Drilling the oilway


Now everything has cooled down, Bob finished drilling the oilway in the timing shaft. The shaft itself was drilled through in the lathe when it was built, as was the flywheel on the Mill.

With the two now pressed together it’s simply a case of drilling through the pilot hole in the flywheel into the shaft, to pick up the hole along the axis. That completed and checked out with an airline, it’s finished!

Now we just have to complete the assembly and press in the crankpin.

Timing side


The timing side also went in well, though we ended up not bottoming down to the shoulder by about 5 thou. Not a problem in any way except for puzzling as to why. We did try pressing fully home later when things had cooled down, but at 12.5 tonnes it didn’t shift.

I don’t think I’ll need to weld the shafts, they are very tight! Pressing the crank pin in for the final assembly is going to be a bit of a challenge. Thinking caps are on!

It’s in!


A good start to the day with the drive side shaft pressed in. The oven performed well with the shelf just about taking the weight. Out with the hot wheel and frozen shaft for a one shot action on the press.

Bob was there with his square, giving the final nudge before pressing away. The shaft went in without any trouble, you can just see the last bit of frost melting away as the heat transfers from the wheel.

When it cooled down we checked around with a set of V blocks and it seems to have gone in straight. Just a case now of repeating for the timing side.

Am or have?


There’s a huge difference between the following two sentences:

I am a welder.
I have a welder.

More than just a word, sooo much more! Considering I’m very new to this, I don’t think I’ve disgraced myself. Certainly I feel confident in tackling the job.

Let’s see how the pressing goes tomorrow….

Practice welding


Tomorrow we’re going to press in the driveshaft and crankshaft to the flywheels. It’s a tense moment as we’ll need to get them parallel and work quickly.

The shafts are in the freezer next to the peas, down to -16°C. The flywheels will go in the oven up to 230°C, taking the 5 thou’ heavy interference fit down to around 1. 9 tonnes of force to press the shafts in down to 600kg. (Well fingers crossed!).

Assuming they go in ok, the plan is to run a short weld around in three places. This is a belt and brace approach but at least the shafts will be in for good! In preparation I’ve bored some scrap steel and bar, so I can have a practice weld in them. Here goes…..



Well that’s that, one conrod all finished. The ally polished up nicely and both the bearing & bush pressed in no bother. As they say in Australia – "it’s like a bought one". 😁

Except that no-one made them ever so there are none to buy. A long way off I know, but right at the heart of my custom bike will be this custom part.

Now to clean down all the machines and sweep the floor before contemplating the next move. I always find that a rewarding end to a job well done. Neat and tidy, spik and span, Gin and Tonic 😉

All done


Apart from the final finishing by hand and a polish, all the work on the conrod is done. The bore sizes I’m happy with so the bearing and bush are in the freezer. When I’ve completed the hand finishing I’ll pop it in the over and push in the bearings.

What a great result for 2 weeks of holiday during lockdown!

One down, one to go


The big end came up well in the end. I had some initial problems with the increased thickness of the rod compared to the test piece. The boring bar wasn’t long enough to do a full pass, so I had to step bore until I could change to a larger tool.

The bore gauge Bob picked up from a local antique shop works really well, so I know that the big end is to size for pressing in the bearing. (Fingers crossed).

Onto the little end, rinse and repeat!

Superfly guy


A few passes with the fly cutter to come down to width. The CNC really comes into it’s own hrre. I wrote some basic GCODE to run the cutter across the job with a slow feed. The cutter is slightly narrower than the area to be cut, so it needs to move and make another pass.

So, basic GCODE does a slow pass on the Y, then a rapid move away and across on the X. Another slow pass back on the Y, finishing with a rapid move back to the start. I’m not 100% on my calibration with the Z axis, so I put the cut on manual by raising the knee.

Like hybrid – which saves me time and is easy to use. And the bonus is that unlike a conventional power feed, I don’t have to watch it like a hawk as it moves to a safe place and stops. 🙂

At some point I’ll sort out controlling the spindle motor. A job for Ron!