Messages

1131

Mach4 General Discussion / Re: Mach4 Homing and Machine Coordinates

« on: July 15, 2021, 04:46:51 AM »

Hi,

So right now I have min to max as 0 to 8000.  If I instead centered to get a home position, I would need to have soft limits at -4000 to 4000.  But moving the stage left or right for X to center, say distance D which could be a positive number or negative, means that the machine coordinates will be in a translated range -4000+D to 4000+D.

Perfectly correct, but once you have determined what constitutes your Home position you MUST repeat that Home position every Mach session.

Thats the whole point about having Home switches, they uniquely define one position as Home and then SoftLimts are the machine extents
relative to that position. It doesn't matter whether that Home position is in the middle of the 8000mm axis, or closer to one end, all that matters
is that the Home position be repeatable EVERY Mach session, otherwise your SoftLimits would have to be modified EVERY Mach session also.

I can only but imagine that any machine with an 8m axis is an expensive beast, in which case buy yourself three $20 (each) snap action microswitches,
good ones, and fit them.  Home switches were the first 'addition' to my original mini-mill and by far and away the best money I've spent over and
above its original build. I used to crash quite regularly before getting Home switches, and I've crashed about three times in the six years SINCE
I got them. Second best improvement was a $300 coolant pump and resevoir.....

Craig

1132

Mach4 General Discussion / Re: Mach4 Homing and Machine Coordinates

« on: July 15, 2021, 12:19:35 AM »

Hi,
RefAll and 'zero your axis' are totally different operations.

When an axis is Referenced, also called Homed, the machine coordinate for that axis is set to zero, or alternately set to your programmed offset. This is
THE ONLY WAY you can set machine coordinates.....there is no other method.

When you 'Zero your Axis' Mach changes the WorkOffset so that the DRO reads zero despite the machine coordinate being nnn say. Clearly the
WorkOffset is set to -nnn.

If you don't have home switches then you have to 'Home in Place'. Note that Mach determines if you have home switches by whether the ISIG_MOTORnnnHOME
is populated with an active signal. If it detects that you have assigned a switch it will look for that switch to activate before it References or Homes that axis
and sets the machine coordinate to zero. If it does not detect an assigned switch it will attempt to 'Home in Place'. Note there is a setting in the Control plugin
on the Homing/Limits page that activates 'Home in Place'.

Lets imagine for a moment that you had a home switch, or alternately you jog to a home position and home in place, but not at the end of an axis but in the
middle. Its perfectly permissible. Thus when your axis is referenced the machine coordinate is zero in the middle of travel. When you move in one
direction the machine coordinate will become progressively more positive, and conversely in the other direction the machine coordinate will become progressively
increasingly negative. If the travel of the axis is 500mm then your SoftMax would be 250mm and your SoftMin would be -250mm. No problems.

Negative machine coordinates are perfectly permissible and work fine. Remember that Mach is not intimidated by negative numbers no matter how much they
confuse us.

Craig

1133

Mach4 General Discussion / Re: Need help with some strange behavior.

« on: July 13, 2021, 07:14:31 AM »

Hi,

I'm a little lost as to what is going on here I don't know if the frozen touchscreen and pendant even have anything to do with it.

When using <FeedHold> the program is paused, not stopped. Mach at anyone time can have only one master....so in this instance
the Gcode interpreter is the master....even if it is paused, and so the pendant plugin will be ignored, as will the touchscreen or any MachGUI
control. If however you <Stop> the program then the Gcode interpreter ceases to be the master and the motion planner can accept a new source of
instructions, the pendant for instance.

Craig

1134

Mach4 General Discussion / Re: SoftMin Error

« on: July 12, 2021, 09:19:25 PM »

Hi,
SoftLimits are a set of numbers that describe your intended machine travel extents relative to the Home position. The mechanical boundaries
will be just a little bit bigger again.

For instance I have my Z axis set up so that the home position is very near the top of the axis stroke. That is to say the home switch is 4mm
lower than the mechanical stop. My limit switch is 2mm lower than the mechanical stop. My Z axis SoftMax is 1mm. That is to say that the Z axis can actually go
1mm higher than the home switch before SoftLimits prevents it from going any higher....hopefully! If it does, for whatever reason, travel beyond 1mm it will hit the limit
switch at 2mm and presumably Estop before it hits the mechanical limit at 4mm.

