Hello Guest it is July 23, 2019, 01:51:25 AM

Author Topic: Y axis move when just X axis is homed  (Read 8656 times)

0 Members and 1 Guest are viewing this topic.

Re: Y axis move when just X axis is homed
« Reply #20 on: December 23, 2010, 06:26:14 PM »
Mach version R3.042.40

Switches are your basic sealed pin switch with roller lever.

Pretty sure it is not a switch thing or any other mechanical issue as Mach knows what is happening and is the one moving things...I can imagine no reason for a ref-x to ever move y but it seems to happen.
The idea of a modified macro seems possible...maybe something got changed by accident in the latest version of mach...pretty sure I didn't change anything
and I reverted to a alternate XML from someone with similar setup and I believe that would get me fresh macros too...at least looking in the macro directory
it appears they get created new when a new xml is used....at least the modification dates are old.

If anyone wants to try this here are the steps to see the problem..

First do a Ref-All with the homing/limits config set to auto zero the axes when homed.  (kinda the normal situation)
now with the machine at zero, change the homing/limit screen so that Y is not auto zeroed on home.
now go to the diag screen
click ref y a few times y moves as expected.....typically mine ends up at .0001 or similar after a few moves I gather my switches are not super rigid and of course I have back lash and such.
At any rate Y is not zero but it is pretty close to its home position, this is important if it is zero you won't see the problem (also note that the ref-y led is red)
now click ref-x (I would expect only X to move as it seeks the switch)

what happens for me is X moves back toward the switch (since it is slightly backed off the switch from the previous ref-all)
as X is moving Y is also moving (in my case away from its switch)
X reaches the switch backs off it and resets it's DRO to zero
Y is now reading and presumably is at something like .05 not the .001 you last moved it to.

there are lots of combinations that result in this odd dual motion.  note that if you followed the steps above and ended up where I did
now go to the main screen and hit ref-all x and z will of course end up at zero since they are still set to auto zero.  Y should also (I think) end up close
to zero since we have nothing that should cause it to be anything but where it should be from the initial ref-all at the beginning but in my case it won't be close to zero, it will be around .05.

I don't think this really affects things too much in the normal course of events...typically you home all and have the auto zero set
But in some cases I do home an axis independently (often Z which exhibits the same behavior)
Seldom do I work so close to the home switches and being off them a more significant amount seems oddly to prevent the double motions.

I did have a case just recently where I am suspecting this odd motion resulted in a couple broken tools when Y moved unexpectedly
as I was trying to recover from a fault condition.

Darren
« Last Edit: December 23, 2010, 06:30:38 PM by macdarren »

Offline Hood

*
  •  25,849 25,849
  • Carnoustie, Scotland
    • View Profile
Re: Y axis move when just X axis is homed
« Reply #21 on: December 23, 2010, 06:45:14 PM »
So are they normally Open contacts, just I would have expected Active Hi settings if Normally Closed.

Anyway regards testing, afraid I cant do that myself as on my machines I do the homing external to Mach via my servo drives. Hopefully someone else will do the test for you.

Hood

Offline BR549

*
  •  6,874 6,874
    • View Profile
Re: Y axis move when just X axis is homed
« Reply #22 on: December 23, 2010, 08:08:17 PM »
One question do you normally use the homing process to NOT zero the axis when you home???

(;-) TP

Offline ger21

*
  • *
  •  6,288 6,288
    • View Profile
    • The CNC Woodworker
Re: Y axis move when just X axis is homed
« Reply #23 on: December 23, 2010, 09:18:47 PM »
Sounds like you have a formula set for the Y axis. Check that first, UNder Function CFG's>Formulas.

Quote
click ref y a few times y moves as expected.....typically mine ends up at .0001 or similar after a few moves I gather my switches are not super rigid and of course I have back lash and such.
At any rate Y is not zero but it is pretty close to its home position, this is important if it is zero you won't see the problem (also note that the ref-y led is red)

Clicking Ref Y should result in a green LED. If it's red, it's not being Ref'd.
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html
Re: Y axis move when just X axis is homed
« Reply #24 on: December 23, 2010, 10:09:45 PM »
Noticed one thing, well 2.
 Gerry, looking at the XML, formulas are not enabled and all are blank.
The other thing is Backlash is enabled and configured. SS is not there yet, is it ? If not, could that have any effect ?
Rc

Offline BR549

*
  •  6,874 6,874
    • View Profile
Re: Y axis move when just X axis is homed
« Reply #25 on: December 23, 2010, 10:26:56 PM »
SS? HUM Does not the SS control homing directly , not MACH ?

Just a thought, (;-) TP

Re: Y axis move when just X axis is homed
« Reply #26 on: December 24, 2010, 11:44:06 AM »
I disabled the backlash adjustment to see if that might be the problem, but the problem persists.
SmoothStepper is installed and being used by Mach.

I notice from the SS site that maybe it does control the homing somehow....there is some old talk about that on their forum.
But I don't think it could just be the SS messing up if the DRO in mach changes, but I could be wrong there.

Re: Y axis move when just X axis is homed
« Reply #27 on: December 24, 2010, 11:55:51 AM »
One other item looked strange to me.
(just suggesting thins that I would try, no expert by any means)
The Homing Speed % looks high, wonder if Mach is in control of that or not.
Might set them at 20% or so just to see ?
Grasping at straws here.

Offline Jeff_Birt

*
  •  1,107 1,107
    • View Profile
    • Soigeneris
Re: Y axis move when just X axis is homed
« Reply #28 on: December 24, 2010, 12:08:06 PM »
I have been pondering what might be happening here as I've used the SS with homing a lot and not experienced this issue. The only things i saw in your XML file was that you were using the same inputs for homing/limits on each axis. To simplify troubleshooting I would enable only the homing inputs. Also in the SS configuration you have really large numbers in for homing distance. I would back these down to something reasonable, you should never need anything more than the max axis travel in there. Also zero out the Max distance for master and slave axis distances, this may be confusing the plug-in.

There is also a beta plug-in out that has had a lot of work done on homing. If nothing else works it might be worthwhile to

http://warp9td.com/files/SmoothStepper_v16bdg.m3p
Happy machining , Jeff Birt
 
Re: Y axis move when just X axis is homed
« Reply #29 on: December 24, 2010, 05:40:45 PM »
Hi Jeff,

I tried your suggestions in order, first turning off the limits then reducing my large homing numbers...I tested with the above test at both steps but no change.
I then installed the plugin you linked to and amazingly the problem was gone.  So I think it is now related to the SS plugin.  The new plugin however has some other issue
related to homing....first it seems to keep turning on the auto-zero in Mach...not sure how but I turn it off and then after I do a ref-all it is back turned on.
Even weirder is even when it is showing as on sometimes the Y-axis (the only one I tested) seems to not zero on home....getting stuck at .0001 usually.
It almost seems as if it is a false auto zero condition showing in mach .. maybe because somehow the plugin does something tricky but then things are not really auto zeroed.
I think this is clearly better than the previous condition where Y moved when it should not, though it might really be partly a mask for the condition as
it forces the Y to zero or .0001 depending on what I don't know but in that situation it doesn't move the Y and with the old plugin it only moved the
Y when it was non zero, and de-refed a condition which the new plugin seems to simply prevent from occurring.

Well at least this issue has lead to where the problem is and I guess the SS people are working on it since the function of this
new plugin is clearly different from the old one.

thanks
Darren
« Last Edit: December 24, 2010, 05:43:14 PM by macdarren »