Interact 412 X-Axis issue

[smirob]

Well Gentlemen,
I need to come back to the well and ask a question with regard to my Bridgeport Interact 412. I have taken the X Axis servo out, had it bench tested and taken apart, an then remounted it. I am getting the same problem I had before, however, not as bad.

The problem is that the axis is jogging or hunting back and forth when homing or running. Before I removed the servo, it would not home in the X, and I couldn't go any further. After the re-mounting, I can sometimes skip beyond the X axis homing function and start running a program. When the program runs, when a move is called in the X axis, again, it will job vigorously left and right. It still looks like the program is running normally, but obviously, the X Axis is going Balistic. I'm getting feedback for the Axis, at the control on the screen, however, it almost acts like its lost postition and is trying to find it. I swapped x and y cables just to be on the safe side with the cables and it stayed with the servo. It seems to me I was reading somewhere here, that there is some screw that may need adjusting, inside the servo motor. Like a tuning screw or something. Does anyone have any idea, if this is the case. Maybe I'm all wet on this, but I'm scratching my head on this one. If you don't understand what I'm reffering to, I can see about posting some video of what the axis is doing.

Thanks for the help.
-Rob, MI

PS- It has a Heidenhain 155 control.

[machintek]

Just swap the X and Y motor. If it follows the motor, it is the motor. Then get it rebuilt. Sounds like a compromised tach loop.

George

[smirob]

Its possible it could be the motor. I will see if I can swap them out tonight. The electrical guy I had look at the servo, said the brushes and everything looked in good shape when he had it on the bench taken apart.
Frustrating problem.

Thanks,
Rob

[gus]

what you describe sounds like the tach is over responding, that the drive is severely out of adjustment. WEre the tach not feeding back, it should take off, I would think, unil it reached a gross positioning error. If this came on suddenly I would suspect the drive card.

[smirob]

Once in a while, you are correct, the axis will take off until it hits the hard stop limits, or I will get a Gross Positioning Error.

So, are you saying more than likely, my servo needs tuning or some adjustment? If so, is there any printed documentation that would assist me in this endeavor?

Thanks for the replies thus far.

-Rob

PS-For the record, I just bought the machine, a month ago. The owner said he was cutting parts before he crated it up for me. I'm trying to get it back to normal, as best as I can.

[gus]

If it takes off it is not likely and adjsutment, more likely something is broken

[smirob]

That's the funny thing. It does take off until I hit the E-stop, and physically roll the pully for the axis 3 or 4 inches away from where it was when I hit the E-stop. And it doesn't do it every time, only sometimes.

Unfortunately, I wasn't able to get to it tonight, hopefully tomorrow evening. I am a 2nd shifter, at my real job.

Regards,
Rob

[smirob]

Ok, here's where I'm at right now.

I swapped the cables of X and Y, at the card side. I was thinking that maybe if everthing were the same, the machine would just have a problem with the limits in the parameters and I might be able to see if the hunting issue goes away. Well, the machine took off in both axes and I had to hit EStop. Tried it a couple times with same result and a Gross positioning error.

So, I swapped out the X and Y Servo Motors. Well, the issue stayed with the X axis. So, from what I can gather, this means either the board is faulty, or the X axis cable is faulty. It that correct? Those were the only 2 consistant things in line in that Axis.

Also, I'm thinking of replacing the cable, just because it is the cheaper of the two choices. Where can I find a reasonably priced replacement?

If the board is toast, can someone recommend a repair shop?

Thanks again for all the help.

-Rob

[bherr]

smirob,
don't mean to jump on your post. but couldn't help noticing that you have the same BP interact as I do, if its a Series II. do you happen to have the maintenance manual??? If so maybe I can help you offset the cost of a new cable or board. I'm willing to pay to have you copy it and send to me.

Please let me know!

email bherr@atlanticbb.net

thanks for your time and hope to get your problem worked out. I'm having problems with my spindle shutting down during a cycle run.

Ben

[bherr]

smiroc,
Just noticed you have a 412 and I have a Interact 4. sorry about that.

ben

[smirob]

Ok,
Well, here's another interesting twist to my problem. I have a friend who has the same model and year Bridgeport Interact 412 that I do, and he offered to pull his axis board and put it in mine. So, we did just that. When I fired the machine up, to my shock, the problem was still with the X Axis, and its jerking or hunting back and forth.

So, to re-cap, here's what I've done to troubleshoot, thus far:

1) Replaced the encoder bulb
2) Swapped the x and y cables at the boar end, (unable to easily do that at the Servo motor ends).
3) Pulled the X Servo, and had a tecnician go thru it..
4) Swapped the X & Y Servo motors.
5) Swapped out the Axis boards with a working replacement.

The only thing that remained constant throughout the entire troubleshooting process, is the X axis cable. So, I'm thinking that I should just buy a replacement cable. Which leads me to the question of where I can find one. I measured my existing Cable and its 16 foot long.

I'm sure having a 'head scratcher' problem here. Any further comments or help would be highly appreciative.

Best Regards.
Rob, MI

[machintek]

The original cables were PVC covered. The parts exposed to the elements (oil and coolant) get very hard and brittle.
I suggest you call EMI. Bart told me he sells urethane covered cable that does not dry out and get brittle and uses very finely stranded copper wires for flexibility without breakage. Unfortunately, I cannot give you another choice at this point.

George