[dylan604]

There's a big difference between an additive process vs subtractive process. To me, additive is much easier as it starts at the bottom and build up. Nothing is ever in the way of the next step. Subtractive is much more difficult as you have to figure out how to get to places that needs tooling, how to hold the piece to do the work on it (especially as the piece changes shape in the process). Most projects I work on requires more work in setup than actual milling/cutting/etc. It's one of those things that most people just don't realize until they actually attempt it.

[gangstead]

I've found the work holding on the CNC to be somewhat analogous to bed adhesion on the 3D printer. When milling you have to figure out how to hold this block down and printing you're using glue sticks and tape to try to get the first layer to stick. Both of these require the same trial and error shade tree mechanic skills that I enjoy developing.

My sticking point is more in the CAM side of things.

First I'll design something in Fusion 360. If I want to 3D print it the next steps are to export the stl (shape file) and open it in a slicer program. Then there are about ten parameters that may need some tweaking especially for a new printer and dozens more that you rarely change from the default before sending gcode to the printer. The slicer program can get you pretty close out of the box and the more I've done it the less time I spend slicing - my go-to settings print perfect 90% of the time. There are lots of resources (blog posts, youtube videos etc) explaining the different slicer settings and their effects on the print.

For CNC Milling after I've designed the part in F360 you switch over to CAM mode and it's like an entire different project that you have to design. With the slicer you say "lay it down on this side and print in PLA" the CNC CAM process makes 0 decisions for you. You can't just say "here's my stock, here's my end mill, put this side up and cut" and then tweak settings from there. Instead there are myriad permutations on feed rates, orders to cut things, multiple passes. Someone's feeds and speeds posted on the internet aren't going to work for your machine/material/design so there can't be something like a slicer program that can automatically route your CAM based on a few parameters and you can't reuse many settings between jobs.

I still like both printing and milling but milling is such a more difficult task with less mature software available (especially open source and hobby level software). That's why a fairly simple task warrants a pretty lengthy tutorial that's worthy of the HN front page.

[jdietrich]

I might be a dreadful old fogey, but I think that everyone should learn manual machining before getting into CAD/CAM. There's a level of mechanical sympathy that can only be learned by turning the handwheels and making chips. CAM is complex because machining is complex - removing the software from the equation makes it far easier to learn the fundamental principles, IMO.