(Solved) PlasmaC new config Z going up when probing

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6 years 2 months ago #176705 by snowgoer540
Replied by snowgoer540 on topic (Solved) PlasmaC new config Z going up when probing

Clive S wrote:

I’m with Phill, what did you mean by P10?


Ok I have had a few sherbets so please excuse me.

P10 is the pid loop whatever in the ini file and the machine in question that I had to help set up was 40 miles away so done with phone and Dropbox. we had to increase the P10 TO 2O to get it to work.


Good to know, a friend of mine had to increase his to 50 to have it keep up. PID tuning for everyone :laugh:

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6 years 2 months ago #176715 by phillc54
Replied by phillc54 on topic (Solved) PlasmaC new config Z going up when probing

phillc54 wrote:

I have bumped this: As the above questions seem to have fallen through the net. Although the machine is working.

I "think" mine is negative but I am not 100% sure. I will check my machine tomorrow.
I also "think" I have the jumpers set as per Peters suggestion. Again, I will check tomorrow.

I have a 7i96 with:
W2 right
W3 left
W5 right
At zero volts hm2_7i96.0.encoder.00.velocity reads around positive 3790
When voltage is applied, velocity counts in the positive direction

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6 years 2 months ago #176762 by Clive S
Replied by Clive S on topic (Solved) PlasmaC new config Z going up when probing

phillc54 wrote:

phillc54 wrote:

I have bumped this: As the above questions seem to have fallen through the net. Although the machine is working.

I "think" mine is negative but I am not 100% sure. I will check my machine tomorrow.
I also "think" I have the jumpers set as per Peters suggestion. Again, I will check tomorrow.

I have a 7i96 with:
W2 right
W3 left
W5 right
At zero volts hm2_7i96.0.encoder.00.velocity reads around positive 3790
When voltage is applied, velocity counts in the positive direction


Thanks. That helps. Mine is the same including the switches so I would like to find out why the other machine is the opposite and had to change the setp hm2_7i96.0.encoder.00.scale to 1.

But if it ain't broke don't fix it :)

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6 years 2 months ago #178430 by snowgoer540
Replied by snowgoer540 on topic (Solved) PlasmaC new config Z going up when probing

Clive S wrote:

tommylight wrote:

Clive S wrote: Yes its strange the machine above would not work with P10 and delay 1.5 just changing these two things made the machine fly we have just cutout a big control panel using Hypertherms cut parameters in 3mm alli at 7.5M/min without any issues.

If there are no pictures or video, it did not happen ! :) I was told this same thing by a member here not long ago.

Ok I will put them both together. Doubting Thomas.


I'm curious how to get my THC dialed in there. It seems that no matter what I do, it's not fast enough.

Video:


I had the P in the PID all the way up to 50, that didnt seem to help (in fact probably made it worse). I also changed the setup speed to 150ipm (though I dont think this affects the THC speed), and that didnt help either. In the video, the P value is 25. Am I expecting too much of the THC? I see videos of people cutting congregated metal with theirs, and there is probably no way that could happen here (not that I need to at the moment, just trying to tune the table in). That cut speed was 150ipm. Perhaps that's too demanding of the THC?

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6 years 2 months ago #178433 by PCW
Replied by PCW on topic (Solved) PlasmaC new config Z going up when probing
Something limiting the Z axis velocity or acceleration could cause this
Also something wrong with the plasma voltage reading could cause this issue (too much filtering for example)

What does the plasma voltage do during the cut?

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6 years 2 months ago #178436 by rodw
Replied by rodw on topic (Solved) PlasmaC new config Z going up when probing
That almost looks like the THC is not enabled when it hits the material. Can you check the THC light is coming on in Plasmac?
Can you tell us the THC delay you have set?

It does work and this was with default settings and probably a bit more onerous than your test.



The Z axis velocity and acceleration is what limits cutting corrugated iron because the torch must follow the sinusoidal profile of the iron.
I have a spreadsheet calculator somewhere. I think for my machine it was limited to about 4 m/sec cut speed (oops there we go again)

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6 years 2 months ago #178438 by snowgoer540
Replied by snowgoer540 on topic (Solved) PlasmaC new config Z going up when probing

PCW wrote: Something limiting the Z axis velocity or acceleration could cause this
Also something wrong with the plasma voltage reading could cause this issue (too much filtering for example)

What does the plasma voltage do during the cut?


