Messages

21

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

« on: January 24, 2018, 03:13:16 AM »

Hi Craig,

if you attempt to change the pulse rate of one axis which is part of a coordinated move the eventual endpoint will no longer be the point which the trajectory planner calculated.

Hm, guess u got me wrong.
Feed override does not change a single axis, but all coordinated axis at the same time.
The industrial controllers I worked with had a dial for G0 moves and a separate dial for all working moves. With that controllers it is possible to start a move with velocity of 0 and increase velocity at will (and so change velocity during move).
For that to happen with mach4 the controller needs to sample an analog value (or an encoder) and pass that value to mach4 fast enuf that the motion can be worked out based on that value.

The only case, where I can imagine to change velocity of a single axis is on lathe when you plane the front surface. In that case the axis don't has an endpoint and the speed of the turning axis depends on the x-position - thus mach4 has to know x-position during move.

Threading (for me) is just a matter of synchronization and for so very close to the closed loop goal

Reinhard

22

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

« on: January 24, 2018, 01:44:26 AM »

No controller can truly fix anything it doesn't have control over (which is the definition of backlash).

Agree. So looks like I didn't understand the meaning of backlash

Reinhard

23

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

« on: January 24, 2018, 12:35:36 AM »

Hi,

No controller that I am aware of can alter a coordinated axis velocity during a coordinated move.

Really?
For me its such a basic requirement, that I can't think how to live without it.

I worked on industrieal cncs and there feed-override is vital. Every cnc-job will be tested by using feed-override.
Well, I build a hobby cnc, but I'm used to professional work and I'd like to do so with my hobby cnc too :O

you are talking here about 200-300-400$ Software, not about "real" (sorry to use this word),
CNC controllers (10000-20000$ aeria).

That's right, but I think, mach4 is not the problem

The features which determine whether a controller is mature or still under development are probing, THC, backlash
compensation and lathe threading.

Well, probing is so essential, that I think, a controller that can't do probing or which causes problems at probing should be retired from market and blamed any time you write a new message.
In the feature-list I miss the feed override by hardware during movement!
I heard about hobby controllers, that support it, but it was not a controller for mach4

THC and lathe threading might be the same software problem - but as already said, I'm convinced, that its not a problem of mach4 but of the controllers.

backlash is separate goal.
From my point of view, there's a path from entry-level-cncs (driven by simple steppers) until professional cncs driven by what ever motors controlled by closed loop with absolut positioning system (which for me is an industrial issue).
For me, the path looks like

• simple steppers
• steppers with closed loop drivers
• encoders moved from motor to ballscrew - closed loop by application (mach4)
• absolute encoders and closed loop by application

I start with level 2 (closed loop stepper drivers) on my cnc and I'm interested in level 3 - which (for me) is the answer to backlash and the like.

But to enable these functions, you need a different interface between mach4 and motion controller. For me, the refresh rate between mach4 and motion controller should be at least double the supported steprate. As most hobby-level stepper drivers support a max. steprate of 200kHz - so 400kHz sounds like a reasonable limit for hobbylevel. Industrial solutions might require refreshrates of about 1MHz or more, but that could be a feature of industrial mach4.

I don't know the amount of data, that has to be exchanged between mach4 and a motion controller, when mach4 controlls the closed loop, but I think, 100MBit Ethernet might not be fast enuf. So may be, those controllers need to be attached to workstations internal bus (like mesa 6i24 anything I/O)...

Reinhard
[/list]

24

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

« on: January 22, 2018, 11:34:34 PM »

Hi,

Mach4 threading support is complete as described in the manual, BUT it is dependent
on the motion controller to implement threading features.

As of 22 January 2018, and as best I know, threading is fully implemented by
Hycon, PMDX SmartBOBs, and PoKeys.

That information is very valueable! Thank you!

When you read propaganda from hardware builder, than it looks like everyone has best product on market. So its very hard for those that don't know that hardware, find out differences. And if you ask at forum, you have to separate answers from fanboys and wise guys.
Would be great, if artsoft would publish a table, that compares hardware support for special mach4 themes like threading. Support for closed loop and pid parameters could be another question. Or hardware support for feed override during motion ...

I guess, such comparision could speed up competition of hardware builders

Unless the controller can report back to Mach and Mach can accommodate moves that don't go where they are supposed to then Mach has no chance of controlling the machine. That requires an out of band axis which can be altered WITHOUT affecting a coordinated move of the remaining axes.

Sure, out of band axis is one requirement. But if mach4 should recalculate speed of turning axis, it need to process motion feedback of an axis (during motion). At least, if speed depends on position.
So the position has to be sampled (if using an encoder) and transmitted quite fast.
If you look at the 40Hz of an ESS: an axis moved at 12m/min moves 5mm between to communication triggers, so no chance to calculate any finegrained speed changes.

Reinhard

25

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

« on: January 22, 2018, 07:01:48 AM »

Hi,

The Hiconn is not way more expensive.
With the ESS you need to add breakout boards. The Hiconn has them built in.
The ESS and most other motion controllers are 5v I/O. The hiconn is 24V.

When I look at the closed loop option with more than 3 axis - then the Hiconn solution charges about 2k bucks, which is ten times an ESS.
With little knowledge of electronics a bob is not hard to build.

