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Author Topic: Noob question on Z Axis setup using soft limits  (Read 6136 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
'I enjoy sex at 73.....I live at 71 so its not too far to walk.'
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
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
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.