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Hi Stefano, which is the environment temperature, but most of all, what difference temp. there than the first polishing sessions .
The ambient temperature is around 23 ° C and then at an ideal temperature for this pitch (Stathis has shown me the optimal range by 18 am 26 ° C).
Before working at about rinfrescasse 28/29 degrees but it was a suffering, channels that closed faceting and micro reset in a few minutes.
Now my modus operandi is:
I open good channels of the tool and do a faceting micro grid with the cutter blade.
Fill a container with hot tap water.
I put inside the tool for two or three minutes or until the pitch begins to soften.
Shooting off the tool and put it on the floor.
I put a bit of cerium oxide, previously diluted in water (1/8) with two drops of dish soap, on the tool surface.
They position it properly centering it over the mirror.
Add approximately 10kg in weight and let stand for a few minutes, around a little mirror and get back weights. Await that pitch and mirror to equilibrate thermally and that the pitch is returned to the working temperature.
I assure you that the whole face is in contact, put a mixture and sprayed with childbirth center movements of the center 1 / 3D taking as a reference a circumference made in marker on the back of the mirror.
I perform 8 past the mirror then it rotates counterclockwise by about 30 ° while I move in the direction of a step time.
I reworked an hour and a half from the previous post:
The thing that is known that the microfaccettatura tends to disappear first on the outer part of the tool, sign that either the party to work more.
One can see in this photo of the tool after a couple of hours of work, the channels slowly closed and the micro-faceted architecture tends to weaken the outside.
And, as you pointed out yourself, there is no uniform contact coating / mirror. The adaptation for a tool to be 30 cm is not simple, also heating it is not said that it reaches. And the more “squares” of that size they are able to support a lot’ weight without deforming ( cold ), the 10 kg may not be enough.
Once I remember I watched the first half of a game on TV “comfortably” sitting above the tool / mirror , and other instead, I have risen above with both feet ( weight 87 kG ) for about ten minutes. At the end of the adaptation was perfect. but do not think that the film quickly gave way under the weight, it was necessary to insist and repeat the operation several times…Cabbage… Yet I was almost sure it was in good contact. By interposing the film contact occurs in all the squares, usually it starts in the center and as they pass the minutes of evens pressure.
Tomorrow I will try to let more time the tool in hot water and to increase weights and pressure times. The thing that leaves me a little doubtful is that the test with the laser to assess the degree of lucidity seems not to bring differences between center and edge. The imprint, although weak, It is still visible with the same intensity on all the face while if I worked with a bad contact should show variable with the move along diameter. Oh well, I am already happy not to have (it seems to me) coarse machining errors, You will find the right compromise and work hard a few more hours. not defeated!
Absolutely yes, You are working well, there are no big mistakes and figure to Ronchi is very good. This is about a few hundred nanometers glass more or less, too few to be evaluated with a film…
The signal which is an adaptation problem comes directly from the Ronchi, as central rides like you're doing, They must lead to the ball, each anomaly detected gives you the measure of where and how much must be optimized setup.
You are very close to having an optimal setup for parabolizzare, but you need to understand and solve this little problem to point directly to excellent results !One thing you can try is to increase the pressure at the center during the races 1/3 COC, in this way “forces” the tool to a full contact and , since you're sottocorretto, do nothing but push the processing in the desired direction, that is, increasing the depth at the center compared to the edge.
If the technique is effective, you'll have the added uneven adaptation confirmation.
But be careful not “to abuse” of this variant, because the “side effects” could be worse than the problem you want to solve.The only parameter that (Having regard to the poor abrasion work made) in my experience I would not find appropriate, is too “long” dilution (1:8) Cerium oxide….
I used the cerium or zirconium oxides with almost the consistency of a cream which gave a brush, using a dilution “restricted” with report 1:2 or vice versa 1:3 (ie one tablespoon of oxide satin kitchen with two or maximum 3 of water), and with the concentration and quantity, however the product was enough for a working evening (but a handicap is that with that concentration is not kept for the next day, and had to be consumed, to avoid excessive dilution to keep it moist, even if in a closed jar).
With the concentration of cerium increases the fouling in the pitch together friction, with cerium and I did not even need to add drops of dish detergent to make it do after foam 20 minutes of work (instead he wanted with the zirconium).
A very diluted abrasive (ie with eg consistency of a barely milky liquid “clear”) It is a characteristics of the machine leavoraszioni with aluminum oxides (Gordon Waite docet).
Here, on this thing dilution I had my doubts… It is a report I read in different reports but which I think makes little and nothing. Perhaps it can be good value for work up during parabolizzazione, but the search for the ball something more consistent and effective I think is more appropriate. I will try to also reduce the ratio, thanks for the advice guys!
