Land-Bear-Shark Episode 4: Now that There’s No Snow on the Ground…

chorl

Poor Melontank.

Another victim of my “randomly open another bracket” style of ADHD-engineering, LBS has been sitting in a pile for a few weeks now thanks to me becoming acutely interested in failboats. With Make-A-Bot finally down for the count after baking its extruder controller, I now have the chance to pry myself away from staring at it and revisit LBS. Part of the reason for the slowdown is the lack of motivation due to the nearing end of winter. The past few days of warm weather has pretty much melted all the accumulated snow away, and what’s left is just hard solid frozen chunks of ice – not very fun. But, LBS can work on (ideally) any terrain, so I’m going to finish it off because I’ve committed too much funds to just ditch the project and repurpose the parts.

As I came to discover, I missed cutting a few parts during the last major waterjet run. Additionally, some of my hardware has gotten lost in the recent rerganization at MITERS, so that’s now going to lead to more delays as I either find it or give up and order more.

Here’s the pile of LBS, which was formerly under the workbench that is now halfway across the room. There’s been alot of reshuffling lately, to put it lightly.

I laid out all the flat parts that will form the new track side plates only to discover that I was missing four of those round 7-holed biscuit plates (for lack of a more descriptive scientific term). It turns out I may have only cut enough for one track module, judging from reviewing my tool files for the machine. Oops.

First order of business was assembling the “biscuit plates” onto the side plates, which involved tapping something like 56 holes.

What? Actually tapping a thread again? That’s definitely something I haven’t done in a while. But old is new, and spiral point taps in a cordless drill  make for easy beast-threading of 1/4″ aluminum. Add in the fragrance of aluminum Tap Magic (that Shane and Amy don’t like because they’re crazy) and this process went rather quickly.

Next, I decided to knock out the four large standoff-axles that bridge the side plates. I have no clue why I chose to go with 5/8″ steel for this. It’s so ridiculously oversized, and hard-anodized aluminum would have done just fine as a bearing surface for the large nylon track sprockets. Even worse, I’m not sure why I went with the case hardened shafts. I think it’s just because they were the cheapest on McMaster for whatever reason.

Either way, a normal drill bit wouldn’t touch this stuff until I broke through the casehard layer with a carbide endmill shoved into the tailstock.

The Old Mercedes looked great in the winter afternoon sunlight today, so I took the opportunity to snap a picture. The 1956 South Bend 10L has been with the club for almost 2 decades. Even though the tailstock is now a good .01″ out of level, all the headstock bearing shims have been bottomed out, and the cross slide has 2/3 of a turn of backlash, it stills hauls and kicks ass (for work close to the chuck – it also turns a natural .01″ per foot taper because of the almost .005″ of bed wear at the front). #dontmakethemliketheyuseto

A while back, I scrounged some interesting looking springs from a pile of crufted hardware. Turns out they were a great fit over the cheap mountain bike shocks I picked up for the bogie suspension. I actually think they might be too soft – since I can actually manage to compress them slightly with my hand – but I think they’re better than the 750 pound per inch “springs” that came with the stock units. For 750lb/in, I might as well just bolt the tracks to the body with rubber blocks. All four shocks were “re-sprung”.

Alright,  that’s pretty much all I can do for now. Both motors have been rewound, but haven’t been terminated yet. I also need to locate some 4.5″ long bolts to reassemble the drive sprocket with, and get the supplemental biscuit plates cut. It’s even more disorganized than last time!

micro-chuckranoplan: I’m Getting Closer.

chorl3 Comments

Ever closer. I think the design of μ-Chuckranoplan 0002 is sound; of course, I say this with absolutely no qualifications or numbers to back it up. It’s visually engineered, as I now like to call it.

It will fly, but it’s still obese. Maybe if I pump it with helium…

Here’s the head of a Chuckranoplan after being stuffed with electronics. I elected to temporarily hot glue the two micro ducted fans onto a single carbon fiber stick pylon. The 3 cell lithium polymer battery ended up wedging very snugly into the nose cavity. The receiver and two controllers form the entrails that get shoved into the main body.

And here it is, all aseembled. The tail struts are all carbon fiber rods… well, except for one of them. Turns out that one was aluminum.  Whoops.

The wire access holes in the sides were dynamically generated (read: shoving a hot soldering tip through the wall).

The final weight of everything? 14 ounces as measured by a chintzy digital hook scale. I’ve successfully built a decent brushless-powered antweight. Maybe I should have entered it into the Motorama Robot Conflict competition or something.


Yup, still looks like some kind of stoned manta ray with a birth defect.

Here’s a front view, while it’s charging. Note the tiny 2-56 screws holding the head on…

So how did it perform? Better than attempt #1 for sure, but still a ways to ago, almost all on the weight reduction side. The “flight” was sort of a very strained and awkward hover, and it actually couldn’t budge itself from a standstill. However, with full throttle on the fans and a push, the model did flare down the hallway. At least, until it ran into the side of the wall from unbalanced reaction torques from the fans. They should really be spinning in opposite directions.

I’m definitely approaching the problem like a mechanical engineer, and the laws of flight don’t really scale down to things this small (something about area vs. volume or some gibberish). Overall, it’s too well-built.

The double-walled PLA prints, while “light” in the hand, all add up when the pieces are put together. I’ve been trying to single-wall some test pieces to not much success, as the PLA just sort of sags and falls over. Before I managed to successfully execute a single-wall ABS print, I accidentally half-baked the extruder controller on MaB, so that needs to be repaired first (The test piece’s first few layers looked good, however). I’ll  give single-wall printing a fair shot before manning up and just learning how to do it The Real Way with covered frame members, or hot-wired foam. The project has caught the attention of some Course XVI majors I know, who know how to do it The Real Way and may be able to get me some time on a CNC hot wire machine.