Author Topic: Homing Again (Newbie needs help!)  (Read 3598 times)

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Offline Rick_L

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Homing Again (Newbie needs help!)
« on: May 06, 2009, 06:40:11 AM »
Hi All,

I'm a newbie just getting to grips with my MDL-2-TR CNC router from Marchantdice.

I've added limit switches to all of the axis and they're all working fine.

When I hit the 'ref all home' in Mach 3 it shuttles back to the negative home switch but stops there and activates the reset switch.

I actually want it it to automatically move off the home switch by several millimetres but it won't do this.

I have to go into the 'ports and pins' to deactivate the limits and then jog it off the limit switch.  Even the 'overide limits' button has no effect.

Here's some important settings:

Input Signals:
Signal    Enabled      Pin No.      Active Low
X++      Ticked          13              Ticked
X--        Ticked          13              Ticked
X Home Ticked          13              Ticked
Y++      Ticked          12              Ticked
Y--        Ticked          12              Ticked
Y Home Ticked          12              Ticked
Z++      Ticked          11              Ticked
Z--        Ticked          11              Ticked
Z Home Ticked          11              Ticked

Motor Home/soft Limits:
Axis     Reversed      Soft Max     Soft Min      Slow Zone    Home Off      Home Neg    Auto Zero     Speed
X         Unticked       178.00        0.00             1.00           -2                   Ticked        Ticked          10
Y         Unticked       215.00        0.00             1.00           -2                   Ticked        Ticked          10
Z         Ticked            0.00        -24.00            1.00           -2                  Unticked      Ticked          10

Any help would be appreciated,
Thanks.

Offline Hood

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Re: Homing Again (Newbie needs help!)
« Reply #1 on: May 06, 2009, 01:28:41 PM »
Try setting the debounce interval to 2000 and see if that helps, its on the General Config page.

Hood

Offline M250cnc

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Re: Homing Again (Newbie needs help!)
« Reply #2 on: May 06, 2009, 02:40:08 PM »
What pin is the limit over ride switch

There has to be a physical switch "Momentary type"

Phil
The Good Thing About Mach3, Is It's very Configurable

The Bad Thing About Mach3, Is It's Too Configurable

Offline simpson36

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Re: Homing Again (Newbie needs help!)
« Reply #3 on: May 09, 2009, 07:48:01 AM »
If I remeber correctly, Mach treats a 'home' switch differently than a 'limit' switch. A 'home' switch can also be a 'limit' but not vice versa or something like that.

It's been a while since I messed with this aspect, but in my setup I have only a single switch on each axis and Mach treats this as both home and limit. It functions as you describe you want . . i.e. it moves till it hits the switch and then automatically backs off the switch.

It appears you have told Mach that you have three switches all on the same pin.  Unless you have three physical switches, you *may* need to use only 'home' on one end and 'limit' on the other as Mach is set up to 'back off' the home switch as you want.

You may also need to have the 'home' switches on one pin and the 'limit' on another, but I'm not sure about that. In my setup, Mach pays attention to the direction of travel and therefor knows which switch it is about to hit. I don't know exactly how the multiple switch per axis setup works.



 

Offline Hood

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Re: Homing Again (Newbie needs help!)
« Reply #4 on: May 09, 2009, 07:52:41 AM »
one pin is all that is required as long as you have NC switches in series.
Hood

Offline simpson36

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Re: Homing Again (Newbie needs help!)
« Reply #5 on: May 09, 2009, 08:06:24 AM »

I really can't think of a reason so separate the pins since you tell mach in the setup which way to go to find the 'home' switch and mach has the very nice 'soft limit' feature for the other side.

Unless I'm missing something, that just leaves e-stop service, in which case it really doesn't matter which switch was hit, so they could certainly all be on one pin for that purpose.

It is unclear to me how many physical switches the OP has. A slick setup I read about is to have a 'home' switch near the center of travel and then separate limts at each end to cut down on homing time. Would Mach then need a separate pin for the 'home' vs limits, or can it keep track via a 'last position' type of process?

 



Offline Hood

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Re: Homing Again (Newbie needs help!)
« Reply #6 on: May 09, 2009, 08:12:37 AM »
Mach would need a seperate pin in that case for home as if it was moving past the home switch it would trigger a limit as there would be no way to tell which switch had been hit.
 My lathe has seperate home switches due to the fact that the cross slide has front and rear toolpost/turret and so it would be unwise to home to an axis extreme as that would possibly bring one or the other dangerously close to the X0 position.

Hood

Offline Rick_L

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Re: Homing Again (Newbie needs help!)
« Reply #7 on: May 12, 2009, 03:28:57 PM »

Thanks guys for all your help.

I looked up some previous posts and set the debounce interval to 1000, and that fixed the problem...it's something that could be added to a few of the video tutorials because it's a re-ocurring problem.

10/10 for support though!

Offline Hood

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Re: Homing Again (Newbie needs help!)
« Reply #8 on: May 12, 2009, 03:37:37 PM »
Glad you are sorted :)

Hood