Progress on the clock is slow but steady. Last time I mentioned that I had posted a question to the NAWCC discussion forum regarding the repair/replace question for the going-train great wheel. There have been an amazing 63 replies, with opinions ranging from “repair-and-conserve-at-any-cost” to “definitely-replace-on-safety-grounds.” You can read the discussion here:

http://mb.nawcc.org/showthread.php?99050-Advice-please-on-long-case-great-wheel-repair

My view has not changed, I am going to make a new wheel, largely on safety grounds, but hope to attempt a repair on the old one later. So last week the new wheel blank was blued, marked out, mounted on an arbor, turned to size, and then mounted on the wheel cutting engine to have the 96 teeth cut.

Calculations suggested a cutter of 0.85M for a wheel of this size (84mm diameter) and 96 teeth, but the slightly smaller 0.80M was a better fit between the teeth of the old wheel – 0.85M was a tight fit and I was concerned that the teeth may be cut too thin.

The wheel with all 96 teeth cut. It took 1 hr 20 mins to carefully cut all the teeth with slow hand feed. I will bore and broach the barrel arbor hole next before cutting the crossings.

I have been a little concerned about the condition of the great wheel on the going train barrel. This wheel had broken at some time in the past and had been soft-soldered together. As I was bushing the central arbor hole it became obvious that the wheel was not flat, nor was it truly circular.

This wheel is subject to great stress as it carries the weight hanging from its barrel. I consulted with my colleagues at EFHC and I also posted a query to the NAWCC discussion forum regarding the best way to repair this wheel. The almost unanimous view was that it would be too risky to try a repair, and for safety’s sake a new wheel  should be cut. I’ve now cut a wheel blank from 1/8 in CZ120 brass and I’ll shortly be marking out the wheel and cutting the teeth. I will make the spokes a little wider for strength, and I will also add a thicker portion where the click will be attached.