Re: [CAD_CAM_EDM_DRO] Sargon encoder disassembly help

I can't see how to get at the parts. The body is an aluminum
extrusion, open at the bottom edge where the reader rides, with end
caps that seem to come off. Maybe the reader would slide out one end,
but I can't imagine how you'd see or clean an encoder strip that runs
the length of the extrusion.

-Bryan


At 9:45 PM -0600 2-14-11, Jon Elson wrote:

>microset3 wrote:
>> My X axis encoder is missing steps. I'd like to disassemble it and
>>see if I can clean it, but I don't see how the read head separates
>>from the scale track. Can anyone help? Do I just need to pull
>>harder? Seems risky.....
>>
>These things usually have some scheme to hold the sensor at the right
>distance for the scale. The scale has a photo-etched nichrome grating
>on it, and the read head has two similar gratings, but one of them is
>shifted by 1/4 pitch, to create the 90 degree quadrature shift. They
>need to be really close, but if they touch, the gratings get rubbed off.
>
>Some have tiny instrument bearings that roll on the glass, or on the
>housing, some cheap scales have plastic sliders that wear away, and then
>the gratings start to rub. Often you can see how it works by removing
>the end caps.
>But, they all go together slightly differently, due to patents, so you
>have to just examine your unit to see how the sensor is loaded against
>the scale. Usually they have a springy metal ribbon or wire that drives
>the sensor back and forth, on some this also provides the loading force.
>
>Jon