Messages

2341

General Mach Discussion / Re: Which 3d image software?

« on: July 02, 2019, 08:43:15 AM »

Hi,
Fusion 360, made by Autodesk, the same company that makes AutoCAD, Inventor and HSMWorks, has made a splash
because its free to hobbyists. It is by no means the only CAD/CAM program around but it is a good one.

Often you have a very simple job for which you don't require CAD/CAM, maybe cut a rectangular slot, drill a bolt pattern
and face the material. NFS MillWizard ($75) is good for chaining simple operations together. It gives what amounts to
'conversational programming' to Mach. I use it a lot.

Craig

2342

Mach4 Plugins / Re: Mach4 plus Ethernet SmoothStepper with encoder or linear scale.

« on: July 02, 2019, 03:59:08 AM »

Hi,

From my experience a board like ESS based FPGA could be able to monitor the pulse train read by the encoder.
I'm talking about a passive comparator (no PID control).

You are correct, the ESS COULD be a feedback controller but Warp9 have expressed no interest in doing so. A major part
of that thinking is because each servo and servo drive is  a feedback loop. Thus all an ESS need do is provide open
loop step/direction commands and allow the servo and drive to follow. The servo/drive have an  following error window
and can monitor if the loop gets out of whack with respect to the input commands.

You need to imagine a situation where the ESS commands pulses but the signal is lost before reaching the servo drive input.

Imagine what situation? Are you talking a faulty breakout board?

My ESS has never lost any pulses in the four years I've been using it. As an example I have a PCB
program that I run from time to time, it is a largish but detailed board and it takes 10-12 hours to run. At the end of the
program  I can drill a 0.4 mm through hole EXACTLY through the hole I drilled at the start of the job. If Mach, or the ESS,
or my BoB's, or my stepperdrives, or my stepper lost a step that would not be the case.

If the ESS board monitored the encoder it would be possible to detect the error (pulses commanded - pulses executed).

What I have proposed is that the servo drive monitor the commanded position (the cumulative step/direction position) by
Mach/ESS and the machines actual current and live position which achieves exactly what you are proposing.

There are controllers that can do as you wish, but they start at six and more times the cost of an ESS. In addition those
controllers are suffering a shrinking share of the market because of the to trend smart servo drives, the motion controllers
don't need it any more, in fact Ethercat does away with the motion controller altogether and 'distributes motion control'
amongst its Ethercat slaves.

Craig

2343

Mach4 General Discussion / Re: Enable momentary on reset

« on: July 01, 2019, 07:37:33 AM »

Hi,
how about something simple like waiting for a second or two after Mach fires up, turn on an output pin for 2 seconds
then off again. This could go in the PLC script, it waits until tescount (the number of times the script has run since the beginning
of the session) is 50:

Code: [Select]

if (testcount==50)then
local outHandle=mc.mcSignalGetHandle(inst,mc.OSIG_OUTPUT5)
mc.mcSignalSetState(outHandle,1)
wx.wxTimer(2000)
mc.mcSignalSetState(outHandle,0)
end
Craig

2344

General Mach Discussion / Re: Send PWM signal from Geckodrive G540 to PC

« on: June 29, 2019, 07:34:13 PM »

Hi,
you have a few misconceptions going on.

it sounds like VB is out because of the speed limitation you noted, since I doubt I'd want to introduce a full 10ms of lag

This 10ms lag is not because VB is slow, but rather is the time taken by the controller to compose a data packet and transmit
it to Mach.

Secondly Mach3 has a macropump which cycles every 10ms. Thus if you have a macro in Mach3 that you wish to run continuously
it will run every 10ms. Mach4 has a similar idea called the PLC script. As default it runs every 50ms, but you can program it
to run more frequently. I have heard that some people have run it a 2ms intervals without causing the rest of Mach to crash.

In ESS config, what does the Controller Frequency do") that the SmoothStepper's fastest buffer rate is 1/4 second.

Windows PCs are not realtime machines, the way Windows uses CPU interrupts for its own purposes precludes Windows from
ever being realtime. CNC however is by definition a realtime operation. Mach gets CPU service in  little chunks. To have a
Windows PC run a CNC machine means that Mach must generate a series of moves called PVT (position velocity over time)
in 1 ms slices. These are bufferd by the motion controller. ALL motion controller must do this. Even the parallel port
has a buffer.

