The Summer of Ven: Operation Exhaustive Measures

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Time for another throwback to the “Post of Everything“! As you might recall, Mikuvan had a little boo-boo on one of my mountain romps:

The entire exhaust path from the axle-clearing bend back fell off in late May when I was on the Tail of the Dragon. Yes, fell off. As in the person behind me had to dodge it.

I last redid the exhaust on this very site back in 2017, but I guess just a few years of winter road salt will do that to you. I had to zip that exhaust together with clamps in the parking lot in a day, so it was never really that well put together anyhow. To do it again, I challenged myself to make a fully welded path with a proper way to disconnect it at the downpipe if I were to have to change it again, how they say…. down the road.

Remember, despite what this site may seem to recently indicate, I am fundamentally not a “car guy”. I had to do some research on what technologies existed out there for connecting exhaust pipes besides impact-gunning a U-bolt clamp down. I settled on using V-band clamps, as they seemed both statically determinate once attached and relatively easy to work with, versus say flaring the tubes or welding on independent flanges.

I began collecting a few parts online such as the 2.25″ V-band flanges and bands. I got the piping itself just from auto parts stores for now – just regular ol’ “aluminized steel”. I’m sure this will last just as long.

In doing the same research, I got some 309 alloy welding wire to make the join between the stainless steel V-band flanges and the mystery ferrous exhaust pipe. I otherwise had plenty of regular ER70 wire.

So one night I decided to go ahead and drop the rest of the exhaust out and start measuring things up. Due to my brute force surgery on the downpipe flange to replace the mismatched nuts with big 17mm-headed M10 bolts, I was actually able to pull it off easily.

I can’t say the same at all for the rest of it. Natural Bostonian Loctite made getting everything else off an exercise in a lot of hammering and impact driving. I mean, not like I was trying to keep this or anything, but even separating that downpipe connection was a ton of effort.

The first adaptation step was turning the roughly 1-7/8 sized (or 50mm, perhaps) downpipe into the 2.25 diameter needed for the V-flange. I simply flared a 1.75″ to 2.25″ adapter slightly and slit the downpipe to shrink down its OD slightly.

I fixtured and tack welded the other end with V-band flanges to get an idea of how it’ll go together.

I then smashed the downpipe adapter onto the downpipe using my previous “flare” and “compression” fit and a hammer. The fit was tight enough that I went ahead and installed it back on the exhaust manifold, and adjusted the angle of the adapter tube to point as straight backwards as I could visually line it up. That means the flange is as straight as possible to alleviate any other bending. I then tack-welded it in place.

Step 1 completed! I fully welded the downpipe to the adapter after making sure the fit was good. This one was a little blobby because I had to be careful not to pierce through the old, thinned downpipe steel. I kept the voltage low and made two passes, and also had to close up the slits I made to let the downpipe compress into the adapter.

Next order of business was to measure the old axle hump dimensions and replicate them in the new piping.

Notice one little detail here? The 45 degree “turndown” at the end of the new setup isn’t actually a turndown tip, it’s just another piece of 45 degree bend. I was just going to cut it off to make my own turndown, as at the time, Pep Boys was out of 2.25″ turndowns.

On the new tubing it was much easier to make a clean weld all the way around. In fact, I think I found 120-volt Limewelder’s calling: lightweight tube fabrication. I mean, it’s all you can really use a 120V welder for anyhow.

The workpiece was getting long enough now that I was having to come up with more and more creative ways to fixture it.

I worked from both ends for this operation. First, I dummy-fit the downpipe, the V-band connection, and the flex pipe. Then I independently hung the main exhaust path where I wanted it, so I could take a measurement of how much gap there is between them.

A little more Creative Fixturing later and I now have the entire “downpipe-back” exhaust path completed.

And here it is! Not a single U-bolt clamp. I dunno, I think my next step might be to learn how to bend straight tubes well. I’ve seen people do intricate “pie cut” bends, but that’s several pay grades above how hard I am willing to neckbeard for something like this.

And now installed in place with the band tightened. I’m a fan of this setup, as I could conceivably (dunno why I would, but…) swap this out at any time for something else. It’s hung in the center with the flexible hanger seen in an earlier photo, and then attached at the very back by the trailer hitch like last time:

Admittedly, my custom “turndown” is a little too turnt down,and I was afraid of stubbing it accidentally on a curb or parking brick, so I trimmed it up further not long after this install.

