Messages

5571

General Mach Discussion / Re: Switches for Home position

« on: January 13, 2018, 02:09:18 PM »

Hi Gary,
because of the ramp actuation you don't have to mount the switches right at the end of the axis and so avoid fouling with limit switches. Very convenient.
Also ramp actuation means no overrun problems.

Prior to fitting these switches I had no home switches. Would manually reference the machine at start-up but inevitably would not be perfect and as a consequence
soft limits were worse than useless. Suffered quite a few crashes and misaligned cuts on jobs that were in the machine over several days. After fitting these switches
I can home reliably, easily and quickly. Now soft limits are effective and at 0.02mm repeatability jobs lasting several sessions are no longer daunting that they used
to be. Good home switches are the simplest and yet the best means of reducing crashes.

Craig

5572

General Mach Discussion / Re: Switches for Home position

« on: January 13, 2018, 01:43:25 AM »

Hi,
I've use these and they work well.
http://nz.element14.com/omron-industrial-automation/z-15gq22b/microswitch-z-roller-plunger-spdt/dp/1181279

The prices are NZD. I got some equally good Honeywell units for $13USD. Pretty good value. With a ramp actuator I get 0.02mm repeatability.

With any snap action switch you get hysteresis. When pushing downwards to cause the switch to activate, call it z=0, but as you release it upwards it will go past
the point where the switch made, say z=.05mm. Hysteresis is not critical, all it really does is place a larger gap between where the switch makes and where
Mach backs up and the switch unmakes.

One spec which you should think about is 'overun'. It is the distance the button or plunger can travel after the switch activation without banging into an internal
stop and damaging itself. You may notice that the roller plunger types I have used (they are commonly and widely used by OEMs and CNCers) will not be
damaged if the axis overruns, the ramp will at worst depress the roller a couple of mm even with a runaway axis and the switch has a 5mm overrun tolerance.

I can stop a job on my machine, de-power and come back tomorrow, rehome the machine and continue from where I left off within 0.02mm. I now use Mach4 which
has index homing support for even closer homing but I've found I don't really need it, these switches are goo enough on their own.

Craig

5573

Mach4 General Discussion / Re: Mach4 Home switches

« on: January 13, 2018, 12:28:36 AM »

Hi,
firstly I would recommend having separate home and limit switches. It reduces confusion and Mach can then treat each switch in a dedicated manner.

When you flick the switches what shows up on the machine diagnostics page input LEDs? If you are using three motors the M0, M1 and M2 home LEDs should
light. If you are using the same switches as limits as well then the corresponding M0++, M1++ and M2++ LEDs should light ( or possibly M0--, M1-- etc).

On the Configure/Mach/Plugin page make sure that the keyboard plugin is enabled. If you have configured the ESS correctly you should see the on Machs input signals
page something like the attached. Note that you could directly set Machs input signals or as is recommended let the ESS do it when you set that up.

Craig

5574

Mach4 General Discussion / Re: Z 0 help

« on: January 13, 2018, 12:10:37 AM »

Hi,
what is the build number of Mach4 that you are using?

I had a bit of a battle with one of the earlier builds. What you have described sounds like noise causing false triggering. Is it possible to lightly 'load' your
probe circuit so that its less inclined to pick up induced noise?

Craig

5575

Mach4 General Discussion / Re: Setting Motor Counts Per Unit in macro

« on: January 13, 2018, 12:04:49 AM »

Hi,
try put this in the PLC script:

Code: [Select]

local radius=mc.mcAxisGetPos(inst,mc.Z_AXIS)
if radius==0 then radius=1 end
local surfacespeed=mc.mcCntlGetPoundVar(inst,2134)
local spinspeed=surfacespeed/(6.282*radius)*360
if spinspeed>=15900 then spinspeed=15900 end
mc.mcSpindleSetCommandRPM(inst,spinspeed)
Craig

5576

Mach4 General Discussion / Re: Setting Motor Counts Per Unit in macro

« on: January 12, 2018, 10:52:09 PM »

Hi,
the speed calculation is reasonably straight forward.

My suggestion is to put some spindle speed adjustment code in the PLC script:
1) Read the current Z position (diameter)
2) Calculate the spindle rpm to suit the required surface speed
3) Apply max and /or min limits to the calculated spindle speed
4) Apply the calculated and limited spindle speed to the hardware spindle.

