Linear Encoders

So, here i am answering my own post. Hp makes only 360 line heads according to the search i did on the agilent (argh! hate that name) web site. So i mosey down to the machine shop where they just had a bp retrofitted with a new Accurite CNC for 10k$. Accurite came in and replaced the old scales with new ones, so i took one of the old ones apart. They have 4 tiny leds on one side and 4 tiny leds on the other side and a piece of glass scale mounted on the head in between. The interesting thing is that there is a spring to jam the head up against the glass scale. The glass scale appears to be 2 pieces of glass bonded together. I didn't have the guts to take apart the ones on the cnc:).

Just to add to the SI (metric)/GOAU (good old american units) debate, all of the glass scales i have seen, including the 30 year old accurite described above actually are laid out in microns and the DRO converts it to inches. I guess the mylar guys are using inches because the like to be GOA's
eric

eric




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