"HOME" position on a CNC Mill, switch locations?

**magicniner** · 16-08-2014

Originally Posted by Robin Hewitt

Sorry Nick, it is this thread, I just couldn't be bothered to add the logical progression that makes sense of it. I have tried but nobody here programs computers so they cannot escape the limitations of using MACH and G-Code.

Robin,
I think it's worth expanding your reply. I cut my teeth on Z80 Assembler and progressed to PLC Ladder Logic & Statement List, VB, SQL, Crystal Reports, etc. and you've lost me.
Any "Limitations" of Mach3 and G-Code (and I've not found them yet) are far outweighed by the capability provided by an affordable CAD/CAM system coupled with Mach3 -
-

[/URL]
-

[/URL]
?????

**magicniner** · 16-08-2014

The stamp does this in hot steel -
-

-
It's about 8mm high ;-)

**Robin Hewitt** · 16-08-2014

Originally Posted by magicniner

Robin, I think it's worth expanding your reply. I cut my teeth on Z80 Assembler and progressed to PLC Ladder Logic & Statement List, VB, SQL, Crystal Reports, etc. and you've lost me.

You say "etc." before you say "Visual Studio". Windows is event driven and will never guarantee to return control to you in time to step the motors. The moment you give in and add a separate processor to sort out the timing problems MACH becomes a totally redundant unnecessary burden and you may as well run Win8, check your e-mails and have a Shoot'em'up game running in the background to while away the time while it cuts.

I don't think I want to criticize MACH here too much, look what happened to the bloke in the news today, the one who accepted a Gaza appeal to be published in the Jewish Chronicle.

**EddyCurrent** · 16-08-2014

Originally Posted by Robin Hewitt

You say "etc." before you say "Visual Studio". Windows is event driven and will never guarantee to return control to you in time to step the motors.

That was my biggest hurdle when moving from DOS programming to Windows, instead of main() running in a continuous loop, it just had to sit there until there was an event.
Will Windows interrupts be too slow ?

**Robin Hewitt** · 16-08-2014

Windows will not let you take over a timer interrupt, you can hook into a 1kHz system tick but that isn't fast enough. This came to a head when Windows could no longer guarantee to service a serial interrupt in time to stop an over-write with only one level of buffer, they needed 16.

**JAZZCNC** · 26-08-2014

Originally Posted by Robin Hewitt

Windows will not let you take over a timer interrupt,

Unless you take over windows.!!. . . . Tell Art fennerty it can't be done.! . . . . .The Boffin's said Mach3 could never be done but Hey presto.. .

**Dragonfly** · 26-08-2014

Yep, Mach3 own high priority driver takes care of that. I'm not sure it can work with Win7 and 8. Although I've read some people use it under Win7.
As for the coordinates of the machine, my personal opinion is that the near left corner relative to the operator's most convenient position should be assigned X0/Y0. It does not matter which axis is the longest one. Thus you maintain correspondence to the CAD and CAM software. Setting work zero is another thing and depends on where you fix the material on the table. For long machining sequences I zero the machine by means of home switches (Mach3) and then write down the real (machine) coordinates of the work zero. Just in case something goes wrong I am able to reposition with acceptable accuracy.

**magicniner** · 16-08-2014

Originally Posted by Robin Hewitt

You say "etc." before you say "Visual Studio". Windows is event driven and will never guarantee to return control to you in time to step the motors. The moment you give in and add a separate processor to sort out the timing problems MACH becomes a totally redundant unnecessary burden and you may as well run Win8, check your e-mails and have a Shoot'em'up game running in the background to while away the time while it cuts.

I don't think I want to criticize MACH here too much, look what happened to the bloke in the news today, the one who accepted a Gaza appeal to be published in the Jewish Chronicle.

Brilliantly put whilst totally avoiding the perfect opportunity to identify your "personally programmed" alternative where you haven't given up hardware control to Windows. You are signally failing to make a point here.
I'm really intrigued, what system are you using? How much percentage wise and specifically which bits are your own code?
If it turns out that this is an OS bias debate then I'll laugh my socks off as all that really matters is how quick and easy a system is to get running reliably, what the software support is like and what results it produces ;-)