alone “fat” in the midst of the anorexic population
, in fact it has a grain size of 500…but it is one in every thousands of other anorexics.
That line with the crater from 100 micron you don't take it off anymore. A scale has slipped in there “deaf”…but it is an accident which is not worth considering as a remedy.In conclusion, in your place I would easily pass to the pitch that will take away ALL the pit from you 10 microns, which are the "legal" majority.
The craters from a notch and a half, (30 microns will come “medicated” partially (but they will not heal completely.. because you will see them get smaller and their edges rounded, but they will not disappear)… While that from 100 micron will remain with you as a reminder of a job that I consider well done (why some "remember" like that is the norm for anyone).I would say yours is a good job
Thanks Giulio.
Sincerely,I was a little’ discouraged seeing the craters from 100 microns, but you pulled me back
with your words.For the photos I take them with a smartphone with a camera 13 megapixel
Hi guys,
I think I exaggerated with the past 1/4 COC and now I find myself in this condition (photo below) and comparing with Ronchi for Windows software 2.0 it seems a parable but inverted that is’ what I should find intrafocal I find myself extrafocal and vice versa.
I think I made the mistake of not doing the ronchi test several times during processing.
Now I have to go back to 1/3 COC to return to the sphere?
Or there are other solutions?http://s29.postimg.cc/jxvo864lj/intrafocale1.jpg
http://s10.postimg.cc/pzz64acqh/intrafocale.jpg
http://s7.postimg.cc/ha0xwivnv/intrafocale2.jpg
http://s12.postimg.cc/vb1mc4ial/extrafocale.jpghello Maurizio, as you rightly said, a mistake you made was precisely that of not having often checked the progress of the work with Ronchi. Obviously this will serve you with experience for the future, also because sometimes it happens to work incorrectly or with an unsuitable patina which can lead to important errors which can instead be avoided with more frequent checks. However, do not despair, the mistake is not that serious…You have to go back to racing 1/3 COC to bring everything back to the sphere…
A question: by chance your pitch utensil is slightly smaller than the diameter of the mirror?Maurizio you are very close to us , that raised edge is always better than a riveted e, as Mirco said, with 1/3 COC settles in no time.
Rather I still think the patina is a bit’ dura ( or that the ambient temperature is too low ) it also checks the fit , that there are no more contact areas on the patina than others. ( direct consequence of hardness )
The irregular edges of the lines of the ronchi, at this final polishing stage, they should be more linear.
To check the fit, check that the wear is uniform in all the squares of the patina, also seeing if the white color left by cerium is uniform and if they are to the touch “smooth” likewise.You can also try to put a retina between the patina and the mirror ( I use a piece of mosquito net ) and keep them under pressure, then see if the marks left by the mesh of the net ( which, moreover, will improve smoothness and friction by creating micro-channels ) are present throughout the surface.
I'm sure that by optimizing these aspects, an even better figure will come to Ronchi.
I probably have a bit hard pitch to give you an idea with the tool stopped for a few hours
I can barely leave the imprint of the nail.
You advise me to remake the softer candies?The main problem with pitch hardness is that it does not allow for optimal adaptation e, if to reach the sphere with a little’ commitment is still possible, in the parabolic phase the difficulties will be much greater.
Now, there are two ways:
– remake the tool with a mixture that has the lowest melting temperature,
– heat the environment or even the tool itself.if you work in a room that allows you to be heated and where the ambient temperature does not exceed 15 degrees, perhaps it is better to follow the second route and continue working with the same tool, dipping it before each work session, in a basin with hot water ( around 40-45 degrees ) just enough to soften the tool and then put it under pressure with the mirror for about fifteen minutes until adaptation is achieved.
I insist on this point because in my opinion the higher trend you see on Ronchi, it does not depend so much on having performed too many passes 1/4 COC, but from a central area of the tool with poor adhesion e, more generally, from a patina that does not work in optimal conditions and generates those irregularities ( micro-roughness ).
Eye because if so, the past 1/3 COC will not regularize the sphere but it is likely that it will maintain the same upward trend on the figure, even to accentuate it.
Maurizio, Massimo's analysis is flawless and I say this because at this moment I find myself in a situation very similar to yours.
After trying, with dubious results, to do some machining, I decided to fix the shape by working by hand with a full diameter tool.
