Attempting control upgrade on my Novakon CNC mill

[kvom]

After 7 years with Mach3, I decided to follow a number of other who've elected to convert to Tormach's PathPilot.  For those with newer machines than mine, the conversion could be easier.   On mine, the machine control by Mach3 involves manipulating  pins on a parallel port.  And all the pin signalling is done by the motherboard under interrupt control in Windows.  That means that my highest speed moves are limited to 75 ipm, and the tool motion can lack smoothness.

Under PathPilot, all the pin manipulation is done by a general purpose IO card produced by Mesa electronics.  Windows is replaced by Linux running a version of LinuxCNC, and the PathPilot application is built on top of that.  When running, Pathpilot signals the GPIO card to send its pin signals out a DB25 connection to the existing breakout board and thence to the Gecko motor drivers.  After a few days work trying to get PathPilot configured properly, I've gotten the XYZ axes calibrated and can run X and Y easily at 125 IPM without losing steps.  This rate is still pretty conservative, but I need to get more comfortable with it going any higher.

Thus far, the only problem I'm stuck on is controlling the spindle speed from PathPilot.  The spindle want to run at 4K RPM regardless of the commanded speed.   

My test setup looks like this:



Cover is off the current control while the PathPilot computer sits on top so I can see the LEDs on the breakout board.

[Art K]

Kvom,
I am also in the process of switching over to PathPilot on my Tormach, although I'm not using the tormach cpu. about all that is working properly is the rpm and the manual move xyza. doesnt even shut off the computer. Guess I'm not linux edumacated enough.
Art

[steamer]

Kvom    you're going to like Pathpilot.

Been using it for a cm couple of weeks   it's alright!

[Vixen]

Hi Kvom,

I am also working towards converting my Austrian built Emco F1 to run on Pathpilot, currently it works great on LinuxCNC.

I have got to the point that it almost works ( heard that before?). Unfortunately the real time display is very slow and lags behind the movement. I suspect my PC is not fast enough to run Pathpilot, however it will run the simpler LinuxCNC.

May I ask the clock speed of your PC? That may help me understand my Pathpilot problems.

Cheers

Mike

[kvom]

I had a new computer built to run it.  I picked the cheapest components I could.  Motherboard is a MSI B250M and uses 2400MHz memory chips.  Pentium CPU chip.  Bootup time for PP is less than a minute.

I made some progress on controlling spindle speed, but it's still not completely correct.  Peter from Mesa has been contributing suggestions.    I hooked up the 4th axis to try to calibrate it and have no movement; just a cryptic error msg.

[Vixen]

Hi Kvom,

That looks to be a nice fast motherboard, it all depends what Pentium CPU they fitted. I quess it will be the fastest available.

Have you looked at the LinuxCNC forum. The have a whole section on getting Pathpilot to run on non-Tormach machines.

https://forum.linuxcnc.org/pathpilot

Thanks

Mike

[kvom]

I haven't seen that section as yet but will check it out.

Today I fixed a config error on the Z-axis reference plus calibrated the A axis.  I'm running the A at a very slow maximum velocity, so will see how fast I can up it before it loses steps.

As of now, spindle control is my only known problem..

[Vixen]

Hi Kvom
'
I have never understood the need for hobbyists to do 'rapid' moves at the speed of light. I set my rapid between 20 and 30 inches per minute. That's fast enough for me and well within my reaction time to stop the cutter crashing into the bed or the work clamps, if the new program is not quite right.

It would be a different matter if I were mass producing a thousand identical parts each day Then ''time is money', in hobby machining 'mistakes is money'

Cheers

Mike

[kvom]

Mike,

The rapids are nice to have in certain situations, but I think secondary to some other benefits.  I have been using some trochoidal toolpaths recently that have a lot of rapid moves;  in addition if I run an operation cutting air the first time through it's convenient to be able to cut the time to finish down.

I won't know if PP is significantly better in other ways until I actually cut some metal.  I do like the way the jog buttons are laid out on the main screen vs. the popup window in Mach.

One thing so far that I don't like is needed to ref the axes on startup before executing g-code.  With mach3 I can save my origin and shut down the machine, not needing to reference again on startup.

[Vixen]

Hi Kvom

The Pathpilot interface is suposed to be more machinist orientated than LinuxCNC (it's a bit software geeky). They both do exactly the same thing using the same core software. Where PP is supposed to score is in the work flow through. The machine control,  popups and program editing functions are more logically laid out from a machinist perspective and require less mouse clicks or button presses with PP.

the LinuxCNC and PP startups are the same. Like you, I did not like the need to reference on startup, so I disabled the reference and end stop functions. I also declared the various axes to be twice as long as they actually are to avoid the soft stops. The onus is on me to avoid crashing into the hard end stops. The origins are reset to zero every time the machine is started, so I take care to park the axes at zero, zero, zero before switching off. Not tried to do this in PP yet. I think I need a faster PC to get PP running correctly

Mike

[kvom]

One problem solved.  For the each axis config in the INI file I set the HOME value to 0 (so referencing doesn't move the axis, and I set MIN_LIMIT to -n and Max_LIMIT to n, where n is the amount the table can move along that axis.  Now the soft limits are set beyond the ends of the table no matter where the table is at startup when I reference.

[Vixen]

That's almost exactly what I had to do with Linux CNC.using the Stepwizard configuration tool
Just shows how similar they are

Mike

[kvom]

A difference between PP and Mach3 is that under PP I cannot jog to zero Z while stopped for a tool change.  In fact, once a program is running no jogging when stopped or paused whatsoever.  So it appears I'll need to break up my g-code programs, one file for each tool.

[Vixen]

Hello Kvom

It will be no surprise to you, that it is the same with LinuxCNC. One file per tool.

Mike

[Dave Otto]

In Mach 3 there is a tool change macro? that when M6Txx is called the mill moves to a programmed tool change position, (no jogging around necessary) after the new tool is installed cycle start is pressed and the program continues. I'm using Mach Standard Mill screen set but think it work the same in the stock program as well. I have run programs that use 8 or 9 different tools, one of the operations on the American 4 post oilers comes to mind.
That has got to be a royal pain having to post out a separate program for each tool.

Dave