# Virtual Axis

Posted by steob86
 Virtual Axis June 13, 2014 06:42AM Registered: 7 years ago Posts: 7
Hello everybody,

could someone explain to me the meaning of the virtual axis?
I don't get it!!

I'm referring to the last part of funcion : PrintLine::queueDeltaMove

From line : virtual_axis_move = max_delta_step * segmentsPerLine

 Re: Virtual Axis June 17, 2014 10:31PM Registered: 10 years ago Posts: 258
Looks like that is Repetier around [github.com]

Speaking out of mostly ignorance, the way the Deltas work is that they break each cartesian line segment motion (e.g., G1 Z10, relative) into a number of steps along a "virtual axis" aligned with the motion, transformed into delta coordinates. For example, a vertical move (G1 Z10) would be an equal motion along all three axes, and require the same sort of coordinated motion driving the steppers as a move on a cartesian machine like G1 X10 Y10 Z10.

I think the 'virtual axis' is along the line segment defined in the particular G-code segment being executed, and it is used as the basis for computing the relative moves in Delta-space.
 Re: Virtual Axis June 18, 2014 10:09AM Registered: 7 years ago Posts: 7
Hi DaveX,

thanks for your answer. Yes I use repetier, but it is really bad commented and sometimes hard to decifrate, at least for me.
Anyhow I reached a similar conclusion too but then I didn't understand why they use just one virtual axis.
I able to follow your lead in this example of yours, it is an easy one, where the three axis have to move of the same number of steps.

For instance if the cartesian coordinate is g1 x20 y25 z15, and ( following what you wrote at the end) the delta axis is a segment parallel to the vector
that describe the move, I'm not able to understand why is necessary to create such a segment...
or maybe I just misunderstood your explanation.

Once again thanks and I hope you have the will to help me again.
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