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1992 VF-2 needs some TLC

Bill Clark

Plastic
Joined
Apr 8, 2012
Location
Ocoee, Florida
Hey guys, looking for feedback on some issues with my old, reliable VF-2. I am embarrased to say that I have not been keepin up with the maintanence like I should and as a result some issues are popping up. I have always been easy on the old girl though and she sees minimal use these days. nonetheless I need to get the machine back up in decent running shape and would greatly appreciate some help.
issue #1 is noticable when cutting a larger size hole. as the Y axis changes direction I hear a "clunk" like there is some slop. I have not checked to see how round it cuts the hole but today I put an indicator on it and pushed and pulled on the table. I could get close to .0015 in Y and .001 in X (total push+pull).
#2- the spindle will not start when programmed with less than about 1300 rpm (low gear?). it will just osccilate back and forth about 180deg and will continue this until I stop it. I can reduce the rpm to a very slow speed after I start it above 1300.
#3- and this may be related to #2. about 1 in every 10 tool changes the pin will fail to engage and orient the spindle for proper tool change. the spindle will move it just doesnt seem to stop in the correct position for the shot pin to go in.

recently I have disassembled the cleaned the tool release pnuematic system (behind the front cover on the spindle) because the tool would fail to release so that has been resolved.
I have vacuumed the brush dust from all the motors. cleaned and greased all I can see including the screws and put new seals in the gearbox for the tool changer "in and out" motor. It had leaked oil into the motor and I am amazed with the amount of burned on sludge around the armature that it was functioning at all. The z axis encoder was throwing an alarm "z axis motor fault" and it appears the connector at the encoder needed to be reseated. once again amazed because my luck would be that the encoder would need replacing. Is there any other maintanence I should do on top of what I have done? thanks in advance
 
Read moparmusl postings on his gearbox repair, he has that very well covered. I would start with the thrust bearings on all three axis, invest in hook spanner wrenches. Most likely a good cleaning, greasing and adjustment will get you back in shape.
 
Hey guys, looking for feedback on some issues with my old, reliable VF-2. I am embarrased to say that I have not been keepin up with the maintanence like I should and as a result some issues are popping up. I have always been easy on the old girl though and she sees minimal use these days. nonetheless I need to get the machine back up in decent running shape and would greatly appreciate some help.
issue #1 is noticable when cutting a larger size hole. as the Y axis changes direction I hear a "clunk" like there is some slop. I have not checked to see how round it cuts the hole but today I put an indicator on it and pushed and pulled on the table. I could get close to .0015 in Y and .001 in X (total push+pull).


#2- the spindle will not start when programmed with less than about 1300 rpm (low gear?). it will just osccilate back and forth about 180deg and will continue this until I stop it. I can reduce the rpm to a very slow speed after I start it above 1300.
#3- and this may be related to #2. about 1 in every 10 tool changes the pin will fail to engage and orient the spindle for proper tool change. the spindle will move it just doesnt seem to stop in the correct position for the shot pin to go in.

recently I have disassembled the cleaned the tool release pnuematic system (behind the front cover on the spindle) because the tool would fail to release so that has been resolved.
I have vacuumed the brush dust from all the motors. cleaned and greased all I can see including the screws and put new seals in the gearbox for the tool changer "in and out" motor. It had leaked oil into the motor and I am amazed with the amount of burned on sludge around the armature that it was functioning at all. The z axis encoder was throwing an alarm "z axis motor fault" and it appears the connector at the encoder needed to be reseated. once again amazed because my luck would be that the encoder would need replacing. Is there any other maintanence I should do on top of what I have done? thanks in advance

#1 - I would check to see if the ball screw is loose. There is a lock nut on each end of the ball screw, make sure they are tight. If they are, it could be the thrust bearing as mentioned or it could also be the ball nut where the table connects to the ball screw.

#2 - sounds like your High/Low gear selector is not shifting. Usually this is caused by the gear shift mechanism sticking (hard to clean) or the solenoid for the gear shift is not working properly.

#3 - The orientation ring is most likely worn which causes the shot pin to sort of "bounce" and not engage the ring. It will get worse! Replace the orientation ring.

Like BGL mentioned, look here. http://www.practicalmachinist.com/vb/haas/91-haas-vf-1-rebuild-234783/ You will probably find a lot of useful information in that thread.

Good luck!
 
more info on my issue #1 from above and my y-axis "clunk"- I checked everything and all appears to be tight so I programmed a spiral cleanout on a 3" hole and shot some video y-axis "clunk" - YouTube
the "clunk" occurs at mid travel in the y-axis precisely when the x-axis is changing direction during interpolation. I rotated the toolpath 90deg and reprogrammed thinking it had something to do with how the code was writin and I got the same result. the machine is running at about 60ipm if I remember correctly and reducing the speed reduces the clunk. sorry for all the background noise.

Also I have been noticing recently that the x-axis is emitting a squeaking noise that appears to be coming from the encoder. squeaky encoder - YouTube
when I removed the cover on the encoder it had what appeared to be some brush dust in it but I cant see how it could have made it in there. is this from the encoder?
 








 
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