My contention is that once a coordinated move is dispatched to the controller it is no longer possible to change the A axis rotation rate, it would break the move.

Well, that probabely depends on what communication is possible betwenn mach4 and the motion controller - and of cause it depends on the communication refresh rate.

Because the A axis is ansynchronous  the speed of rotation can now be changed during a coordinated move of the other axes. In particular if the Z axis is equivelent
to radius then the speed of the A axis can be calculated and repeatedly updated by a short PLC script.

Well, that requires a fast PLC thread, as well as fast communication between motion controller and mach4.
Don't know the interface speed of other motion controllers. ESS has 40Hz - which is quite slow for such operations.

Reinhard

26

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

« on: January 21, 2018, 01:28:55 AM »

Hi Mauri,

I do not know of any CAM program that can output surface speed and the A Axis using the Z Axis as the radius to control the speed.

I think, the radius in the picture is just a helper information for human beings.
CAM, as well as motion controller has a path with starting- and endpoint. Cutting edge of the drill bit is the Z-Axis, so CAM and/or motion controller need to calculate a path with possibly 4-axis moving. The surface speed is the speed working out that path. The path may be radius based, but need not be so.

If you want a controller that can in all conditions you need to speed the $$, HiCON cards can do it all.

Hm, if I get the picture right, Hicon does not raise closed loop to mach4. Closed loop works at motion controller level.
I guess, same would be possible with ESS too. Not sure, if that makes any difference to closed loop at stepper controller level.
Closed loop at application level may have an impact at path optimizer.
... and I did not see any special input for feed override.
So I'm not convinced, that Hicon offers better solution than ESS does. Hicon is just way more expensive.

Reinhard

27

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

« on: January 20, 2018, 09:45:55 AM »

Hi,

Yes there are still some outstanding issues like A axis not being able to maintain surface speed as the diameter controlled by the Z axis changes like Mach3 does.

Hm, is this an mach4 issue? Shouldn't that be calculated by the cam process?

Mach4 V3481 and HiCON are rock solid and can machine all 3 Axis G-codes perfectly, I have not tried 4 Axis as we need the above 2 issues included into Mach4.

Hm, that's the point, where I became unsure.
I bought an ESS, but when I started configuration, I was astonished by the update-frequency of 40Hz, which already is 4 times faster than with mach3.
But ...
My cnc will be a 4-axis gantry, where I start with CL-steppers. The stepper-drivers handles the closed loop, but I'm interested in moving CL up to mach4. But I think, 40Hz is way to slow to start with CL.
Next doubt: I want feed-override in hardware - no matter whether to use potentionmeter or mpg - and I'm quite sure, that 40Hz is to slow for it too.
Therefore I wrote, that I miss decent motion controller, that ist affordable (for me less than 500 bucks).
But that's not an issue for artsoft - it's just coupled to the decision mach4 or not mach4, as any software requires its own motion controller and each is incompatible to the rest.

Reinhard

28

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

« on: January 20, 2018, 01:10:40 AM »

there is a development version on the FTP that may work better for you if your interested in trying. Version 4.2.0.3643

Thank you so much! You're my hero
Looks like 3643 works again (as 3485 did before). So only 3633 fails on XP

Well, don't take me wrong - I only used m4 with the screen editor as I don't have a working cnc yet. So I can't say if it will fail on real work. But at the moment I'm happy, that I can continue working on my screens

Reinhard

29

Mach4 General Discussion / Re: crash on starting edit mode

« on: January 20, 2018, 01:04:52 AM »

Hi Craig,

then expecting it to run without a later Windows release is a matter of YOUR intransigence not Microsofts OR Artsoft's.

I did not blame anybody for my paranoia!

you obviously consider Windows as at best a necessary evil and refuse to get a later version than XP.

No, that rule of abstraction does not fit.
I don't install anything, that requires internet access during installation - no matter what it is.
Afaik there's no offline-installer for windows after release 8 and as I don't have any other apps, requiring windows, I did not buy another windows version for years.
To check compatibility of my own apps, I run windows demo in VM - I install it, when I need it and remove it, when I'm done.

Equally clearly you are very computer savvy and have no doubt that you can extract the utmost from Linux.

Don't know, on what base you state the first sentence.
I'm just a linux user. Compared to windows, I need to care less for linux, than for windows. I need less OS-skills and less administration time. In other words, I don't need to spend time for administration.
I took me some years to find the right distribution for me (for me its safety and stability first), but since 05 I use debian stable and since then, I never had to care for OS - so I can use the workstation at my will.

Why bother with Mach4, I understand Liniux CNC is very capable and given that it is open source any required functionality could be programmed into it.

linuxCNC may be considered capable an powerfull until you try to code something for it. linuxCNC is the best sample on how not to do things. Its a crap, its ugly and many things are performed twice or even more - so it is very slow too.
After few weeks I did not want to bother any longer and removed the local copy of linuxCNC.
... and what distract me most: there's no help on "real" questions.
So no - not my way!

Reinhard

30

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

« on: January 19, 2018, 11:26:36 AM »

Thanks again, Jim!

the dll's from technet discussion did not work and the redistributable C++-runtime did not solve it either.
So I think, that's (finally?) the end of XP - and I'm very sad to have to say good bye to m4.

So whenever you decide to start the linux trail - please drop me a mail and I would be happy in helping.


best regards

Reinhard