Pretend engineering

Before we proceed to make a decision about the best path forward for attaching wheels to axles here in North Vancouver, I have one more round of experiments to share. I still believe that a keyed wheel will be superior in holding onto the axle compared to any sort of a glue bond, but the […]

Percy and the bad drivers

The question of tolerance continues to interest me. With those loose connecting rods, how tolerant is Percy of misalignment of the wheels, or uneven crankpin eccentricity? It turns out, Percy is not only tolerant, he’s indifferent! I didn’t have a front axle with the original crankpins, P87 wheels and the gear printed on, and so […]

Percy and the crankpins

On disassembling Percy, the first surprise was how loose the connecting rods were on the crankpins. I’d read, and have probably reiterated, that the finest line is the one that separates running clearance from slop. I’d always imagined that where crankpins are concerned, it really mattered. I’ve now tried four different crankpin sizes in Percy’s […]

U-G-L-Y quartering tool

It could hardly have been less beautiful or elegant, but the Polymorph seems to have put me back in action. Indeed, it was so quick and effective, I’m hard-pressed to see why anyone would quarter drivers any other way! Having learned that the spokes would stick to the Polymorph, I masked off the front drivers. […]

622 gets connecting rods

I am not so naive as to believe that the connecting rods would drop effortlessly onto the crankpins. When I built #10, I bet I spent a month fussing over the wobbly bits, before finally declaring a truce and moving on. They were never perfect, but I felt they were probably good enough. After a […]

622 on her wheels

You might expect that at this point it would be a simple matter of dropping the drivers into the chassis, screwing the engine truck on and sending the whole assembly out for a test roll. Sadly, no. Somehow, the design for 622´s springs got changed, and a whole lot of extra metal got added. So, […]

Engine truck wheels

The engine truck, which I primed yesterday, went together more or less as planned this morning before I left for work. Unlike #10, which has tiny equalizing beams and floating bearings trapped in rigid sideframes, #622 allows the whole sideframes to rock. The bearings are simple holes in the sideframes, meaning the wheels are permanently […]

Removing the long axles

With the drivers quartered, the long axles have now served their purpose. I started cutting the first one with a jeweller’s saw. An hour and two blades later, I decided to switch to a cut-off disk and the Dremel tool. I took it slow to avoid melting the spokes or (worse) the axle-wheel joint, and […]

Drivers quartered

There is a saying in the Maker community: if you can’t make it perfect, make it adjustable. The corollary is surely that if you can’t make it adjustable, make it perfect. These drivers are a one-shot deal. Either I get the quartering perfect, or I’m soaking them in acetone to loosen the epoxy, which will […]

Crankpins installed

I decided to use the quartering jig to hold onto the crankpins while the epoxy holding them in place cured. The theory was that regardless of where the actual holes in the wheels wound up, the vital metric was the distance between wheel centre and the crankpin itself. So, I gave the quartering jig bosses […]