G code question

[mcamp001]

I'm relatively new to this, so please bear with me;
When setting your home location (G92 X0 Y0 Z0 ) and then wanting to raise the bit before starting the cut, is there anyway to move a fraction of an inch? example: G90 G0 Z1 raises one full inch, What about a half inch? ( i know I can use MM, but don't want to in this case)

I tried .5, but doesn't like the decimal.

Thanks for any insight.

[SteveNelson46]

I don't know how your controller handles the gantry and head movement but in WinCNC there is a command line at the top of the control screen. I just type "Z-.5" (no quotes) and press enter to move the spindle down 1/2 inch. Similarly for the X and Y movements.

[mcamp001]

Thanks Steve. In my case the spindle would be moving up, so I don't think the "-" is good. I tried "G90 G0 Z .5", but it doesn't like the decimal point. This is the NGC interface that MillRight supplies.

[SteveNelson46]

Try just entering Z.5 and press enter

[TReischl]

Or, if all that fails, try G0Z0.5

That may not work either, LOL.

Or, it may be finicky in that it wants all the decimal places. eg.: Z0.5000

[martin54]

Once you have set your 0 positions do you need to move your spindle up an exact amount? Just manually jogging the spindle up a little is enough, the machine knows where it is in relation to the work piece so it really doesn't matter.

[mcamp001]

thanks all. I can just jog it up as suggested, but the question was more of wondering how to translate a fraction of an inch in a command. No Worries, all good!

[rink]

Good evening.
I’m not the expert here, but just a thought…

In the toolpaths you run, doesn’t the gcode move the z-axis by fractions of an inch all the time throughout the job?

Have you looked to see how your post processor spits out those commands?

Thx, rink.

[adze_cnc]

I tried .5, but doesn't like the decimal.

I'm a bit late to the party but...

How doesn't "it" like the decimal? i.e. what response are you getting that shows you that "it" like the decimal?

For that matter what is "it"? I'm presuming you're enter these numbers via some pendant but what are you entering the numbers into (GRBL, Mach 3, etc.)?

[martin54]

Good evening.
I’m not the expert here, but just a thought…

In the toolpaths you run, doesn’t the gcode move the z-axis by fractions of an inch all the time throughout the job?

Have you looked to see how your post processor spits out those commands?

Thx, rink.

Not really, the z axis (or any other axis) will only move when it is instructed to do so & it will move at the speed it is instructed to a distance it is instructed to. Not sure instructed is the right word but not sure how else to describe it
On a profile cut for example without ramping the z axis will plunge to a depth that it has been instructed to move to & will then remain at that depth for the complete pass.
On something like a detailed 3D finish pass then the z axis can often be moving almost continuously which is what you might be thinking about
Gcode is just a series of instructions that the CNC control software reads & then takes the appropriate action

Just to add, the OP was trying to move the z axis a set amount using the control software before running a toolpath for the project