Hello Guest it is February 25, 2021, 06:15:37 AM

Author Topic: Machine wont zero after Homing  (Read 19595 times)

0 Members and 1 Guest are viewing this topic.

Offline Tweakie.CNC

*
  • *
  •  8,653 8,653
  • Super Kitty
    • View Profile
Re: Machine wont zero after Homing
« Reply #20 on: April 20, 2014, 05:06:28 AM »
Hi Piccyman,

Those Velocity and Acceleration settings are fine also although I think you may run into problems with the axes mass if fitting a Porter-Cable style of router spindle.

In my view, the object of the exercise is not to have the fastest machine on the planet but rather the most accurate and reliable.

You may want to look again at your ‘steps per unit’ as according to my calculations…

20 tooth pulley, 3mm pitch belt, 200 steps per rev stepper, 1/16 micro-stepping equates to 53.3333… steps per mm.

36 tooth pulley, 2mm pitch belt, 200 steps per rev stepper, 1/16 micro-stepping equates to 44.4444… steps per mm.

This, of course, assumes that your belt is accurate (has not stretched etc.).

Tweakie.
« Last Edit: April 20, 2014, 06:21:58 AM by Tweakie.CNC »
KEEP SAFE !
Re: Machine wont zero after Homing
« Reply #21 on: April 20, 2014, 06:23:28 AM »
I have just checked  the 2mm pitch on the y axis pulley is 30t

so both steps / mm should be around 53.333


http://calculator.josefprusa.cz   this is handy
« Last Edit: April 20, 2014, 06:38:20 AM by piccyman »
Re: Machine wont zero after Homing
« Reply #22 on: April 20, 2014, 09:05:12 AM »
Thanks Tweakie.

I have a bit of shielded cable. I will try your suggestions on one axis only and see if it that makes a difference.

I have spent an age wiring all this - this week. Not to keen on doing it all again to find no difference.
If i can get a smooth running motor, then I will be well chuffed. You really think it will work?

Best Regards
Martin.
Re: Machine wont zero after Homing
« Reply #23 on: April 20, 2014, 09:47:07 AM »
its not the shielded cable, mine doesn't reset all axis to zero after auto homing, but i wouldn't expect it too

After you auto home, move x and y axis to say Z 50 and X 50, then press zero x and zero y buttons , you can do the same with z axis

after all 3 are zeroed move the axis's to a new location, then press the goto zero, i am not sure you really need the axis set to zero after rehoming, as far as i know you would normally move all 3 axis to the work zero point and then press zero x, zero y button and z zero button, this is now your working zero, and goto zero will take to back to your work starting point.


i might be wrong
Re: Machine wont zero after Homing
« Reply #24 on: April 20, 2014, 10:32:33 AM »
Well i have tried disabling all my other axis and switches and just running the x axis.
I also pulled all the boards out of my box away from the power supply and kept all the wiring separate.
I also used thicker wire for the power supply to the driver.
That made no difference.

Piccyman - have you got your motors running 100 smooth now, with no skips, notches or bumps ?
Just for information I don't think its the motors either because the NEMA 17 for my z is skipping as well as my NEMA23's on x & Y.

Any other suggestions ?
New drivers, motors, USB board or all of it?

Cheers
Martin
Re: Machine wont zero after Homing
« Reply #25 on: April 20, 2014, 01:14:28 PM »
I wound down the current on the 23's it made them smoother, there is a pot on the driver board, with current markers, you can set it with a voltmeter, mine are now .8v
Re: Machine wont zero after Homing
« Reply #26 on: April 20, 2014, 02:09:05 PM »
Thanks Piccyman - I did try that, but i will try it again tonight. I think I mainly tried it higher....
What accuracy do you get?
Any skips jumps and bumps?

Thanks for your help
Martin
Re: Machine wont zero after Homing
« Reply #27 on: April 20, 2014, 02:26:51 PM »
no skipping, but it made noises like it was struggling, if you push you x axis by hand with the power off, it makes the same noise, i wound the current down and switched to clean vista, that sorted it.

 i have built mine differntly to yours, the motor drivers and breakout card are mounted on the x axis.

I am not sure where all the noise comes from if it does at all, however bunching all your cables up is not a good idea noise wise.


maybe someone can enlighten me

Re: Machine wont zero after Homing
« Reply #28 on: April 20, 2014, 04:14:11 PM »
Nope that didn't work for me... In fact at a lower current it got worse until the motor just hummed and didn't move.
Just noticed my power supply has a variable voltage. Will try tweaking that next. What voltage are you running at ?

Are you using VSlot extrusion on your machine?

Martin
Re: Machine wont zero after Homing
« Reply #29 on: April 20, 2014, 04:18:56 PM »
Just to say - These skips just sound like a little blip. Not a graunching jump. However if you watch the cutting head,
you can see a slight jiggle as it happens sometimes. I am sure that's causing the in-accuracies.

Cheers Mate
Martin