Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: Charlie_M on March 15, 2015, 04:36:43 PM

Title: Gantry Racking
Post by: Charlie_M on March 15, 2015, 04:36:43 PM

 Hello all,

           my y axis is driven by two motors. One on each side. I have Y slaved to A.  I notice that when I jog from my soft limit position the one side initially steps before the other. Then after the gantry is moving all seems ok. I don't have home/limit switches yet, do I need them so mach knows where the A axis is in relation to the Y axis?  Also I copied all the settings from the Y axis  and pasted them in the A axis in motor tuning. So I know the Y and the A axis are stepping the same. Any ideas? Thanks.

Charlie

Title: Re: Gantry Racking
Post by: ger21 on March 15, 2015, 05:49:54 PM

Do the Y and A have the same softlimit settings?

Title: Re: Gantry Racking
Post by: Charlie_M on March 15, 2015, 07:00:18 PM

 Hi ger21,

            Thanks for the reply. I did not set the softlimit for A. Thanks. I will do that.


Charlie

Title: Re: Gantry Racking
Post by: Charlie_M on March 15, 2015, 08:01:48 PM

 OK So I set the A axis home, limits the same as the y. I get now get raking when I jog. I can see the left side(Y) step before the right side(A). Do I need to adjust the A motor tuning so I don't get racking? I thought if the Y and A motor tuning numbers were the same then all should work.

Title: Re: Gantry Racking
Post by: ger21 on March 15, 2015, 08:58:54 PM

Can you post your .xml file?

Title: Re: Gantry Racking
Post by: Charlie_M on March 16, 2015, 06:02:17 AM

Hi Gerry,

            Here is my xml file. Thanks for the help.

Title: Re: Gantry Racking
Post by: Overloaded on March 16, 2015, 07:24:08 AM

 Hey Charlie,
  That XML is empty.
Maybe the wrong one ?

Russ

Title: Re: Gantry Racking
Post by: Charlie_M on March 16, 2015, 05:23:29 PM

Sorry. Here is the correct one. Just remove the Dot txt and it should be ok.

Title: Re: Gantry Racking
Post by: ger21 on March 16, 2015, 05:59:09 PM

Are you using the parallel port, or a motion controller?
What stepper drives?

Everything looks OK, except your pulse widths set to 0. Try setting them to 5 and see if it makes a difference?

Title: Re: Gantry Racking
Post by: Charlie_M on March 16, 2015, 06:27:45 PM

Hi Gerry,

          I am using a hobbycnc pro driver board. 4 axis. I will try that. Let me ask you something. I read on a forum that I have to have two limit switches on the slaved axis in my case it would be the y axis. After homeing Y then the Slaved axis touches off the limit switch and then mach can sync the two axis. does this sound right?

Title: Re: Gantry Racking
Post by: ger21 on March 16, 2015, 07:16:38 PM

No, the slave axis is always slaved to the master, whether you have switches or not.

I believe what you are referring to is auto squaring the gantry. If you use a separate home switch for the Y and A axis, then Mach3 will unslave the axis while homing, allowing each side to home to it's own switch, squaring the gantry during homing. The axis are then re-slaved after homing.
But if you only use one switch, or no switches, the slave is always synced with the master.

Title: Re: Gantry Racking
Post by: Charlie_M on March 16, 2015, 08:01:14 PM

Ok thanks. Can I connect both motors to one driver say the Y axis? would this solve my problem?

Title: Re: Gantry Racking
Post by: ger21 on March 16, 2015, 08:04:24 PM

No, I wouldn't try that.

Did you change the pulse with as I suggested?

If that doesn't help, you might want to uninstall and reinstall Mach3 and see if that helps.

Title: Re: Gantry Racking
Post by: Charlie_M on March 17, 2015, 05:13:12 AM

 Hi Gerry,

           I did change the pulse width, but it made no difference. If I reinstall mach3 do I need to back up my xml file?

Title: Re: Gantry Racking
Post by: Charlie_M on March 17, 2015, 06:22:14 AM

ok so I reinstalled mach and I get the same behavior. I can see a delay between the Y axis motor and the A axis motor. Now I just need to figure out why. I think I will look into a different driver board.

Title: Re: Gantry Racking
Post by: Overloaded on March 17, 2015, 07:43:11 AM

Hi Charlie,
  Are you sure that the set screws are tight on all components of the trailing axis ?

Is the motor possibly stepping as commanded, but not transferring the movement to the gantry on the trailing side ?

If you swap the motor wiring from Y to A, would the opposite side be affected ?

Just something to check.
Russ

Title: Re: Gantry Racking
Post by: Charlie_M on March 17, 2015, 05:53:52 PM

 OK So I started messing around with the wiring and I have a bad motor. I took a ohm reading on the different coils and they are all in the meg ohm range >:D. Gotta to love Chinese crap.