Messages

2001

Mach4 General Discussion / Re: Turn | Is eccentric turning possible with Mach4?

« on: October 06, 2019, 09:15:44 PM »

Hi,
I seem to recall NOT having to have a variable Y axis when 'turning' a hex, and I likewise cant imagine that you would need a variable
Y axis to turn an eccentric.

I'll try to find the post that had the hex code.

Craig

2002

Mach4 General Discussion / Re: How to mark an axis as "Homed"

« on: October 06, 2019, 07:26:33 PM »

Hi,

Looking at the API reference, I see mc.mcAxisSetHomeInPlace(inst, AxisID, T/F). I would think I could set this TRUE before calling to home the axis using my servos so they don't move (for absolute homing from the servo drives), and FALSE to home normally?

Yes, that is exactly my understanding.

There are other situations where you can change 'settings' like that. Ordinarily, and in Mach3, once a setting is made then the only way to change it is to restart Mach3.
All semblance of changing machine behaviour on the fly is lost.

I suggest you look at the ability to link, or conversely un-link individual motors to or from an axis. There are some interesting cheats/hacks that can be done using the ability
to programatically change machine settings without the need to restart the program.

One trap is that if you change a setting in this manner is when, or even if, it will ever be written to the .ini file. There is an API that flushes the machine state to the .ini file,
and its use is recommended or unpredictable things can happen.

Craig

2003

Mach4 General Discussion / Re: Turn | Is eccentric turning possible with Mach4?

« on: October 06, 2019, 06:41:07 PM »

Hi,
one other alternative is to approximate the shape in Gcode.

I, some time ago, generated some Gcode that allowed a lathe to cut a hex by moving the X axis in and out in
synchronicity with the C axis (spindle). You could do the same thing but instead of a hex make it an eccentric.

Craig

2004

Mach4 General Discussion / Re: How to mark an axis as "Homed"

« on: October 06, 2019, 06:04:16 PM »

Hi,

So technically I need to be able to home both to the switch and in place (which is what will be done most of the time).

But there are APIs that let you do just exactly that.

Craig

2005

Mach4 General Discussion / Re: Newbie with Mach 4 Lathe - again - Mach 4 and dial ind do not agree

« on: October 05, 2019, 08:24:43 PM »

Hi,
you should not have to guess what the steps per unit value is....you should calculate it precisely.

The variables required to calculate the correct step/unit value are:
1) The pitch of the lead screw. Note this must be accurate to be of any value. The common pitches are 4mm, 5mm, 6mm
and 10mm in metric screws and 0.2, 0.25 inch in imperial screws. Note that 0.2 inch is very close to 5mm (5.08mm to be
exact) and is easy to confuse the two. MEASURE PRECISELY or take up another hobby other than CNC.
2) The microstepping regime, common are fullstep, halfstep and 1/4 setp. These are simple but prone to midband resonance
and so 5, 8, 10 and 16 microsteps per fullstep are recommended and the norm. Microstepping beyond 16 microsteps per fullstep
gains you little or nothing.

For example if you have your stepper driver set to 8 microsteps and given that the basic two phase stepper has 200 steps per
revolution so with the micorstepping works out to 1600 pulse per revolution.

3) gear or belt reduction, this should be exact. It becomes less than exact if you are using Vee-belts as the diametrical pitch is not clear.

Idnentify those numbers and we can give you a hand to calculate the exact steps/unit. Any discrepancy between the calculated and
actual will teach your more about your machine than anything else.

Craig

2006

Mach4 General Discussion / Re: Mach4 & ESS Dual motor homing

« on: October 05, 2019, 01:56:34 PM »

Hi,
yes it can be done.

The procedure is that one home switch is designated as the master switch. When homing both motors are homed to that master switch.
After all, the motors have to move together. Once the gantry is at 'home', then each motor is homed to it own switch.
With any sort of luck each motor will only have to move 1mm or less and the gantry wont wrack with one motor driving at a time.
Once the gantry is square, that is both motors homed to their own switch, then they are linked back together so they travel/move
in unison.

Craig

2007

General Mach Discussion / Re: Settings Mach3

« on: October 04, 2019, 02:21:46 PM »

Hi,
it means you have lost the license file.

Craig

2008

General Mach Discussion / Re: How to get more digital outputs for 4 axis?

« on: October 02, 2019, 02:12:33 PM »

Hi,
you need a second port. This will require that you fit a second parallel port card to your PC. Not all parallel ort cards work,
I would recommend buying one from PMDX, they have selected and tested a working card. You will also need another
breakout board, you could get another of the one you already have or you could get one from PMDX.

https://www.pmdx.com/2PARPCI

Craig

2009

General Mach Discussion / Re: Automatic setup of steps per unit

« on: October 01, 2019, 03:51:20 PM »

Hi,
there is one occasion where the steps calculator can have an advantage.....where you have a rack and pinon or a belt/chain drive.

You can do the calculation but it requires an exact 'pitch' diameter of the gear/sprocket/drive wheel. The pitch diameter will be
close but no identical to then outer diameter. My suggestion in those circumstances is do the calculation and get to within a few percent
and then use the wizard to refine the calculation to the required accuracy.

Craig

2010

General Mach Discussion / Re: CNC Plasma Table Which Controller where to start.

« on: September 27, 2019, 02:40:59 PM »

Hi.

Still reading up but from what I gather the t3CM is where you hook your torch up to then into the ESS and that controls it all right, height and burn?

That is essentially correct. There is a voltage divider (50:1) in the Hypertherm plasma. Thus the torch voltage, which is lets say
150V when cutting is presented to the TCM3 as a 3V signal. If the target voltage is 120V the TCM3 will issue a THC_DOWN
signal to the ESS and the ESS will lower the torch a step or two. Note that Mach4 is not involved, the communication delays
and the buffered control loop would mean many milliseconds of delay if Mach4 were consulted.

As the TMC3 talks directly to the ESS and the ESS has direct control over the Z axis pulses the delay is reduced to microseconds.

The closed loop bandwidth, a measure of speed of response, with the TMC3 and ESS is around 100Hz whereas if you use
Mach4s script solution, with all those pesky delays, the bandwidth is down to a few Hz. As you can see the realtime
hardware solution (TMC3/ESS) is somewhere between 10 and 50 times more responsive.

Unfortunately that speed of response, while highly desirable, is not cheap. Firstly only two controllers (Hicon and ESS)
support realtime THC and in the case of the ESS has been written and optimized with a particular THC controller (TCM3)
in mind. You want good....you can have it....pay up and no whining!!

As far as stepper drivers go you want the highest voltage ones available, at the current time 80V is the practical max available
commercially. All steppers lose 'grunt' the faster they go and a high voltage driver counteracts that, and you'll want your
steppers to go as fast as they can if you are going to cut thin metals.

Gecko is the stand out brand for quality and reliability but their  80V capable models are up to $150 each.
Leadshine AM882's can be had for around $70 from Ebay and they are 80V and up to 8.2A capable.

I would recommend a toroidal transformer/rectifier/capacitor power supply......they are much more forgiving than
the cheaper switchmode power supplies commonly used. This is an example:

http://www.antekinc.com/ps-15n80-1500w-80v-power-supply/

It has two 80V 9A outputs and will keep on going when all your switching power supplies have let out a puff of smoke
and are no more than a grease stain on the floor!!!

Craig