What the buffer is doing is 'smoothing it out'. Mach might get CPU service from the Windows scheduler for 1.8ms. During that time
Mach might calculate 150 PVT data packets, enough moves for 150ms. They are transmitted to the controller buffer.
The Windows scheduler will then take CPU service away from Mach to do whatever else Windows decides needs doing.
Provided Windows get all those other jobs done or advanced a little and gives CPU service to Mach BEFORE the 150ms worth of
moves has been consumed all is well. If not the motion controller runs out of data and the machine stalls. Even if shortly
thereafter more PVT data becomes available its too late. Mach cannot accelerate to speed instantly. So when the controller
runs out of data the machine stops irrevocably.

I have never used the ESS on Mach3, only ever Mach4. I imagine there are differences but the same principle applies.
In the ESS Mach4 plugin the default buffer is 180ms. You can program it to be more, up to a maximum of 500ms, or less.
If there is a bottom limit I don't know it. The choices are to reduce the buffer length so that the PVT data from Mach is enacted
as soon as may be but then you risk the buffer running out of data. I have left it at 180 ms and have never had 'run out of data'
events.

The 'Controller Frequency' is the rate which the controller runs its internal loop. The ESS in Mach4 default is 40Hz, or 25ms. You can
program it to be faster but it demands comm service from the PC, thus an underpowered PC or one loaded down with extraneous
software and services may not keep up.

ALL motion controllers have this idea. The controllers, being hardware devices, could probably run very VERY much faster
but the PC couldn't keep up. So the 'controller frequency' is determined by PC not so much the controller.

With  the comm delays, the controller frequency and the buffer using Mach to enact a feedback loop is to slow.
Having said that NFS have just released a software defined THC module for Mach4. Clearly NFS are convinced that it
can run fast enough to provide a useful solution. It may well be fast enough for a die sinker as well. If indeed it
is fast enough then you can bring all the calculating/processing power that Mach and a PC can bring to bear. That would
allow you to tailor the machine response to your machine, highly desireable.

If you determine that you need faster response then you must rely on the function built into the on-board firmware/hardware
provide by the manufacturer of the controller.  Each manufacturer does it their own way and they won't share it with you,
its proprietary. Even if you had access to the manufacturers firmware how would you alter it?

There are some controllers like the Hicon, the PoKeys 57CNC and of course Galill that expose an on-board API to users that
they may form there own realtime functions. As I commented earlier Gallil is the absolute past master at this but is very
expensive. Just what the capabilities of the Hicon and 57CNC are in this regard I don't know. There is little or no discussion
on the forum about users exploiting the API.

Your choices are:
1) try to use THC as enacted by Machs parallel port
2) buy an external controller like an ESS and use the THC function provided as best you may, which may (or may not!)
    be more advanced/flexible than the parallel port
3) buy a Gallil or other controller (Hicon or 57CNC) that exposes an API and write your own realtime function. This may require
    some serious programming expertise. Researching what is achievable (both the hardware and your skills) BEFORE you buy
    is required.
4) use Mach4, either the THC module as is or as a template for your own scripted function. This option exists only if
    you can secure the closed loop speed to be effective.

Brains (Mach3)  run very fast but they still do nothing about communication delays or buffering so they won't
save you. If they were fast enough would not a Mach3 software defined THC function been developed? In short Mach3
is too slow for a software defined control loop for THC and by analogy, your die sinker.

Craig

2345

General Mach Discussion / Re: Newbie with a few questions

« on: June 29, 2019, 08:40:30 AM »

Hi Gerry,
great insights, thanks very much.

I had always suspected that Aspire was optimized for decorative work. So your conclusion is not a surprise.

I am not averse to buying a program and it not being updated. I mean if it was good enough when you bought it
and it still doing what it as supposed to five years later.....I'm OK with that. One of the reasons that Aspire appealed
was the perpetual licence. In this instance though while I might get a perpetual licence the program is probably not
what I really want.....and Fusion, despite the subscription model, is.

I will probably check out VisualMill by Mecsoft a bit closer. Some of the toolpaths that were videoed were very much like
some of the Mastercam toolpaths I had become accustomed to. Downside is it would appear that the version of the software
I liked was in the Mastercam price range!

Thanks again for your insight.

Craig

2346

General Mach Discussion / Re: Newbie with a few questions

« on: June 29, 2019, 07:12:44 AM »

Hi Gerry,
if you forgo the $400 every two years for the Aspire upgrade and figure on the normal subscription rate of $500 per year
for Fusion the numbers even up somewhat.

