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Author Topic: Noob question on Z Axis setup using soft limits  (Read 479 times)

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Re: Noob question on Z Axis setup using soft limits
« Reply #10 on: January 14, 2019, 05:54:08 PM »
Okay, now have Ref. All Home working with the limit switches and Soft Limits turned off. I can jog to anywhere on the table, click RAH and it goes until each limit switch opens, then backs off until they close. I see each switch as it trips in the History box. Now what?

Also, for the Z axis, my Home switch as at the top of the slide. Should I move it to the bottom to keep it from crashing into the table top or will the Soft Limits (when they are active) stop that?

Re: Noob question on Z Axis setup using soft limits
« Reply #11 on: January 14, 2019, 05:56:19 PM »
Okay, now have Ref. All Home working with the limit switches and Soft Limits turned off. I can jog to anywhere on the table, click RAH and it goes until each limit switch opens, then backs off until they close. I see each switch as it trips in the History box. Now what?

Also, for the Z axis, my Home switch as at the top of the slide. Should I move it to the bottom to keep it from crashing into the table top or will the Soft Limits (when they are active) stop that?
Re: Noob question on Z Axis setup using soft limits
« Reply #12 on: January 14, 2019, 06:14:26 PM »
Hi,
most CNCers have the Z axis home point at the top of travel.

Once you have the machine homed you can now fill in the softlimits. Note that the softlimits are MACHINE COORDINATES.
So your Z axis for instance will have Soft Max of 0 and a Soft Min of -4 say.

Craig
My wife left with my best friend...
     and I miss him!
Re: Noob question on Z Axis setup using soft limits
« Reply #13 on: January 15, 2019, 08:48:59 AM »
Hello,

OP seems to be in good hands, but I wanted to share our support video on homing and soft limits as well: https://youtu.be/IXuuGRACU1I

Happy CNCing,
Bryanna
Newfangled Solutions Helpdesk: http://support.machsupport.com
YouTube Support Channel: https://www.youtube.com/c/MachSupportOfficial
Re: Noob question on Z Axis setup using soft limits
« Reply #14 on: January 15, 2019, 09:03:08 AM »
Thanks Bryanna!

I've watched it a dozen times, slowed it down trying to figure out each step you made.

I've subscribed to that channel too. Looking forward to more content on Mach 4.
Re: Noob question on Z Axis setup using soft limits
« Reply #15 on: January 15, 2019, 12:52:21 PM »
Now that the home limit switches are setup, the roadrunner file runs successfully. But if I turn on soft limits on, the roadrunner file still errors and stops on the second gcode line in the file with:

Error, Z axis commanded over SoftMaxError

The line is:

G0 X0.000000 Y0.000000 Z0.200000

The Z axis Soft Min = -4.000 and the Soft Max is 0.000

Now what?
Re: Noob question on Z Axis setup using soft limits
« Reply #16 on: January 15, 2019, 01:26:52 PM »
The request to go to Z0.200000 is indeed outside the soft limits that you have set.

It is unfortunate that the sample file asks for motion more positive than Z=0 as
it is normal practice to call home at Z=0.

You can get around this by setting up your homing to call the homed location for
Z to be 0.200000 or greater. For example go to  Config > Control> and select the
tab for Homing/SoftLimits. In the row for Z and the column for Home Offset enter
the value 0.250000 and in the column for Soft Max enter the same value.

In the real world, just avoid generating G-code that requests values outside of
the range configured for your machine. You can also utilize work offsets such
that work Z=0.200000 is located at less than machine coordinate Z=0.000000
Steve Stallings
www.PMDX.com
For PMDX product support, please use PMDX forum or direct email for quickest response. We do not use this forum as our primary product support site.
Re: Noob question on Z Axis setup using soft limits
« Reply #17 on: January 15, 2019, 01:41:20 PM »
Would it be okay to just go through the sample file, setting anything greater than 0.0000 for the Z axis to 0, save with a new file name, load it and run?

Part of the reason I am being so careful is the table is 2" higher than the lowest the Z axis can travel. That is before I put any waste board on it.

Never mind on changing all the values as there a hundreds of them > 0. Doing as you suggested now to test again.
« Last Edit: January 15, 2019, 01:43:01 PM by billskeen62 »
Re: Noob question on Z Axis setup using soft limits
« Reply #18 on: January 15, 2019, 01:50:19 PM »
You should be able to set Z soft min to a value suitable to protect your table.

Granted this may simply move to problem to being one of the machine stopping
when Z min is exceeded, but this is what you actually want if the goal is to
prevent cutting the table.
Steve Stallings
www.PMDX.com
For PMDX product support, please use PMDX forum or direct email for quickest response. We do not use this forum as our primary product support site.
Re: Noob question on Z Axis setup using soft limits
« Reply #19 on: January 15, 2019, 01:58:11 PM »
Yes, the Soft Min of -4.000 stops the Z from hitting the table, but that is before I put a tool in. I'll adjust to a bigger number, depending on the tool, like -2.000 then, correct?

BTW, "Thank You"  to you, Bryanna, joeaverage and others for all the help. It is appreciated.