I agree with Giulio, I had missed this and I can only confirm what he says ” the teacher”
This “hoax” of cerium “I superdiluito” It runs the network for some years, I do not know who was the author but was definitely somebody that pointed more to the savings that the effectiveness… and how it's wrong, given the prices of these products !
Regarding the aluminum oxide, the high dilution is made necessary by poor tenacity of this material, in practice after a short time on the grains I am “beveled”, the edges of the granules, which originally are angular and sharp, After a few strokes become rounded and end their abrasive action.
If you exceed with the concentration of aluminum oxide, I realized when I used it, you create a “bearing effect”, where the grains glide over one another and the mirror seems to be moving on the tool as it would on the ice, He warns the lack of any friction also increasing the pressure.guys, I went back to work after a wait Forced from having dropped the stock of cerium into the bucket of water
I'm back now operational and I worked about an hour, solution of water and cerium much denser, hot pressing going on with all my weight for half an hour, past 1 / 3D center to center. No way, I can not see improvements. I am posting only the intrafocale much is already Explanatory… I just do not understand, I'm sure the contact is perfect, cerium oxide makes a nice noise, The froth is generated along the canals and everything seems to be okay. I tried with more pressure at the center, without pressure, nothing:cry:
Cabbage but at least change for the better or the worse should see them no?
In fact, a variation can be seen compared to the previous Ronchi, but unfortunately it is not for the better, the tendency to “to open” in the periphery is increased, the center remains spherical but the periphery is further decreasing the radius of curvature.
Although it may seem strange ( and I understand why I had the same problem with a 300 f3.8 ) the only way to obtain this type of defect is that the edge is reached by processing less than the peripheral area. In this way you create a profile in “bowl”, where the peripheral curvature is more accentuated with respect to the center. So there remains the problem of adaptation.At this point, even if the pressure does not get anything, try to stretch their rides for a session, until 1/2 D ( but you can stretch further if it does not work ). This elongation can give a measure of how to be extended compared to the diameter of the actual contact area.
Please note that this is a very effective method to get a nice edge retorted, that when you do not because the edge is exactly the contrary, that is “raised”.
Ok, Here I have to understand where the problem lies. It could be a tool with pitch too thin layer which thus better promotes the adaptation at the center? I just 3mm thick now. When in doubt agree that a new remake.
Based on what you suggest I have a bowl shape, then, looking at the cutting mirror, the edge turns out to be flatter than at the center. I wonder, if allungassi races, not further appiattirei edge up in extreme cases to make countered? I almost thought I was in this situation:
Edit:
Where the dotted line is the figure that I should have and the black figure where I am. They are in this situation?Re-reading your response Massimo think I misunderstood. I understand that it is the opposite of what I just drew! Namely, that the center follows a spherical trend but towards the edges of the walls tend to rise in fact shortening the ROC! I thought I was the opposite as in the previous post we talked Ellipse:
ok, I thought that the names of the images were reversed, but if the first image is actually extra time you're away from the parable, you are currently in a conical tending ellipse with K ( conic constant ) positive, while you have to reach the value of K = -1 parabolic, and we must inevitably come back to the ball ( K=0 ) and then distort it to the parable
The feeling that you had to be on the road in the parable, It would be correct if the images had been "on the contrary", and that the image had been extras in the intra and vice versa
However, this does not take away the good work you're doing, these aspects are "fixed stages" in the career of a grattavetro
So I thought outside the ROC was longer.
What a mess! You'd better make breakfast
You Stefano, your last reasoning is correct:
Look at the lines of Ronchi carefully: we intrafocale in suburban lines are wider, or more open with respect to the center. This means that in the suburbs we are closer to the fire than the center.
In other words, the periphery of the curvature radius is shorter than the center, namely, the peripheral profile is is more curved than in the center. So the profile of your mirror at the moment is elliptical with K> 0.
Cabbage, then what I need might be more long runs or TOT. What I do not understand is that they should do the normal 1 / 3D, but in my case not seem to work for outside, sign as you say maladaptive. The reality is that I have no idea how to better adapt the tool as well as stand on it with 80kg for half an hour despite the pressing both hot and not cold! Bah, if in doubt redo the tool
Yes, right, with longer strokes Could it work better the outdoor area, but only up to a certain moment, namely, until the tool retains the same “defect”.
In the moment in which the tool will change again form ( because forced to work more their central ) then even long runs will not be the most effective to reach the ball, but it appears a new abnormality in operation of the new tool shape. Then he will return to face the problem of adaptation.Keep in mind that in reality the defect is minor, the fit is all in all very close to the optimal one, to the point that the difference between the contact areas could also be explained by an abnormal pressure in some points, due for example to the position of the hands during the races, or to a non-uniform temperature that develops during the tool / mirror racing.
Surely the thickness of only 3 mm does not help in this sense, then redo the tool is a good idea.
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