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Cincinnati Milicron #5 hard to move in the vertical direction

RevolutionMW

Plastic
Joined
Aug 6, 2020
I have a Cincinnati Milicron #5. Worked fine last night. First thing this morning. Started it up and was very tight on the up/down. Rapided it down and it could not come up on rapid until the feed was at a higher IPM. It is extrememly tight to move in both up or down, and there is about 3/4 turn back lash now, which was not there before. Does anyone have any ideas here? Thank you!!
 
If the lock isn't on the Z axis bottom gib screw broke and the gib slid down and got tight. Remove the wipers on the top of the knee and look for the gib. It should be close to the top, if it isnt then put it on slow down feed and loosen the top gib screw as it moves down. If the gib is to tight you may have to move the bottom of the gib up using a small bottle jack on and angle or use a brass shaft over 1" diameter and hammer it up if you can swing a hammer. Then fix the broken gib screw.
 
The jammed gib is more likely but the elevating screw/nut pair could be causing you problems. You could block up the knee, remove the screws that hold the elevating nut bracket to the base and then see if you can wind the bracket and nut etc up the screw.

Regards Tyrone.
 
Thank you for your reply! We have the gib out. The knee has been very tight in both directions as the gib was taken out. With the gib in or out, the knee is still very hard to move. Although, down has been easier. Since this problem occurred, there has been a full turn of backlash as well. What would look at next? Again, thank you for your input here. Really appreciate it.
 
Hi. Thanks! We to the gibs apart and cleaned up everything. Gibs are back in and adjusted as per Cincinnati manual. Still really tight on the Z axis in both directions. Thoughts? Really appreciate your advice here. Thank you!!
 
Thank you for your reply! We have the gib out. The knee has been very tight in both directions as the gib was taken out. With the gib in or out, the knee is still very hard to move. Although, down has been easier. Since this problem occurred, there has been a full turn of backlash as well. What would look at next? Again, thank you for your input here. Really appreciate it.

You need to look at the elevating screw/nut pair. A full turn of backlash doesn't sound good. Winding down will be easier because the weight of the knee, saddle and table is working in your favour. Block the knee up with either a solid piece of timber or a good hydraulic jack. Remove the screws that hold the nut carrying casting under the knee and see if you can turn the casting and nut up the screw. I preferred a good jack, that way you can jack up the knee slightly after you've removed the screws so the casting is clear of the base before you try to turn it. If it turns easy you'll know it's a gearing problem within the knee. If it won't turn by hand obviously you have a problem with the screw or nut or both of them together.

Regards Tyrone.
 
Thank you for your reply! We have the gib out. The knee has been very tight in both directions as the gib was taken out. With the gib in or out, the knee is still very hard to move. Although, down has been easier. Since this problem occurred, there has been a full turn of backlash as well. What would look at next? Again, thank you for your input here. Really appreciate it.

The acme elevating screw is preloaded by the 3000 lb weight of the knee and table. If the knee is able to slide there will be no apparent backlash in the screw other than the play in the gear train driving the screw. . Either the gear keys have sheared off or the knee is still jammed.

If the keys were sheared off the backlash would not be limited to one full turn.

If the gears or the shaft bearings were damaged the hand wheel would not move easily through the one turn of backlash.

A chip stuck between the knee and the front surface of the ways from the previous days work might explain the problem. Do you see any scoring on the ways?
 








 
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