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Author Topic: MPG Deceleration issue  (Read 732 times)

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MPG Deceleration issue
« on: October 09, 2017, 01:57:42 PM »
My customer is running Mach3 with a Galil DC4153, and iMach P3A pendant, and 2 surestep servos.  When using the pendant to manually move an axis, the motion continues an excessive amouint after the operator stops rotating the dial.  Is this deceleration time/dist controlled by MAch3, the controller, or the pendant? 
A little more info if it helps: The original XP computer that ran the system died. They installed another XP computer and copied files over and have been struggling to get it all back to the original condition. 
Any help is appreciated as they are down.

Thanks.
Re: MPG Deceleration issue
« Reply #1 on: October 11, 2017, 03:06:49 AM »
Hi,
I don't know about the Galil controller and my pendant is a P1A from the same manufacturer.

I've found that it is very easy to spin the MPG fast enuf that the machine can't keep up and therefore carries on after you've stopped to catch up
with all the pulses you issued. It can be a bit frightening when you realise that you are much closer to the work/vice/clamp than you thought.

I have my most aggressive/fastest setting at 1mm per click. It is easily possible for me to overdo it and have the machine run on after. I do not
usually find it excessive provided I keep my head screwed on. If I want to be a dickhead and spin the thing like mad then Mach is not going to
save me! At less aggressive settings like 0.1 and 0.01 mm per click I never have a problem.

You can reduce the overrun tendency by setting Mach to run at high even maximum speed when jogging, it is very likely to be able to keep
up with the MPG pulses without lagging to far behind thereby minimising the overrun. It is common to have jogging speeds set fairly low so that you may
sneak up to a feature without crashing into it. If you then subsequently start spinning the thing to travel some considerable distance with the jogging speed
still at a low setting you have the makings of a crash happening. It might be possible to have a Brain or a macro which causes the jogging speed to be
automatically increased when using fast step settings and again reduce them when using fine step settings for touching off. I can certainly see how I
might go about coding that in Mach4 but Mach3 is less flexible and not sure how it could be done.

In my situation I have found a reasonably fast jog speed and intelligent use of the pendant to be quite adequate. I haven't crashed into anything because
of overrun for ages.

It may be worth experimenting with some of the motion modes, if I recall there is one mode where if you spin the MPG slowly the machine advances
the normal step per click but beyond a certain user settable MPG speed the machine advances at maximum jog speed. Maybe a better or at least safer
mode for your customer. In the final analysis if your customer is going to show poor judgement or concentration can you really help them?

Craig
My wife left with my best friend...
     and I miss him!