I tried to finish the wheelmotor side plates at the Almighty Dale’s yesterday. Keyword is tried – I thought I would be able to get both done in about three hours. The details don’t matter much, but in the end, I barely got one carved out and that one might need redoing.

The side plates have a little taper on the outer edges to mate with the tapered inner rim of the scooter wheel. It’s a tire bead, if you may call it that. The problem is, it’s a somewhat odd angle (about 40 degrees). So the toolpost on the lathe had to be readjusted to cut it.

Well, after cutting the taper, something was either missed on the realignment or something wasn’t tightened down enough, but the cutoff tool ended up cutting at an angle. That’s weird, it went in straight enough!

Either way, the side plate is slightly concave. The ring structure also indicates “oops, something got loose”.

There’s a 55% chance I might scrap this part too. The 45% “don’t scrap” comes from the fact that most of the dimensions are extremely close to the design – by about .002 or so.

It sucks that I might have to redo something that got this close. Next time, there will be a change of strategy regarding the final cutoff – I’ll probably part it a bit long, turn it around, face cut to the proper length, then cut the taper. Even if I have to do it with a file to not disturb the alignment of everything else!

Lesson? Don’t trust the machine to be perfectly aligned even if it looks like it. It’s a fallacy of luxury that something which looks and runs better requires less brainwork to operate.

Same can be said for soccer moms in plushy SUVs. Oh well.

In TB4.5MCESP1 news, more stuff came.

Drive motors! Since I was going to be running an elevated voltage this time around, I went looking for some slower motors. There are plenty of moderately hot-wound 550 motors on the surplus channels, but not as many with a K_v of around 1000 to 1500 – that is, 12000 to 18000 RPM at 12 volts. That was the “sweet spot” for TB this time around. Fortunately, AllElectronics came to the rescue with some surplus Power Wheels motors. You can never go wrong with Power Wheels motors.

What’s more fun, though? NEW CHARGER! Up until now I haven’t ever had a “real” charger – one that actually follows battery chemistry charging curves and wasn’t a dumb wall wart. The move to Lipolies sort of necessitates my upgrade, since you can’t plug a Li battery into a wall without some fun explosions.

The “good charger” did not get struck off the list, since I can use it for so much more than just TB. This should cover most of my electrochemical needs – 27 Ni cells, 8 Li of various subtypes, and even lead-acid.

The battery in question. This should fit snugly between the Ebay plates of TB. Some additional standoffs make sure it doesn’t fly around inside the bot. TB should never need the full 25C of this pack – if it is drawing 80 amps for any reason, something has gone terribly wrong.

I intend to make an “integrated charge connector” which combines the balancing port with the main battery lines. This way I don’t have to have 2 cables coming out of the bot.

What I particularly love about United Hobbies / Hobbycity is that they make absolutely no attempt to hide the fact that yes, everything on the site is Chinese in some way. This includes full broken English manuals, which I find quite funny. Often, they express things in such a manner that you get what is being conveyed, but wouldn’t ever find it in a real English manual.

I mean, come on, what charger besides the most kickass and awesome has a WASTE TIME function?!

Anyways, it’s currently working on the 4-cell Lipoly and I have the new cutting fence set up on the miter saw, so I should get some chassis work done before I have to fly back to the Northern Wastelands.

Oh, and Jesus welcomes you.

I remember two weeks ago when I said that I would build nonstop through the break; anything I could think of, and come up with more things if I ran out. Anyways, that totally went to hell. But progress is slowly coming.

I’m in the process of completely redoing the Snuffles Reloaded wheelmotor. The previous one was okay for getting the concept to materialize into something solid, but was done across 3 different machines and with little regard (or ability) to center the workpiece properly.

There are also some design changes this time around. Most notably, I’m redoing the magnet can out of steel to better fit the very strong magnets that will be used, as well as to simplify things.

The finished product. This was the single most torturous piece I have done yet. Steel of this diameter needs to be turned reeeeeeeally slowly. I mean like 70RPM slowly. It was very hard for me to keep my feedrate down (because I’m used to small aluminum parts), and if I went too fast, I would just be cutting shallow screw threads.

Not to mention that it was a hot-roll steel pipe that I carved this out of, so the steel was total shit and was gummy. The surface finish is horrible, but it’ll live. The perimeter holes were put in on a CNC machine (most awesome thing evar, only matched in awesomenss by a 5-axis abrasivejet. The two combined can carve the laws of physics and grammar such that they can both be most awesome.)

I’ll do the aluminum parts later. I might possibly redesign some of the internals to make the parts less weird.

In TB4.5MCESP1-related news, the arm controller came.

Ooh, shiny. This is a Syren25 single-channel controller from Dimension Engineering. It’s a nice piece of work, and supposedly features regenerative braking. That’s hardcore. So having opponent bots backdrive TB4.5’s lifter could actually be a good thing, but they should do it slowly and gently!

Since I was going to remount the ESC on my own heatsink plate anyway, I decided to take a look at the underside where the driver chips are.

O GOD WAT

NO! NO NO NO NO…. For the love of Robot Jesus Michael Fizgerald Jackson Christ! SO-8 surface mount FETS?!

I am SO GLAD I’m mounting this thing on a plate of aluminum that weighs more than it does.

I hate those tiny SMT FETs. Especially when the manufacturer (generally of brushless controllers) use like 20 in parallel to get a decent amp rating. What money and weight do you save then?

It’s even worse when you listen to the chip maker who says a 25A part is a 25A part. The SMT has absolutely no thermal mass and no capacity to withstand momentary overload. In fighting bots, you NEED THE OVERHEAD. I’m sorry, I will NOT run 25 amps through this thing for any extended length of time, and am very glad the arm is an intermittent duty cycle.

I’m making my own ESCs from now on, or I’m never building another robot of any kind.

Oh, and the heat spreader plate doesn’t contact the driver chips. That’s even less of a 25A ESC. DE might want to consider backing off the pressure a bit on whatever press that is stamping the aluminum sheet.

Anyways, time to actually start building the bot. The carbide teeth on the miter saw’s new blade are slowly subliming, so it’s best to use them while they’re still fresh.