[StealthAz]

Hey Guys!
I have been running my 1992 Haas VFO for a few week and now it is shifting in -Y- axis about .009.
I haven't had any issues with this in the past and now it has become a chronic problem.
The machine does not do it consistently.
I ran a part this morning and it shifted in the middle of a tool.
I spoke with my Haas tech and he said that it is hard to pinpoint the problem on these older machines.
He says it could be the bearings, the ballscrew, maybe the motor.
He came down yesterday and looked at the machine.
He adjusted some backlash parameters and we ran a part to see if it helped.
It didn't help any.
I gotta get this fixed and I am not wanting to replace parts that might not need to be replaced.
Anybody got any ideas?

[mtlwiz1]

Hey Guys!
I have been running my 1992 Haas VFO for a few week and now it is shifting in -Y- axis about .009.
I haven't had any issues with this in the past and now it has become a chronic problem.
The machine does not do it consistently.
I ran a part this morning and it shifted in the middle of a tool.
I spoke with my Haas tech and he said that it is hard to pinpoint the problem on these older machines.
He says it could be the bearings, the ballscrew, maybe the motor.
He came down yesterday and looked at the machine.
He adjusted some backlash parameters and we ran a part to see if it helped.
It didn't help any.
I gotta get this fixed and I am not wanting to replace parts that might not need to be replaced.
Anybody got any ideas?

try moving vise to different table location and see if it still happens using a different section of ballscrews, that should help narrow it down.

[haastec]

Hey Guys!
I have been running my 1992 Haas VFO for a few week and now it is shifting in -Y- axis about .009.
I haven't had any issues with this in the past and now it has become a chronic problem.
The machine does not do it consistently.
I ran a part this morning and it shifted in the middle of a tool.
I spoke with my Haas tech and he said that it is hard to pinpoint the problem on these older machines.
He says it could be the bearings, the ballscrew, maybe the motor.
He came down yesterday and looked at the machine.
He adjusted some backlash parameters and we ran a part to see if it helped.
It didn't help any.
I gotta get this fixed and I am not wanting to replace parts that might not need to be replaced.
Anybody got any ideas?

Can you give a better description of what is exactly happening? The more details the better.

[StealthAz]

Hey MTLWIZ1,

I took your advise and shifted the vise all the way forward to the slots closest to the operator door.
I had the vise in the middle of the table originally.
The machine is still shifting.
I had to run these parts, so, I ended up putting an indicating hole in the part and indicated the part before it ran.
I then indicated the part after every tool ran.
I noticed that the machine was drifting about .002 - .003 after every tool.
After about 4 hours of indicating the part and running the machine, I noticed that the machine wouldn't drift between some tools.
I only had 7 parts to run after I decided to indicate the part in after every tool.
Once "it seemed" like the machine was holding position, the job was done.
Either way, the machine should not be acting like this.
Being that it is drifting after moving the vise, would it be possible to rule out the ballscrew?
Also, as interesting as this is, I had a different problem right before this problem, which MIGHT be affecting the machine.
Last week the machine threw up a low voltage alarm.
My electrician wired in four 50 farad capacitors to boost the voltage on the third leg, I am running the VF0 on a phase converter in my garage.
This is the first job that I have ran after the fix, and now I am experiencing the -Y- axis shift issue.
Could it be possible that the -y- axis motor is experiencing some issue with the addition of the capacitors?
I wouldn't think so, I would get a over voltage alarm.
I just thought that I would mention the previous problem because the fix might be the catalyst of the new problem.
Let me know what you think

[StealthAz]

Hey Haastech,
What I originally was experiencing was a shift of about .009 in the -Y- axis after the part had ran.
I saw the problem happening and then indicated in the part and ran it, only to find out it shifted .009 after the part had ran.
Also, the shift is always happening towards the positive direction, coordinate shifts up, towards the back of the machine.
I moved the vise to the closest t-slot in the table, towards the operator, hoping to rule out the ballscrew.
I then indicated in the part before the first tool, and then indicated the part after every tool ran.
I noticed the machine drifting about .002 after every tool.
After about 4 hours of indicating the part and running the machine, I noticed that the machine wouldn't drift between some tools.
I only had 7 parts to run after I decided to indicate the part in after every tool.
Once "it seemed" like the machine was holding position, the job was done.
Either way, the machine should not be acting like this.
Being that it is drifting after moving the vise, would it be possible to rule out the ballscrew?
Also, as interesting as this is, I had a different problem right before this problem, which MIGHT be affecting the machine.
Last week the machine threw up a low voltage alarm.
My electrician wired in four 50 farad capacitors to boost the voltage on the third leg, I am running the VF0 on a phase converter in my garage.
This is the first job that I have ran after the fix, and now I am experiencing the -Y- axis shift issue.
Could it be possible that the -y- axis motor is experiencing some issue with the addition of the capacitors?
I wouldn't think so, I would get a over voltage alarm.
I just thought that I would mention the previous problem because the fix might be the catalyst of the new problem.
Let me know if you need anymore information.

