Converting a Laser Engraver to a CNC Machine!!

 

One of the toys that’s ALWAYS been on my list is a CNC machine, however I’m just a regular ol’ person; I don’t have $10k+ just sitting around to buy something that is for a hobby (or for almost anything else for that matter…).  I’ve learned a ton from playing with my laser engravers over the years.  As you’ll know from reading the blog, I traded a stock laser engraver controller for one meant for a 3D printer and in the process learned a ton.  In my last post I introduced y’all to my latest (monster) laser engraver, but about 15 minutes into using it I already had the idea to add a spindle onto the Z axis.  BTW, my laser engraver has a z axis and can cut through thin wood, haha.  GCODE is such a universal tooling language that it just seemed like the next logical step.

I went ahead and removed the laser after I received the spindle.  I bought this spindle and added it the Z axis.  I had to get a little bit creative on the mounting.  I’ve been using this z axis actuator, but it wasn’t quite wide enough to cleanly mount the spindle onto.  I removed the plastic edge tabs and inserted M6 nuts into the slot.  They fit into the slot just wide enough to hold enough pressure onto the mounting plate.  Just to be safe I went ahead a zip tied the spindle to the mount; it sure would be a mess if it slid off mid cut and was still spinning.  I also mounted a small steel piece to help with the inductive end stops.  In my testing sometimes the z axis would be too high and not catch the sensor and go a little crazy for a bit.

The very first thing that I’ll speak to is that the motor strength.  I am always super impressed with stepper motors, they are strong.  As long as I don’t get too greedy with what I’m ripping out the NEMA 17s that came with my bundle from OpenBuildsPartStore have been going just fine.  To keep the strength up, I’m also moving slow.  In my first tests I’ve been running the motor at 600 mm/min while it’s cutting and using a depth of .5mm per layer and its working no problem.  I don’t think I’ll grow old of wood for a long time, but wood and plexiglass will probably be the hardest things I can cut with this.  The spindle uses 1/8″ shank router bits.  I bought a couple sets so far and have been experimenting.  For plywood I think the straight flute bits will be best.

That brings me to the next point, the GCODE.  Like what I did for the laser engraver, I’m using VBA to mod the code that I get from a 3D printer slicer.  I use Simplify3D but I’m pretty sure a similar concept can be used from any of the normal slicers.  I’ll make another post about the script I use to mod the GCODE soon.  I know the real CNC folks will say that this is not a true 3D CNC but more of a 2.5D CNC since it’s only going down a layer at a time, but for me this is still a tremendous start.  If I can ever find good CAM software for a Mac I’ll eventually try demo’ing true 3D CNC machining on this thing, albeit slower than a real (expensive) one will do.

An issue with using 3D printer software is that it’s really confusing mentally.  I flip flopped the direction of the Z motor so when the firmware thinks it’s moving up, it’s actually moving down.  What the firmware thinks it’s printing it’s actually subtracting and when it thinks it’s moving up a layer it’s actually moving a layer deeper into the workpiece.  I’m not very good with common sense so I really have to take my time and think about it.

I’m still pretty much in proof-of-concept mode with this thing, but so far I’m super impressed with the results.  And with the version of the ACRO bundle I bought, it’s huge and I’ll have the opportunity to try all kinds of things so long as I’m patient.

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