As it happened to you, I did it a little too hard (so much so that even the imprint of the nail was barely visible to me), but I decided to try to work anyway to see what happens if you work in these conditions. The result is that the form does not want to get close to the sphere and in addition, a roughness is created that makes the lines of the Ronchi jagged.. In addition, I think that a good adaptation can be obtained by pressing together the patina and mirror, but an excellent adaptation is obtained only afterwards 10-15 min of work, during which the pitch has the opportunity to spread itself perfectly on the mirror. But this probably didn't happen as the patina was too hard, and this may explain the fact that the shape was not fitting even though I was working with racing 1/3 COC…so yesterday I remade the tool making a softer patina (keep in mind that the environment in which I work cannot be heated and in this period of the year I have to be content with working at a temperature between 11-13 °C). The improvements are remarkable, it just feels like there is a greater friction between patina and glass and at the same time a better fluidity in movement.
The signs of roughness have disappeared in a few dry and the shape is setting in place quickly… I, with skepticity comforted by the readings, and even with the beginner's luck I had not used the two kilos of rosin given to me with the purchase of the Blank, buying a kg of Gugolz black pitch in France #55. And with its well-defined softening temperature around 50 ° C, I had the good fortune not to encounter any problems with the various tools and processes done so far.
In the light of your experiences I therefore believe that to newbies who will read, and that do not have large-scale experimentation as a priority, but the making of their mirror, it is worth buying a kilo of graduated black pitch, to reduce the problems that are already in large numbers on that road.
I work in the heated environment around 19 – 20 degrees and therefore even if I do’ a hole in the water I want to try again with the same tool trying to make the adaptation as advised by all of you,then if things don't change I'll make the softest candies again, because my goal is’ also gain experience even if this will lengthen my time(I'm not in a hurry).
However, your advice is always very useful and I thank you.I don't think you'll make a hole in the water, you are working well, unfortunately, rosin / beeswax / linseed oil / turpentine is subject to so many variables that it even takes a little’ luck to achieve the optimal patina which, in another period of the year or in a different environment it would no longer be optimal.
The positive side is that the field experimentation of the various blends / patinas highlights and leads to understanding many aspects and problems related to the processing that would otherwise escape and would be attributed to something else., because a hard patina or obtained by bad fusion or even badly adapted leads to:
– zonal errors (which are often attributed to an incorrect technique / pressure )
– rugosity
– micro-lines on the glass ( well yes, this also, was to prove it
)
– detachment of flakes from the glass edge.
– partial polishing
– variable friction-smoothnessthe simultaneous and unrecognized presence of the causes of some of these aspects leads to obtaining different results from those expected from the mere application of the techniques ( of which we know life, death and miracles ) and you find yourself disoriented with a great confusion about what to do.
for those who are more pragmatic and not interested in complicating their lives more than necessary (not my case, I love to complicate my life
) I cannot help but subscribe to Giulio's wise advice, aiming directly at a quality product designed and created precisely to solve these problems at the origin.Well I must say that it went really well for me, in the sense that, as I said, I bought a kg of excellent black pitch #55, and I haven't finished that quantity yet.
IF we add that the pitch used is totally recyclable, not having even demolished the tools used yet, I will have enough for the future of my works.
But I too usually complicate my life in order to achieve my primary goals.
Hello guys, for a few weeks I couldn't work the mirror due to family commitments but today
I've been on it for circe 4 hours and something e’ changed(I'm getting closer to the sphere) but I still can't understand why I have these irregular Ronchi bands, yet I made the tar candies again (now they are softer), the temperature always around 20 degrees. When I take the photos I have some light in my opinion a little strong I tried to narrow the gap between the blades ,but nothing.
I don't know where this is going.
I show you some photos all intrafocal
http://s14.postimg.cc/kefk1pu69/IMG_20150321_100211.jpg
http://s21.postimg.cc/i7llo18lj/IMG_20150321_102336.jpg
http://s15.postimg.cc/5g9ygazff/IMG_20150321_104005.jpg
http://s10.postimg.cc/e6scut03d/IMG_20150321_120653.jpg
http://s3.postimg.cc/irud0plyr/IMG_20150321_142000.jpgMaurizio, do not be discouraged, it happens much more often than you might think, to get to the bottom of it we have to go by exclusion, and determine the cause starting from the simplest things.
-If you still have the lattice with the transparent threads, try making one with glossy paper printing, or even with copper wires, I believe that the defects present are extremely altered by the transparent and reflective threads of the lattice.
– the intensity of the light to use is that of the last photo, that's fine that way. Furthermore, the distance between the light source and the grating must be reduced to the minimum possible.Irregularities are too pronounced e “random”, there is a lack of symmetry that should also exist in defects , I believe that in reality any defects are much less evident and more of a general shape than of superficial irregularity “locale”.
therefore before attempting corrections or investigating possible causes, it is best to make sure that all ronchi setup is functional and optimized. If you need the file for printing the lattice I can send it to you.
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