I love CAM! And really hate it. Also: Laptop hinge tests!

Post date: Dec 29, 2016 6:21:19 AM

So... CAM is great. You don't have to write G-Code- draw up the parts, generate the code, and off you go. It will make sure your tool won't crash, will do fancy high-speed-machining toolpaths (constant tool engagement), handle all those nasty shapes you don't want to, ...

...but it's really stupid sometimes. Especially with the Z axis. The two CAM packages I've used (though it's a stretch to call one of them a CAM package) have both done the same thing- immediately plunge the tool down to 0 and go to the start of the cut. Obviously this is bad as, at best, you'll draw a line through your material. More likely you'll ruin the workpiece and/or break a cutter. Fortunately this time around it was just the first option. Maybe it's because my mill has Z=0 at the bottom of it's travel; I don't know. Either way, it shouldn't do it, and it's dumb.

Other than that (and having trouble getting it to do what I want), I'm liking Fusion 360. Especially for the low-low price of FREE!

Anyway, on to business. The cuts I was making were for the hinges on my laptop- it's hard for me to measure the irregular shapes, so I wanted to try machining the pieces to make sure they actually fit together and line up properly.

You can see the CAM mistake on the left part- that big line isn't supposed to be there. It's packed full of semi-melted chips from the piece and the spoilboard underneath (black stuff). Small miracle it didn't break the cutter, rapid-moving through all of the material like that. I definitely don't need to worry about horsepower on plastic... clearing chips is definitely a concern, though.

The left piece is the bottom, and the right is the top- you can see the cutout where the hinge would go, plus the area machined out for it to attach to.

A couple more images showing the misalignment (good thing I made some test pieces!). It's maybe 0.5mm off left-to-right, and pretty close to spot-on front-to-back.

(This is the left-right misalignment)

And another picture showing the whole thing assembled:

I also forgot to machine the features for actually attaching the hinge on the lid portion, but I'll be doing another test piece anyway, so I guess that's OK.

I'm going to try to get some pieces made out of aluminum before I'm out of vacation, but historically that really hasn't worked, so don't hold your breath.