My thoughts? I’m not planning on becoming an exhaust bending master, but I now know the capabilities of my shop. Vantruck is likely next on the list for exhaust work, as it’s had the same exposure to salt up north and I’m itching to add some stacks to the thing some day.

The Restoration of Overhaul 1: With Liberty and Shuffles for All

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Last episode of this “Overhaul” “Build” “Report”, I straightened the frame from its accumulated damage and began drawing up a plan to put new motors in. Now it’s time to execute! I had no particular goal or deadline with this project, mind you. It was something I made incremental progress on if I wasn’t doing anything else, and I already had basically all the parts in the garage already. One of those (few) nice things about building a 250lb Battlebot is that future robots are basically free for a long time due to your initial “investment”!

First order of business: get the spider couplings mounted on the motors. These scooter motors have an odd stepped shaft that usually holds a #25 sprocket. I had to make a similar stepped bore in the spider coupling halves in order to get them to seat correctly. The shoulder starts at 8mm and increases to 10mm, so I ordered 5/16″ bore couplings to start with (0.3125″ vs. 0.3145″, an easy knock-through).

The motors don’t have a good way of attaching anything to the motor shaft except with the roll pin which the original sprockets used, so I had to drill a matching hole in the spider coupling. This was “interesting” to say the least.

I mean, besides doing this on a mill having no digital readouts, the hubs were very mildly tapered to release them from their sintering molds. That means I had to first machine a flat into one side in order to register it with the vise at all. Next, I squared up the backside against the vise with a parallel, right up on the edge. This was going to be good enough to drill one hole.

In lieu of another roll pin, I went for a 1/8″ diameter solid dowel pin for extra strength. The shocks of each shuffler foot hitting the ground, I suspected, wasn’t going to play well with the hollow and split roll pins.

Some time around this point was when I decided to absolutely send it with available materials.

I decided instead of machining and welding an endcap onto the “motor rails”, I would take a page from the finest robot arm additive manufacturing research and just lay a massive circular weld bead inside the tube….

…upon which I cleaned the bore, drilled to size, and tapped it just like a regular ol’ metal piece.

Are the threads clean? Mostly. Do they go all the way around? Moooostly. Good enough for this job?

That’s what I’m after.

These… uhh, “weldments” met the motor mounting plates fresh off the printer as well.

The standoffs that bind the motors together? Left over 30haul and Uberlocker leadscrew stock I’ve had for years! I mean, these aren’t serious high grade steel or anything. I used these in the absence of having appropriately sized solid aluminum or steel stock.

The motor “cartridge” completed and assembled. It’s bound together with 5/16″-18 hex cap screws.

On the other end, the flanged Ampflow adapter with bearings in it is mounted as well.

Here’s the totality of the setup, both shuffle pods and the motor cartridge.

To install this was a little strange, as Overhaul 1 wasn’t actually designed to have something dropped in from the top. I wiggled the motor cartridge in first through the side, then lifted one side up at a time to slide the mounting rails in and add shaft collars.

At first, this assembly is left loose to slide side-to-side on purpose, since I’d need to get the horizontal alignment constrained by having the shuffle pods in place.

Funny enough, I kept the original drive chains we cut for for the shuffle pods – they were used on Sadbot when it had a geared 63-74 motor per side, and still fit today using the same sprocket!

And now we have fully assembled and motion-ready shuffle pods!

Mounting these things was fairly easy, as I’d already blown out the frame rails enough that they can slide sideways again. Drop in, mate the spider coupler, and attach the four bolts.

Soon enough, they were ready for an “initial break-in”.

I performed a bit of look-ahead work by repairing some of the motor wires and running them through spare loom. This will be handy once the new electronics assembly is installed on the four rubber wubbies seen in the bottom of the image.

Overhaul was missing a few of the very large shock mounts, or mega wubbies, that had secured the pontoons. I had to order some new ones, and then remembered that they had to be “chamfered” a little to clear weld beads on the inside of the pontoon cross beam.

With relatively minimal complaining, the straightened out pontoon weldment goes right on. I might cut the Pull-Tab off later.

From here on, I’ll take out and apart the lift and clamp actuators and work on an electronics solution. I’ll probably keep this thing on 6S (24V) or thereabouts – there is NO need for the shuffle mode to go breakneck speeds like we had it at BBS1.