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Author Topic: Z Acceleration  (Read 3332 times)

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Online Davek0974

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Re: Z Acceleration
« Reply #10 on: April 19, 2016, 05:59:13 AM »
The code i have is G28.1 Z10 and seems to work "most of the time" :)

It does slow down to the value set in homing/limits so that is being read ok, its just the odd rapid bit thats baffling
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline RICH

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Re: Z Acceleration
« Reply #11 on: April 19, 2016, 06:00:02 AM »
Use version 062 here and haven't found any problems with it yet.
As Hood replied the G28.1 is used to reference your machine, axes rapids to them and then there is a % slow down per configuration.
Didn't mention that your using that command in a macro to probe to the material surface. G31 is used to probe. Probing works fine in V062 and use it to touch off my lathe tools.

Post your macro.

RICH

Online Davek0974

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Re: Z Acceleration
« Reply #12 on: April 19, 2016, 06:19:45 AM »
Hmm, ok so what changes do i need to make to my probing routing to switch to G31

I'm fairly certain this is my latest macro..

Code "G91" (switch to incremental mode)
Code "G00 X22.00" (position probe switch)
Code "G90" (switch to absolute mode)

ActivateSignal(OutPut3) (triggers the probe cylinder)
Sleep(400)

Code "G28.1 Z10.000" (probe the surface)
Code "G92 Z#15045" (apply the probe switch offset from settings screen DRO)

DeActivateSignal(OutPut3) (raise the probe)
Sleep(200)

Code "G91" (switch to incremental mode)
Code "G00 X-22.00" (put the axes back to where we came from)
Code "G90" (switch to absolute mode)
Code "G00 Z0.00" (Go to Z Zero)

Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Online Davek0974

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Re: Z Acceleration
« Reply #13 on: April 19, 2016, 06:40:42 AM »
Also, on a plasma, isn't referencing the axis the correct procedure anyway as all the measurements are relative to the TOM?

Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline Hood

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Re: Z Acceleration
« Reply #14 on: April 19, 2016, 07:29:30 AM »
I dont think there is a right way or a wrong way, all depends what you are hapy with I would suspect.
You are using the reference move then offsetting from the machine zero position, doing a probing routine would do similar I would think.
I am hoping to do it external to Mach by using my servo drive to home via current limit, means I wont need a floating holder or a switch set up similar to yours.

What the problem seems to be with you is the axis is stalling on occasion, why I am not sure as the G28.1 seems to adhere to motor tuning Vel and Accel for me, although as previously said it is hard to be sure as my accel and velocity are quite high.

Away to weld some alu on a boat but if I get a chance later I will set my Z Accel extremely low and see if the G28.1 follows it.

Hood

Online Davek0974

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Re: Z Acceleration
« Reply #15 on: April 19, 2016, 07:47:36 AM »
It does seem odd, I have the homing subroutine/macro as a test file on the desktop so i can run it as a program over and over, it works ok, but then I have never set a high F rate and tried it, hopefully have a play tonight, there must be a root cause for this.
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline RICH

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Re: Z Acceleration
« Reply #16 on: April 19, 2016, 07:57:56 AM »
Don't have a plasma machine but my friend does and uses Mach to control it. His machine works great. He uses LC to create the code. I really should update the LC Manual to reflect using
the Plasma module. Just for info......


I would suggest you put a feed rate in your macro, the F should be a reliable value  
for the Z axis. So just add:

Code "Fxx" where xx is the value after the first Code "G90" line.
To test if the set feed rate is accepted / used just try a slow feed rate and see what happens.

May just work and no need to fool around with G31.

Now I am somewhat rusty on the G92 command, BUT, be carefull  as it affects the coordinate values and should not be used with other offsets and never use with G52 ( which replaced G92). Just something off topic to keep in mind.

RICH      

Online Davek0974

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Re: Z Acceleration
« Reply #17 on: April 19, 2016, 08:16:03 AM »
Thanks, i'll have a quick play tonight and also try throwing an F in there.

The subroutine and macro perform perfectly but I have read stuff on the G92 etc, but as it all does exactly what i want it to I will leave it as-is.

I am hoping it is just as simple as the G28.1 using the machine feed-rate and ignoring the z limit, as that really would explain why it works sometimes and not others, if it really does use the z limit all the time then i am back to square one!

I have tried tweaking micro-step values, also fitted a coarser lead screw but made no difference.
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline Hood

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Re: Z Acceleration
« Reply #18 on: April 19, 2016, 01:25:53 PM »
Ok just finished so went to the Chiron and set the Accel in motor tuning to 100mm/s/s and then did a g28.1. The rapid move at the start adhered to the very slow accel and so to did the second part of the move.

I am still wondering about the description in the manual saying about using current feedrate as mine certainly doesn't, I even tried calling a feedrate prior to the G28.1 and also tried with a feedrate on the G28.1 line and both used rapids.

So it does look like it adheres to the values set in motor tuning so something else must be the issue with your setup, either that or possibly calling a G28.1 from a macro does things differently on occasion.

Hood

Online Davek0974

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Re: Z Acceleration
« Reply #19 on: April 19, 2016, 01:53:40 PM »
Thanks Hood, that backs up my tests, same results - it uses the rapids and not the feed rate.

I have also been advised my setting is too high - currently 2500mm/min and 2400mm/s/s on Z axis.

I got there by just whacking it up until it failed then dropped 30% and tried again then 30% and so-on. There is very little mass in the Z and it seemed happy when using manual G00 commands and jogging etc so i left it - the THC and piercing love it ;)

I will wind it back a notch and see how she goes, maybe I'm just pushing too hard and one in ten times it says "no way buddy"...


Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives