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Hello! The autocollimator objective lens diameter is 0.2 arcseconds 60mm. The focal length is about 900mm. Can this additional information help you figure it out?

​@@gena_bazarko Well, I can repeat now the above calculations with the true numbers. So the the ac. equation gives theta1 = D/(2*F) = 60/(900*2) = 0.002/(2*900) = 0.00000111111 radian, where I assumed that the reticle linewidth is 2 microns. This angle corresponds to 0.23 arcseconds, which is given in the spec. list of your ac. However, the optics limits this theoretical resolution due to diffraction. The diffraction equation gives theta2 = 1.22*lambda/D = 1.22*0.55E-3/60 = 0.0000111 Radians, which corresponds to 2.3 arcseconds. If we image now the 2 microns wide reticle line back to the focal plane of the 900mm focal length objective we obtain 0.01mm linewidth. This line broadening is due to the effect of diffraction at the edge of the finite size objective lens. One can do nothing about it. To get smaller linewidth in the image plane and better resolution one should increase the diameter of the objective lens. In your case one should use 5 times larger objective lens to achieve the theoretical resolution of the ac.

Thank you for the theoretical information you provided. I will try to understand this information, but at the moment I do not understand it in detail. I need to expand my knowledge of optics. But at the same time, the problem you mentioned is somehow solved. If you install a good camera on the autocollimator lens and display the image on the monitor, it will be possible to register even a smaller angular deviation than 0.2 arc seconds. Since now, when working with an autocollimator, I do not use additional devices and control measurements simply by eye, and my vision is no longer perfect due to my age, I can confidently say that with an autocollimator of 0.2 arc seconds, and this is its sensitivity determined by the manufacturer, I undoubtedly see, at a minimum, a deviation of 0.5 arc seconds. I would like to understand the theory of optics as well as you do).

@@gena_bazarko Helo, If you give an email address I can send you more detailed explanation. And yes, with the help of a camera and image processing you can get finer details than the resolution formula says.

I found your email address, so I am going to send you some more explanation and maybe documents or links to documents.

"Inheritance Machining" is an impressive channel, thank you! I've watched a lot of their videos before.

Hello! Thank you for your clarifications. My horizons are different from those generally accepted in the West, so it is useful for me to receive additional information. I have a tube of blue paint for scraping, made in the USA, I tried to work with it, but I could not see the marks well. Therefore, I use my usual black pigment for artistic paint, "Mars black", this is black iron oxide, powder mixed with oil. Do not doubt, I will not deceive myself with an uneven layer of paint, I understand that this is important. In the end, I will switch to a very thin layer. But you write all the comments you can, it is useful, it gives reason to think.

ruclips.net/video/v5Tm2Co6vL8/видео.html Maybe this video contains information that interests you?

Since I have to make the tools for this repair myself, I’m working within the limits of what's possible. However, I have no doubts about my straight edge. I periodically check its surface by taking measurements, and the geometry of the working surface meets the highest standards. What exactly raises doubts for you? Are you questioning its ability to maintain flatness?

@@gena_bazarko disclaimer: my only metal working experience comes from a drill press. however AFAIK welding introduces material tensions, which, over time, produce far to big and unpredictable deformations. But as long as you cross-reference it often enough you should be good to go. correct me if i am wrong, good luck and слава Україні!

Since the distance of one meter is covered by my straight edge, and its flatness does not cause me any doubts, since I have carefully checked it, then a 1000 mm long mirror stand is enough for me now. When I finish the alignment, I will use a 300 mm mirror stand too, in addition to the measurements on the 1000 mm stand, since additional measurements will not interfere with the truth.

@@gena_bazarko you can try with 250/300mm,maximun 500mm.later you can see why i told you that.

@@fabioth283 I understand this well now, by reducing the length of the stand I will make the autocollimator's response to unevenness more significant. In this case I will check the straightness more accurately.

@@gena_bazarko you try.also your experience can get more high

@@fabioth283 I will do so after finishing the alignment, I already have a stand for this 300 mm long prism, and I have already carried out similar measurements with it before this repair, in order to understand the condition of the prism. A video about this has already been published earlier.

I read your comment through a translator, and I answer through a translator, so some information may be lost or distorted. Do not judge strictly. I am looking for the most convenient and effective scraping method, I do not rely on generally accepted methods to a greater extent than I consider rational. I value other people's experience, but if something attracts me to do differently, I try as I consider rational. But in the end, I will demonstrate the result of my work, I have enough means for precise control of flatness, you will see everything, and there will be no reason for doubt.

Привести до ладу триметрову направляючу найскладніша проблема в відновленні подібного верстату, якщо я виконаю це завдання, то розберусь й з іншими проблемами.

Hello! I don't have a good idea in this regard. I had to remove the largest layer of cast iron on the right side along the near strip, there was a smoothly rising and then smoothly decreasing hump about half a millimeter high near the edge. I had already created support pads, and I cut until I hit them with my meter-long straight edge. I cut as intensively as possible. It took me about one working day to cut off this hump and get a straight line from one support pad to another. So this event is not so labor-intensive. But, of course, your proposal is rational, only an effective method is needed.

hello in YVR, from far away, but familiar with businesses in the area, like early days of MDA, MDI, CREO... do you know Dan Gelbart?

leave the flame unlit. study how a collimator works. with a mirror on a base and a laser pointer bounced back to a poster on a distant wall you can figure out the deviations. start by setting the references as the two opposite ends of the piece, then determine how the rest of the surface relates to that reference line. mark them out, then learn how to scrape. i suggest starting with a lump of scrap iron. yes, you need a basic surface plate. then as you get the feel of it, you make your straight edges. hunt scrapyards for suitable lumps of iron. or try the "3 piece lapping" method. except you then end up with two relatively useless parts... once you feel confident and can scrape something flat, then attempt the "nasty" job. once you get the "feel" for scraping, you can make a flat surface in a matter of minutes, seriously. a lot of it is being able to "read" the bluing. roughing them in is really a lot of "guesstimation"...

@@paradiselost9946 Hi, thanks for the reply, I already scraped the saddle with help of a small granite plate, ofc, I plan on scraping the table. I just wanted to reduce the months it will take me to do it, as soon I see a big granite surface close where I live I'll buy it and put it to use :D, I'll probably copy 'An Engineer's Findings' design.

@@anemac9 sometimes it pays to ruminate for a while as well :) nothing worse than scraping in a particular part using the wrong reference, then another part... then another... and having to backtrack when things arent lining up...

Hello! Thank you for the compliment! My affairs are going well, of course, as much as possible during a war (.

Hello! For me this is also an intrigue, I can roughly theoretically assume what the result will be, but what will happen in fact? Very interesting! But I have super-precise optical devices for flatness control, so in fact I will provide absolutely reliable information, and technologically I will arrange its video recording in such a way that there will be no doubts about the accuracy of the measurements.

Hello! It’s interesting how sensitive an autocollimator assembled from inexpensive components will be. By using a webcam, this can and will happen, I admit that there is some probability of getting a good result.

К сожалению мой телеграм сломали. Напишите мне на почту.