Archive for November, 2007


Snuffles Reloaded: Update 4

Nov 30, 2007 in Project Build Reports, Project RazEr, Stuff

Over the past two weeks, I managed to loiter enough around the Media Lab to get some work done on the wheelmotor. All I can say is that it’s “getting there”… those weird things called “classes” get in the way of building things. Who the hell needs ‘em?!

The first step in shoving a motor inside a wheel is to carve the center out of the wheel. This proved to be challenging – polyurethane wheels are squishy and would be nearly impossible to mount on a lathe chuck the conventional way. The spokes also prevent grabbing anything inside the wheel.

Naturally, I come up with a clever, dangerous, and potentially expensive plan to get around it. The method of attaching the wheel on Snuffles 1 was pressing them onto a circle of pins in a large aluminum pulley.

Large aluminum pulley? Perfect! I popped the other wheel off on a press and mounted the new wheel. Then I ran some high speed steel into the plastic spokes at the diameter of the rim, stopping just short of breaking the rim off so I could snap the core out and avoid possibly getting the rim trapped in between big steel spinning things.

The stator mount designed for the motor is a dished-in piece of aluminum with stubs on it to seat the bearings. However, I decided that it would be much easier to make the dish separate, then press the shaft through. It would involve less wrangling and maneuvering of the tool bit and simplify the process.

The shaft was the first piece I actually made on the lathe (to precision – ripping the spokes out of a plastic wheel isn’t particularly clean). This is a CNC-only lathe that has meta-handles to let you jog the axes. Maximum resolution is .0001 on fine stepping, which was really awesome.

Unfortunately, I can no longer bump the tool into the material to set a zero, because… well, the handles aren’t force-feedback. I had to eyeball tool contact, but could otherwise hold any dimension I wanted down to .0001 +/- the deformation of tool and piece. It turned out well enough for pure eyeballing of the reference zero – .590 was actually .587, but Loctite fills spaces.

After a night’s work, the pieces. I was halfway done with machining the dish part when I realized that I had probably outstayed my welcome – it was almost midnight!

Notice the ring inset into the wheel. This is the “can” part of the motor which will support the magnets.

In order to not have to deal with aligning the finished motor parts on a vise to drill out all 16 perimeter holes 3 separate times, thick aluminum round pieces that have the holes already piloted were cut on a waterjet. That way I could trim them to taste on the lathe. All dimensions on the ring were made .125″ oversize. The two thick blocks under the wheel will eventually become the side plates/bearing mounts, and will be chrome plated for pimpness.


Here’s one result of misjudging zeros by a bit. I thought I had lined up with the inner part of the dish, but actually ran the unforgiving Z-axis slightly into the material . Hence zero was a few hundredths off. Nothing life-threatening, but I had to stop and re-eyeball it again. This small part would be better done on a smaller manual machine since it requires smaller tools and more improper machining techniques than the CNC allows.

Fuck Yeah, Seaki…… not.

Nov 28, 2007 in Stuff

Hey, look what’s on Gizmodo!

Soon, my project will be hacking a wheel-sized brushless motor into it.

I thought they did the press release earlier, but I guess not. Here is the other link from the site.

“a group of MIT’s Undergraduate Research Opportunities Program students.”

Guess who’s in that group? WHEE!

Staring into the sun for fun and profit!

Nov 26, 2007 in MIT, Bostoncaster, Cambridgeshire, Stuff

Just to make my view out of the 5th floor window over a construction site even better, the sun has decided to reflect its winter low-angle self off all the upper floor windows and glass-faced buildings in the area.


So as much as I enjoy the bright afternoon sunlight flooding the room, I’m forced to pull down the blinds as a dozen or more specular reflections hit me in the face starting around 3PM and lasting until sunset.

On the other hand, the moon has become sausage-shaped.

Fighting evil by moonlight....

So I didn’t use a tripod when taking this. The buildings managed to smear in a believable way, so the moon just looks crazy. I probably could have achieved much the same effect by holding the shutter open for an hour while keeping the camera still.