[s00073055]

what may have happened is that the encoder which is attached to the rear of the Y motor shaft with 2 very tiny allen key screws may have become loose as there is no key way the encoder is totally reliant on the tightness of theses 2 screws, The Z motor works the same way have a look at it to see what you think first. The encoder is covered by a round lid secured with 3 allen key screws.

[Machineit]

Also check to see if the vise and the jaws are tight, I have seen it!

[StealthAz]

Thanks for the advise!
I have run these machines for years but never opened one up to work on it.
I just started my own machine shop about 4 months ago and started running this machine.
Could you walk me through the procedure?
I know that might take some time.
Thanks!

[StealthAz]

Oh yeah! I have seen that all too often.
I got both the vise and the jaws tightened down with a cheater bar.
They are firmly secure.

[s00073055]

Thanks for the advise!
I have run these machines for years but never opened one up to work on it.
I just started my own machine shop about 4 months ago and started running this machine.
Could you walk me through the procedure?
I know that might take some time.
Thanks!

What I would suggest is to look at the Z motor set up first to see the encoder and how it is attached just remove the round lid from the Z motor on the top of the machine. now your Y motor is located at the rear of the machine behind and under the electrical cabinet locate it and see how you feel about working on that motor my machine is a 94 vfo

[Krishell]

The PSU didnt deliver a stable -5V signal to our haas. it did crazy **** like that some times.

[haastec]

If the amount of shift is progressive in one direction as you stated, then it does give the impression that something is slipping. Some possibilities are that it could be the encoder slipping on the motor shaft, it could be the motor coupling itself slipping; possibly caused by a sheered key on either the ballscrew or motor side, or it could be a bad encoder alltogether.

First make sure that all of the machine voltages are good. Incoming power, machine transformer taps set at proper range, DC Buss voltage, low voltages to pcb's, etc.

Next you can move to checking out the motor. Unfortunately you are having issues with the Y-Axis motor which means you will have limited visual access to perform your tasks at hand. You can look at the Z-axis motor as suggested, but I usually recommend using the X-Axis motor as a visual example of what you will be looking at because it is easier to access. For safety, if your macine is equipped with an actual counterweight, I highly recommend a safety bar under it while working on the Y-Axis motor.

The X and Y axis motors are identical so take all directions and apply to the Y-Axis. Access the x motor by pulling back the left side cover. You will see the motor with the cap on the back covering the encoder as described earlier. In front of the motor you will see a small casting with a cover on it. Under the cover you will find the motor/ballscrew coupling. First, confirm that the screws for the motor coupling are tight. The coupling has drive keys on both sides but the screw is for a locking collar that works similar to a collet to secure the connections You will also find a locking nut for the ballscrew in front of the coupling; verify that this is tight as well. If all of those components were tight, you can check to make sure the drive keys for the motor and ballscrew shaft are still good. Loosen one side of the motor coupling, then the motor can be unbolted and is free to be removed from the machine. Inspect the key on both sides of the coupling.

Re installing the motor can be the tricky part because you have to line up the keyways blind. Take a big dose of patience as it can sometimes be pretty frustrating, just keep at it. I usually like to have the coupling installed on the ballscrew side first, then install the motor, not sure if it makes any difference, but that is just me. Did I say patience already.

Normally I am like to do one fix at a time, but if you are going to the trouble of pulling the motor for inspection, I would be inclined to suggest swapping the X and Y motors also. This way you can see if the problem changes axis as well.

Hope this helps.

[s00073055]

https://diy.haascnc.com/sites/defaul...pdf?0=%253F206

You can download a service manual from the link above which I found to be very useful.

[salahi]

Hi, I bought a milling machine like your milling machine. Unfortunately, the parameters and all settings have been deleted. It does not run programs. If your machine model is vf-0. Please send me the general parameters and settings of the milling machine so that my machine can work again. Let me start, thanks, dear colleague [1993] vf-0