MPG Recomendation
21 Oct 2012 14:01 #25543
by LAIR82
MPG Recomendation was created by LAIR82
I am interested in putting an mpg pendant on all of our following retrofits, and don't really know where to start in selecting a good mpg candidate.
Does anyone have any recomendations on an MPG pendant for our next couple of lathe conversions?
Thanks
Rick
Does anyone have any recomendations on an MPG pendant for our next couple of lathe conversions?
Thanks
Rick
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21 Oct 2012 16:14 #25554
by BigJohnT
Replied by BigJohnT on topic Re:MPG Recomendation
All my machines use the standard MPG with 100 pulses per rev. If your using Mesa hardware then you connect it directly to an encoder input.
CNC4PC and others all have the basic same pendant.
John
CNC4PC and others all have the basic same pendant.
John
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21 Oct 2012 19:58 #25564
by jmelson
Replied by jmelson on topic Re:MPG Recomendation
BigJohnT wrote:
about $65 delivered in the US. It has worked VERY well.
Jon
I got an HEDSS 50mm MPG from China via an eBay listing. It was pretty expensive,All my machines use the standard MPG with 100 pulses per rev. If your using Mesa hardware then you connect it directly to an encoder input.
CNC4PC and others all have the basic same pendant.
John
about $65 delivered in the US. It has worked VERY well.
Jon
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22 Oct 2012 08:33 #25584
by ArcEye
Replied by ArcEye on topic Re:MPG Recomendation
jmelson wrote:
On the mills I have a pendant I made, but with identical components to the lathe.
As Jon says, MPG works very well and childs play to hook up.
regards
I have one too, built it in to the control fascia on my lathe, with 2 rotary switches to set axis selection and jog unit size.I got an HEDSS 50mm MPG from China via an eBay listing.
On the mills I have a pendant I made, but with identical components to the lathe.
As Jon says, MPG works very well and childs play to hook up.
regards
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22 Oct 2012 11:56 #25594
by LAIR82
Replied by LAIR82 on topic Re:MPG Recomendation
Thanks for the info guys,
Gives me some ideas for getting these on our machines now.
Thanks
Gives me some ideas for getting these on our machines now.
Thanks
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22 Oct 2012 12:27 #25599
by BigJohnT
Replied by BigJohnT on topic Re:MPG Recomendation
This is the hal for my MPG which uses two 4 position switches to select the axis and the increment of movement for each click. Also the ilowpass smooths out the moves.
# MPG
setp hm2_5i25.0.encoder.05.counter-mode true
loadrt mux4 names=mpg-scale
addf mpg-scale servo-thread
loadrt ilowpass
addf ilowpass.0 servo-thread
loadrt or2 count=2
addf or2.0 servo-thread
addf or2.1 servo-thread
setp ilowpass.0.gain 0.02
setp ilowpass.0.scale 1000
setp mpg-scale.in0 0.0
setp mpg-scale.in1 -0.0000001
setp mpg-scale.in2 -0.000001
setp mpg-scale.in3 -0.00001
net jog-smoothing ilowpass.0.in <= hm2_5i25.0.encoder.05.count
net jog-position <= ilowpass.0.out
net jog-position => axis.0.jog-counts
net jog-position => axis.1.jog-counts
net jog-position => axis.2.jog-counts
net scale1 or2.0.in0 <= hm2_5i25.0.7i77.0.0.input-03
net scale2 or2.1.in0 <= hm2_5i25.0.7i77.0.0.input-04
net scale3 or2.0.in1 or2.1.in1 <= hm2_5i25.0.7i77.0.0.input-05
net pos2 mpg-scale.sel0 <= or2.0.out
net pos3 mpg-scale.sel1 <= or2.1.out
net axis-mpg-jog-scale axis.0.jog-scale <= mpg-scale.out
net axis-mpg-jog-scale axis.1.jog-scale <= mpg-scale.out
net axis-mpg-jog-scale axis.2.jog-scale <= mpg-scale.outPlease Log in or Create an account to join the conversation.
23 May 2013 20:11 #34583
by LAIR82
Replied by LAIR82 on topic Re:MPG Recomendation
Have a question about the ILOWPASS component, should the "setp ilowpass.0.scale 1000" parameter be set to pulses per rev of the encoder? In the manpage it says default is 1024, a common ppr for encoders. I have a 100ppr encoder in the mpgs we put on the machines, and it is a little "jerky" on slow, larger increment jogs using the handwheel.
Thanks
Rick
Thanks
Rick
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23 May 2013 20:40 #34584
by andypugh
www.linuxcnc.org/docs/html/man/man9/ilowpass.9.html
The component pretends that the MPG has more counts per rev than it really does, which makes the movement smoother.
If you have a 100ppr mpg and want one turn of the dial to move one inch in rapid, then the machine will move in a sequence of 0.01" steps.
If you add the ilowpass with a scale of 100 then the axis will move in 100 steps of 0.0001", much smoother.
However, you do need to change the jog-scaling factors, or you get 100" of travel per rev instead, for exactly the same jerkiness, and rather a surprise....
The reason for the "scale" factor is that you can't otherwise smooth the output of an integer counter.
Replied by andypugh on topic Re:MPG Recomendation
Have a question about the ILOWPASS component, should the "setp ilowpass.0.scale 1000" parameter be set to pulses per rev of the encoder
www.linuxcnc.org/docs/html/man/man9/ilowpass.9.html
The component pretends that the MPG has more counts per rev than it really does, which makes the movement smoother.
If you have a 100ppr mpg and want one turn of the dial to move one inch in rapid, then the machine will move in a sequence of 0.01" steps.
If you add the ilowpass with a scale of 100 then the axis will move in 100 steps of 0.0001", much smoother.
However, you do need to change the jog-scaling factors, or you get 100" of travel per rev instead, for exactly the same jerkiness, and rather a surprise....
The reason for the "scale" factor is that you can't otherwise smooth the output of an integer counter.
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23 May 2013 20:50 - 23 May 2013 23:57 #34585
by LAIR82
Replied by LAIR82 on topic Re:MPG Recomendation
Surprise would be an understatement, That explains why the slight turn of the handwheel just sent the x axis flying!!!!!!!
Heart rate is slightly elevated now.
Ok I think I understand, now, I did the math quick in the middle of this reply on JT's hal snippet and the math works out to a .01, .001, and a .0001 increment with the 1000 scale factor.
I will adjust my values and see what happens.
Thanks
Rick
******* Works like a dream now, nice and smooth, and the correct distance.
Thanks Guys
Heart rate is slightly elevated now.
Ok I think I understand, now, I did the math quick in the middle of this reply on JT's hal snippet and the math works out to a .01, .001, and a .0001 increment with the 1000 scale factor.
I will adjust my values and see what happens.
Thanks
Rick
******* Works like a dream now, nice and smooth, and the correct distance.
Thanks Guys
Last edit: 23 May 2013 23:57 by LAIR82.
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