Main shaft

With more parts to make, there are more tools to make 🙂

In making the main shaft, which mounts the flywheel and the exhaust valve, I needed to cut 3 flats 120 apart. From my stash of metals I dug out some hex and bored, then reamed for 10mm. A set screw finished that tool off. While cutting the 2.5mm slot in the end I broke the cutter.


So up comes tool #2 of the day, a slitting saw arbor. I used the example by Stefan Gotteswinter, his YouTube video was great learning for me. This is the first real test of my accuracy skills on the (new to me) KC1022ML lathe. Having some .75″ stainless rod and an ER32 collet chuck made working easy. The fit of the 13mm hole and spindle is enough to get some air push back on assembly. The saw blade exhibits no noticeable run-out so very pleased.


In order to drill the 2 holes for pin wrench I made a mount for my Grobet hand piece. I mounted the Al plate to the side of a QCTP tool holder, with mounting holes suitable for axial and longitudinal placement. 3 10-32 SHCS hold it in place. Those QCTP holders are tough metal, I drilled the holes slightly oversize to avoid breaking a tap. The pin wrench itself is the offcut of my tailstock drill mandrel. Recycle, Repurpose, Reuse 🙂


The shaft was finally end slotted using the slitting saw. As part of recovering from the gash created during the cutter breaking, the slot is now 3.5 mm but the exhaust valve can easily adapt to this ‘modification’.


It is really satisfying to see/feel the first rotating part on the engine.


Comments are closed.