My axis has 358mm of travel, in machine coordinates from +4mm to -354mm at the bottom before it hits the lower mechanical stop. The SoftMin is set at -350mm, the limit switch
is at -352mm and the mechanical stop is at -354mm.

Note that all these number are machine coordinates, and they are ONLY valid after the machine has homed that axis:

mc=4mm              mechanical upper bound
mc=2mm              upper limit switch
mc=1mm             Z axis SoftMax
mc=0mm            home switch
mc=-350mm         Z axis SoftMin
mc=-352mm         lower limit switch
mc=-354mm        mechanical lower bound

When Softlimits are active the machine will travel from +1mm to -350mm for a travel of 351mm. Between the two limit switches (+2mm to -352mm) the
travel is 354mm, and of course the absolute max travel from mechanical stop to mechanical stop (+4mm to -354mm) is 358mm.

Craig

1135

General Mach Discussion / Re: Confused on Units

« on: July 12, 2021, 08:48:20 PM »

Hi,

I've used soft limits successfully in the past, but would be afraid to do so now until I know I have the machine coordinates sorted out.

SoftLimits only make sense and work if the machine is homed to a known and repeatable location....ergo Home switches. You don't strictly
need limit switches, but if you want to be able to home to a fixed location then home switches are essential. Most people use a one limit switch (of each axis)
as a dual purpose home/limit switch. Its not a practice I favor, I would rather have separate home and limit switches.

Craig

1136

Mach4 General Discussion / Re: Mach4 freezes up while running

« on: July 10, 2021, 03:17:05 AM »

Hi,
one possibility, and just a guess, is that the ESS is running out of data.

Machs trajectory planner issues PVT (Position Velocity over Time) data packets and the ESS buffers them up, 180milli seconds
worth at the ESS default. If the ESS consumes all that data BEFORE Machs trajectory planner can replenish the buffer the the ESS will
run out of data and stop. Its usually fatal.

I would expect the ESS plugin to offer a fault description, but perhaps its missing doing that.

One suggestion would be to run a diagnostic log to see when it happens and why. Another possibility is to monitor the ESS diagnostic
as it shows the content of the buffer in real time.

Craig

1137

Mach4 General Discussion / Re: Mach4 pendant

« on: July 03, 2021, 12:14:48 AM »

Hi,
I have used a VistaCNC P1A with Mach4 for six years.....it works OK.

The only time I have any bother with it is when or if I push the spindle hard....it tends to interfere with the pendants USB connection.
I've found it necessary to power cycle the entire machine in order to get the USB connection back, a PITA. Fortunately it does not happen
often....in fact so infrequently I've never bothered trying to track down the source of the fault. Maybe my new build mill will be  better, or
maybe worse!

Craig

1138

Mach4 General Discussion / Re: Why doesn't this work? (FEED HOLD state)

« on: July 03, 2021, 12:10:21 AM »

Hi,
there is another listing for the return values and quite a few other ENUMS etc:

https://www.machsupport.com/forum/index.php?topic=40051.0

Craig

1139

Mach3 under Vista / Re: Mach3 backlash compensation

« on: July 01, 2021, 05:13:20 AM »

Hi,
when Mach 'compensates' for backlash what it does is accelerate an axis the distance of the lash when
that axis reverses direction......not very sophisticated.

There is NO such thing as real software backlash compensation, as the lash increases the Mach solution works less and less well.

There is one, and only one, real solution.....cure the lash.

Craig

1140

General Mach Discussion / Re: Need a recommendation for control board for plasma cutter.

« on: June 29, 2021, 07:55:06 PM »

Hi,
the TMC unit is recommended with Mach4 and the ESS. The Proma unit does not have any anti-dive algorithms
whereas the TMC unit does.

The TMC unit has a Mach4 plugin which means it has software running on the PC which includes anti-dive. The Proma on the
other hand as no such plugin. They both have THC_UP and THC_Down signals as they need to be realtime but that is where the similarity
ends. The ESS THC support was designed and optimised for use with the TMC unit. It will still work with the Promas  THC_UP and THC_DOWN
signals but you'll miss on ALL the anti-dive.

Anti-dive is what separates hobbyists tables from the real thing.......you need to decide what sort of table you want.

Craig