Problem with my old Meade zero shift focuser

[h0ughy (David)]

I did the cardinal sin of not removing the batteries a few years ago And then ordered a new battery pack two years ago and only just reinstated it on Thursday. Now the issue is it won't go in or out, but I hear the operation of the motor. I did play with it a little, only removing the inner sleeve to show a roller pin. So don't know what it does in the scheme of things but that's where I stopped. Out of the wading pool now and completely in the deep end.

[Merlin66 (Ken)]

Hmmmm
The track marking I think shows significant interference between the drive pin/ shaft and the inner cylinder.
With the cylinder removed does the shaft turn freely with the controller????

[LewisM]

I could be wrong, but there seems to be metal roughness and degradation on the left side of the pinion slot commensurate with the width of the gouge/scratch on the drawtube. I'd inspect that, refile/dress if necessary.

All else seems OK, but there is definitely something gouging into the drawtube .

[AndrewJ]

Gday Houghy
Its just a simple DC motor, and can be driven by a 6V,9V or 12V battery.
The 4 ball bearings in the outer housing are adjusted to set the inner tube concentric to the outer tube, and then the roller pin is adjusted to give enough friction grip to make it work.
Andrew

[h0ughy (David)]

Originally Posted by Merlin66

Hmmmm
The track marking I think shows significant interference between the drive pin/ shaft and the inner cylinder.
With the cylinder removed does the shaft turn freely with the controller????

not sure i can hear the motor engaging

[h0ughy (David)]

Originally Posted by LewisM

I could be wrong, but there seems to be metal roughness and degradation on the left side of the pinion slot commensurate with the width of the gouge/scratch on the drawtube. I'd inspect that, refile/dress if necessary.

All else seems OK, but there is definitely something gouging into the drawtube .

i do agree but not sure why?

[h0ughy (David)]

Originally Posted by AndrewJ

Gday Houghy
Its just a simple DC motor, and can be driven by a 6V,9V or 12V battery.
The 4 ball bearings in the outer housing are adjusted to set the inner tube concentric to the outer tube, and then the roller pin is adjusted to give enough friction grip to make it work.
Andrew

not sure why it wasn't doing what it should but i can see what your saying. i haven't used this for 10 years. doesn't seem like you can use a feeler gauge as it is a tight fit

[Merlin66 (Ken)]

PM sent

[h0ughy (David)]

Originally Posted by Merlin66

PM sent

thanks ken take you up on that

[AndrewJ]

Gday Houghy

doesn't seem like you can use a feeler gauge as it is a tight fit

Dunno why
You just need to set the focusser so its inner barrel and outer barrel are concentrically aligned lengthwise, which you can do visually.
ie use the adjustment screws on the four external bearings to centre the inner tube and you are done.
Then just adjust the roller pressure to prevent slipping.
easy peasy
Andrew

[h0ughy (David)]

Originally Posted by AndrewJ

Gday Houghy

Dunno why
You just need to set the focusser so its inner barrel and outer barrel are concentrically aligned lengthwise, which you can do visually.
ie use the adjustment screws on the four external bearings to centre the inner tube and you are done.
Then just adjust the roller pressure to prevent slipping.
easy peasy
Andrew

well my simple skill set has managed to stuff that process up

[AndrewJ]

Gday Houghy
Then try this
With the crayford roller out of the way/backed right off
use your thumb inside the barrel
and forefinger on the outside and push the inner barrel
onto the 4 rollers ( using as much pressure as you can ).
You should be able to easily move the barrel too and fro.
If it sticks, adjust the 2 bearings as required until it moves freely
( You need to use pressure to force the inner tube into the bearings
as they are only a floating fit. I have a piccy somewhere but the adjustable bearings sit on simple axles and the screw heads push down on the end of the axle. Crude but it works )

Andrew

[h0ughy (David)]

Originally Posted by AndrewJ

Gday Houghy
Then try this
With the crayford roller out of the way/backed right off
use your thumb inside the barrel
and forefinger on the outside and push the inner barrel
onto the 4 rollers ( using as much pressure as you can ).
You should be able to easily move the barrel too and fro.
If it sticks, adjust the 2 bearings as required until it moves freely
( You need to use pressure to force the inner tube into the bearings
as they are only a floating fit. I have a piccy somewhere but the adjustable bearings sit on simple axles and the screw heads push down on the end of the axle. Crude but it works )

Andrew

OK will try that