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Author Topic: Z Acceleration  (Read 3322 times)

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Offline Hood

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Re: Z Acceleration
« Reply #20 on: April 19, 2016, 05:11:18 PM »
Does seem a bit steep for a stepper, even with it being a light axis.
Hood

Offline RICH

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Re: Z Acceleration
« Reply #21 on: April 19, 2016, 05:58:25 PM »
Do you have a floating head for your  plasma?
I talked to a friend and he said the G28.1 was nothing  but a PITA to him and he is using V062.
His head floats so before each new cut, the torch is touched off using a G31 which takes care of variations of where the top of the plate and sets
the proper height before turning it on, depending on defined  material thickness being cut. Hopefully he will send me the M3 macro that he is using.

You can tweak it to suite your machine. 
Plasma dumb but till then.......

RICH

Offline Davek0974

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Re: Z Acceleration
« Reply #22 on: April 20, 2016, 02:20:29 AM »
Ok, i'll wind the acceleration back a bit.

This is how i do my TOM before each pierce...

G91 (switch to incremental mode)
G01 X24.00 Y2.00 F6000 (position probe switch)
G90 (switch to absolute mode)
M1050 (trigger the probe cylinder)
G04 P0.3
G28.1 Z5.000 (probe the surface)
G92 Z#15045 (apply the probe switch offset from settings screen DRO)
M1051 (raise the probe)
G91 (switch to incremental mode)
G01 X-24.00 Y-2.00 F6000 (put the axes back to where we came from)
G90 (switch to absolute mode)
M99
%

It runs as a subroutine. I have a separate probe switch on a little pneumatic cylinder, works well and has practically zero downforce which is great on thin stuff.
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline RICH

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Re: Z Acceleration
« Reply #23 on: April 20, 2016, 08:29:13 AM »
As said, I don't know much about the details of plasma. You can thank "Dan" for
the macro.
 
This macro probes the TOM using G31 to set torch height. Used with a floating head such that
a switch mounted on the Z provides an input to Mach post probing. Consider creating a
user DRO on the screen for inputing a torch height based on material thickness and use that
value for the Z offset value in this macro as that provides for cleaner cuts.

Code generated by LC provides an M3 before / after each cut. Since the plate TOM may not be
flat due to mounting, the plate itself , or warping the macro takes care of that problem. Your offset of
the torch ( piece height ) will be based on your experience of cutting different material and
thickness. You will need to adjust the macro depending on machine setup and generated code.

Call SetOEMDRO(802, 0) 'Set Z DRO = 0.00
Code "G31 Z-8.0 F60" 'probe surface and z needs to be > actual TOM lcoation so it touches off
While IsMoving()
Wend
Code "G4 P.5" 'wait
ZprobePos = GetVar(2002) 'get Z contact point
Code "G0 Z" &ZprobePos 'return to point to remove overshoot See note below
While IsMoving()
Wend
Call SetOEMDRO(802, 0) 'Set Z DRO = 0.00 This is TOM
While IsMoving()
Wend
Code "G4 P.5" 'wait
Code "G0 Z.480 F30" 'remove floating head travel Adjust for your travel
While IsMoving()
Wend
Code "G4 P.0" 'wait
Call SetOEMDRO(802,.100) 'Set Z DRO = 0.00 See comment on pierce heght above for Z offset value
While IsMoving()
Wend
ActivateSignal(Output2) ' Modify for your inputs and outputs Fires torch

NOTE: One can calculate touch off overtravel. There are different thoughts about feedrate and
how best to do it,but,for my lathe tool touch off the axis rapids close to material and then a
slow feedrate is used for the touch off ( touch off is repeatable to around 0.0002"). So it's
like a single axis move and no adjustment is needed.Don't think that the overtravel distance
will have that great of an infuence on the pierce height, but, depends on yout switch
characteristics and feedraqte used. You calculate to see what the timimg influence is. I just
mention this  since maybe there is no need for the overshoot adjustment in the macro.

RICH