My 4-Axis Prototyper
Well, the first test cuts are complete. I think I'm going to keep the mill. Heh.
I spent a few hours in Rhino making a simple vehicle, akin to a Hover-Hummer or LAV. Multi-purpose. Nothing too fancy. No weaponry attached, but armored in nature. I then fed the vehicle's file into a CAM translator program called Deskproto. Deskproto crunched the numbers, and spit out a few Megs of G-Code. Mach 3, another program, then took the G-Code, and told the mill's motors when to activate, moving the mill's bed and head to carve the block of wax I had chucked up in a vice. I performed three operations: bottom roughing, top roughing, and a finish pass on the top of the tank.
Here's the chaos of my prototyping bench. I thrive in chaos.
Once the block of machinist wax is milled square and true, and the machine "zeroed," I then begin roughing out the bottom of the vehicle.
I've made a fixture to fit inside the socket that I am milling into the undercarriage of the hover-hummer. This socket will show its usefulness later. The right hole on the fixture egged out, due to cracking wax. Not a problem. This is just a milling test, not a final production piece.
Besides, the great thing about machining wax is that you can reclaim the chips, melt them down, and get right back to work. I owe momma a new meatloaf pan, though.
The milling out of the bottom is completed quickly, say 30 minutes or so. See how the fixture (the truncated pyramid) fits into the milled socket of the undercarriage?
I affix the bottom of the hover-vehicle to the fixture. When I start cutting in delrin and aluminum, this will be accomplished via 10-32 machine screws. Right now, superglue is keeping the work in place atop the fixture. Roughing begins on the top of the vehicle...
Eventually, 45 minutes later, a chunky, rough, hover vehicle awaits inspection.
This is nice, if my vision was the same resolution as the old 8-bit Nintendo games. Unfortunately, my laser corrected eyes demand perfection! Out comes the finishing data, and the 1/32nd ball end mill (with just 3/32nd of reach, mind you). Resolution is squished, and milling time soars. The going is slow, but the results are worth it.
34 (yes, thirty four) hours later, the top of the hovertank is done. This process definitely takes the "rapid" OUT of "rapid prototyping."
Never the less, I'm happy with the results. I'll change and tweak things to get the milling time down, and will report back soon with results.
All in all, not too shabby, eh? This was just a simple vehicle, but it has grown on me. I'll probably remaster it for production, with a few modifications and weapons.
Until then, keep checking back!
John Bear Ross, March 2008
Well, it's been a long time coming, with a considerable personal investement, but I've brought my prototyping services in-house. Before, I was like an architect, making blueprints, but never creating a finished product. Now, I can do both, sculpt digitally, and then turn around and hand a prototype to a client.
I'm basically using a Taig bench-top mill, controlled by a computer, to carve a mech or tank out of a solid rod of plastic, wax, aluminum, or even steel. Is it as accurate as a 3D printer? Yes, maybe even more so. Can it perform undercuts? No, not so much. Can it make a vulcanizeable master the first time, everytime? You betcha. Thus, I'm able to skip a step in the prototyping process, giving my clients a master they can drop right into a vulcanizer, and cut their costs for production.
Here's the Taig set up just for function testing, making sure the motors work and the computer is talking to the motors that turn the axes.
Here's my enclosure, to keep in the noise, coolant, and flying bits of steel and plastic out of the rest of my garage/tool shop. It's 3/4 inch MDF, measuring 48 inches wide by 30 inches deep by 32 inches tall.
Now I've mounted the Mill into the enclosure, and have started making test cuts on a piece of Delrin chucked up into my 4th axis.
Here's my entire set-up, with the high-speed spindle mounted to the head stock. Next to be built is a door with a clear window, and some internal racks for chucks, tooling, and a million other things you need to machine materials into sculptures.
The only major modification I've made to my Taig is the addition of a Bosch Colt palm router as a second cutter for fine detail work. The ER-16 head stock I have for the Taig is 1/4 horsepower, and tops out at 10000 RPM. This Bosch router is 1 horsepower, and is variable speed from 11000 to 30000 RPM. The limiting factor is the size of cutters that I can use, in this case, only cutters with 1/4 or 1/8th inch shafts.
The mount is made from HDPE, the same plastic found in most cutting boards. It is two 3/4 inch sections bolted together, then drilled and fitted to the router. It's rock-solid, and test cuts look great.
Here's a tailstock I made from a piece of angle iron, a piece of scrap aluminum, and a 1/2-20 Socket-Head bolt. It's ugly, but it works!
Here's my Taig Benchop Lathe that I scored off of Ebay. It's very handy, and a tough little brute to boot.
Well, that's my tiny machine shop, for now, anyway. I've been bitten by the machining bug, and enjoy hearing the whine and scream of metal being formed to my will. Yes, I have issues.
Keep checking back, as I muddle through a steep learning curve to bring prototypes direct from my workstation to your hot little hands.
My thanks to Nick Carter, online CNC guru, for his patience and great service. Check out Nick's site at www.cartertools.com
John Bear Ross
Copyright (c) 2007 John Bear Ross