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Messages - joeaverage

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591
General Mach Discussion / Re: Mach 3 USB version
« on: July 31, 2022, 04:58:26 PM »
Hi,

Quote
So, Craig, are suggesting that an ethernet cable could be used? Obviously, it can plug into the computer, but what about at the breakout board?

No, I think there is some confusion about what a breakout board and a motion controller is.

A breakout board has no 'processing power', but rather just buffers signals and offers screw terminations for wires , and maybe a relay or two, and sometimes a PWM to analogue
converter for the spindle.

A motion controller on the other hand  accepts numerical trajectory data from Mach/PC and converts that numeric data into stream of pulses. In many cases the output
of the motion controller goes into a breakout board, or more than one, and then to the machine. Other motion controllers require no breakout board.
The motion controller can be connected to the PC by either a USB cable or Ethernet, with Ethernet cables having a noise advantage. Such a motion controller will require
a micro-controller and/or an FPGA to process numerical data to accurately timed pulse streams

The confusion has resulted from the way Mach was originally developed, namely the parallel port. In a parallel port PC there are two distinct software chunks running, the one
most familiar is the Mach program itself and its GUI, a Windows application. Machs task is to interpret Gcode and generate the numeric trajectory data, also called P(osition)V(elocity) over
T(ime), PVT data. The second chunk is Machs pulse Engine which is code that lives in the kernel alongside Windows. Its this software that converts the PVT data to pulse streams
and communicates that to the outside world via the printer port. So according to the definition above Machs Pulse Engine IS the motion controller.

The issue is that Machs Pulse Engine has to co-exist with Windows is very subject to stalling and jitter because of the shared processing. With an external motion controller like the UC100,
the UC300 or an Ethernet SmoothStepper that conflict does not occur because the processing of trajectory data is handled NOT by the PC but the motion controller. The hardware used
for the motion controller does just one job, and does it well. As a result the pulse streams coming from a good external motion controller are much faster, smoother and more accurately timed
without the stalling and jitter that occurs with Machs Pulse Engine. It also means that Mach, the Windows application is no longer tied to running on a 32 bit machine that was mandatory for
Machs Pulse Engine, so you can use laptops, 64 bit and Windows 10 etc, none of which were possible with Machs Pulse Engine.

In short a good external motion controller is a major step up in performance and capability over Machs parallel port. The choices we have alluded to are a (genuine)UC100, a UC300, or
an Ethernet SmoothStepper, but there are other worthy choices also like a PoKeys 57CNC, as CSMIO or a Hicon. The later two are very good but quite expensive, starting at $600USD.

If you are considering a motion controller a good purchase will result in you using that board for many years and the suggestion is consider the current requirements but also what you might like to do
in the years to come. For instance a UC100 has the equivalent of 'one parallel port' or 17 inputs and outputs. That's enough for a basic machine, but if you ever need more IO you're screwed,
whereas the UC300 has 85 inputs and outputs, or the Ethernet SmoothStepper (ESS) has 51 inputs and outputs, so either would be of use in later years. The UC100 operates up to 100kHz,
a good step up from the parallel port, but the UC300 operates up to 400kHz and the ESS up to 4MHz! Thus if you ever upgrade to servos you'll want at least the speed of the UC300
but better the speed of the ESS to take advantage of the resolution and speed that servos offer.

About eight years ago I bought an ESS (cost at that time $180USD) and Mach4 ($200USD) and have been using them ever since, and both have proven to be the best value investments in CNC
I've ever made. Machines, spindles, tools, vices, breakout boards, steppers, servos are all subject to change over the years but Mach4/ESS has the backbone right from the start.

Craig

592
General Mach Discussion / Re: Mach 3 USB version
« on: July 31, 2022, 02:44:05 AM »
Hi,
the issue is that USB is not an galvanacly isolated connection. Thus any voltage disturbance that occurs at one end upsets the comms at the other end.
Ethernet is transformer coupled at both ends, ie its galvanacly isolated, and has much greater immunity to noise. Physics.

Craig

593
Hi,
by the way if you try to run your spindle lower than say 12000, or maybe at a stretch 9000, you risk blowing it up.
These high speed asynchronous spindles do not like low speeds, they overheat and blow up.

Craig

594
Hi,
I'm not sure but what are you expecting?  You are using a PWM to analogue in the BoB, which may or may not be linear, certainly no better
than 5%, then the analogue voltage is applied to the VFD which will be linear to say 10%. Unless you have encoder (or some other pulse) feedback
and use the PID function of the ESS you'll get no better than 10%.

Alternately you need a Step/Dir type spindle, ie a servo driven spindle. I have a secondary spindle based on a 1.8kW Allen Bradley servo, and in Step/Dir mode
its speed accurate to within 0.1%, but I don't really care about that, what I care about is that it has low speed torque to drive tools in steel
and stainless. I spent the money so I had the torque to do the job in steel and stainless, I couldn't give a damn about ultra speed control.

Any way who cares? When you used a manual lathe or mill you got the closest speed  the gearbox/drive offered and then did the job. For example:
might have been nice to spin the lathe at 550 rpm, say, but the closest setting was 400rpm, and I could still turn up a nice part.
Just because the speed was off by 10 or 20% did not stop you from doing the job did it? Why get hung up on trying to get the speed spot on?

Craig

595
Mach4 General Discussion / Re: DIY pendant & Visual LCD Studio
« on: July 30, 2022, 04:50:38 AM »
Hi,
what motion controller are you using?. Do you have five , or six or more spare inputs?
If you do why shag around and just make a wired pendant?

I made one to replace my VistsaCNC pendant, I wore it out over seven years and thought I'd make one.
Real simple, has two wires for axis selection, one for velocity/incremental mode, two wires for A&B of the MPG, and two wires for
power and return. Seven wires but only five inputs required. Works OK.

