Messages

871

Mach4 General Discussion / Re: Mach4: Log Axis movement time.

« on: January 20, 2022, 11:27:03 PM »

Hi,

mcAxisIsStill doesn't really work for real time info. It will report still even when it looks like the dro is moving on screen. With PLC interval at 10ms you can expect it to report still much more than it reports moving.

Does it matter? Who cares if it out by 10% either way?. The axes will still get lubed, and that is using relatively simple and light weight code with minimal impact on important (ie motion)
processing.

Craig

872

Mach4 General Discussion / Re: Mach4: Log Axis movement time.

« on: January 20, 2022, 08:37:59 PM »

Hi,

Should I just use the motors step or direction pin in my signal library and log how long it is active for?

That won't work, the Step/Dir outputs are outputs of your motion controller....not Mach. Mach does not pulse, it passes numeric movement commands to the
controller and the controller generates the pulse streams to enact the movement. You could presumably monitor the output of the controller but is would a factor of a 100,000
or more too fast for Mach.

May I suggest use these:

Code: [Select]

still, rc = mc.mcAxisIsStill(
number mInst,
number axisId)

Description:
Report if the axis is still.


Code: [Select]

velocity, rc = mc.mcAxisGetVel(
number mInst,
number axisId)

Description:
Get the velocity of an axis in user units per min.


Either could be used to determine whether an axis is moving.

Because I'm so comfortable with the concept...I would use the PLC script. At each pass of the script determine if an axis is moving and if so increment a register (of your devising)
pertaining to the accumulated time and axis has moved.

The PLC script runs every 10ms or so, you could consider it a live update. The only fly in the ointment is that your code would want to be fairly slick otherwise the computing overhead
would count against the overall performance of the machine. What I would suggest is somehow time the repeat rate of the PLC, and just increment a register by one unit, that unit being
equivalent to 10.5ms say.  Every 22857 units, ie 240 secs 'Do Some Lube Process" and reset the register.

Craig

873

Mach4 General Discussion / Re: Glitch on X movements

« on: January 20, 2022, 04:50:30 PM »

Hi,

I'd love to machine up a new spindle cartridge but I'm afraid my little lathe is just not up to the task.

You might surprise yourself too.

I have a 750W 24000 rpm asynchronous spindle, and I use it extensively and have done so for seven years. It spins too fast with way to little torque to be
a serious contender in steel and stainless......so I made my own spindle. I was lucky enough to find here in New Zealand a second hand 1.8kW Allen Bradley AC servo
and drive for $900NZD including shipping ($650USD). I still had to buy and/or make the cables, another $250NZD and buy the setup and tuning software for another $200NZD.
I still had a good torque dense motor for a spindle at reasonable price.

Like you I thought I would be unable to make a creditable spindle housing, my machining skills just aren't up to that standard. The problem was however that the cost
of a precision spindle or getting one made was just beyond my means. By this time I had already bought a 'You Beauty' Rego-Fix cyclindrical tool holder ($450NZD) and
a set of P4 matched angular contact bearings, seals from the UK,....so I had all these parts on hand and yet could not use them. In the end I decided 'to hell with it' I'll make
my own and see how it goes....and thats what I did. The design was very straight forward as I needed to consider very carefully how I was going to do it to maximise
my chance of success WITHOUT sending it out for cylindrical grinding....and costing a fortune. While my attempt was far from perfect it works a treat. I don't have the bearings
as well aligned as I would like and they run hotter than I would expect so instead of getting thousands of hours use I suspect I'll get hundreds....but still I'm very happy with
my effort. Most importantly I have been able to utilise all the parts I invested in and have got the functionality that I wanted. I've had about 200 hours use with it, my highspeed
spindle has seen thousands in the same time but when I need low speed-high torque, I NEED it.

Craig

874

Mach4 General Discussion / Re: Glitch on X movements

« on: January 20, 2022, 04:38:00 AM »

Hi,

I'm running the ESS with a C25 BoB, 5v. I think it would be beneficial to run a 12v or 24v system to mitigate signal interference.

No, if you choose the impedance levels correctly then the noise performance is IDENTICAL between 5, 12, 24V systems....it all comes down
to Signal-to-Noise Ratio....not voltage level.

My mini-mill which I operated for seven years had a 5V BoB and 5v signaling. My new build mill, in service for about six months now, uses Delta
servos, which use 24V signaling as is common with industrial gear, thus I made my BoB 24V also, excepting the Step/Dir outputs which are
5V differential for higher signal speeds. My choice to use 24V signaling is not about noise performance, its about having a clear and consistent
design throughout supported by a wide range of suitable electronic and electromechanical parts.

I looked at the MB3, its a well thought out design and a quality build and deserves its high reputation. If using the MB3 you are perforce limited
to the design choices CNCRoom have made. When I designed my BoB I could have exactly what I wanted and absolutely nothing I didn't.....no
compromises. My own BoB has been working great....but like all designs it can be improved.

