Hello Guest it is December 10, 2019, 05:10:25 PM

Author Topic: Am I loosing Steps, and what should I do  (Read 13986 times)

0 Members and 1 Guest are viewing this topic.

Re: Am I loosing Steps, and what should I do
« Reply #40 on: August 01, 2016, 02:26:11 AM »
 "Pulse + to scope A in and scope ground to pulse -"

This is not recommended as it could damage the line driver on the Jamen board, rather connect both channel 1 and 2 ground to ground and channel 1 to pulse plus and channel 2 to pulse -.
This will show the full differential output.

This link has some explanation on measuring differential signals.

http://electronics.stackexchange.com/questions/76514/how-do-i-measure-differential-signals-like-rs-485-or-dmx-on-an-oscilloscope

Kevin

Offline g21

*
  •  15 15
    • View Profile
Re: Am I loosing Steps, and what should I do
« Reply #41 on: August 01, 2016, 07:56:01 AM »
Hello KevinRSA

You are correct, I not realize this was a differential input although I downloaded his driver manual. My mistake, let's see what RussH finds out.

Lowering the current is a quick and easy thing to try I think. Checking if the ballnuts are not loose in his machine is also quite easy.

Thanks for straightening this out and correcting my mistake.

G21

Offline russh

*
  •  40 40
    • View Profile
Re: Am I loosing Steps, and what should I do
« Reply #42 on: August 03, 2016, 06:57:24 AM »
Ive taken a video of the ball screw action, let me know what you think.

Im just working on taking the oscilloscope readings


https://youtu.be/q4UkBnZKrwg

Offline russh

*
  •  40 40
    • View Profile
Re: Am I loosing Steps, and what should I do
« Reply #43 on: August 04, 2016, 08:56:04 AM »
Ive taken a video of the ball screw action, let me know what you think.

Im just working on taking the oscilloscope readings


https://youtu.be/q4UkBnZKrwg
Re: Am I loosing Steps, and what should I do
« Reply #44 on: August 04, 2016, 08:45:51 PM »
You can see the ballscrew shaft moving up and down! You have a problem with the bearings at the end(s). The shaft should not move at all and even be preloaded against a stop so that it has no backlash at all.

Offline Davek0974

*
  •  2,580 2,580
    • View Profile
    • DD Metal Products Ltd
Re: Am I loosing Steps, and what should I do
« Reply #45 on: August 05, 2016, 02:26:41 AM »
I viewed that as play in the spindle?

If you look early on, you can see the spindle nose moving in relation to the spindle body, where its wedged on the wood???
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline russh

*
  •  40 40
    • View Profile
Re: Am I loosing Steps, and what should I do
« Reply #46 on: August 05, 2016, 02:46:54 AM »
I think what your seeing is the spindle sinking slightly in to the wood under the force. I can assure this is not play in the spindle. The ball screw slips and the head bounces back up
.
Re: Am I loosing Steps, and what should I do
« Reply #47 on: August 05, 2016, 03:35:17 AM »
Can we just confirm a couple of things, your early threads said the loosing of steps is on all three axis. If this is still the problem it cannot be mechanical it must be electronic. As I said early on in this thread my problem with my machine was with the weight of the z axis motor and slides overriding the motor trying to stop it falling and the failure of the damper to help it back up. if you say slowing the slides down reduces the errors I still think its the acceleration and deceleration parameters on your machine or the pulse settings. Surely if its on all three axis they cant all have a mechanical fault even if its Chinese built. Pursue the electronic route and settings. Jim
Re: Am I loosing Steps, and what should I do
« Reply #48 on: August 05, 2016, 10:37:30 AM »
Hi Russ, I can't see from the video that there is any problem there(especially not one that would create a 1.4mm error). I would go with Jim's advise and pursue the electronic suspects.

Like I said in my mail to you, I would expect to see a reasonably clean square wave on the pulse output, Once we have established that the pulse output is indeed good I would be keen to see if reducing the steps/rev has any effect.

Kevin

This is the Pulse+ wave form from a Jamen controller
« Last Edit: August 05, 2016, 10:46:11 AM by KevinRSA »

Offline russh

*
  •  40 40
    • View Profile
Re: Am I loosing Steps, and what should I do
« Reply #49 on: August 10, 2016, 01:12:57 PM »
Bit of a delayed update, work got in the way of me running more tests.

Right I stopped stripping down the machanics and reverted back to the electronics as recommended. To confirm, this issue was noticed on all 3 axis, with the Z axis being the mostr prominent.

As you have probably seen from previous posts, I have stripped back the machines electronics right down to the requirements of only the Z Axis.

As such, I have testing the Pulse + signal as per Kevins photos. Below is the results of this test. The first image is the overall signal. The second image is a zoom in on the start of the signal, wasnt sure if that was class as undesirable noise and if it would cause any issues. The third image is just the setting of the osiciscope in case I had set anything wrong.








I also ran through all the voltage pre controller again, the following is what I recorded.