First project - need a little help with Z axis

[Malty]

G'day mates!

I just got a generic '3018 pro' and I've been playing around in Fusion 360 and UGS. I think I've got the X and Y axes under control but Z is doing my head in a bit.

All I'm trying to do with this first project is engrave a simple design into a plastic jiffy box that's 30mm high.

My cunning plan was to zero the Z axis too high for the first pass, then tweak it down in increments until I'm happy with the result. My design is a few circles, lines, and text, all of which are paths which I'm 'tracing', no variation in depth.

Truth is I don't really understand the following:

1. how/where to zero my Z axis, both in real life and in the model;
2. what my model should look like in terms of origin and clearances etc;
3. whether there's a better way to sneak up on the cutting depth in successive passes?

After a few failed attempts to get any sense using a full 3D model I resorted to a 2D model. I managed to get the Z axis to zero on the top surface of the workpiece, but when I run it it wants to track across the surface to the start point, then lift up before plunging back down. From then on it looks like it would be successful.

I realise that someone could probably just tell me how to tweak my gcode to clear the workpiece at the start, but I'd rather learn what I should be doing to get this right in the first place?!

[peteeng]

Hi Malty - Yes these are common learner issues with fusion.
1) In Fusion create a plane say 10mm or 20mm above the top worksurface. I use 12mm as my tool setter is 12mm high
2) On that plane create a point at a place that suits you for the machining. Call this plane the CAM zero plane and the point the cam zero point or part origin
3) In set up select the part origin point as the origin

That will establish the zero plane above your part and then set your other heights accordingly. I use a 12mm thick piece of aluminium to set the Z height on the machine. say your zero plane is set 12mm above the part top. So on your machine set the tool zero at 13mm above then run, then reset at 12.5mm and run etc until you are at the depth you want. Once you get confident with set heights and machine accuracy of Z you will program heights straight up. But I come down in increments sometimes because raw timber is not flat and I can't predict various heights until I see the cut.... Peter

edit - The Z plate can't be too thick. It's a cantilever and its the part that does the most work. Its at the sharp end of the machine. So don't skimp here, make it as thick and stiff as possible. Take advantage of flanges and any geometry available fill with metal....

[joeavaerage]

Hi,
I use my machine to make isolation routed circuit boards, an engraving process. Its critical that the engraving tool be at exactly the right depth, 0.05mm is good,
0.1 is too deep and 0.025 is not deep enough. In the ideal case the tool just cuts through the thin copper layer, 0.035mm, but not too much into the fiberglass underneath,
too deep and the already thin traces get too narrow and can disappear altogether, to shallow and the copper is not cut right through. I use a software utility called Autoleveler
to fine tune my Gcode to accommodate any bow or warp in the PCB blank, and there is always some.

I set the Z axis to '0' on the very surface of the material. Thus any negative Z means that the tool is cutting below the surface while any positive Z is above the surface.

Craig

[peteeng]

Hi malty - You will notice in F360 simulation that the toolpath "start" is at the entry point to the toolpath, not the part origin. The "first" move is dictated by the controller & where the tool is (the tool could be anywhere) not the generated toolpath (this is an out of program move). So typically you either have to manually add a Z up move to the posted code or start at a Z height above the part as I suggested. The "first" move (out of program) depends on the controller. I use UCCNC and if the part top is Z(0) and the tool is at Z(0) then the first move is along the part top to the the toolpath start, then up to the clearance ht then the "posted" toolpath starts. This is undesirable. So by establishing a part origin above the part and I set the clearance ht to the origin ht, the first move is along Z(0) ( but this is in air ) to the toolpath start (all good!) cheers Peter

[Malty]

Thanks folks and apologies for the delayed response. Peeteng hit the nail right on the head, setting an origin plane above the workpiece made all the difference.

I have successfully engraved my first thing and I'm stoked with the result! Next step is to move it off the dining table and set it up in the workshop, add a spoil board and dust extraction and limit switches and all that good stuff. I'll digest the other info above over the coming days as I learn more about this, but just completing a workflow from start to finish has been a huge leap - everything now is just improvements!

Thanks again for the kind help, and I'm sure I'll be spending plenty of time hanging out on this forum going forward!

[RCaffin]

Next step is to move it off the dining table and set it up in the workshop,
Curiosity only: are you married?

Cheers