We have seen how the past with W races constitutes one of the most effective methods for the approximation of the parabola starting from the spherical surface. Let us examine some variations of this technique to accentuate or diminish the effect of the processing in some areas of the surface. The W race presupposes a constant displacement and linear , orthogonal to the direction
In the design phase of our astronomical mirror, it is essential to determine the focal length at which you want to reach, since the same focal length depends on the extent of the arrow, ie the depth of the center of the mirror with respect to its edges that we will achieve especially in the roughing phase. The formula for calculating the extent of the arrow is
This type of technique can be used in the first phase of the generation of the parabolic shape of short focal mirrors or large diameter, the mirror is always and only in the lower position. hand position ( for small tools below 15 cm)It is the one with the thumbs pushing a
In the past 1/3 COC, the movement of the mirror on the tool (being the focal reduction) or viceversa (in the process of increase of the focal) They must be made by following a few simple but important rules: the center mirror and the tool at each pass must meet and the straight line virtually drawn from the center of the disc in that
Before starting any mirror processing phase, it is essential to make sure that the edges of both mirror that tool are blunted. This precaution is essential to minimize, during processing, the risk that by the sharp edge of one of the two discs coming off a flake that can slip between the two
La pass with races “W” It is the main technique used in the process of parabolizzazione. Normally it runs with mirror above and below the tool, It can also be applied in some cases with inverted positions. The position of the hands is the one with the palm which rests and pushes from the edge to "hours 8:20"And your thumbs facing the center to
Is’ the day “zero”, one in which it is decided to start the processing of its first mirror. Everything's ready: a transparent glass disk is lying on her pretty stable support, restrained but not too much by three wooden dowels. We seize another glass disc uncut and, coarse carborundum hand
Past 1 / 3D c.o.c, alias the forward-backward centered race (or, all’americana: “center over center”), processing for abrasion, amplitude equal to one third of the mirror diameter, in which scratching of the glass is used to make a mirror (for example parabolic) is, with patience, UNIVERSAL WINNING WEAPON. Like the: The acquired new life
DESCRIPTION La pass with racing 1/3 center over center ( shortened: COC = “C. o. c.” ) is the classical stroke, the most widely used because it can be applied in all stages of processing both with the mirror above and below the tool, than vice versa. The position of the hands is the one with the palm that supports and pushes
Sub diameter tools, general aspects.
The techniques with sub-diameter tool, try to solve some of the problems that arise with the use of the full-diameter at the time when the size or the curvatures of the optical surface of the work, assume limit values in which standard techniques can be ineffective or difficult to apply or even, in some cases, counterproductive. we can summarize
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