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Soft Limits Questions
« on: August 08, 2013, 04:32:32 AM »
I am using a CNC wood router table and I am trying to set up soft limits using MACH 3. I do not have limit switches on any of my axes so I would like to be able to set them up to protect my machine. I'm not sure if this is possible.

1. If I take the time to set up soft limits via the machine coordinates, will the program (g-code) ignore the soft limits anyway?
2. Does a program respond to limit switches?
3. How do I "zero" the machine coordinates?
4. What is the exact purpose of soft limits?

I have been setting up my material and "zero"-ing my axes to the program coordinates/offsets. I haven't paid any attention to the machine coordinates and, while this works, it has caused me to nearly damage my machine a few times. I've watched a couple of videos and it seems that most everyone who uses soft limits also has limit switches, but this seems to be a little redundant to me.


Offline budman68

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Re: Soft Limits Questions
« Reply #1 on: August 08, 2013, 05:07:36 AM »
Hello, Rahbi,

It sounds like you do not have home switches either? Homing switches are setup so that the machine can have a known "zero" point to go to every time you start and "home" the machine. This is very helpful for locating work consistently and repeatedly. You do not have to have home switches setup, you can have a set location in some way on your machine, and just hit "ref all" and everything will zero from there (home switches can not be enabled for this way to work).

Soft limits are set up in relation to the home switches so your machine does not run into the bump stops (or at the end of the axes).

If you haven't seen the video, it can be found here: http://www.machsupport.com/videos/  Look for the video "Homing, limits, and offsets"


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Re: Soft Limits Questions
« Reply #2 on: August 08, 2013, 08:41:13 AM »

The manual has some great info too.

(it has a good index also ..)  :)

Re: Soft Limits Questions
« Reply #3 on: March 12, 2014, 07:21:06 PM »
I'm curious about this as well. My machine has home switches, is there a way to set up mach3 so it can never travel to far even if the code tells it to keep going? Does soft limits do this? I watched the video but maybe I'm missing something?

Offline RICH

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Re: Soft Limits Questions
« Reply #4 on: March 13, 2014, 08:00:06 AM »
Soft limits will restrict the travel and you get an error message if you command to go beyond them.
I don't have or use limit swithes but do use soft limits sometimes just in case. Can turn on or off easily.


Offline Fastest1

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Soft Limits Questions
« Reply #5 on: March 13, 2014, 10:42:57 AM »
Soft limits will also tell you if your loaded code exceeds the work envelope before executing the start.
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