Trevithick Dredger.. attaching the flywheel and driving gear to the mainshaft.
The flywheel and driving gear both are attached to cranks which join the connecting rods to the mainshaft. It is important that both cranks are attached with the same angularity. Seems simple. The cranks are identical. But small taper holes, through brass and silver steel.
Drilling the 2 holes took most of the day.
Figuring the setup was the biggest challenge.
First problem was that the 2.5mm drill bits were not long enough for the chuck to clear the gear. I did not have adequately small ER collets (would have required ER8’s), but I did have a Dremel chuck which was small enough. But no spindle for the Dremel chuck. The Dremel chuck has a really odd thread. I measured it at 40tpi, and 7.05mm diameter.
So I made a spindle. Thank goodness for CNC threading.
Dremel chucks are convenient, but they are not very accurate. Fortunately, once the hole was centred, the drill bits and reamer seemed to follow the centred start. Here I am about to ream the hole which has 3 steps 2.5mm, 2,8mm, and 3mm. The shop made spindle is held in the milling machine drilling chuck.
I took the reaming very gently, not wanting any broken bits of high speed steel stuck in the workpiece…. and all was well.
So I sat back and enjoyed one of my Xmas presents. Ah! Bliss!