Published January 31st, 2017 by

Well, I got so engrossed in completing this project that I didn’t update the blog for quite some time. I’m now going back and “filling in the gaps” with the build info. I’ll start by wrapping it up with the final summary and pictures.

I’m very proud of how everything turned out, especially since when I started I had little more than some metal and a saber saw. A lot of things were built along the way and every one of them was worth it since I learned so much. This project was one long education.

The final arm is fully articulated and I finished a acrylic display for it with some custom lighting. It took approximately two years of spare time from start to finish. In hindsight that seems extraordinarily fast when I include everything else that was built to help the process, not the least of which was my custom written CNC software & software (see the my blog section on MillDroid).

 

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4: Terminator T800 Hand - Metal Build

Published November 20th, 2014 by

Now we’re getting serious. I have spent about two years tooling up for this build and now I’m making real parts.

I’ll start with the three middle fingers bones. These are similar enough to be machines together and should save some time on tool changes and holding.

I started by rough cutting three bars of 3/4 6061 Aluminum on the bandsaw then truing them up on the mill with a carbide facemill.IMG_0008

One side of each of these phalanges gets milled down a bit. This makes it a bit of a chore to hold in a chuck because they are more difficult to center….so i use a four-jaw independent chuck.

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I don’t have a lathe so I planned to mount my rotary table as a fourth axis and (slowly) mill out the center of the stock to create the “bar-bell” shape of the phalanges. I wrote a custom tool for my MillDroid code that makes setup simple and mills each one in about 40 minutes. A Lathe would undoubtedly be faster, but I don’t think i would want to subject a small mill to the interrupted cutting of taking a square piece of stock down to a cylinder….that’s a lot of abuse to the hardware.

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The pieces moves past the 1/2″ end mill left and right, rotating the A axis every pass by several degrees.

 

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Three barbells later! Good finish on the cylindrical parts is achieved with a quick pass of wet sandpaper grades 360-500-1000-1500-2000 in increasing order before I remove them from the rotary table chuck.

I wrote a Slotting custom tool for MillDroid to cut the slots that run through the core of the cylinder in the barbells.

Holding these odd-shaped parts securely for the next cutting operation required a bit of R&D. I built a jig for my tooling plate to keep the parts centered between two aluminum plates then clamped them down with an aluminum bar. The offset side it lifter with a metal shim to keep the whole thing square.

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Now I could use a carbide flycutter to cut away the ends into the required L-shapes.

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4: Terminator T800 Hand - Metal Build