Craig

596
Hi,
in Screen Edit mode place a toggle button. On the Properties Tab of the button you can associate an Input and/or an Output.
On the Events Tab of the button you can call from a range of Mach4 internally coded Actions, an Up Action and /or a Down Action.
You can also write Lua scripts, an Up Script and /or a Down Script.

Craig

597
General Mach Discussion / Re: Mach 3 USB version
« on: July 29, 2022, 06:28:34 PM »
Hi,

Quote
Still curious to know: Do all breakout boards use a parallel port input so that you either have to have a parallel ported PC or a UC100?

Most breakout boards conform to the old parallel port pin numbering and plugs. Its not that they have to, but rather that the history of Mach, being rooted in the parallel port,
when new products came onto the market they to conformed so they would meet wide scale applicability.It's a bit like Henry Ford, having decided on a wheel at each corner for
his new car, that now every car manufacturer does the same thing!!LOL

Another example is the Ethernet SmoothStepper (ESS) by Warp9. The ESS have three parallel port equivalents, but rather than DB25 connectors they have IDC headers, but still
numbered like a DB25. The PoKeys 57CNC however has IDC headers, numbered in standard IDC manner, with no similarity to a parallel port.\

Craig

598
General Mach Discussion / Re: Mach 3 USB version
« on: July 29, 2022, 06:17:57 PM »
Hi,
beware that there is many a Chinese knock-off UC100 on Amazon and Ebay. If you are going to buy a UC100 make sure its the genuine
article, the Chinese rip-offs are not a patch on the real thing.

Depending also on your electrical environment you may find USB to be subject to electrical noise and fail in service. A very short USB cable is required, a long cable is inviting
trouble. In this regard Ethernet connected motion controllers are much better, for instance the UC300 which is also made by CNCDrive.

Craig

599
Hi,
I echo what Chas has said. Rigid tapping is a motion control feature not Mach.

Go back to your experience with a manual lathe. With the lead screw lever engaged the saddle is mechanically linked via the gears to the spindle.
If you rotate the spindle in either direction the saddle will move in precise synchronism with the spindle.

To do rigid tapping with a CNC machine requires the same link between axes, say the vertical Z axis and the rotation of the spindle, in the case of a VMC
the C axis.

I am not aware of any Mach4 ready motion control which can do that.

Lets take some hypothetical motion control that could do what we want....what features and properties would it need? In particular lets say that you have
an encoder on the spindle. Any rotation will be reflected in a changing encoder reading. Our hypothetical controller would need to multiply the changing encoder
reading and issue Step/Dir pulses to the Z axis so that the Z axis height faithfully remains in pitch synchronicity with the C axis.

You might say 'but my CSMIO/A is analogue', and that's true....the signal to the servo from the controller is analogue.....but the motion commands issued to the controller
are still Step/Dir.

Neither CSMIO or the Hicon, or in fact any Mach4 motion controller can generate Step/Dir signals for one axis on the basis of encoder input from another.
I may of course be mistaken about that.....I await with baited breath!

Mach is of limited use here because the communication delays both from the encoder back to Mach and then from Mach to the Z axis preclude realtime action.
This is one are where LinuxCNC wins hands down being essentially realtime.

There is another way to do rigid tapping which I have used. It relies on Machs ability to produce a trajectory that is coordinated between axes.
A block of Gcode like:
g1 a3600 z-10 f21600
would cause the C axis to rotate 3600 degrees or 10 revolutions (in 10 seconds) while the Z axis descends by 10mm. This is a helical toolpath with a pitch of 1mm per
revolution. Note that the C axis moves according to the trajectory its given as is the Z axis, the fact that they describe a helical toolpath is because of our choice
of the two trajectories rather than the rotation of one axis 'driving' the other linear axis.

I have a secondary spindle based on a 1.8kW Allen Bradley servo, and I have the possibility of driving it with Step/Dir signals which allow me to use it as a genuine C axis
which in turn allows me to rigid tap.

There is a limitation that you must be aware of however. If I call a move like the above it requires that the C axis rotate at a precise speed despite having to supply the cutting torque of the
tap. If the C axis slows because of that load then the Z axis will get out of sync with the C axis, ie a pitch failure. Thus the spindle must have sufficient torque authority to drive the tap, which in turn
places a restriction on the size of the tap and the material into which it is cutting and the engagement.

My servo is rated at 6.1NM and 18NM overload. I have found that 6mm in mild steel with 65% engagement or 8mm in mild steel with 50% engagement is perfectly doable but is dubious above
those limits. The bottom line is you need mega-torque to rigid tapping, and that I suspect goes for conventional rigid tapping (spindle 'driving' a linear axis) OR coordinated motion between axes
such as I have described.

While I have the ability to do rigid tapping, and I have used it up to 10mm in aluminum, its not a technique I use regularly. It means that I have to load my spindle into the machine,
set up the tap etc, and for the few holes I do I can't be bothered....mostly. In those few situations where I have a run to do, say a whole bunch of bolt hole circles on multiple
pipe flanges, then it becomes worth it.

Craig


600
Hi,
this post should be on the Mach4 General Discussion board rather than here.

CSLabs are well behind other manufacturers when it comes to their Mach4 plugin.

Some years ago CSLabs did a very good job of a Mach3 plugin and supported customers very well, and got a great reputation for it. At about the time Mach4 came out they
started their own CNC software and the Mach4 plugin was just an afterthought, and has had very few updates since. There may well have  been a personal change also as
the great customer support they had exhibited before dried up completely.

CSMIO are still good quality but for the price the Mach4 plugin is too buggy and patchy and the lack of support makes them hard to recommend for Mach4.

Craig

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