Focuser issues (1 Viewer)

[Tord]

This is what happened to my TS102. It is fitted with a 3" improved Crayford focuser that I have been very pleased with. Precise, smooth and very robust.

When using the scope yesterday I noticed in the field that the focuser was stiffer than usual, and at times there was this sound of metal against metal. I noticed the bottom tightening screw was lose (about to drop it, but still in place luckily!) and as result of this the half-circle shaped nylon bushing that adjusts the pressure on the shaft had gone lose. The sound was the metal housing of the bushing against the tube.

To be able to put the bushing back in place I had to disassemble the sliding part of the focuser from the focuser housing. I managed to reassemble the focuser with firm pressure and without too much difficulty, paying attention at placing the shaft so it's on the same plan as the plate but the focuser is now not as smooth as it used to be, and there is a noise that I think comes from the 1:11 gear mechanism. It's not terrible, but it's there.

What do you think I should do? Use it and hope it will become as good as it used to be? Or try to adjust the mechanism? The people at Teleskop Service once warned me against trying to disassemble and reverse the focusing mechanism (my intention was to reverse it to left hand operation) so I haven't dared to adjust or disassemble it to find out if anything is wrong.

 

[kurakura]

my fast and slow focus wheel brush against eachother making a sound on each turn...need to take care of that

 

[roztoczol]

When using the scope yesterday I noticed in the field that the focuser was stiffer than usual, and at times there was this sound of metal against metal.
What do you think I should do?

That happened with my SW , I disassembled focuser and found cracked one of four ball bearings placed opposite the shaft . I ordered a set of bearing and whenever something like this is going on, just replace broken part.

 

[JGobeil]

Tord, I also had a broken bearing on my SW80ED which caused erratic focuser movement and metal to metal noise. Replacing the bearing fixed the problem. Of course, this doesn't happen if you don't drop the scope and camera... :C :C :C

 

[kurakura]

yup same here a ball bearing, made the focuser bad. Especially the first cm of so... If it is a ballbearing I have some here in Kastrup Tord... so if you comming to cph you are welcome to drop by... 2min from the taarnby station

 

[Tord]

Tord, I also had a broken bearing on my SW80ED which caused erratic focuser movement and metal to metal noise. Replacing the bearing fixed the problem. Of course, this doesn't happen if you don't drop the scope and camera... :C :C :C

Jules,

I am quite certain that no bearings got broken in the process (but cannot confirm since I haven't dared to disassemble the shaft mechanism).

It's not high pitch "metal against metal" sound. It's more a medium pitch grinding noise reminding of the sound from cog wheels that are not well aligned or are worn out and need lubrification. The noise originates from inside the dual speed knob and is present even if there is no pressure from the shaft involved.

The focuser was almost silent before I disassembled and re-assembled it, so I guess it is a matter of adjustment somehow.

After a quite intensive 3 hour session in the field it has become a bit smoother, and noise level is maybe 5 dB lower. Still audible but not prominent. Hopefully it will self-heal totally. Future will tell.

Lessons learned: it pays off to check the tension of the screws once in a while. I was lucky not dropping it.

 

[kurakura]

Tord, I just solved my "sound" from the gear... In my case it was the big wheel that was not 100% aligned with the fine adjustment wheel. Loosen the big wheel, make sure it is properly aligned and tighten it... solved it for me

by the way just installed magic latern on my 7D... trap focus, zebras, movement sensor, focuspeaking, and dual ISO... am so exited to try it out in daylight

 

[JGobeil]

Jules,

I am quite certain that no bearings got broken in the process (but cannot confirm since I haven't dared to disassemble the shaft mechanism).

It's not high pitch "metal against metal" sound. It's more a medium pitch grinding noise reminding of the sound from cog wheels that are not well aligned or are worn out and need lubrification. The noise originates from inside the dual speed knob and is present even if there is no pressure from the shaft involved.

The focuser was almost silent before I disassembled and re-assembled it, so I guess it is a matter of adjustment somehow.

After a quite intensive 3 hour session in the field it has become a bit smoother, and noise level is maybe 5 dB lower. Still audible but not prominent. Hopefully it will self-heal totally. Future will tell.

Lessons learned: it pays off to check the tension of the screws once in a while. I was lucky not dropping it.

I would be surprised it has a broken bearing if you didn't drop it. Like Karakura suggests, it could simply be the knob that is misaligned, a simple fix. Or maybe it just needs a drop of oil.

Good luck finding the problem.

 

[kurakura]

my scope broke a bearing without a drop