@PCW
I recall when you were helping me with my Joint 3 following error via email that you said something similar about something constraining the Z axis. At that time, you had me double the acceleration for the stepgen. I also should remind you that I had latency that's pretty high for a PCI machine (over 100k ns) I attached the ini file, but here is the Z axis snippet:
Code:
#****************************************** [AXIS_Z] # set to double the value in the corresponding joint MAX_VELOCITY = 10.000 # set to double the value in the corresponding joint MAX_ACCELERATION = 100.00 # shares the above two equally between the joint and the offset OFFSET_AV_RATIO = 0.5 MIN_LIMIT = -3.875 MAX_LIMIT = 0.001 [JOINT_3] TYPE = LINEAR HOME = 0.0 FERROR = 0.5 MIN_FERROR = 0.05 MAX_VELOCITY = 5.000 MAX_ACCELERATION = 50.00 # The values below should be 25% larger than MAX_VELOCITY and MAX_ACCELERATION # If using BACKLASH compensation STEPGEN_MAXACCEL should be 100% larger. STEPGEN_MAXVEL = 6.250 STEPGEN_MAXACCEL = 100.00 P = 1000.0 I = 0.0 D = 0.0 FF0 = 0.0 FF1 = 1.0 FF2 = 0.0 BIAS = 0.0 DEADBAND = 0.0 MAX_OUTPUT = 0.0 # these are in nanoseconds DIRSETUP = 10000 DIRHOLD = 10000 STEPLEN = 5000 STEPSPACE = 5000 STEP_SCALE = 5080 MIN_LIMIT = -3.875 MAX_LIMIT = 0.001 HOME_OFFSET = 0.050000 HOME_SEARCH_VEL = 0.416667 HOME_LATCH_VEL = 0.083333 HOME_FINAL_VEL = 0.083333 HOME_USE_INDEX = NO HOME_IGNORE_LIMITS = YES HOME_SEQUENCE = -1 #******************************************

Also, I have the lowpass frequency set to 0 (by default) in my connections.hal file (setp plasmac.lowpass-frequency 0).

The voltage seems to read correctly, and the THC seems to try to keep it at the prescribed voltage, just not fast enough. Here is a video:

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6 years 2 months ago #178439 by snowgoer540
Replied by snowgoer540 on topic (Solved) PlasmaC new config Z going up when probing

rodw wrote: That almost looks like the THC is not enabled when it hits the material. Can you check the THC light is coming on in Plasmac?
Can you tell us the THC delay you have set?

It does work and this was with default settings and probably a bit more onerous than your test.

The Z axis velocity and acceleration is what limits cutting corrugated iron because the torch must follow the sinusoidal profile of the iron.
I have a spreadsheet calculator somewhere. I think for my machine it was limited to about 4 m/sec cut speed (oops there we go again)


I thought the same, so I played around with the delay. I had it as low as .3 seconds, but after I was done I put it back to 1s.

I'm fairly confident I couldnt do what you did on my table :(. I went back and watched Clive's video after he tuned his, you can see his crash into the material in the beginning as well, but his limit switch must not be as sensitive as mine.

At any rate, a video, and my ini settings are attached above.

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6 years 2 months ago #178441 by phillc54
Replied by phillc54 on topic (Solved) PlasmaC new config Z going up when probing
That seems to show the down led on just before the crash.

It would be interesting to see a plot with the arc voltage and the up and down leds

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6 years 2 months ago #178443 by PCW
Replied by PCW on topic (Solved) PlasmaC new config Z going up when probing
Looking at the cut, I think it runs into the material before the THC is enabled
(0.3 seconds from the start of motion would do this even if there was no velocity lockout)


The other issue is how much distance is needed to get to the THC enable velocity threshold
with you current acceleration from a static start?

My guess is that the basic issue is that the THC is assumed to operate at constant XY velocity
so when you have a case where it needs it to work instantly and during acceleration, it fails

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