Messages

2141

General Mach Discussion / Re: Probably simple but...(G-Code help)

« on: January 11, 2016, 03:08:40 PM »

Apart from my little oddity with the G04, I need a little help with control logic - brains etc, here's what it needs...

The variable #15239 / 1239 is set to 1 or 0 by G-code in the probe subroutine, this variable is monitored by a brain which activates/deactivates output2 (extends or retracts the probe)

This works perfectly UNLESS g-code is loading or you do a path re-gen and it runs the code again as it does when loading - this has the effect of slapping the probe up and down multiple times as it reads the subroutine at every call.

So I am looking for a smart way to block operation when its parsing code.

I have tried to use the other output and the variable AND'ed together in the brain, which works BUT not when i do a dry run or drill holes with the torch as output 2 controls my extract fan and that is off when dry running or drilling so that idea fails.

Is there a smart way to do this please???

2142

General Mach Discussion / Re: Probably simple but...(G-Code help)

« on: January 11, 2016, 02:32:23 PM »

Thanks TP but it only confuses my issue more - I have a subroutine that calls G28.1 as listed below, if I remove the G04 P.0 line I get a short screech from the Z motor like its being told to move fast with no acceleration - the same as setting the Z rate way too high and slapping the motor with a move.

WITH the G04 P.0 line in there it works perfectly.

G91 (switch to incremental mode)
G01 X28.00 Y4.00 F6000 (position probe switch)
G90 (switch to absolute mode)
#15239=1 (this var is monitored by a brain and triggers the probe cylinder)
G04 P0
G28.1 Z5.000 (probe the surface)
G92 Z#15045 (apply the probe switch offset from settings screen DRO)
#15239=0 (raise the probe)
G04 P0.4 (allow the probe to retract before moving or we drag it along the plate)
G91 (switch to incremental mode)
G01 X-28.00 Y-4.00 F6000 (put the axes back to where we came from)
G90 (switch to absolute mode)
M99
%

2143

General Mach Discussion / Re: Probably simple but...(G-Code help)

« on: January 11, 2016, 09:39:32 AM »

Thanks for the link, got that one

Yes the THC is a bit aggressive but needs to be really. In my case though the screech was when doing a G28.1 so could well be just the wrong the feed rate somewhere and flushing the buffer with the G04 P0 cures it?

I will try F1000 and no G04 see what happens

2144

General Mach Discussion / Re: Probably simple but...(G-Code help)

« on: January 11, 2016, 08:54:38 AM »

This might be the clue for the Z motor screech...

"The axes will move at the current feed rate towards the home switch(es)"

My current F rates are way higher than the Z can handle, maybe i should pull the G04 P0 out and put an F1000 in there??
Z is limited to 1300mm/min max

2145

General Mach Discussion / Re: How do you Cut a Slide Rail?

« on: January 11, 2016, 08:07:06 AM »

Unless the rails are big, I would just use an ultra-thin cut-off disc and cut it off, the end won't get hot enough to bother anything unless you really attack it with the disc, a lot of discs don't like coolant and it makes a mess.

Just ease through it and get it done

2146

General Mach Discussion / Re: Probably simple but...(G-Code help)

« on: January 11, 2016, 08:04:38 AM »

Found it, not applicable as its a plasma and Z home is always referenced to the top of the metal at the point of cut not a fixed homing location.

2147

General Mach Discussion / Re: Probably simple but...(G-Code help)

« on: January 11, 2016, 07:46:38 AM »

Thanks but,

The speed I can see and understand but what effect / purpose does "G28 Home Location Coordinates" have or do ??

2148

General Mach Discussion / Re: Probably simple but...(G-Code help)

« on: January 11, 2016, 06:41:16 AM »

Here's how i see it working, this version is untested yet.

G28.1 finds the surface

I know that at the point the probe switch trips, there is a fixed gap between my torch and the metal of whatever I set in the offset box so lets just tell the DRO what the gap is i.e. it's current position, no need to be zeroing and going up and down, just tell it where it is.

The double inc/abs changes are because i have no idea what will happen if i probe when in incremental mode as i only ever run in abs mode, may work, may not.
I figured if it does no harm then just switch back and forth.

The G04's are dubious, without the first one it makes my Z motor screech for some unknown reason, maybe trying to move the Z at the current rapid speed which it cannot do??? Is there a "F" parameter for the probing, maybe throwing in a F1000 would cure it?

2149

General Mach Discussion / Re: Probably simple but...(G-Code help)

« on: January 11, 2016, 05:28:18 AM »

Slightly more compact subroutine...

G91 (switch to incremental mode)
G01 X28.00 Y4.00 F6000 (position probe switch)
G04 P0 (wait until the move finishes)
G90 (switch to absolute mode)
#15239=1 (this var is monitored by a brain and triggers the probe cylinder)
G04 P0
G28.1 Z5.000 (probe the surface)
G92 Z#15045 (apply the torch height offset from settings screen DRO (currently switch offset))
#15239=0 (raise the probe)
G91 (switch to incremental mode)
G01 X-28.00 Y-4.00 F6000 (put the axes back to where we came from)
G90 (switch to absolute mode)
M99
%

cuts out two z moves and three lines of code, should work ok

2150

General Mach Discussion / Re: Probably simple but...(G-Code help)

« on: January 11, 2016, 03:40:43 AM »

Will have a look tonight but this is purely a personal thing i think, i have the accelerations as high as possible as its a plasma table.