Step 4) is the critical one. I don't think trying to change the 'steps per unit' value on the fly is the right idea. Once Mach has planned the trajectory and dispatched it
to the controller you can't change it. The controller itself may be able to insert or remove pulses from the pulse stream like a THC function but Mach can't.

Niether can you issue another Gcode command without overwriting the current move and losing it. Lets say you have a coordinated move in X and Z:
G1 X100 Z100 F300.
After a second or so into the move Z has changed and therefore you want to change the spindle speed. If you did something like:
mc.mcCntlGcodeExecute(inst, "S680") 
for instance then it would crash the previous move which has yet to complete, and so wouldn't work.

This API may help:

LUA Syntax:
rc = mc.mcSpindleSetCommandRPM(
      number mInst,
      number RPM)

I've experimented with it a little and it seems to do the job. That is to say that you can issue a coordinated move, the PLC script will run during the move and it will calculate
the new required spindle speed and issue a speed command WITHOUT the currently executing move being affected.

Note that for the purposes of experimentation I have used a Step/Dir out of band motor as a spindle. I observed the spindle speed by monitoring the Sim plugin diagnostics
and it appears to work. I have not tried on my machine and it would represent quite a quite a re-wire from my current configuration. I presume it would also work
with the PWM output but I haven't tried it, that's your job!

I will hash up some code and post it soon.

Craig

5577

Mach4 General Discussion / Re: Setting Motor Counts Per Unit in macro

« on: January 12, 2018, 02:34:16 PM »

Hi,
the Mach4 Lathe profile has CSS support already. Would that not suffice?

Given that CSS is possible then it should also be possible to get it to work when using a mill profile. Either write a module/plugin using the C++ data structure
or find and use the pound variable, either is doable and the toolkit to do it is provided.

Waiting for NFS....don't hold your breath...anoxia is not pleasant.

Craig

5578

Mach4 General Discussion / Re: Latest Version of Mach 4 will it Copy over all the settings?

« on: January 12, 2018, 03:10:02 AM »

Hi,
your profile is one source of personalized settings but not the only source.

When you set up your profile you will be asked to choose a screen set. I used wx4.set for example. Over a period of time I modified that screenset with various
buttons, scripts and so on. If you now update Mach with the latest build wx4.set will AlSO be overwritten and whatever personalisations you've made will be lost.

The solution is to make a copy of one of the standard screensets, I used wx4.set as above but called it Mywx4.set and used that in my profile as the default
screenset. Now any customisations get saved to Mywx4.set and will not therefore get overwritten.

If I understand correctly modules and plugins need to be saved so they can be reused after an update.

Craig

5579

Mach4 General Discussion / Re: Setting Motor Counts Per Unit in macro

« on: January 11, 2018, 09:10:41 PM »

Hi,
Mach4's API lists an 'override' axis, which if I understand correctly modifies the movement of the main axis, a THC function is suggested as an example.
I haven't used it so don't really know what can be  achieved with it but it sounds hopeful.

Currently THC is enacted by the motion controller, the regular Z axis motion pulse stream have to be broken up and more pulses inserted or alternately pulses ignored to effect
THC variation 'on top of' regular coordinated Z axis motion. The Hicon controller of Vital Systems is the only Mach4 controller that has THC support, to my knowledge.
Warp9 have been promising THC support for the ESS for best part of a year but no dice as yet.

As for programmatically adjusting the 'steps per unit' of the fly.....Access to the data structure that includes the value is not available to us via LUA but
I would presume that the 'steps per unit' value would be stored in on of Machs pound variables. If you knew which one you could manipulate it directly. It might
not be as convenient as an API nor would it be as robust, NFS makes no representation that a pound variable will retain its precise function over later builds, but
it would work. Would it be worth asking NFS what the pound variable number is?

Craig

5580

Mach4 General Discussion / Re: Setting Motor Counts Per Unit in macro

« on: January 10, 2018, 09:34:35 PM »

Hi,
that API does not have Lua bindings, it is intended to be used in a C++ plugin.

I am not aware of any method to change the steps per unit by means of a script. I think you could write to the ini file and Mach would reflect the changes at the next
restart, clumsy but doable.

Craig