All-in-one problems: motors jump when commanded

[cncsnw]

AP wrote:

When in MDI mode when I try and jog, it trips the estop and if I try and move any axis manually in MDI it violently spins a couple revolutions and trips the estop.

Typically that either indicates a lack of encoder feedback; encoder feedback connected to the wrong axis inputs; or reversed motor polarity.

First, with E-stop pressed, go to the PID configuration screen: F1/Setup -> F3/Config -> "137" -> F4/PID.

The axis encoder positions are displayed, among other data, in the lower center of the screen in a column labeled "Abs Pos".

Turn each motor by hand.

Do the encoders count on the correct axes? X should be on the first line; Y on the second line; and Z on the third line.

Do they count both up and down consistently, and by the right amount? For example, if you have 2000-line encoders, then you should see the position count up or down by about 8000 counts when you turn the motor one revolution; and you should see the position count back approximately to where it started when you turn it back the other direction one revolution.

Next, while staying on the PID Configuration screen: release E-stop; select Slow, Incremental, x10 jog; note the current encoder count position on the axis you want to test; and press the axis Plus jog key.

Assuming the axis jumps at high speed as you describe above, did the counts go plus or minus?

Press and release E-stop, note the new counts, and press the axis Minus jog key. This time did the counts go minus, or plus?


At this point I am assuming that you do *not* have "Direction Reversed" set to Yes on any axes. That selection is on the Machine Configuration -> Motor Parameters table. At this point, you should have all axes set to No. Later, after you have controlled motion on all axes, then you can use the "Direction Reversed" setting to match servo motor rotation to apparent tool movement.

If, with "Direction Reversed" set to No, you get a violent jump in the opposite direction from the direction you tried to move, then you need to reverse the polarity of your motor power leads.

[cncsnw]

AP wrote:

running windows
running CNC11 v3.01 rev 15 (Is this the latest?)

No, there have been significant updates. You can download the latest CNC11 software for Windows through the links here:
http://ajaxcnc.com/ajaxbb/viewtopic.php?f=20&t=63

I have a jog pendant
I replaced the encoders with new ones provided by Ajax

The X and Y axis seem to count up and down in the right direction about 16,000
counts per revolution of the handwheel. The z axis is a little more difficult
to turn manually, so I dont know about z.

That would presumably indicate that you have a 2:1 pulley ratio on X and Y, so that one turn of the manual handwheel on the ballscrew causes two turns of the motor.

While still in PID mode, when I try to jog the machine, it will go in the right
direction fast for a couple revolutions and then immediatly trip the estop.

Just to confirm, do you mean that when you press the X+ jog key, the X axis encoder position jumps in the positive direction; and when you press the X- jog key, the X axis encoder position jumps in the negative direction?

For some reason under motor parameters, I dont have the option to reverse
direction like I see in the instruction manual.

From the main screen, press F1/Setup -> F3/Config -> "137" -> F2/Machine -> F2/Motor.

Do you see a screen something like this?

CNC11 Machine Configuration Motor Parameters

With v3.01 r15 you will probably have only five axes on the screen instead of eight, but otherwise the table should be the same. Do you perhaps have a monitor or display issue that is cutting off the right side of your display?

Do you think my problem is due to the encoders counting the way they are?

It still seems like the most likely possibility. Try swapping the polarity of the motor power wires on one of your axes, and see if the problem changes or goes away.

[PCM]

I just updated to the latest CNC 3.01 update.
I just checked the pulleys, and I do believe they are 2:1.
And yes, the axis jumps to the proper direction, both ways, pos and neg. x and y axis.
I tried swapping the motor wires on the x axis and when I try and jog the motor,it doesnt move, it just makes a buzzing noise, but does not trip the estop. Just stays in that spot under load. The green bar under the x axis number also fluctuates a little.

My motor parameter screen looks just like your picture, except the axis numbers have dashes through them and the dir. rev. and screw comp lines are not even there. I tried playing with screen settings on my computer and Im also going to try and get my hands on a wide screen display and see if that fixes it.

any ideas?

[PCM]

Ok, I figured out why the part of my motor param screen was missing, it was due to my computers screen setting. I can see the dir. reverse and screw comp.

[cncsnw]

I tried swapping the motor wires on the x axis and when I try and jog the motor,it doesnt move, it just makes a buzzing noise, but does not trip the estop. Just stays in that spot under load. The green bar under the x axis number also fluctuates a little.

That is a lot closer to what it is supposed to do. The buzzing is probably a matter of servo tuning. If it is not too extreme, you can address it later.

Try selecting continuous jog mode (press the INCR/CONT button so the LED next to INCR goes out). Then jog X in each direction. Does it move steadily to a new position, and stop and hold position there?

[cncsnw]

AP wrote:

Ok thanks, Will I be able to setup this machine completly without a working
demo version of cnc11? If not, can you please send a code.

In the current CNC11 software you can navigate all the setup and configuration menus, and you can use jogging controls, without an active demo code. You will need an active demo code to run any cycles (including MDI).

I can get you a demo code if you post your System ID number from the F1/Setup screen.

[PCM]

I swapped polarity on the Y axis as well and got the same results. When I try and jog the axis the motors just buzz a little and dont move and wont stop buzzing until I hit the estop. Also it makes no difference what jog speed it is on, it just does the same thing...Nothing!

[PCM]

OK, I just tried again in the PID screen to jog, and now I have movement on the X and Y Axis while jogging. The Z axis seems to trip the estop regardless if I swap the wires.

[PCM]

I just figured out why the z axis was binding and tripping the estop because it has an internal brake which I knew it had, I just didnt know it needed power to free it up. What should I do with these two z axis brake wires? It needs 90vdc to free the brake, Is there an input for this or should I remove the brake?

[PCM]

Ok, after running the autotune program, I seemed to have gotten the x and Y axis moving and jogging around pretty good although they are still buzzing a little and show it on the green bar graph. As far as the Z axis, I cant get it to do anything other than show that there counting on the DRO, but I cant get it to jog for me. Also, when I go to the PID Screen the machine estops out within a few seconds of being up without even doing anything. When I run the autotune and it goes through the x and Y axis just fine, but when it trys the z axis, it just does nothing. The motor still has electrical drag that keeps the motor in place, and if you trie and move the servo motor by hand it shows resistance on the red and green bar graph. Any suggestions where to go next please?