How to MPG Jog before homing?

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6 years 1 week ago #186643 by jhandel
How to MPG Jog before homing? was created by jhandel
I would like to be able to use my Pendant before homing the machine.. Because my limit switches are past my homing switches it is possible to be in a place where homing first may be a bad idea and jogging a bit before homing is wise.

So, yah.. what HAL config should I be doing to allow my pendant/MPG to jog the axis before they are homed?

Thanks in advance.

FYI: Here is my MPG.hal which works great :) (Axis A & B will be configured after I get the basic XYZ worked out )
Code:
setp jogincr.in1 0.00025 setp jogincr.in2 0.0025 setp jogincr.in4 0.025 net mpgscale1 jogincr.sel0 <= hm2_7i76e.0.7i76.0.0.input-22 net mpgscale2 jogincr.sel1 <= hm2_7i76e.0.7i76.0.0.input-23 net mpgscale3 jogincr.sel2 <= hm2_7i76e.0.7i76.0.0.input-24 net pend-scale <= jogincr.out net pend-scale => axis.x.jog-scale net pend-scale => axis.y.jog-scale net pend-scale => axis.z.jog-scale net mpg-x <= hm2_7i76e.0.7i76.0.0.input-17 net mpg-x => axis.x.jog-enable net mpg-y <= hm2_7i76e.0.7i76.0.0.input-18 net mpg-y => axis.y.jog-enable net mpg-z <= hm2_7i76e.0.7i76.0.0.input-19 net mpg-z => axis.z.jog-enable #net mpg-A joint.3.jog-enable <= hm2_7i76e.0.7i76.0.0.input-20 #net mpg-B joint.4.jog-enable <= hm2_7i76e.0.7i76.0.0.input-21 net pend-counts <= hm2_7i76e.0.encoder.09.count net pend-counts => axis.x.jog-counts net pend-counts => axis.y.jog-counts net pend-counts => axis.z.jog-counts

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6 years 1 week ago #186644 by rodw
Replied by rodw on topic How to MPG Jog before homing?
The intended use is for the Home switch to remain triggered all the way to the limit switch then Linuxcnc can work out where it is in relation to the home switch at the start of homing and back off to find the home trigger point before commencing homing proper...

So I would recommend you sort that out.

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6 years 1 week ago #186723 by jhandel
Replied by jhandel on topic How to MPG Jog before homing?
May be harder than all that because this is a retrofit so I can't just easy move where the limit and homing switches are.. the designer (for what ever reason) decided that the home switches should be a good 20mm away from the limit switches..

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6 years 1 week ago #186726 by Mike_Eitel
Replied by Mike_Eitel on topic How to MPG Jog before homing?
You could use a makro to move to a suitable position before shutting down lcnc

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6 years 1 week ago #186752 by rodw
Replied by rodw on topic How to MPG Jog before homing?

jhandel wrote: May be harder than all that because this is a retrofit so I can't just easy move where the limit and homing switches are.. the designer (for what ever reason) decided that the home switches should be a good 20mm away from the limit switches..


Thats not unexpected and in fact, I think its desirable. I would not move the switch. Can you extend the home switch striker plate from where it ends now to the limit switch?

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6 years 1 week ago #186779 by jhandel
Replied by jhandel on topic How to MPG Jog before homing?
my main consern was if I got "stuck" due to something going bad I wouldn't be able to move my way back past my home switch (its on the ++ side so if I am past it and I lose power/etc then Linux CNC won't let me go negative.. )

I learned about the POSITION_FILE setting this evening.. That gives me what I really need.. sure the machine doesn't stay homed between boots, but this will let me get out of a sticky situation if something horrible happens..

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6 years 1 week ago #186784 by JohnnyCNC
Replied by JohnnyCNC on topic How to MPG Jog before homing?

Mike_Eitel wrote: You could use a makro to move to a suitable position before shutting down lcnc


This basically what I do. I used a G28.1 to store what I call the park position where my table is centered in the X & Y. I added a button that issues a G28 that I use before shutdown. However my USB connect P4-S pendent does allow me to jog before homing.

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6 years 1 week ago #186788 by rodw
Replied by rodw on topic How to MPG Jog before homing?

jhandel wrote: my main consern was if I got "stuck" due to something going bad I wouldn't be able to move my way back past my home switch (its on the ++ side so if I am past it and I lose power/etc then Linux CNC won't let me go negative.. )


Thats not how it works if you set the homing up according to the docs. All you would do is home hte mchine again, Linuxcnc would see the home switch is triggered and move back offf it and commence the homing cycle.

Trust the Linuxcnc paradigm! If you don't then find another controller you can trust!

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6 years 1 week ago #186802 by jhandel
Replied by jhandel on topic How to MPG Jog before homing?

rodw wrote: Thats not how it works if you set the homing up according to the docs. All you would do is home hte mchine again, Linuxcnc would see the home switch is triggered and move back offf it and commence the homing cycle.

Trust the Linuxcnc paradigm! If you don't then find another controller you can trust!


Its an inductive switch so make a block long enough that it stays triggered by home even when I am at my machines hard limit, then linux CNC will roll backwards off of the block until it turns off then seek it again....

I'll probably have to machine that block once the machine is running... but its doable...

For now having positional file is enough to get me out of a sticky whicket while I am programming & configuring the machine

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6 years 1 week ago #186813 by rodw
Replied by rodw on topic How to MPG Jog before homing?
Now you are talking. I welded mine up. but machined some slots for adjustment. Described on P1 of my build thread
forum.linuxcnc.org/show-your-stuff/32029...cutter-build?start=0

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