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 (probably 80, but perhaps also 60), we have to break the ice with the action that we will repeat a thousand times: the past.
Alt, Pause a moment: if we are at this point, it means that we chose to do really all the work, resisting the blandishments of those who offer us a blank disc that more we like the F. We did well? Well, This lengthens the total processing time, it's true. But it is an excellent exercise that allows us to get to the polishing with a number of passes “in arms” as to feel quite sure of the gesture. And the charm of a mirror Forged, starting from zero, It is not secondary. So my advice is: the first mirror it boasts alone. Ok, crush play and proceed.
Making a pass is nothing earth-shattering, but we must inevitably take my hand. There is an approach to work that, in my opinion, It helps to optimize the first steps towards the mirror and make the first phase can be more profitable, made of doubts and hesitations: rely on some way you can help us. We see:
THE SENSE OF TOUCH
in the past chordal (pardon the pun) It takes a little tact and a lot of strength: Here you dig, the perfect forms'll do later. But this way also helps us to see the work that is being done on the surface. In fact, through the feeling that will be transmitted to our hands, pass accuracy we can figure out when you will be the right balance between abrasive and water, that will return some sort of “scorrevole friction”, ne risque (a clear sign that in some areas has accumulated carborundum which creates “dry and firm islands” that certainly are not doing their job), neither too smooth (too much water, Unlike, from the feeling of slipping on a bearing that prevents abrasion and makes pour the abrasive intergro still outside of the two discs). In summary: the carborundum grains do their job if they break crawling on the glass, not among them, and water should help them “to roll” between the two glass surfaces, not escape their fate.
HEARING
the sound of carborundum that breaks the glass by exporting microchips on each pass, and inevitably evokes unmistakably the sound of a thousand microscopic stones rubbed on a glass plate. A sound in itself unpleasant. However, it takes little to get used to a menacing sound, that instinct to send us the thrill of something that is ruining….. What, instead, the sense of hearing may suggest there is when it is time to upload new abrasive-water mixture: the sound, I decided at the beginning and almost annoying, It becomes increasingly dull until you pass by a “sgraaat sgraaat” until “shhhhhh shhhhhh”. Cleaning summary, abrasive, water and away again.
THE SIGHT
do not mislead the board not worked after dozens and dozens of dried, with respect to the center mirror which totally loses its original smoothness after a few hours of work. What we are creating with the last chord is a bell, that allows us to get off at the desired arrow, then dedicate, other techniques, the creation of the sphere.
With the view, But, We can also check the consistency of the work on actually worked surface and the absence of scratches that may indicate that between mirror and tool an intruder is hurting our work. With finer grits will be essential to use a laptop or a microscope eyepiece to examine the surface enlarging; during blanking with the grain coarser abrasive is possible a fast control even to the naked eye, but it is better, however, to observe more magnification the surface immediately.
These three senses guide us: the feelings that return us to blend and become Sixth Sense, instinct to guide us in an effective and efficient processing.
How to use the chordal? When you switch to other techniques? Here are not the senses, but the measurement of the deflection to give us an answer: I suggest until at least 90% arrow, preferably 95%. The 1/3 to dig digs, but do millimeters Arrow is like going to the track with a tractor: he does the rounds, but it is not his job……to the 1/3 coc let him his mission: the scope.