Messages

31

General Mach Discussion / Re: Am I loosing Steps, and what should I do

« 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

32

General Mach Discussion / Re: Am I loosing Steps, and what should I do

« on: July 22, 2016, 04:34:49 PM »

OK russh I've read somewhere that using the sherline 1/2 stepping option and changing the pulse widths on the ports and pins setup page helps control problems with stepping faults on Chinese machines.
I'm out of my depth on this subject but someone on the forum with that knowledge might be able to help, then again I might be barking up the wrong tree.
PS I'm also in the UK, a Brummie

33

General Mach Discussion / Re: Am I loosing Steps, and what should I do

« on: July 22, 2016, 10:20:45 AM »

Don't like to keep going on but being a mechanical engineer and I'm sure any problems with the electronics would be a thread going through this design of CNC and highlighted on the web. You never said the make of your machine however I looked on the web and decided it was a Chinese SVM1. looking at the specifications it does not have slide adjustment as you told me earlier in your thread  however the specification does state this.

GAS SPRING COUNTERBALANCE DESIGN
To counter balance the machine head to provide smooth Z axis movement and prevent the head from dropping when the machine is powered down, a heavy duty gas spring is installed. This also reduces the work the Z axis motor has to do when lifting the head.

I still think this is the problem with your machine as I recently repaired a similar Chinese machine with a new gas spring as he kept losing steps due to over run as the gas strut was not assisting the slow down and change of direction of the Z axis. The main problem the user was having was every time he put a new component in the depth was a little deeper than the last one. replacing the gas strut solved the problem.
Jim

 

34

General Mach Discussion / Re: Am I loosing Steps, and what should I do

« on: July 08, 2016, 02:17:24 PM »

They are usually strip of metal inserted between the column and the spindle head Vee slides. They take up the slack in the wear of the slides. My Machin has 3 grub screws you adjust to push the jib out to adjust the possible play in the slides. Don't overtighten as you might put a strain on your motors. Jim

35

General Mach Discussion / Re: Am I loosing Steps, and what should I do

« on: July 08, 2016, 01:51:06 PM »

Ok just looked at your video, if its just your Z that's loosing position that's the problem. I noticed you have a dampers fitted, is it still working correctly and then tighten up your jibs. If you overtighten them the Z will loose steps in the Z+ too loose it will be the Z - 

36

General Mach Discussion / Re: Am I loosing Steps, and what should I do

« on: July 08, 2016, 01:36:13 PM »

just checked and the acceleration/deceleration can vary from 0 to 0.25 seconds at the start and end of the axis travel whilst maintaining the velocity.

37

General Mach Discussion / Re: Am I loosing Steps, and what should I do

« on: July 08, 2016, 01:23:18 PM »

Not sure how the velocity V acceleration/deceleration works but I think you can maintain the velocity its just the amount of steps you use to decelerate. One other suggestion is to check you jib strips especially on the Z axis if they are to loose the head drops so fast it overruns your intended stop, I used a digital vernier clamped to the table and kept mechanically measuring the overrun until it stopped at zero. adjusting the jib strip helped with the fine tuning. Early hobbyist machines had a damper/assist shock absorber fitted to solve the Z axis over/under run.  If your main problem is with the Z axis that could be your problem
Hope this helps
Jim

38

General Mach Discussion / Re: Am I loosing Steps, and what should I do

« on: July 08, 2016, 12:44:17 PM »

Trial and error, before you do anything put some slow feeds in and see if you loose steps if you don't it has time to slow down so keep adjusting till its gives you the correct position (manual measured)

39

General Mach Discussion / Re: Am I loosing Steps, and what should I do

« on: July 08, 2016, 12:37:42 PM »

I had the same problem but mine was the acceleration and deceleration of the steppers in the Motor tuning. I had not allowed time for the stepper to slow down. This was more pronounced in the Z axis due to the weight of the vertical column overriding the steppers. Mach counts the steps then moves on, if there is overrun being as there is no travel feed back it continues with the next command.  Just though I would throw in my thoughts.

40

General Mach Discussion / Re: Special driver

« on: April 02, 2016, 08:29:07 AM »

Sorted. I reloaded the program and the icon reappeared. after testing it. It say "pulsing to fast" is there anyway I can slow it down or is it set by the computer?