Making A Crankshaft -1
In a previous post I explained how I replaced a broken roll pin in a fabricated traction engine crankshaft. The repaired crankshaft worked well enough for the renewal of the boiler certification, but I suspect that one of more of the other roll pins is also damaged.
… there is still a flywheel wobble of about 1mm at the rim. 1mm does not sound much, but it looks horrible. So I have decided to make a new crankshaft. Using a single piece of steel.
For the third time in a couple of weeks I removed the crankshaft from the engine. The first time took me more than 4 hours. Second time was quicker. Today it took me only 93 minutes, including the time wasted looking for small open enders.
And meanwhile I bought a chunk of steel big enough to carve into a replacement crankshaft….
The crank-shaft has two cranks, at 90 degrees from each other. The shaft itself is about 26mm diameter.
My plan is to use the milling machine to remove most of the waste, then to finish the accurate diameters on the lathe, turning between eccentric centres.
It is apparent, looking at the size of the bar, that most of it will end up as swarf. Oh well. On the floor it will keep the tigers out of the workshop.
I will post photos of the stages as they happen.
Hi John, thanks for the update (No3) great progress! I am impressed with your bandsaw, cutting that thick steel so easily with the 1 inch blade, the bandsaw must be a stout ole gal! puts mine to shame with its 1/4 inch carbon steel blade and tin plate construction it’s only good for timber and thin ally, but it is useful when needed. No doubt you will be sawing off more bar stock to save lumpy turning! Speaking of which, are you going to counterweight for the turning especially and afterwards for the balancing of the finished crank. Keep going, looking forward to further posts.
Chris C in Albany WA.
yes I am lucky to have a good solid bandsaw with good speed selections, and heavy castings. Read the next post though, because I had a problem today, and had to revert to milling the waste. John