Boot to the Head

Sometimes it takes a serious kick in the pants or a boot to the head to get off top dead center. And sometimes the things that should be painful really aren't in the end.

I've got a small benchtop CNC mill. It's an older machine, and runs bi-level chopper drivers on its stepper motors rather than a microstepper, which is more common these days. Because of this it's suffered from a couple of quirks, one of which is resonance at some speeds, which results in lost steps, destroyed parts, etc. Also, because my shop tools are more or less being operated on the basis of "if you can't afford it you can't do it", I don't buy a lot of new hardware for my mill. The computer that drives it is a curbside pickup special on computer recycling day, and up 'till now I've been running TurboCNC on a DOS installation.

It has been painful!!!

Don't get me wrong. TurboCNC is a good product, but it's not much fun running DOS for something that needs files to be moved around. I do my CAD work on a Windows XP machine. I have to get those files onto the CNC machine. With DOS that pretty much says floppy or nothing. I managed to get a DOS setup working that talked to USB flash drives, but you had to reboot the DOS machine in order to disconnect and connect your drive. And since the CNC machine is the only machine in my house with a floppy drive, it has not been fun. It's been so much of a pain I more or less quit using my mill out of frustration at how hard it is to design a part, tweak it, test it, change it, etc. and only then finally make it. It's been more trouble than it's worth. But it's what I had.

Until recently, anyway. I suffered yet another hard drive crash (shops are mean to computers), and realized I no longer even had the installer for the version of TCNC I was using. I hadn't used my mill in over a year because of the difficulties already mentioned, so I figured it was time to start fishing for a new program.

(As a quick aside, while thinking about what to do I disassembled the dead drive, a 2GB Samsung. I got two really nice flat round plates I can use as index plates or robot wheels, I got a brushless DC motor, some bearings, and a killer pair of fridge magnets!)

After a little hemming and hawing, I stuck a used 13GB drive in the machine, grabbed a copy of the EMC2 Brain Dead Install CD, and gave it a whirl. I am impressed! I had a bad experience with EMC in the Y2K era, so I had a lot of misgivings going into it. I have to say, though, my fears were utterly unfounded. This thing is impressive!

The developers of EMC2 seem to have fixed just about every EMC bug that drove me nuts back in the day, and in the exchange I get constant velocity contouring (CVC), much faster travel, a really nice interface that displays your toolpath before you commit to running it, cutter diameter offset, cutter length compensation, and all sorts of other goodies I haven't even begun to find out about yet. It's COOL!

In a little over half an hour I went from a dead mill and a dead computer with no hard drive to a really slick mill that'll do 50 inches per minute, whiz the rotary stage like a top, cut deep and clean, and let me use networking, file sharing, USB flash drives, etc. I'm in heaven!

So what's a feller to do? Make parts, of course! I don't have anything lined up, but this is serving as a perfect opportunity to re-learn my CAD/CAM software. That, too, has changed since I last used my mill. I draw things in Rhino3D these days, and generate toolpaths in Vector CAD/CAM. I whipped together a quickie to make a turner's cube on the mill, and will give it a try tonight in a couple of different materials. It'll test circular interpolation, backlash compensation, and all sorts of other things that more complex parts will need. In the end I'd love to make some of these in brass, throw them in the mass finishing setup, polish them to a mirror finish, and get them plated so they don't oxidize. Should be pretty!

What's down the road? In the short term I'd like to finish out the deck fittings for an RC sailboat, make a new backpack winder for my kite with fold-down handles, make a new chassis for my line follower and downhill racer robots, make a Delrin case for the Orangutan and for the AVR Dragon, make some gear cutters out of some O1 tool steel I've had lying around forever, and see what I feel like doing from there.

MAN it's nice to have my mill back! I can't wait to start playing.

Tom