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Author Topic: Stop on probe signal for G0/G1 moves to protect probes...  (Read 1676 times)

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Re: Stop on probe signal for G0/G1 moves to protect probes...
« Reply #10 on: March 16, 2018, 06:27:11 PM »
I still think it needs to be implemented in the motion hardware. If I remember right this is the only solution for Mach3 users. I have the same question at the Warp9D forum and Daz replied there also. I still asked Andy if it's possible to implement on the ESS. At the very least throw an E-Stop if the probe is detected during a non-G31x movement. Something more graceful would be nice, but I'm not in the know on how to implement that.

Daz's solution may help when the feeds are slower, how many hobbyist CNC are running at the high end of the feed rates?
I'm not a complete idiot...
    there are some parts missing.
Re: Stop on probe signal for G0/G1 moves to protect probes...
« Reply #11 on: March 16, 2018, 07:08:51 PM »
Hi,
you may recall:

Quote
I think the answer is yes but it will be insufficient to protect your probe.

The reason being that Mach has communications delays that make it probable that probe damage would occur before the controller/Mach/controller loop
could act.

The ESS cannot at this time to be programmed at board level, ie realtime. Andy from Warp9 has indicated a wish to release an API for the ESS which might well
allow you to do a high speed probe protection function. When that will be available is anyones guess. Andy is commonly  so involved with customer support that
development goes out the window.

PoKeys boards have as standard a board level programming feature. Whether it has the capacity to do this I don't know.

Vital Systems Hicon boards can be activated at a cost to be programmable also.

Craig
My wife left with my best friend...
     and I miss him!
Re: Stop on probe signal for G0/G1 moves to protect probes...
« Reply #12 on: March 19, 2018, 05:36:59 PM »

Well someone had to check this out to see if it could provide viable probe protection. Protection for the single supported probe is afforded by the CSMIO with plugin 2.910, but the later version 3 plugin, which supports 4 probes, does not (as yet ) offer built in protection.

Based on Daz’s suggestion I added the following to the signal table:

Code: [Select]
[mc.ISIG_PROBE] = function (state)
    -- AW Add probe protection
    if ((state == 1) and (machState ~= mc.MC_STATE_MRUN_PROBE)) then
        mc.mcCntlEnable(inst, 0)
    end
end,

The inclusion of state in the if statement ensures that only leading edges of the signal inhibit motion. As a result, it is fully compatible with the built in probing functions of Mach4 and should work  with all motion, whether initiated by jogging, MDI, Gcode or MPG.

So how does this perform in practice? Craig makes the valid point  that response times may be inadequate, mainly because when the drives are disabled the machine will coast to a standstill. Such behaviour is obviously system dependednt.  It may be possible with some systems to stop motion under power, thereby improving deceleration.

In my case I have an elderly converted manual Bridgeport driven by ac servos. Its rapid speed is modest at 1800mm/min.  I measured the position of the vice jaws and then jogged the probe towards them at 1800mm/min until probe protection kicked in. The excess travel was pretty repeatable as follows:
    X axis:   2mm
    Y axis:   1.5mm
    Z axis:   1mm

As my homemade probe can accept an overtravel of 3mm in Z and 6mm in X and Y, I have a safety factor of about 3:1, and conclude that this is an entirely viable method of protection which I shall continue to use.

Allan
« Last Edit: March 19, 2018, 05:40:44 PM by Fledermaus »
Re: Stop on probe signal for G0/G1 moves to protect probes...
« Reply #13 on: March 19, 2018, 05:59:17 PM »
Hi Allan,
kool, good post.

Craig
My wife left with my best friend...
     and I miss him!
Re: Stop on probe signal for G0/G1 moves to protect probes...
« Reply #14 on: March 19, 2018, 07:26:38 PM »

As my homemade probe can accept an overtravel of 3mm in Z and 6mm in X and Y, I have a safety factor of about 3:1, and conclude that this is an entirely viable method of protection which I shall continue to use.

Allan


Most excellent, Allan.

I'm not a complete idiot...
    there are some parts missing.