Merry wtfkthxgiving and a Snuffles Reloaded update!

Nov 22, 2007 in Project Build Reports, Project RazEr, Stuff

Mecha-Turkey says hello.

I need to modify one of those 'Easy' buttons to instead announce 'HEAD SHOT'

I’m taking a target shooting class (Yes, Charles with guns. Run away quickly.) , and this was just something fun done before the wtfkthxgiving holidays. Unfortunately, I missed the head shot, but hit the H in “shot” dead on. This was under a half inch tall from 50 feet away and I’m not particularly steady. Mecha-turkey would have mowed me down with its minigun and rocket launcher.

In somewhat related news, I’m going to take the opportunity of missing the opportunity to fly back to Atlanta and get some work done on the wheelmotor. These stupid “class” things really get in the way of building cool stuff. As I had some spare time but no materials for most of the past few weeks, I did some more design work to optimize and simplify some things.

16 gauge wire sculptures, anyone? A box of McMaster stuff. Some of the Media Lab guys are starting to take note of the work I’m doing, and so have extended some lifelines, so to speak. The 3.5″ aluminum round is for the motor body parts. The wheel will be supported by the 15mm bearings.

I just now realized how ungodly huge 16 gauge magnet wire really is. Not that it won’t work – there’s plenty of margin around the stator – but I’m going to have no hands left after winding 30 stator poles using it. I’m not sure how this guy does it with monster wire like this, but… good freakin’ robot Jesus. The ML has miles of 20 gauge I might just end up paralleling to wind the first motor. It’s a semi-prototype anyway, and those few efficiency points I might lose because of wire choice – oh well.

No, sorry, no multilink setup here.

Something else I fiddled around with was the idea of adding rear suspension to the A3. As much as the front suspensions on the scooters try to absorb the impacts of sidewalks and bumps, the rear is stiff and unforgiving. It didn’t help that all my electronics were located right on the rear wheel centerline before, and so every bump in the street was a major shock.

If all of this actually works, I'm going to be all giddy and Japanese schoolgirl-like.

This little module will slide and mount inside the aluminum T-tube that forms the chassis of the A3. I particularly like the design of the A3, because you can mount and number of things just by sliding them onto the channel and locking with screws from the side. I’ll have to trim the metal around the back wheel a bit, but that’s no issue.

By examination, the “shock towers” sort of interfere with operation of the rear fender brake, but I’ll actually have to build it to see those tolerances.

The sliding block will be brass, bronze, or some other metal better at being a bearing than aluminum, which tends to gall and gunk everything up. It will replace the entire axle spacer assembly.

Springs will be some small die springs from McMaster, rated to 250 pounds per inch of throw. I’ll only have about half an inch of travel because of the springs’ solid length, but that’s enough. At a total of 500 pounds per inch of travel for two springs in parallel, it should not be too floppy. 500 sounds like alot, but you can easily exert that much force by jumping, and a good bump will certainly exceed that instantaneously.

So it looks like if I’m building anything, I’m building the whole thing. The ML guys are interested in seeing the motor itself first, though, so that’s number one on the priority list. I’m also using the same “slide-in module” design for the electronics bay and battery pack. It’s quite handy.

Bot on!

Super-Duper-Ultra-X-Y-Z-K-W-ξ-Wing-Combo Boat-Robot Hyper Force Team GO!

Nov 15, 2007 in Stuff

In another installment of “WANT NOW”, here’s a concept über-boat from some folks in Turkey.

Volitan Concept Boat Uses Wind Power and Solar Energy

Ecotard philosophies aside, I’d get one (that is, if I had the option and ability to)  just on its sharp looks and the number of illegal hacks that can be performed. Of course, the ultimate hack would be to brace up the wind structure such that it can actually fly, or at least hydroplane. The solar panels are a great touch for cruising around in the open ocean.

There’s not enough details for me to figure out where to stick the giant outrunner(s), though.

More photos from the affiliated website! Where can I get some giant 1920px renderings of this sucker?