service, adjust Crayford focuser

[John999R]

My troubles started when I attempted to install the ZWO EAF auto focuser. Long story short, I made the fatal error by trying to adjust the OTA Crayford focuser on my Astro Tech 106 APO refractor. I ran out of options trying to get the EAF to work, so I dismantled the AT focuser and fell into a rabbit hole trying to adjust the multiple adjustment screws the AT focuser has. Does anyone know someone or a company that can repair/adjust the focuser? I actually got to the point where I can at least get the EAF to move the focuser tube up and down, but I'm not confident it's precise enough to do temp adjustments, plus, the slow EAF mode doesn't work well. Everything I did was by trial and error. There are three issues that I believe need adjustment. The first is the alignment between the focuser tube and the outer cowling of the focuser. The focuser tube is not exactly centered in the middle of the focuser cowling. The other is the fact after the focuser has been used for a while, for some unknown reason the fine focuser knob wants to back out, exposing the small shaft that connects to the knob. Another issue is the main spindle shaft that connects the right side where the EAF is attached and runs through the focuser and attaches to the left side coarse and fine focus knobs. I had a problem inserting the coarse and fine knob onto the shaft because the shaft was not centered in the middle of it's own focuser cowling, I had to push it down a bit in order to get the knobs into the said cowling and onto the shaft.

If pictures would help, I could come up with some since I'm not good at correctly identifying the parts.

[Richard]

These toothless focusers rely only on friction and therefore need much finer tolerances than the rack and pinion , but taking them apart one must be a bit more careful but its not that hard I have found this cant remember where it came from perhaps AF old forum?