I am rather interested in what you perceive as the differences between Fusion and Aspire.

For several years I had access to decade old version of Mastercam. Not withstanding the steep learning curve I did come
to appreciate its power and flexibility. The choice of toolpath types was simply amazing and has only gotten better over the
subsequent years. If I could afford to replace it I would.

The majority of the work I do is engineering parts.

How would you rate Aspire and Fusion for that style of work?

Craig

2347

General Mach Discussion / Re: Send PWM signal from Geckodrive G540 to PC

« on: June 29, 2019, 03:41:57 AM »

Hi,

From what I've read, Mach3 can home each axis in sequence so that it knows which one is homing when. I know that would be slower, but other than that is there another reason why it's worse?

Yes, by all means it will work. As I stated I am a lone voice is this matter. When you crash your machine because Mach can't
distinguish between an X axis X++ event from a Z axis Z-- this conversation will come to mind....'I bloody told you so'.

I assume I'd still want optical isolation (or a breakout board with the same) on those extra inputs?

I use Homan Designs MB2 bi-directional breakout boards which don't have optical isolation. I have been using them for over five
years and have had no issues due to the lack of isolation. Electronics is my thing, so if I determine a situation where I suspect
that optical isolation is required then I make it to suit. What I do not do is demand that all inputs have optical isolation.
That would make bi-directional boards impractical. If you are of the opinion that optical isolation is mandatory then be prepared
to pay for the breakout boards that can do it.

THC only tells one axis (presumably the Z axis) to move up/down. I'm concerned that if I wanted to do more complex cuts it wouldn't work right; if, say, I had a sinker that was angled or flanged.

That is correct. You are adapting a realtime, that is to say an 'on board' feature over which you have no (software)  control, to do a job
for which it was not intended. There will be limitations and incompatibilities. Whether you can live with them or mitigate them
remains to be seen.

You could of course go to a Gallil motion controller. That is programmable at board level, it is the gold standard among motion
controllers. Expect to start at $2000 for a three axis controller. You want good....you can have it, you just have to pay up!!.

Also, does that mean that the sinker would always be moving, since THC only has up and down?

In short yes, but when at optimum voltage it will move one step up, say 1um, then one step down, say 1um. In such a manner
it is quasi stationary. I think you will find most controllers, each of which enacts THC in their own way, have a 'voltage window'
such that if the actual voltage is within the target range THC_UP and THC_DOWN signals are suspended.

I also wonder if the sinker might plunge too far if it somehow bored all the way through; then it'd never have the signal to stop because the capacitor voltage would stay high. What part of the THC system prevents that?

Most THC plugins have some means of anti-dive control. For instance if a plasma cuts over a previously cut track its voltage
will spike high which in turn causes the THC unit to cause the torch to dive low. This is undesireable and much like the
break through event you have described. Most controllers offer some variation of anti-dive control. The sophistication and performance
of the anti-dive strategies offer insight into which control is better suited than another.

I still feel like the best solution would be to forward/reverse feed.

Yes I can well imagine that would be the best solution. That largely precludes THC as viable solution for a die sinker.
As TPS has pointed out that Mach3 has a defined macropump rate which would determine that a software defined feedback
loop would be very slow with a closed loop bandwidth of 5Hz or less. This I suspect would be too slow for a die sinker.

Mach4 however has a much faster, and within limits programmable PLC rate, which would allow for a software enacted feedback
control loop with a bandwidth of 20 maybe as high as 50Hz. Certainly the Mach4 THC module which I described is intended
as a software only solution for THC, so NFS believe that it has sufficient bandwidth.

If you were going to do a software solution that would accommodate things like angle cuts, flanged cuts and a mechanism to
prevent break through then Mach4 is by far the better platform to code it. TPS is one of the VB masters to whom I have
previously referred. If he is of the opinion that it can be done with VB and Mach3 then I'm sure it could be. If however he
is doubtful then I wouldn't go there.

Brains, also called PMC in Mach4 are fast but still far from realtime. To whit.....no-one has ever been able to write a Mach3
Brain that has successfully enacted THC, its just too slow.

NFS has however released the first and only software enacted THC control loop in Mach4. You make the decision.

Craig

2348

General Mach Discussion / Re: Mach3 freezes constantly_little to no support from.....support.

« on: June 29, 2019, 01:08:34 AM »

Hi,
I would guess, and it is only a guess, that the USB controller is Chinese. If it seems like I bash Chinese made controllers....
its because I do! They have earned all the bad press I give them.

