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Hi guys,
at this time I'm working a lot on the mirror,But
I'm realizing that it is not’ simple remove this edge retorted.
I worked almost always 1/4 COC and a few laps 1/3 COC (80% e 20%) e
by the images I see a hill close to the border countered and more dug center,
I thought of doing of past 1/3 or maybe even more to take that hill you think?https://s11.postimg.cc/ac9sa47gj/IMG_20160328_101833.jpg
https://s22.postimg.cc/v0f9h7tmp/IMG_20160328_103127.jpg
https://s27.postimg.cc/4k445czwj/IMG_20160328_103340.jpghello Maurizio, make the point…
To correct a defect must first figure out what caused it and delete it, otherwise you find yourself wanting to solve a problem by the repeated application of his own cause.-You said you've been working with plants and short races, then the cause of the edge can not be countered the technique used, which normally serves precisely to correct this error ( with full tool diameter ). So if the fault does not decrease, It is useless to insist or we find ourselves in the situation that I mentioned before.
thus excluding the technique my guess is this: to skate ( coincidentally
) It has poor grip in the suburbs. in practice it is as if you had used a smaller tool mirror which, working with central and short races, He has deepened the central area along the median, while the edge is remained as it was not having been reached by the working.
In other words, It is not the edge that is “lowered”, but the rest of the mirror that has become deeper than the edge.
“Deeper” means that its curvature is increased , while remaining quite spherical, while the connection with the periphery has generated a profile that decreases its curvature to the edge, which it has maintained its original curvature and is exactly what you see on Ronchi.A smaller tool of 30% mirror , with central ran to 1/4 would have led precisely to that figure, namely: spherical center, median zone ascending and descending edge.
It is not necessary that the entire periphery has no grip, as long as only some areas are a lower contact.solution:
-mirror under ( important! )
-2 laps with moderate pressure to the tool center , LONG races 1/2 ( and beyond ) CENTER to CENTER
-2 laps with moderate pressure to the tool center , LONG races on ZONE MEDIAN ( as shown in figure )
try doing some sessions in this mode, if I'm right about the cause of the defect you should see decreasing soon enough, otherwise the problem is another ( but, I do not think so )…
more and if I'm right, do not go on and on with this method, Rather fits well the patina !!!Hello guys,
I know and’ a bit’ I'm missing,I hope to pick up right where they are
remained in a few weeks.
On this occasion I make him Merry Christmas and Happy 2017Maurizio
Thanks Maurizio. Replacement greetings. Do not worry because the reflective pauses ….is natural for those who handle mirrors.
Just Giulio, But… for those handling lenses instead of mirrors, are more natural refractive breaks
Merry Christmas and Happy Holidays !..They are more natural and even longer because it is gratavetro “slow”.
Merry Christmas Massimo , Maurizio, Mirco, Henry and all other gratravetri!
Hi guys!
…Maurizio, what to say, Also in my part, Unfortunately, work is proceeding at a slow pace….
We hope that the new year will bring some’ more time
A heartfelt Merry Christmas wishes to you all
Hi guys,
I join in the even I do the good Christmas wishes to you all…
See you soon…ciaooooo
Hi Massimo,
I made some past as you suggested and are in this situation,but I have to keep
so, up to the ball or do I have to change something?
It seems to me a paraboloid.http://s29.postimg.cc/4g2ela43b/IMG_20170103_140547.jpg
http://s28.postimg.cc/5798nbmrx/IMG_20170103_140822.jpghello Maurizio, at this point, after you have eliminated the tendency to “to grow up” the median zone, you can return to the classic races 1/3 COC with mirror above, always checking the good fit of the patina.
What you see on Ronchi is a sphere that remains so until 2/3 of the surface and then, going toward the edge, flattens.
In the picture you can see schematically the current situation, with exaggerated proportions, but in principle it is this:
The black line represents the profile of your mirror as shown on Ronchi, the red dotted line represents the sphere that most approximates the surface for about two-thirds.
At this point you have to dig centrally, in the sense that you have to deepen the spherical part without changing its shape, up to the blue dotted line.
This you can do with the central rushed to 1/3, provided that the adaptation is optimal, because otherwise Would you go back in the previous situation with the median high because not reached by the machining area.
In any case, the lines are regular Ronchi, sign that you're doing well, the surface roughness does not present and it is quite evident “smooth” no local errors, which means that even the patina is working in good conditions of temperature and adaptation. The lower edge is the flaw that remains to be correct and you can do it in only one way, deepening the central and middle zone with the races to 1/3 up to the ball.
Dear guys, I hope you are all well. I would like to resume work on my 12" mirror″ f/5, stopped for some time. Because I would like to start working glass again around September, in this period I would like to refresh my memory on the theory and techniques. I am writing to ask you if it was possible to count on your support and advice for the doubts that will certainly arise. Thank you very much for your availability.
Maurizio
But can anyone help me I'm in this situation?I'm also writing to the Dobsonian forum but no one is replying
hello Maurizio, wow it's been a while ! Nice to hear from you again. In recent years the forum has come a long way’ fashionable, now people mainly frequent social media and our discussions have been at a standstill for a few years. Also you reopened the topic in a month where we were a while’ everyone with their heads on holiday, but here we are. Now that I have seen the messages I will try to respond as soon as possible and give you all the support you need.
Hi Massimo, they're almost gone 10 I haven't touched the mirror for years but now, as I wrote, I want to try again and see how it goes…Then I'm a bit old, I prefer forums and I really hope for your help (
Yours and Giulio's). I wanted to tell you where you prefer us to talk here or on the Dobsonians?Thank you
Maurizio
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