I have found that I can make a better PWM circuit than my existing circuit. When I get around to making the new circuit it will be within 1% of
linear with duty cycle whereas my current circuit is linear within  7.5%.

About a fortnight ago I discovered that the circuit (2 dual channel OP-amps per axis) I used for generating the differential Step/Dir signals
while fine with my Delta servos is just a little to noisy for Step/Dir of my Allen Bradley servo used for my heavy duty spindle motor.
I have redesigned the BoB so that the differential Step/Dir signals are generated by a new generation line driver IC.....with considerably better
characteristics than my previous home-brew attempt. The ICs are $11.00NZD each, I require three of them, which is a little more than I like
paying for analogue ICs, but they look the part. I ordered them 10 days ago and they turned up yesterday from the UK, freight free.

My mill is working perfectly well with my existing BoB....so I'm in no great hurry to build another....but will get around to it in the next few weeks.
I want to be able to use my Allen Bradley servo spindle motor in Step/Dir position mode so that I can use it for rigid tapping. I've used it for rigid tapping
on my mini-mill a dozen or so times over the previous two years since I built the spindle. I have only just started to make the changes necessary
to have the same functionality with my new mill which lead to the discovery of the noise shortcoming of my first BoB design.

Would you like to share a picture of your BoB? Do you sell them?

I'll take some photos of them, they are split into two boards. Given that I have design improvements to make to both of them...no I haven't sold any,
but may do. They are hand-made and hand soldered which makes them a labor of love rather than a profit making exercise. I could post
the design files if you wish to make your own, although it might pay to wait until I have the GenII boards made, tested and in service before
copying what I have done!.

Would cost to get it from the states and add a whole other level of ugly to the control panel.

My ESS, BoBs and power supplies are screwed  to a plastic chopping board, they are about the right size and cheap source of plastic. So when I say
that my control system is 'breadboarded'....I bloody well mean it. I have another breadboard that has the single board PC and its power supply,
yet another breadboard that has the three Delta servo drives, the AC distribution buses and  EMI filter and yet another breadboard for the VFD and
Allen Bradley servo drive for both spindles. You might laugh, and to be fair its pretty untidy......but better than my mini mill. When I built that
I just nailed the various boards and things to a piece of MDF, promising to go back and do it properly later. Seven years later and its still the same. There
is nothing more permanent than a temporary solution.

Craig

875

Mach4 General Discussion / Re: Glitch on X movements

« on: January 20, 2022, 02:11:23 AM »

Hi,
if I'm not mistaken the HLFB output is an opto-transistor. Given that the base is purely optical there is no DC ground reference
so you can indeed wire them in series.

Phototransistors saturate in a broadly similar manner to a regular BJTs but tend to have higher saturation voltages, say 0.8 V or so compared
to 0.2V-0.3V for a small signal BJT. Thus if you had three in series all saturated then the voltage would be 2.4V. If you have a 5V BoB then you are in
no-mans land. If you have a 12V or better still a 24V BoB then 2.4V should still be comfortably below the low level threshold.

What sort of motion controller or BoB are you using? Is there any need to economize on inputs? Do you not have enough spare inputs to have one HLFB per
input?

I use an ESS and I made my own BoB. I elected to have ports 2&3 of the ESS as input dominated, ie pins 2-9 of each port as inputs in addition to
the regular inputs 10,11,12,13, and 15. Port 1 has pins 2-9 as outputs and are used for Step/Dir

Port 1
Outputs 1, 2-9, 14, 16, 17 =12 outputs
Inputs 10, 11, 12, 13, 15 =5 inputs.

Port 2
Outputs 1, 14, 16, 17 =4 outputs
Inputs 2-9, 10, 11, 12, 13, 15 =13 inputs

Port 3
Outputs 1, 14, 16, 17 = 4 outputs
Inputs 2-9, 10, 11, 12, 13, 15 =13 inputs

Total
Outputs =12 + 4 + 4 = 20
Inputs = 5 + 13 + 13 = 31

I have used them this way:

Port 1
10 outputs = Step/Dir for up to 5 servos
1 output = Enable, applied to all installed servos in common
1 output = Reset, applied to all installed servos in common
5 inputs = one alarm per servo

Port 2
10 inputs(
X++, X--, X home,
Y++, Y--, Y home,
Z++, Z--, Z home,
Probe.)
3 inputs (Spare)
3 outputs(
Spindle On/Off
Spindle PWM
Coolant Pump)
1 output(spare)

Port 3
5 inputs(
Incremental/Velocity jog
2 inputs, X/Y/Z axis select
2 inputs MPG A/B inputs)
8 inputs (spare)
4 outputs (spare)

Outputs 15 committed, 5 spare
Inputs  20 committed, 11 spare

So as you can see I have used inputs where I need to without trying to economize at the expense of function, and yet still have a healthy margin
of spare IO.

