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Messages - Steve Stallings

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The Z co-ordinate in the G81 command line is the hole depth.

Before you can execute a G81, the previous code must have
established the Z starting point.


Mach4 has a "setup units" option for Metric or Imperial. This will allow for
the simplest possible computation of steps per unit.

The actual running of G code is independent of this and you can set
your defaults to run Metric or Imperial G code, and can override this
setting at any time using a G code to select mode.

Mach4 General Discussion / Re: Motion Controller recommendation
« on: December 01, 2017, 07:10:47 PM »
The PMDX-424 SmartBOB operates directly from 120 to 250 volts AC.

The other products in the SmartBOB family are powered from the
USB connection to the host computer.

Mach4 General Discussion / Re: Motion Controller recommendation
« on: December 01, 2017, 06:47:49 PM »
Every motion controller that I am aware of for Mach4 will support 4 axes.

I assume the 36 volts is for the stepper motor drivers. The motion
controller will not see or care about this voltage. It delivers 5 volt
logic signals for Step and Direction to the stepper drivers.

Spindle control can be simple On/Off or can be an analog voltage to
control spindle speed using a VFD or other variable speed drive. For
PMDX SmartBOB motion controllers, the VFD interface would be
an optional PMDX-407.

The PMDX SmartBOB family offers several motion controller that could
do the job.  You can compare them here:


Mach4 General Discussion / Re: Mach4 newbie here. I need some help
« on: November 27, 2017, 07:34:43 AM »
Threading in Mach3 with a single pulse per revolution does rely on
the pulse to measure spindle speed as well as to sync the Z axis
motion at the start of a threading pass.

The spindle speed is not modified by the threading process when
it measures the spindle speed. Only the Z axis traverse rate is

The Z axis traverse rate is not a regular PID control loop. The new
measurement of the spindle speed is fully adjusted for the change
as soon as it is measured. This is effectively a "P" only control loop.
Only the acceleration limit of the Z axis inhibits instant changes in
the Z axis motion.

Adding a PID speed control loop to the spindle drive may improve
things, but it also runs the risk of the two feedback loops interacting
in difficult to analyze ways. A strong servo with direct PID feedback
control will likely improve theading without causing interactions. Using
the regular speed control input to a VFD and software in Mach making
speed change requests will likely be too slow and complicate things.

The Z axis threading control loop is not ideal, but as stated, with a
strong enough spindle motor and sufficient spindle inertia, it does work
for "hobby grade" theading.

For machines run by a motion controller in Mach3 or Mach4 and
utilizing more than one pulse per revolution, better control loops
are possible. The nature of the loop will depend on the motion
control vendor because they can filter the speed feedback as

Mach4 General Discussion / Re: Mach4 trial fully functional?
« on: November 24, 2017, 08:13:35 AM »
The DEMO version of Mach4 is not a 30 day trial.

It will run forever when the motion device is the Simulator.

It will run for about 5 minutes of cutting time after each startup
when used with a real motion controller. After that, you must
shut down Mach4 and start it again. There is no limit to the
number of times you can do this.

As best I know there are no features suppressed while in the
DEMO mode.

Mach4 General Discussion / Re: Can you use Inputs with Macro B Programming.
« on: November 21, 2017, 11:53:51 AM »
Note: If you do use a Hobby screen set with an Industrial license, you
may need to be sure that the Use Advanced GUI Controls option is turned
off  on the General tab under Config > Mach dialog. Having advanced GUI
controls enabled can cause colors to display in a strange fashion when
running a Hobby install with an Industrial license, and may do the same
when running a Hobby screen with and Industrial install.

Mach4 General Discussion / Re: computer requirements for mach 4
« on: November 18, 2017, 07:38:17 PM »
For Mach4, the unlicensed DEMO mode will run with all features active, but is
run time limited to somewhere around 5 minutes before requiring a shutdown
and restart. As such it is fully capable to testing with a real hardware motion
controller during the demo time or for unlimited time with the simulator..

If you have a registered license, you can go the with Machsupport.com web
site and log in to use the License Maintenance button to issue additional
licenses to yourself for up to a total of 5 computers for hobby use. These
are fully functional licenses, but you do need to supply the PCID for each
computer in order to generate the license. Simply loading the existing
license onto a new computer does not work.

Macro B programming is not in the Hobby version of Mach4, but is present
in the Industrial version. The list price for Industrial is $1400.00 which also
includes other industrial features for more complicated machines, and
access to telephone support.

I do not recommend a wireless pendant for any CNC control due to issues
with loss of control. That being said, there are several that advertize Mach3
support via USB. It is likely that the more basic controls on those would
also work with Mach4 or could the made to work with some scripting.

VistaCNC.com offers wired pendants that understand Mach4.

Mach4 General Discussion / Re: M03 yes, but no M05
« on: November 06, 2017, 08:09:36 PM »
OK, I found the manual for this VFD and did not see any mention of 3-wire control mode,
so my earlier guess at your problem may be off base.

The manual can be downloaded here:


If you can talk with the people who serviced your VFD, try asking them if it is possible
that it could be operating in a mode that requires a separate STOP signal input.

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