Has anyone ever had any problems with Newall Spherosyn encoders

[mowersman]

Hi all, as the title says really. Over the last couple of months, my lathe has become really stiff to operate in the Z axis. I assumed crud had built up somewhere and was rubbing on the slideways, so I stripped it down today to have a look, but as soon as I removed the Z axis linear scale, it all freed off. Playing with the scale shows that it is very very stiff, to the point, I can barely move the head by hand. Has anyone come across this before? I've had a look on google, but there isn't much on there about it. It appears that inside the end of the head, there is a PTFE(?) bush at each end and one of these seems swollen, causing it to all jam up. Anyone come across this before?
Cheers
Andrew

 

[graffian]

Not had any problem with them.
Mine are covered in crap all the time, the wiper seems to clean them up.
My problem was the old digipac head, mine was full of errors..

 

[Windy Miller]

... It appears that inside the end of the head, there is a PTFE(?) bush at each end and one of these seems swollen...

I wonder if it's nylon, and not PTFE? Nylon can absorb oil, which will cause swelling...

 

[awemawson]

Surely it must be a bit of swarf stuck between the ball tube and reader head ? Not had any such issue with my Spherosyns or Microsyns - excellent DRO'

I seem to remember that the tube / reader head is guaranteed for life.

 

[mowersman]

I've taken the reader head off and cleaned out the hole, no swarf, but you can clearly see where the plastic bush is binding on the tube. I'll ping an email off to Newall when I get home.
Andrew