A different approach to CNC


Troll Spammer





So cool! That's food grade ink you are using right?



Some guy in the desert
I'll bet your daughter is psyched about this huh.

She likes the end result...but gets bored watching it and isn't quite ready to start using inkscape to make her own designs. So she's enjoying it....but not quite loving it yet ;) Maybe a in a few more years she'll appreciate it more.

As for the ink. These are just regular extra fine tip sharpies. Not food safe. But that doesn't bother me as I grew up with non edible easter eggs. The traditional Pysanky dyes are non-food safe too and you don't hard boil them either. We usually do a batch of edible eggs with boring plain colors to eat on Easter - but the fancy eggs are kept from year to year as mementos. At least the ones that don't go bad are kept. We lose a few every year - but the majority of them dry out and last for decades. (I'm not a fan of blowing them out either - have lost too many doing that and it's not traditional as pysanky are a fertility symbol and having the "guts" still in them is part of that.)

There are food safe markers - but they aren't as vivid, most of them don't write on eggs well, their shanks are bigger so I'd have to make a different pen arm to hold them...overall it's not really worth it to me. But...I may pick up a pack to try just out curiosity and to do some less intricate designs with. We'll see....


Some guy in the desert
I'm really happy with my eggbot...but...I can't leave well enough alone.

I wasn't totally happy with the pen arm. I ended up not using the spring mechanism to link the servo and the pen arm and instead drilled out the holes so it was nice and loose on the bolt and just let gravity do most of the work like in the original egg-bot design. But doing that the servo arm lined up with the hole in the pen arm for the spring to mount in...I worked around this with a bit of tape over the hole. That tape has been bugging me.

Since I'm also trying to learn onshape this seemed like a good excuse to try and learn how to re-draw an existing part. My first few tries were a little hit or miss. Importing an STL into onshape was easy. But I couldn't figure out how to reference it's geometry to modify. OnShape doesn't really do a lot with meshes (Fusion does...but fusion runs kind of slow even on this macbook air which is the nicest computer I have at my disposal.) So my first attempts I just used the imported STL as a reference and drew on top of it. But was frustrated that there must be a better way to accurately re-use the geometry.

Turns out there is. The "Use" tool in sketches. You just turn it on and then you can pick vertexes off of the mesh to use in your drawing. So basically I loaded the arm, viewed it normal to the top, used points that defined corners of all of it's features...and made my drawing. Then did the same thing on the side to punch out the screw holes. I just didn't re-create the hole I didn't want. Instead I extruded it as a little plateau so I would need less servo travel.

Boom done! No...wait...I can make this nicer with some fillets. Smooth out the plateau transition...give a little 1mm fillet around all the edges to make the part a little less sharp...hey..this is looking nice! Printed well too!

But...why stop there? This is turning out to be a nice way to learn onshape! So...let's draw all the parts and do an assembly!

Screen Shot 2017-03-29 at 10.40.20 PM.png

It's not totally done...and I haven't printed all the parts yet. But the ones I have printed are coming out great. So much nicer with smooth edges instead of harsh 90's. It's more...organic now. Like eggs. How fitting.

Here's the link if anyone wants to play with it:

When I'm done I'll export STL's and upload them to thingiverse. But you're welcome to make your own off of that and/or make your own modifications as well.

I still have to re-do the egg cups, and the assembly needs a bit more work. I need to grab some nema17's to put in there (don't feel like drawing those from scratch myself since they already exist) and add some more mates to make it fully assembled. Maybe add in some nuts too. I also tried to put threads on the 5/16" all thread but for some reason can't get that to work yet...need to experiment some more I guess.

Still...it's a fun little project and makes the egg-bot more "mine" :D


Some guy in the desert
So, got an e-mail this afternoon from an onShape representative. Apparently they noticed that my eggbot drawing was getting kind of popular and had been copied 13 times so far. They dropped me a note pointing this out and asking if it wasn't IP I wanted to protect (obviously hoping I'd be interested in paying for the commercial license.)

I just replied back saying thanks as I've been actively encouraging people to copy it :)

Oh, and since I haven't updated this...I did finish printing all the parts and most of them are in use. But I didn't fully rebuild the machine because it was getting so much use leading up to Easter. My daughter loved having fancy eggs to give to her friends, teachers and scout leaders and most of them really appreciated the eggs as well.

Now that Easter is over I should rebuild it...but it's been put aside to make room for other projects. So the big rebuild with my own parts will have to wait until it gets pulled back out again. Maybe I'll dig it out for Christmas and do some custom ornaments so I don't have to wait until Easter....


Neat idea! And a nice limited project size for those wanting to "wet their feet" within CNC.

Can't help but think the ideas of this other project might be usable as inspiration for building an "Eggduino" on the cheap - at least for the horisontal axis:

Mind you, this guy is by far not the first to try this approach. But I picked the vids as he gets fairly well around all the parts of the project in his presentation, including how he set up the Arduino and made his first G-code examples. His build is a bit flimsy due to the tall standoffs, and there's a limit to how much info you can pack into 10 minutes of video, but still not a bad example. And there's a lot of other vids and pages on this out there.

And heck, he even went on to turning the contraption into a simple 3D printer! And it works!:
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Some guy in the desert
I started with a CD drive based CNC 2 years ago:

Was a great learning experience. I never did implement a Z axis...the drive motors were so weak it was hard to design something that wouldn't be too heavy. I didn't have a 3D printer back then either which made it harder to make custom parts. I started building a Laser for it from a diode taken from a DVD burner...but never followed though since you can buy ready to use laser modules cheaper than buying the housing and driver to rig up a scavenged one.

Still a fun project and worth doing if you've got a spare arduino laying around and some old drives. The only thing I had to buy was a few stepper drivers and those are dirt cheap now.


Some guy in the desert
Oh, interesting side note. I mentioned to the Onshape rep who contacted me that their tutorials were helpful but a little frustrating since the final answers were wrong in some cases. They replied back basically saying "yeah, we aren't really maintaining those or creating new learning material for the free version but have a lot of great new training material we've been creating that's only available to paid users."

So that's a little disappointing and short sighted. Seems like keeping the learning material for the free version updated and useful would make a lot of sense. People evaluating it are going to get frustrated and give up rather than become paid users if that keeps up.


Staff member
It's actually one reason why I switched to Fusion360 after fiddling with Onshape for a while...


Some guy in the desert
I keep trying to learn Fusion...but getting frustrated with how slow it is on every computer available to me :(

Though - I've found that a lot of what I've learned with Onshape is helping when I do try Fusion. But doesn't transfer over to the CAM side which I still want to figure out for my MPCNC one of these days.