Is G04 (dwell) time utterly inaccurate? Below a certain value, pauses are equal.

[BR549]

The problem is your trying to make an accurate Z motion with an air cylinder and a mechanism. I don't think that is ever going to happen.

I use a scribe BUT it is mounted on the Z slide and lowered into position when needed. THEN I have full ZXY control over it with Gcode. NO problems with timing issues trying to NOT mess up a decent engraving.

You will not get the precision timing control on your air cylinder control from a VB macro it will be as bad or worse than the G4 to control.

But if you determend to use what you have do as TWEAKIE suggested use the DIR pulse from a phantom axis to control the Solenoid. IT is extremely accurate and precise in it time slices.

(;-) TP

[Tony Bullard]

Another way to insure the scribe is up before moving is to use a limit switch at the up stroke of the air cylinder wired as a probe.

Your code here to activate the solenoid
G91
G31 C2 f30      'G31 = straight probe move
   While ismoving()
                                      'Sleep 100
Wend
G90

This will wait until the switch makes and then return to the program.

[Tony Bullard]

Another way to insure the scribe is up before moving is to use a limit switch at the up stroke of the air cylinder wired as a probe.

Your code here to activate the solenoid
G91
G31 C2 f30      'G31 = straight probe move
   While ismoving()
                                      'Sleep 100
Wend
G90

This will wait until the switch makes and then return to the program.

Just checked this out. G31 only works with X, Y and Z

[Tweakie.CNC]

Tony,

I think you will find that G31 works with 'A' as well. 

Tweakie.

[Tony Bullard]

Thanks Tweakie, I was just playing with it and you are right.

Maybe Brian could add the "C" and "B". It makes for good switch sensing

[FXC]

I think the easiest solution is as both Tony and Terry have suggested in their posts above. You can get reliable delays from a few uS upwards by using a non-existent axis in this way.

True, and that's exactly what I ended up doing: used my [non-existent] A-axis, the motor of which I tuned to be the equivalent of 1 inch = 1 second.

Now, I'll disappoint everyone here and reveal the utterly useless (but fun) purpose of this whole endeavor (turn your speakers on): http://www.youtube.com/watch?v=Fq4VLwLFXaE&t=11s

[Tweakie.CNC]

Nice one, a Nintendo CNC machine. 

Tweakie.