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<\/a><\/p>\nLook! It’s a bitch chuck!<\/p>\n
Also known as a 4-jaw <\/em>chuck, but I call it the Bitch Chuck since it’s a total bitch to use. It was determined that we could afford to spend some club money on replacing sketchy equipment, so I hopped on eBay and lassoed in some new 6 inch chucks, in 3 and 4 jaw form.<\/p>\n In testing and installing the new chucks, I discovered that the machine does indeed have a collet mode<\/a>. My next step in shopbuilding is to get a wider variety of 5C collets.<\/p>\n The cool thing about Bitch Chucks is the ability to use the 4 jaws as the axes of your own coordinate system. This means you can, with enough jiggling of a dial indicator, center just about anything. It’s most often used for machining round features in substantially non-round objects.<\/p>\n Such as my leadscrew actuator anchors, above.<\/p>\n Bored out pieces. These were waterjet-cut first, which leaves a rather raggedy bore, necessitating secondary operations.<\/p>\n More actuator parts. The piece on the left was also waterjetted, then secondarily operated upon. The part on the right was milled from a block of aluminum.<\/p>\n These two pieces bolt together and trap an Acme-threaded nut between them. When the nut is spun, the whole assembly travels up and down a leadscrew.<\/p>\n Pretend-o-actuator. A 28mm Banebots gearmotor (I’M SORRY IT WAS THE ONLY THING THAT WOULD FIT THE DESIGN) drives the leadscrew nut through a 1.5:1 additional reduction.<\/p>\n Fr0k main shaft, made of hard-anodized 6061 rod. The flat is for the fr0k hub to grip onto using a line of Giant Set Screws. It is otherwise smooth for the clutch connection with the fr0k gear.<\/p>\n BEARINGS!<\/p>\n All the important bits (gearbox outputs) on \u00dcberclocker will be ball-bearing supported. Ball bearings, especially small and metric ones, are not cheap. That said, I got these from VXB<\/a>, which…hey, sells cheap, small, metric bearings.<\/p>\n They are of dubious origin, devoid of manufacturer labels. But everyone knows that renowned ball bearing manufacturers have cool<\/a> 3-letter<\/a> company<\/a> names<\/a>, so they must be totally legit, right?<\/p>\n When I need a thick section of material to fasten a larger T-nut, but the rest of the part is thinner plate, it’s handy to use a screwed-in thickness buffer. Here are two quarter inch plates combined to make a single half-inch fastening location.<\/p>\n Mockup of the fr0kshaft. The three aluminum donuts with Giant Set Screws are the fr0k shaft hubs. A long shoulder bolt passes through a two-hole pattern in the side (barely visible). The left fr0k tine is a clearance, the right one a tapped hole. The entire assembly binds together, then is Giant Set Screwed down.<\/p>\n Alright, back to the upper fr0k actuator. The motor pinion bore is 5\/16″ and the motor shaft is 6mm. That’s a space too wide for even the thickest Loctites to bridge.<\/p>\n So a spacer is warranted. Here, I turned down a random steel rod to press fit into the gear’s stock bore. Then I pushed the gear onto the future spacer by locking down the tailstock and using the quill to apply a force to the gear.<\/p>\n Yeah, that’s right, I used a metal lathe as an arbor press. I hope the shop instructors aren’t reading this.<\/p>\n Drilled, tapped, and mounted. Conveniently enough, the Banebots motor has a keyway in the shaft which seats a #6 set screw very well.<\/p>\n Here’s the fr0k base in mockup configuration. Eventually, the Integrated Dual Frakenb0xen will go in the middle, secured by the four mounting holes.<\/p>\n Secondary operations on the fr0k base parts. I center-found one hole, then referenced the rest from there. This is to avoid Waterjet Weirdness creeping too much into the parts. If I had centered and bored each hole individually, they would be in 3 different incorrect places. At least with the former method, they may all be off by a hair, but it’ll be in the same direction, so things still go together.<\/p>\n These ring bearings will support the hubs of the Frakenb0xen pinions.<\/p>\n Leadscrew anchor block. This was originally going to be a waterjetted-then-machined part, but I found the most conveniently placed block of 1″ x 1.5″ x .75″ aluminum ever, so I just fabbed it in a few minutes.<\/p>\n The radius was smoothed on the belt sander after I made 3 45-degree angle cuts to approximate it.<\/p>\n This anchor looks kind of like the previous one which failed miserably, but is actually much improved because the set screws reside in deep-cut flats on the leadscrew. I would have to shear the set screws, strip the leadscrew, or just plain rip the leadscrew anchor ears right out of the fr0k assembly.<\/p>\n i.e. It takes alot more force to fail, but will fail irrepairably and probably inopportunely.<\/p>\n Great.<\/p>\n Testing the actuator! The banebots motor is _fast_. Ridiculously fast. The arm hits physical travel limits within maybe one second. This is so fast that I think I should have picked a finer leadscrew or something.<\/p>\n Or it could arise from the fact that I’ m triple-overvolting the BB motor, meaning it will also not last very long. This is one candidate for a high voltage motor swap. Regardless, it will need a limit switch or sensing element of some sort, because in the heat of battle I’m probably going to just jam on the throttle stick with reckless abandon.<\/p>\n The upper fr0k in its lowest position can actually hit the ground below the bot. I’m not sure if this is a good or bad thing yet. Again, an argument for travel limiters.<\/p>\n The whole arrangement sort of reminds me of cantilever-style C-clamps<\/a>.<\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n