We ran our machine on the chinese bearings for about 5 months with no problems- the TIR was under 0.001". But we had a real problem with fine sand- it seemed to be every where no matter how you tried to seal up the area- computer keyboards were always gritty- even in the coffee. During one of the quiet times we decided to re-pack the spindle as "preventative maintenance" ( had nothing else to do). We pulled the quill and took it to maintenance to press out the bearings- those guys were used to doing a lot of heavy stuff and not re-using things, so this little item was just slapped in the press- unfortunately they did not get it clear of the press plate and when the shaft came out it pulled the cage off the bearing. All the races were fine, and I actually considered putting it back together, but it so happened that it was a stock size we had in parts. Once it was all back together, there was no real difference in TIR or heat, but we managed to keep busy for a day. |