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Messages - joeaverage

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1
Mach4 General Discussion / Re: Keyboard Jogging Not Working
« on: October 20, 2019, 08:12:11 PM »
Hi,
have you enabled the keyboard plugin?
Have you enabled keyboard jogging?

Craig

2
Hi,

Quote
Oh, to throw another wrench in this. My Z axis has a brake on it that is controlled by the servo drive.

I would not expect the brake to come on UNLESS the servo is disabled. Even then, its common for the brake to take 10ms or so to come
on and so unless you have long  deceleration times programmed into your machine then it will have decelerated and stopped
BEFORE the brake has come on.

If you probe sufficently slowly relative to the machine acceleration overrun should be vanishingly small. That overun has been included
in the calculation is for those circumstances where it is significant or for nit-picking perfectionists who demand to chase every last micrometer.

Craig

3
Hi,
unless you are probing at high speed or your machine has very low acceleration overrun should be very small.

The distance of over run, d, is given by:

d=1/2. a.t2

where a is the acceleration (or de-acceleration to be precise) and t is solved by:

t=vp / a

where vp is the probing speed.

Using numbers from my mill where I have standardised on a probing speed of 100mm/min (1.66mm/sec) and the machine has an acceleration of 375mm/s2.

t=1.666 /375
  =4.44ms
d=1/2 x 375 x (0.0044)2
  =3.7 um

3.7um is about the limit of the accuracy of my machine so I don't worry about it, its near enough to zero for my purposes.
Substitute the numbers from your machine and see if the overun is significant.

Craig

4
General Mach Discussion / Re: Setting up Longs Motor breakout board
« on: October 19, 2019, 05:53:04 AM »
Hi,

Quote
Don’t have the budget for G540s, but there has to be something else out there.

There is a reason that G540's are as popular as they are, they work exactly like they are supposed to and are about
the best 'bang for your buck' out there. Anything cheaper is going to be Chinese made and then your back in the same pickle
you are in now.......no manufacturer support.

Craig

5
Hi,

Quote
It has been a frustration in he past. My only delay is in the fact that it work previously with Mach3.

Yes it will work, almost exactly as it did in Mach3, just as dws has confirmed but.......you used the word 'frustration'......
so do you want to relieve that frustration or not?

Craig

6
Hi,
the question I ask is why when you have an ESS with 51 inputs/outputs you are restricting yourself to
one pin fulfilling multiple roles?. If you bought a second breakout board like a bi-directional C10 ($23) then
you would have enough inputs to have one pin per switch/touch plate or what have you.

Craig

7
Hi,
I've started a new mill project, much bigger and more powerful than my mini-mill. I have some great 32mm diameter, 5mm
pitch, C5 double-nut ground ballscrews for the X,Y and Z axes.

I decided to get three new 750W Delta servos, B2 series. I got two plain servos/drives and one braked servo/drive for the Z
axis. I took delivery of them a few days ago but ran into a hitch....operator error.

In particular as I posted earlier the electronic gearing applies to to the 160,000 count encoder. What I wanted to do was
have 16000 as numerator and 100 as denominator. These numbers were for me to experiment with the servos using a signal
generator as the pulse source.

f2=f1 x16000 / 100

Thus if I feed the servo a 1kHz signal from my signal generator it would, after the electronic gearing generate an f2
of 1600kHz and thus spin the rotor at 10 revs per second or 600rpm......simple right!

I programmed P1-44 and P1-45 accordingly....or so I thought. I was using the buttons on the drive to set the parameters.
The range of numbers that can legally be used as numerator/denominator are very large, up to 10 decimal digits. The display
on the front of the drive is only five digits wide. Thus you can only see part of the particular parameter without hitting
<shift> to observe the higher order digits. What I had done , accidentally was erroneously programmed 116000 instead
of 16000 as numerator. It was not apparent that I had made a mistake because the higher order digit was obscured from
my view.

This lead to several hours frustration before I tumbled to my mistake.

What helped in the end was that I had, as a separate purchase bought a USB-to-IEEE1390 cable that I could program
the Delta drives with the manufacturer software. When I finally got the software installed and got the right drivers installed on
my PC and was able to read the programmed state of the servo the mistake I had made with the numerator became obvious.

Indeed programming the drive is just so much easier with the software than trying to push little teeny-tiny buttons
that I would have to recommend that you consider a programming cable an essential item if you buy a Delta servo.

The USB-to-IEEE1390 that I bought was manufactured by Delta and cost me $62 including shipping.
RS232-to-IEEE1390 can be had for less, about $30. Of course you only need one cable, you can program multiple
drives in succession, no need for a cable for each.

Aside from the great assistance the software gives you to program the drive there is a comprehensive scope and monitoring
suite that allows very detailed tuning analysis. All in all the manufacturer software and a cable to hook your PC to the
drive is all but essential in my opinion.

