[Scott_M]

Doesn't matter. If he had softlimits set up and had zeroed the machine at the beginning of the session, the crash would not have occured. Mach would have thrown an error message and not allowed the machine to move at all. No move, no vise crash, no nothing. It looks ahead; does not wait until it is at the limit to stop the machine. Proactive, not reactive.

Lets pile on Keith while he is out sailing.


I just enabled soft limits in PCNC rev. 3.12b and did a few tests. With the machined homed ( Positive in all 3 axis )After ensuring that the soft limits worked while jogging I typed G1 Y-100.00 F3 in the MDI and Y started moving in the Y- direction. I let it go and it went all the way to the soft limit and stopped.

It did not look ahead and throw an error message. It was reactive not proactive.


Added- I just ran some g-code from file and it did error out and throw a soft limit warning before moving.

Is this how your machine acts Randy ? Or did I set my button up incorrectly ?

Or maybe the Tormach Flavor of Mach3 acts differently ?


Scott

[mactec54]

Scott You have set it correctly, & that is how it is supposed to work. It is ony a digital stop, That you can ajust if you want, to work anywere in the machine work envelope, it is always better to hit a digital stop than a hard stop.

[zephyr9900]

Is this how your machine acts Randy ? Or did I set my button up incorrectly ?

Scott, I don't have a softlimits button on my screenset, so I just used Mach XML Viewer to set SoftLimit to 1 in my XML. My machine respects the softlimits on both directions on all axes for jogging, but I can type ridiculous values into MDI and the machine will move until the limit switch. But I've been messing with reconfiguring soft limits so much that I don't know what I've done... Right now soft limits are only effective for jogging.

Or maybe the Tormach Flavor of Mach3 acts differently ?

As far as I know, I am using the Tormach flavor of Mach3. I'm using PCNC 3.12b, and only changed the stepper and spindle motor tuning for my Old Skool machine (original stepper drivers and VFD). I have a fresh, untweaked install of 3.12b on my desktop PC, and I'll go through the motor tuning tweaks again and generate a fresh XML to try.

Randy

[mactec54]

Randy you want to give your soft limit a least .100 before your hard stops (anolog switches) you should be able to drive the machine at full rapid to the soft limit & it will stop right there, You do not need a deceleration before a soft limit, only the hard stop you can have the deceleration

[lgalla]

Boy was I wrong.I thought a stepper would just stop on a crash.The machine must have very powerful motors.If powered by servos would the crash be worse?I would assume the servo would be toast or would the current limit save the motor.
Larry

[zephyr9900]

You do not need a deceleration before a soft limit,

For a controlled stop (which, according to my understanding is the purpose of a soft limit in the first place) I need at least the .125" of deceleration that Tormach has programmed for the axis motors. I agree that 1" is probably overly much, but it does give a good audible warning when approaching the limit, and as I discovered doesn't affect gcode operations in the deceleration zone.

If the soft limits didn't have a controlled stop, they'd be of no more use than the limit switches. If I hit a limit switch, I need to re-reference the machine (and pick up X-Y-Z on my workpiece again) before I can continue, since it is a sudden and uncontrolled stop with probably lost steps on an axis.

What's your rationale for not needing the deceleration zone, Mactec54?

Randy

[mactec54]

I use the soft limits & have set up soft limits on many different machines But I can see now that the reason for the deceleration is so you don't lose steps, we don't use stepper motors on any of our machines so don't have that problem & we can hit a soft limit at any speed & the machine will just stop,

Soft limits are way better than limit switches, limit switches are a fixed position & are easy to over run & damage your machine, Soft limits can be moved any were in the machine envelope & you can not over run them if they are set correctly in your software/control