Craig

876

Mach4 General Discussion / Re: Key command stop working after running laser gCode

« on: January 19, 2022, 09:24:28 PM »

Hi,
good news.

When a Gcode file is running Machs Gcode Interpreter and Trajectory planner are engaged by the Gcode file, and therefore you cannot jog be it keyboard or otherwise
simultaneously. All I can suggest is that Mach is disabling Keyboard jogs when the Gcode file is running......it seems redundant to me given that the Trajectory Planner is engaged
by the Gcode Interpreter and will be until the Gcode job is finished and/or stopped.

You could write a script that turns the Keyboard on whenever Mach is 'NotInCycle', ie not running a job or MDI'ing. This would turn the Keyboard back on whenever a Gcode file completes or is stopped.

Craig

877

Mach4 General Discussion / Re: Driving a Shapeoko 3

« on: January 19, 2022, 04:33:59 PM »

Hi,
 I use mach4 and an ESS and have done for seven years, and the combination will drive your four axis machine no trouble.

Mach4 has a surface mapping module called mcSurface. Its really meant to probe the nominally flat bed of your machine for small deviations from 'flat' and then to process
that data such that the machine automatically compensates for the bed not being perfectly flat. This may not be what you had in mind.

I use a software (freeware) utility called Autoleveller that was intended to probe PCB blanks and compensate (via Gdcode edit) for a not perfectly flat PCB blank.
This software can be used in creative ways and may be adapted to your requirement. The software is open source so you could modify it or rewrite it at will.

There is another freeware software solution, the name of which escapes me at the moment, that uses similar ideas to Autoleveller that may be even better suited to
adaption to a particular purpose.

Craig

878

General Mach Discussion / Re: Manual pulse encoder & mach3

« on: January 19, 2022, 02:17:53 PM »

Hi,

I guess by your diagram you are grounding out your outputs and when the output grounds out your board sends the signal to the motors to move 1 step?

Yes, that is correct and its called 'active low', and what it means is the circuit 'sinks current' when the signal is active. If you were to use this you would have the resistor in the
C10 set as a pull-up. Thus in its natural state it would be at 5V. When the transistor conducts, ie signal active, it will be pulled low, to 0V or close to.

Then I'd need A signal to move CW and B signal to move CCW motion of the motor?

In Machs Input tab you can select or alternately deselect 'active low'. You will alter that setting until and possibly swap the AB wires until Machs logical direction matches
the MPGs physical direction.

You are trying to overthink it. You may NOT even require the extra transistors yet,  just a resistor and diode to limit the 12V swing of AB to 5V. It will all become clear once you've got the MPGs.

Craig

879

Mach4 General Discussion / Re: Help with C# DLL usage development

« on: January 19, 2022, 01:35:20 PM »

Hi,
how are you connecting your sensor to Mach?

If you connect it to your motion controller/breakout board combination then you'll have to wait for the motion controller
reporting cycle before Mach gets to hear about the change in sensor state.

Using the ESS as an example, it has a deafult cycle frequency of 40Hz or 25ms interval. Thus if you have a switch connected to the
controller/BoB it could take as long as 25ms for Mach to get the changed signal state depending on when the event ocurred within
the cycle.

I have heard people increasing the cycle rate to 200Hz or 5ms intervals, but even 5ms is not realtime.

You might ask then 'how is it that Mach can respond instantly to Limit and Home switches'. The answer is that Mach does NOT respond instantly,
the motion controller DOES, and it does so autonomously. The events gets reported to Mach, using the same reporting cycle I described above,
but not instantaneously.

Clearly the motion controller manufacturer must program/hardwire his motion controller to handle certain events in realtime, and in a manner
which is consistent with Mach's expectations. For this reason the motion control plugin, written by the motion control manufacturer, is a technically
demanding but absolutely vital part of any Mach4 installation.

If you choose to write your own plugin to manage your sensor suite for instance you may. It requires that you sign an NDA with NFS and then you get
the inside gen on Machs core enough for you to write a plugin in C/C++.

Craig

880

Mach4 General Discussion / Re: Help with C# DLL usage development

« on: January 19, 2022, 01:17:27 PM »

Hi,
if you require toolpath planning in realtime then I doubt Mach4 is the solution.

Mach4, in fact ALL Windows platform based CNC software, is a buffered motion control. That is to say the the trajectory planner
issues numeric P(osition) V(elocity)over T(ime) data to the motion controller in a buffer. For example the default buffer length of the ESS
is 180ms.

If you have a sensor that changes state even if Mach responds instantly with a Lua script or DLL call any alteration in tool path will
still have to propagate through the motion buffer.

I have heard that users with high power and well sorted PCs have reduced the motion buffer to 20-30ms.......but its still far from
realtime.

The PLC script in Mach4 runs at about 10ms intervals. The PLC script is programmed in Lua.

The PMC module is an emulated ladder logic module that runs at ms intervals. The ladder is enacted in C.....you don't code C directly.

Craig