Messages

11

Mach4 General Discussion / Re: Is Mach4 really Hobby Material?

« on: January 27, 2018, 12:20:26 AM »

Thank you Steve, for your extended reply!

And Galil offers no support for used controllers.

good to know! Thanks. I appreciate support.
As I already wrote: DSPMC seems to fulfill all my requirements. It looks easier to use and is smarter to my budget
So most probably it will be my upgrade path. I already have an ESS, but I consider feed override so important, that I'm not sure, whether to start with ESS or sell it and go for DSPMC from start on.

IF you are willing to learn about it and IF you can/want to afford it.

The first is no question. Learning is my main hobby
... but the second is.

Multiple pass threading starts each thread pass on the index pulse on the encoder or the pulse per rev input.

Ok, that sounds to me like there is an external signal sampled for threading synchronization.
I agree, that a threading pass is atomic and does not need to be recalculated.
The point is, I don't see a way to synchronize after return between two passes.
But hey - I you made it, it is good to know

There are real-time extensions for Windows.  The problem is that all of them cost big bucks.

one more reason for mach4linux to arise

Reinhard

12

Mach4 General Discussion / Re: Is Mach4 really Hobby Material?

« on: January 26, 2018, 03:47:00 AM »

Some motion controllers operate in a closed loop manner with Mach.  Galil, Vital System DSPMC, etc...

Vital System DSPMC looks what I was searching for. Great!
So I might have to eat dog food for a while and beg for bigger budget

Reinhard

13

Mach4 General Discussion / Re: Is Mach4 really Hobby Material?

« on: January 26, 2018, 03:06:08 AM »

Oups, I'm confused. Prices I saw at first sight where used prices at ebay

14

Mach4 General Discussion / Re: Is Mach4 really Hobby Material?

« on: January 26, 2018, 02:43:04 AM »

Hi Steve,

thank you for pointing out the higher level controllers. Didn't heard about galil before - so have to read a bit to get familiar with them. Pricing is high, but looks interesting.

About the question linuxCNC versus mach4 - I'm quite sure, that mach4 could be much better than linuxCNC - you only have to try
... linuxcnc does not work on linux standard distributions - it needs a special (realtime-)kernel.
May be, there's something similar possible on windows systems too?

Threading ...  No encoder need be involved though.

Some pages before I was told, that you can not guarantee, what you don't have under control.
For me, position of Z-Axis is related to position of the turning axis. If you know the position, velocity is irrelevant - so I don't know, how you can guarantee precision without measuring?
AFAIK threading is worked out by multiple passes usually. How can you match the same starting point without measuring?

Anyway - your decision.

Reinhard

@Steve
I skimmed  galil pages for the instantaneous feed rate override. Did not found any.
Do you have a link, where I can read more about it?

15

Mach4 General Discussion / Re: Is Mach4 really Hobby Material?

« on: January 25, 2018, 02:22:20 PM »

Hi,

well, to follow an encoder, you have to process encoder signals. That's the hard part of the closed loop.
A pid controller in software is nothing complicated, so if you already have the data ... ?!?

... just my 2 cent

Reinhard

16

Mach4 General Discussion / Re: Is Mach4 really Hobby Material?

« on: January 25, 2018, 02:04:46 PM »

Thank you Mauri,

I already read about that possibility. The point is, that that solution will consume 2thousand bucks, so I look around if I find alternatives ...

Reinhard

17

Mach4 General Discussion / Re: Is Mach4 really Hobby Material?

« on: January 25, 2018, 01:28:04 PM »

Hi,

Mach4 is not a closed loop control, so this is irrelevant.

Hm, for me, lathe threading is closed loop based on external encoder signals.

What I don't understand: if the functionality is already in mach4, why use it for little use case only and don't use it for common use case?

Reinhard

18

Mach4 General Discussion / Re: Is Mach4 really Hobby Material?

« on: January 25, 2018, 07:56:44 AM »

Mach4 is not a closed loop control, so this is irrelevant.

That's a clear statement.
Thank you

19

Mach4 General Discussion / Re: Is Mach4 really Hobby Material?

« on: January 25, 2018, 01:22:28 AM »

Mach4 can change the feedrate by changing all axes within the corordinated move.

I know that
... but add to that the capability to handle an external control

It can update the feedrate 40 times per second.

I blamed ESS for this frequency and I very hope, that its not mach4 that forces that slow communication.

Is that update rate not adequate?

Ask yourself! For me 40Hz is extremly slow.

So just take the time (1s / 40) and calculate how far your cnc might move at i.e. 12m/min (result: 5mm)
For me, that stepsize is too big.

I understand the PLC runs faster than that, about 12.5ms. You can program it to run faster although I believe there are practical
limits which suggest about 5ms.

I don't know, where you take such asumptions from. 5ms is damn slow.

Lets calculate the requirements for hobbylevel close loop with common steppers:
A 2-phase stepper takes 200 Steps for one turn and has an encoder with 1000 lines. The encoder has 2 channels and is decoded by graycode. Hobbylevel stepper drivers support a max. steprate of 200kHz
Lets calculate the encoder: 200 steps means 1000 encoderlines or 4000 graycode pulses, so 200kHz steprate means 4MHz signals coming from encoder.
AFAIK ESS is capable to sample encoders with 4MHz.

4MHz means 125 nanoseconds between two pulses (5ms is 40,000 times bigger than 125 nanoseconds).

Your PC runs at some thousand GHz/s and a current SATA interface is rated at 6GBit/s - so with a motion controller, that is attached to internal PC-bus, that timing is no big thing - and I'm quite sure, that it isn't for mach4 neither.

Reinhard

20

Mach4 General Discussion / Re: Is Mach4 really Hobby Material?

« on: January 24, 2018, 09:54:42 AM »

This should have been available from day one, and the fact that it didn't happen is a big negative.

YES Sir! That's the point!