Series I, BOSS Z-Axis Binding - Help

[split63]

I recently just got a Series I, BOSS 6.0 Machine running, after buying it at auction. When I tried to move the Z-axis, it would not move. I removed the belt and the stepper ran with no issue. Just grabing the belt and trying ot move the Z-axis would not move it. I opened the front access panel and the Ball Screw is nicely oiled. I removed the lower seal and found that the felt Seal was also nicely covered with clean oil.

I did find that if I just tapped the stepper forward, it had just enough torgue to turn the ball screw 1/3" turn before it froze. Doing this I was able to extend the quill a few inches, but the "binding", if that is what it is, did not go away.

This is a Rigid Ram design. Any ideas?

Help

[ironDigit]

chekk for any missalignment of the ballscrew i know from experience that can be a hard to spot PITA.especially after moving it there is some chance of this being your prob

then again consider i never even been near a real quality machine

good lukk m8

[unterhaus]

I've heard something like this happens when you exceed the limits at high speed. No experience with it though.

[machintek]

Binding or bound up?
Most common is that the quill goes up too far and binds up. Bridgeport, on later machines, put a rubber disk on top of the quill but this binds up as well.
I usually take a pair of channel locks and move the motor pulley such that the front part of the Z belt goes into the quill area. This should free it up.
Remember that the stepping motor BOSS machines need .200 inches of decel or else they will mis-position.
Rare, but seen is that with a lot of Z work, the chrome on the quill can peel and bind up the quill VERY tight.

George

[split63]

Originally Posted by machintek Binding or bound up? I usually take a pair of channel locks and move the motor pulley such that the front part of the Z belt goes into the quill area. This should free it up. Remember that the stepping motor BOSS machines need .200 inches of decel or else they will mis-position. George

Sorry, I dont follow. I already extended the quill out a few inches, and it is still bound up. No chrome peeling that I can see

[machintek]

If you pull the belt off the motor, can you turn the ball screw with the belt by hand? It should move very easily. If not, you may need to pull it apart to see what the problem is. Do not let the ball nut come off the ball screw! Could be a bad ball nut, bearing, trash in the quill, etc.

George

[split63]

Originally Posted by machintek If you pull the belt off the motor, can you turn the ball screw with the belt by hand? It should move very easily. If not, you may need to pull it apart to see what the problem is. Do not let the ball nut come off the ball screw! Could be a bad ball nut, bearing, trash in the quill, etc. George

No, the pully will not budge.

I know that once I take it apart it will probably be obvious what the problem is, but at this point it all looks like new. Is there some alignment adjustment that might correct this problem?
How difficult is it to get this apart?
Do you come in from the top?
Reading the maintainence manual, its not very clear how involved it really is.

Thanks,

[BptRoadman]

If it goes down and jams but moves up OK... could be a thrust washer.
If it move abot 3/4 turn and jams ...the ball screw could be bent.

Maybe it got damaged in shipping.

In any case you have to take it apart.
Good luck

[split63]

Originally Posted by BptRoadman If it goes down and jams but moves up OK... could be a thrust washer. If it move abot 3/4 turn and jams ...the ball screw could be bent. Good luck

The force required to turn it seems to be a constant up or down.

[split63]

With the prospect of having to take the thing apart (The horror), I decided to ignore the fact that the ball screw and quill are nicely oiled. I pulled out the big guns and grabed the penetrating oil. I sprayed the quill up in side the case. I then took bearing grease and slapped it on the ball screw. I then forced the quill up and down by tapping the stepper. To my amazement it seemed to get better. Now instead of 1/3" of a turn, it would going two turns before stalling. I kept this up and keep applying more penetrating oil, now to the top and bottom of the quill surface. Soon it was motoring the whole way extended and then fully contrating without stalling.

So the problem was the oil that I could not see. There is a 5" area that the quill passes into and out of that is inaccessable. It is this area that must have contained tar like oil. Interestingly, I had the penetrating oil pooled up above on the quill and it was not penetrating through and coming out along the quill below. (This is with the lower felt gasket removed) So that area seems to be real tight. Hence if tar were to get in there, it would be like a brake.

I'm just glad it is fixed and I don't need to take it apart

[machintek]

Terrific!
It is common for the Z to start stalling. Ocassionally, I recommend flushing the quill with kerosene, and then re-oiling it. a little drag can cause the Z motor to lag behind the field changes and then be attracted to the trailing field, causing a stall and the whine.

george

[HillBilly]

I bet your glad to see all three axis moving! I know you ran into some quirks with this machine.

Most of the way lube in the old days was parafin based and when it dried out it basically left behind wax.

I would also imagine with Mach3 now running your machine repairing the BOSS control is on the back burner. By the way how would you rate the ease of installing Mach3 on your Bridgeport with my breakout board and instructions?

Darek