First fraction(100). Tools: iron matrixes(R=2 000 mm, R=2 400 mm), glass disks(r=150 mm, r=140 mm),silicon-carbide mixed with some water and then we started to sharp. We were doing up-and-down movements with circulating round the barrel and all-time rotating the glass disk. Sharping with the first fraction ends when the spreading of the circle comes to the end of the disk. After that begins preparing the matrix for the work with the second fraction. With the twocomponent epoksyd pitch we started to glue the little quadratic pieces of glass witch we previously sharped the edges so wouldn't harm the mirror. After the matrix cooled down a bit,we were still sharping the mirror for some time so the glued pieces of glass adjust on the spherical shape of the mirror. After that we washed the mirrors,matrixs,wooden plates and the whole room, so there won't come to mixing the fractions.
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Second fraction(220).We continued sharping with the same technic,but we were using silicon-carbide crystals of smaller size so we could have a smoother surface. This faze lasted for about a hour and a half. Later we were checking the mirror's surface with a magnifying glass;on the edges there were still some craters left from the first fraction. We continued sharping so we could remove these craters. That lasted for about an hour. Then we were checking the focal lengths. We made that when we in a darken room aimed the beam of light to the wet mirror and we were watching the image on the shiny plate. We were moving the mirror until we got a sharp image of the source of the light. After that we measured the distance between the mirror and the reflected image. That distance we divided with two so we got the focal length of the mirror. With doing that we ended the work with the second fraction and we cleaned again the tools and the whole room.
The third fraction(320). We continued sharping the mirror with the third fraction. Working with the third fraction we were trying to short or to increase focal lengths. Increasing was done as we were doing central movements only,and shortening as we were pushing the mirror above the edge of the matrix while sharping. Once in a while we were checking the focal lengths and the quality of the mirror's surface. We finished the work with the third fraction after an hour and a half.
The fourth fraction(480). After cleaning we prepared the new fraction and we started sharping. We were still trying to increase or short the focal lengths and were checking the quality of the mirror's surface. If in checking is found a stratch,sharping has to be repeated usually from the first fraction. The work with this fraction lasted for about an hour and a half. After cleaning we cleaned the room, again.
The fifth fraction(600). All the previous fractions we were putting in big amounts and more often on the matrix because they were worn out more quickly than the previous ones,and with this fraction it could be worked for about 15 min. The mirror shouldn't be too much pushed on the matrix but it should be pushed easily up and down and left and right. We had to be careful about sliding the mirror above the edge of the matrix because the pieces of glass can easily harm the smooth mirror's surface,and that counts for the previous fractions, too. The work with this fraction lasts as the previous one-about an hour or an hour and a half.
The sixth fraction(1 000). The work with this fraction is our last chance to fix the mistakes on the mirror so we were checking focal lengths more often than usual so we could see if it everything's going right. In the work with this fraction there was enough to put the silicon-carbide every 20-25 min. Actually it is useful to work with the same silicon-carbide because after some time it gets finer and finer so in this way we can attain,for example,the fraction 1 500.Sharping the mirror with this fraction lasted for about an hour. After the work with this fraction we had to clean the room very carefully and that way prepare it for the polishing.
