Need help with TREE 310 servo problem

[num1bryanp]

Hello Underthetire, There must be a good story to go with your user name! :-)

This morning I went out swapped P3 (from actual current to Absolute) on the X axis, removed the belt, referenced the machine, exercised the X axis, and it sounds the same.

I also looked at the input signals, and like before I am seeing ~+-10 volt signal on (red wire) pin 1 (differential input) and no signal on (black wire) pin 4 (signal input). This makes me think it is single ended input signal, not differential input.

Would it cause any major problems if I configured the card for single ended input?
I would move P2 to off, for single ended.
I would move inputs red to pin 4 (signal input) and black to pin 2 (common)
leave belt off, and test?

Thanks,
Bryan

[num1bryanp]

Update,

As Mikecolee suggested #2 I have disconnected the drivers from the controller. I have the inputs set to 0 volts for the Z & Y axis, and X has a battery base input of +9 to -9 volts.
I can adjust motor speed from end to end with no driver errors.
I have tested the X driver in both single ended and differential configurations. The motor seems to spin up to the same speed in each direction, using either mode of input.

Question is +-9 volts enough for testing, or do I need to make a +-10 volt supply?

Is there a ratio of volts/rpm? Or does the motor rpm range just vary from 0 to max based on 0 to 10 volts input.

Thanks,
Bryan

[num1bryanp]

Update,

I started adjusting the X axis driver today using the power supply.
When I started the motor would turn up to about 1k rpm with max of input 9 volts. After adjusting the Signal pot, I would guess it's about 3-4k at max input.

Next, I adjusted the Current to max, there was no change in how the motor responded to the input.

After marking the zero point on the power supply pot, and setting it there, I reattached the belt.

With the X axis table belt attached, I was not able to get the motor to spin up even close to what I had seen before.
I would say it was only 1/5 of the unloaded speed at max input. It is acting just like when the controller had control, rough movements.

This driver has 5 test points, can I take readings with a scope or meter to more accurately tune the board?

Thanks,
Bryan

[mikecolee]

Hey Bryan,

You are making progress. Good work! Sounds like it's a servo amp or servo motor problem after all?

Regarding input voltage vs RPM, I believe it's a linear relationship. ie. 10vdc = max rpm, 5vdc = 50% rpm and so on... Maybe someone more knowledgeable can confirm that?

Regarding the slow/rough X axis table movement you are seeing when the belt is attached: Make sure nothing mechanical is preventing easy rotation of the ball screw, I'm guessing you checked that. If the ball screw rotates easily then you can measure the current the servo motor is drawing with a VOM. If you find the motor is drawing more than 15 amps with slow/rough table movement then you'll need to look at the servo motors as that would indicate they are not providing full torque when the servo-amps are providing maximum current. If however the current draw is small then it's a servo amp problem in that the amps are not providing the necessary current to turn the servo motor with maximum torque.

Hope this makes sense? torque generated by the servo motors is a function of the current supplied by the amp. Check the specs on your amps/motors...

Hope this helps!
Good luck!

Mike

[num1bryanp]

Update 5/8/16

I have tuned the X driver to max speed and max current, and have tuned it to half speed and max current, with no big changes.

With belt attached, if I increase speed quickly or give a input greater than ~100 IPM I get a clunking sound, I have also reduced the ball screws preload to zero with no change.

If I have the table moving at ~10 IPM, and add resistance to the motor shaft, I get the same clunking sound I get when trying to move fast.
I am guessing, either my tuning is wrong, or the ball screw and slide has too much resistance. If the motors are rated for 40 lbs, I would not think it should be a problem.

When I turn the ball screw by hand, belt off, I would say it needs a little more torque than my handles on my old Bridgeport mill.
I put a inch/pound torque wrench on the motor shaft, with the belt attached. Then turn the shaft either way and it takes ~10 inch pounds of torque while moving by hand.

Questions:
What inches/pounds of preload should I put on the backlash bearings?
What should be the max preload resistance torque I should see on the ball screw shaft?
Should I be tuning for max speed on the motor?

Thanks,
Bryan

[mikecolee]

Hey Bryan,

You should tune according to the instructions in the amp manual. Tree says rapids should be 200ipm. screw pitch is .2" and reduction is 2:1 so 200ipm comes out to be 2k servo motor RPM. No idea about preload or torque for rotating screws? Would expect them to offer similar resistance to a manual mill like your BP.

Mike

[num1bryanp]

TREE 310 Update 051516,

Very big thanks to all of you, giving so many great ideas and knowledge!!!!

Now that I have disconnected the controller and have an isolated test supply, I have retested all boards with all motors, tuning each time. (As recommended)

This is what I found:

_______X driver___Y driver___Z driver
X motor__Fails_____Fails____Ran Badly
Y motor__Fails_____Fails____Ran GOOD
Z motor__Fails_____Fails____Ran GOOD

Fails = Motor turns, but with no torque.

Conclusion: X, Y drivers, and the X motor need help.

Questions:
Could the X motor just be full of brush dust causing problem? (Also, the X motor is more likely to have coolant running on it and it shows the wear of saddle collisions.
Is there any fixable failures for this motor? (Brushes look good)
Can I take the MTE-4534-SPECIAL motor apart and look for problems?

Is there any common failing parts on the LD3015HS160 driver I could just replace, like the power FETs and or electrolytic compactors that could be dying with age? Does anyone have a schematic for this driver, It would really help with fixing it.

Thanks,
Bryan