incrementing the z axis and repeating the pattern?

Good evening. I am building a CNC milling machine out of a cheaply acquired Sieg x1 which needed a new motor controller. This wasn't the Clarke board but an E bay purchase which is nearly identical but costs £18 and wires straight in once it has been removed from its box. I have stuck neoprene foam on the inside of the upper box which has quietened it a good bit and I replaced the lower spindle bearing. Total cost for the machine was £127 and a couple of evenings meddling so I am a happpy man.
I have three Nema 23 motors and have fitted the first one to the z axis.

I'm using an Arduino Uno running GRBL1.1 and I'm using the Universal G-code sender to drive it.
After a couple of days of frustration and engineering language, I got the programs talking to each other and yesterday, I connected it all up and calibrated the screw.
Blow me down, it works!
Now I'm much less good at Cad programs than I am at rocket science but I have done a lot of laborious assembly language over the years so G-code isn't too intimidating. I found an online g code simulator program that allows me to edit the code and see the toolpath (I am making simple one piece objects with little embellishment.) so I could make the part in wax or plastic for test purposes.
Here is the problem. Once I start to make this in metal, I shall need to make a series of repeated shallow cuts, won't I?
The machine and cutter won't have the grunt to work deeply so I was wondering whether there was a method of executing a block of code, for example,
mill an outline,
step the z axis,
repeat until done.
Move on to the next process,
mill a shape,
step the z axis.
Repeat until done.
sort of like a subroutine in a conventional program.
Is this how it is done?
If it is, would somebody please explain to me how to do it as I can't see any way of doing it without cutting and pasting a huge amount of code with z statements between them which looks pretty clunky to me.

Sorry, it is an elementary question but I'm a beginner and this would be a very great help
Thank you for reading this far!

hi tom :) is me, jerry ! welcome to pattern codes

some cnc controllers can patternize, while others can not; in your case you don't need a complex patterning code, but to change the "Z origin " after each cut ( or keep the " z origin " as it is, and use a temporary " z shift " )

most cnc controllers have the possibility to change both " z origin " & " z shift "; i don't know if your rocket does it :)

sometimes i also need to repeat a cut; even if i may edit " z origin " & " z shift ", in time, i have developed a soubroutine for the Okuma cnc :
... it can take whatever XY code
... repeats the code among Z axis ( for example equal steps for roughing + one last step for finishing : 0 1 2 3 4 + 4.3 )
... handles also circular rotation ( comes in handy when cutting wheels with teeth )
... handles tool entrance and tool exit : rapid, feed, increased feed, etc
... uses 2 clearance planes : the plane where feed begins, and the plane above the fixtures
... handles radius compensation, without auxiliary movements
... some positioning optimizations, etc
* now i simply need to input the toolpath inside this soubroutine, edit some parameters, and i am done :) i like it because it requires less edit time, making it possible to edit the code fast, near the machine, without going back to the pc, etc

hmm, for your rocket, i would recomend a simple approach : if possible, put the cutting toolpath inside a soubroutine, and call it repeteadly :
... Z-1
... cut ( call soubroutine )
... Z-2
... cut ( call soubroutine )
... Z-2.25
... cut ( call soubroutine )
* soubroutine content should be only the toolpath

depending on your rocket capabilities, such codes can be improved :) kindly :)


ps : https://www.youtube.com/watch?v=QpjwNa5izzM

Thanks Jerry. Seems my Arduino based GRBL has some limitations! It will not run subroutines and takes no account of tool size. This means a lot of hand coding. I'm simulating the toolpath and this seems to work albeit slowly. Then again, I'm planning to work in stainless and taking a .004" cut with a 65mm cutter.This may be conservative and I shall have to see if it works well enough to increase this to .010", feeding at 7 IPM.
Nothing wrong with starting out gently, I suppose. just as long as it doesn't harden.

hi tom, i have seen an arduino at work only once : it was a guy that was creating some code, and after that he was loading that code inside the arduino; it was like, once the program begins, you can not stop&restart it, or adjust it on the run :)

i don't know, it may be ok for some applications, maybe there is more to Arduino ... etc

about cnc machines, there are many programmers that create codes from CAM, so, for example, even a simple line that goes incremental on Z axis, will have a long code, that requires time to be edited

i try to shorten the edit time as much as possible, because a lot of auxilary time is lost with program adjustments and restart sequences

so, same thing can be done in different ways, depending on the available functions; i don't know, try to see what functions can be added to an Arduino ? kindly :)