- Joined
- Jul 2, 2014
- Messages
- 7,594
Another thing. When I first got my second Millrite, and was cleaning it up, I ran the knee up until the lead screw ran out of the nut and then the weight of knee and table dropped down by the pitch of one thread (.200"). I went the other direction, but the screw would no longer retract. Nothing I did would get it going back down again, kept locking up. I finally jacked up the knee and table so I could get to the end of the nut and the screw. There was no real sign of damage, but there were a couple pieces of swarf in the threads, which I picked out. I suppose the screw thread could have chipped when the table fell down one thread, and the chip jammed the thread. The machine had NEVER been used at this point, it was new old stock (NOS), so it was not swarf from use. When I attempted to jack it back down again, the screw engaged with no issues. I marked the column, at the top of the knee, an inch down from where the screw engaged the nut. From then on, I will not lift the knee higher than that line, which gives me 1" of lead screw in the nut minimum, and prevents the lead screw and/or nut from getting damaged from over extension. There is no dedicated stop at the top or the bottom of the Z axis lead screw, the nut bottoms at the bottom and exits the threads at the top. Millrite operators should know about that issue and take care not to cause damage.
Because of that, I have no idea exactly how the Z travel might have been measured for the spec in the manual.
