Messages

811

Mach4 General Discussion / Re: dangerous malfunction of a machine driven by Mach4

« on: February 20, 2022, 03:30:31 PM »

Hi,
your machine is loosing steps, or one of the steppers is stalling.

Mach4 IS NOT A FEEDBACK controller, that is to say if Mach issues pulses for a stepper to go to a certain location it assumes the stepper does so because there
is no way for Mach to tell otherwise, it does not get feedback from the stepper.

Many Mach users prefer closed loop steppers or servos because the the stepper/servo drive uses feedback from the stepper/servo to determine whether its in agreement with
Machs commands. In fact if it differs from where Mach has commanded it be then the drive will issue pulses to try to correct the error. If the stepper/servo cannot for whatever
reason keep up with Machs commands and it slips behind it will fault out, produce an alarm and usually Estop Mach rather than carry on machining when its well out of correct
location. Note that Mach is still not a feedback controller in this circumstance, but the stepper/servo drive is smart enough to know when its stepper/servo is out of position.

Craig

812

General Mach Discussion / Re: Mach3 borderless window

« on: February 17, 2022, 10:34:23 PM »

Hi,
Mach3 requires a separte editing suite to effect graphics/Window changes.

Mach4 on the other hand has a built in GUI editor and supports wxLua, that is wxWidgets but with Lua bindings which results in a huge range
of features and oppurtunities for graphic customisation.

Craig

813

Mach4 General Discussion / Re: SoftMin Error

« on: February 16, 2022, 07:41:30 PM »

Hi,

And using your train of thought...must mean there will never be another bug fix release ever.

incorrect, there have been dozens....out of thousands reported.

Craig

814

Mach4 General Discussion / Re: SoftMin Error

« on: February 16, 2022, 06:30:42 PM »

Hi,

Thanx again for trying to help, but I seriously think this is a bug somewhere.

Heard it dozens of times...'must be a bug in Mach4'. I've been using Mach4 for seven plus years...do you suppose if there were such a basic bug I
would not have encountered it? Or the thousands of other users?

It will be interesting what you come up with, keep us posted.

Craig

815

Mach4 General Discussion / Re: SoftMin Error

« on: February 16, 2022, 04:37:46 PM »

Hi,
a quick scan through the code shows that g91 ocurrs ONLY at the end of the file:

Code: [Select]

G28 G91 Z0.
G90
G28 G91 X0. Y0.
G90
M30
A g28 move is the machine moving to its Home location. I think the g91 is misplaced in both occasions that it ocurrs. This code looks like some post processor would generate?
What program are you using to generate it? If its Fusion 360, and I suspect it is on the basis of the Gcode that results then you can reconfigure the post so that it does not happen.

I've just run a Fusion design through the post processor with the 'G28' option  active and it produces this code at the very end of the file:

Code: [Select]

M9
G28 G91 Z0.
G90
G28 G91 X0. Y0.
G90
M30

I've just re-run the same design through the post processor but with 'Clearance Heights' option active:

Code: [Select]

G0 Z15.

M9
M30
Note that this code just retracts to z=15mm, the current z axis clearance height, and no BS g91 moves in sight!

Craig

816

Mach4 General Discussion / Re: SoftMin Error

« on: February 16, 2022, 04:23:32 PM »

Hi,

And you are correct, there are G91's, so that is probably the root of my issues....but...why would it run the first time?

My guess is that at the first pass Mach concludes that there are no moves that would violate the SoftLimits but at a second pass it has accumulated
a 'history' from which position an incremental move would violate SoftLimits.

hmmm, since it runs fine after I do a "ref all axis" I should probably investigate that code too.

No, there is nothing wrong with the RefAll code, it has an effect because it resets Mach ie wiping it previous movement history.
Most CNC Gcode texts  (Peter Smid) recommend NOT to intermix incremental and absolute code....and this is a prime example why that is.

Craig

817

Mach4 General Discussion / Re: Z won't raise above 2"

« on: February 16, 2022, 04:06:47 PM »

Hi,
well the only thing I can think of is SoftLimits. Are they active?

Craig

818

Mach4 General Discussion / Re: Z won't raise above 2"

« on: February 16, 2022, 03:05:39 PM »

Hi,
what software are using, Mach3 or Mach4? I ask because that sounds like 'SafeZ' which is a feature and setting of Mach3 bit does not have a direct equivalent in Mach4.

Craig

819

Mach4 General Discussion / Re: SoftMin Error

« on: February 16, 2022, 02:33:26 PM »

Hi,
I'm not sure that these are the same issue.

In the case of my previous post I described Mach4's adherence to ANSI standard Gcode that requires careful attention to modal cycles like g83.

What you are talking about it that Machs trajectory planner has determined that a planned move would take it beyond the programmed SoftLimit.
If you turned SoftLimits off and ran the code, it would run but according to the warning at some stage of the job it would exceed the boundaries
of your machine.

I would guess that you have g91, that is, incremental moves in your Gcode.

Lets say your SoftLimit x-- is -221mm, say. Now if you had code:
g1 x-255   say,
then you would expect that Mach4 would error out. You have called a move beyond the boundaries....thats what mach is supposed to do.

Lets say however that the machine is in position x=-100, y=0 and you had code :
g91
g1x-150 y0
This code would fail also, because you have made an INCREMENTAL move of -150mm when you were already at -100mm, that is an absolute position of x=-250mm, y=0.
This is an excursion of of bounds and Mach would error rather than crash. My guess is that Mach is not able to detect that error will be encountered until the moment actually
arrives, whereas Mach WOULD determine a fault with an absolute move out of bounds from the very moment the Gcode is loaded, parsed and the toolpath plotted.

Lets say you want to drill a series of five holes 10mm apart, you could do it this way:

g90
g83 x0 y0 z-5 f500 r2 p1
x10 y0
x20 y0
x30 y0
x40 y0

Each hole is drilled at a specific and predetermined ABSOLUTE position.  You could also do it this way:
g0 x0 y0
g91
g83 x0 y0 z-5 r2 p1
x10
x10
x10
x10

Where the first hole is drilled at the start position, namely x=0,y=0 and then INCREMENT x+10mm each subsequent hole.

Mach would know immediately if the first code violated SoftLimits whereas it may not know with the second code because that requires tracking of previous history.

Craig

820

General Mach Discussion / Re: Mach3 Threading with Gear head lathe

« on: February 14, 2022, 12:51:04 AM »

Hi,
Mach doe not need to cotrol the spindle but it does need an index signal from it.

The manual for your board is a joke.....there is no information about the electrical properties of the inputs, and without that
there is no way to get the index signal working.

Craig