Craig

8
General Mach Discussion / Re: Z-axis conditional displacement
« on: October 15, 2019, 03:08:34 AM »
Hi,

Quote
Does anyone know if this is possible? Is there a way to set-up a load cell as an input and use conditional Gcode to control my z-displacement?

The short answer is no. There are a number of reasons which may well enlighten you to what can and cannot be achieved
with Mach.

Firstly Gcode does not by and large have conditional statements. The notable exception is Fanuc's MacroB which allows parameterized
Gcode and conditional statements. Neither Mach3 or Mach4Hobby have that ability, Mach4Industrial does have MacroB however.

Even if however you were to stump up and pay $1400 for Mach4Industrial it would still not meet your demands.

All varieties of Mach (3, 4Hobby and 4Industrial) have a scripting language, Cypress Enable (a subset of Visual Basic) in the case
of Mach3 and Lua in the case of Mach4. Lua is by far the more flexible and many times faster to execute than Visual Basic.

With a scripting language conditional Gcode becomes irrelevant....you can write conventional computer code to accomplish the same
thing....right?

Well....no.

The bottom line is that a Windows PC is not and cannot (without huge expense) ever be a realtime system. CNC is however by
necessity a realtime process. The way this incompatibility is covered by Mach, and in fact ALL Windows based PC CNC solutions,
is buffered control.

In a buffered control the Windows application, in our case Mach, is the trajectory planner. It plans axis moves and communicates
them to a realtime motion controller as a series of numeric data, P(osition)V(elocity)T(ime). The data is stored in a FIFO buffer
which could be 500ms in length. The realtime motion controller digests the PVT data and generates the required synchronous pulse
streams to drive the axis drivers. Thus even when Windows stop processing Mach temporarily, the motion controller still has data
in the buffer 'to go on with'. If the buffer ever empties the CNC machine stops usually castastrophically for the workpiece.

The communication delay from the motion controller (monitoring the downward force) to Mach, followed by the processing delay,
followed by a communication delay from Mach to the motion controller, followed by the buffering delay all but precludes
a sensible feedback loop. With Mach3 a reasonable 'around the loop delay' is about 100ms(10Hz). With Mach4, and if you push it,
you can reduce that to about 5ms(200Hz).

If you talk to you Electrical/Control colleages in your Engineering school they will tell you, at length, about the Nyquist sampling
theorem. The upshot is that the fastest possible response to a series of samples is HALF the frequency of the samples.
Even then the 'controllability' of such a system is very poor, and is still maringinal at ONE TENTH of the sample frequency.

Thus with Mach3 the closed loop bandwidth would be about 1Hz. With Mach4 the closed loop bandwidth is about 20Hz.
Thus while Mach4 is much better at 'closing the loop' than Mach3 its still poor. Even a modest servo will have a closed loop
bandwidth of 500Hz or so and good ones up to 5kHz.

Mach is a poor feedback system.....and that is a reflection of the Windows PC on which it is based.

Having said that, NFS have released a script version of THC (which is normally considered a realtime only process) for Mach4.
While it is not nearly as fast as realtime THC enacted by realtime motion controller, NFS obviously consider it sufficient for
most THC purposes. You could possibly adapt it to your application....if you can tolerate a closed loop bandwidth of 20Hz or so.

Your other options are various realtime feedback capable controllers like Kanalogue/KFLOP, Gallil, Hicon or CSMIO/A.
Another very worthy alternative is LinuxCNC. The Linux distro on which LinuxCNC runs must have R(eal)T(ime)E(xtensions)
and as such LinuxCNC makes a capable realtime feedback controller. You could expect jitter of a few microseconds which is pretty
respectable. Of course LinuxCNC is free which will no doubt appeal to you.

Craig

EDIT; Unnecessary and disrespectful comments referring to Mach3 user's removed.

9
Mach4 General Discussion / Re: ISIG/OSIG Master List
« on: October 14, 2019, 02:40:34 PM »
Hi,
I have listed a few here:

https://www.machsupport.com/forum/index.php?topic=40051.0

I think I have a list of OSIG's somewhere if you need it.

Craig

10
Mach4 General Discussion / Re: Mach4 and Huanyang HY series VFD
« on: October 13, 2019, 11:53:45 PM »
Hi,
there have been a few posts about the early model Huanyang VFDs that require a special plugin.
To my knowledge no-one has written a similiar plugin for Huanyang/Mach4.

The latest model Huanyng VFDs ARE standard ModBus, I think the models are appended with a suffix -GM, or GS or
similar. Clearly Huanyang must have been getting flak because of their non standard interface.

I personally have always had good success with Delta VFDs.

Craig

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