Yes I would recommend an Ethernet connected controller and my suggestion would be an Ethernet SmoothStepper (ESS)
by Warp9. For Mach3 it is certainly not the only good (US or European made) controller, but it is what is familiar to me.

The ESS requires a breakout board, so one C10 ($23.00) or if you want/need more IO then a second one.
Without seeing inside the box we can't know whether the stepper drives are integrated onto on board, if I had to guess I
would say not. That being the case an ESS, a C10 and you can hook to your existing stepper drivers.

A Hypertherm 45 is probably a long term goal, Hypertherm is very good, probably the best on the market but they aren't cheap.
If the Razorweld is punematic contact break start as now seems likely then it should work OK, especially if it is recommended
by the table manufacturer. With any sort of luck by the time you blow the Razorweld up....and you will eventually.....you'll
have a swag of dough in the bank to buy a Hypertherm.

The first step is to get an Ethernet connected controller underway. I would guess that 50% of your problems will be solved right
there.

As for shielding and other measures....get set for the long haul....probably all of them will be required.

The first thing is to physically separate the cables associated with the plasma from any of the machine and signal wiring.
Where they cross they should be at right angles.

The second area that is often overlooked and therefore untold effort expended in other means to overcome is conducted noise.
The plasma being an inverter is a noisy device and draws non-sinusoidal current from the 230VAC supply. That non-sinusoidal
current can be many (10-30A) amps and that can be impressed on the 230VAC input to your PC and machine/controller
power supplies. One or several good AC line filters are in order four your PC and machine power supplies.

You could use a line reactor to tame the input current to the plasma but that is a fairly extreme step. I would save that for
'I'll only do it if I have to....later down the track' A line filter big enough to handle the plasma input current is likely to be
very expensive and that makes a line reactor more cost effective....should you need to.

You might try as an experiment to get your 230VAC for your plasma from a different and preferably remote socket from which
you get the 230VAC for your PC/machine. If it helps the line filters are strongly indicated.

https://nz.element14.com/schaffner/fn2090-6-06/filter-1-ph-6a-chassis-mount/dp/1304858?st=line filter

Note I got that off the NZ website, depending on where you are Premier Farnell and/or Newark will have the same listing
in the local currency.

The next area you should look to is shielding signal cables, particularly cables such as limit and home switches. Their long length
makes then susceptible. They should be screened with all the screens earthed at one end only, usually the controller end with all
going to a single 'star point'. It is also good practice to fit ferrite cores, either by passing the cable through the core several times
or by using split cores. Two ferrites per cable, breaking the cable into approximately three equal sections has proven to work
for other installations.

https://nz.element14.com/fair-rite/2643804502/solid-round-emi-suppression-core/dp/1133951?st=EMI ferrites
https://nz.element14.com/fair-rite/0446164181/ferrite-core-split-12-7mm-205ohm/dp/1781360

You should have several ferrites on the Ethernet  cable and even more importantly on any USB cable.

If you go with an ESS you will have the chance to add some de-bounce, effectively a digital input filter to all your incoming
signal lines. It is sometimes beneficial to have some 0.1nF ceramic capacitors on the inputs on your breakout board as well.

Quite a few installations have a separate earth stake just for the table. An electrical earth stake, or even more than one, if the
local earth impedance is high, are driven into the ground and connected to machine about where the torch sits.
Given that in New Zealand increasingly all circuits are protected by Residual Current Devices I am not  enamored with the idea
of another earth stake in competition with the main electrical system, however so many people do it, so there must be some
benefit.

That's enough to start with.

Craig.

2349

General Mach Discussion / Re: Mach3 freezes constantly_little to no support from.....support.

« on: June 28, 2019, 11:06:36 PM »

Hi,
I have just been reading the NZ site for the Razorweld and it suggests  that the start is not HF but rather pneumatic
contact break start. Please dis-regard my last post, it may be inaccurate.

If memory serves Trafimet did have some contact break start torches, this may be an example of such.

Craig

2350

General Mach Discussion / Re: Mach3 freezes constantly_little to no support from.....support.

« on: June 28, 2019, 10:51:07 PM »

Hi,
just re-reading your post and see that you have already provided the make and model of your plasma.

I worked for seven years for a company that sold and serviced welding equipment. I worked in servicing and my training is
in electronics. That plasma is an HF start, the Trafimet torch determines that. That means you are going to have a battle trying
to get electrical noise from stuffing up Mach.

Craig