Making a Lead Ball for the safety valve
The deWaal plans for the Trevithick Dredger Engine call for a 30mm diameter lead ball for the safety valve.
I considered substituting steel or brass, and turning the ball, but lead is almost 50% more dense than the other metals, and that could be detrimental to the functioning of the safety valve, so I worked out how to make the ball in lead.
I have previously cast lead balls 14mm diameter, but this is significantly bigger. I did briefly consider making a plaster of Paris mould, but I could find no balls of the correct diameter for the POP mould, so I decided to mill the mould.
On rummaging through my big milling cutters, I discovered that I have a ball nose cutter, 31.75mm diameter. It was part of a package of cutters which I had purchased years ago, and almost forgotten. I had bought the cutters BY WEIGHT. I think that I paid $US5 per pound, and I bought 20lb. Mostly the cutters were resharpened end mills, but one of them was an unused 31.75mm ball nose. Pretty close to perfect for this job!
Only one part for the day’s work again. But it was a LOT OF FUN!
Be thankful SWMBO didn’t catch you and have a great new year. Aloha!
Same to you Richard! Love your feedback!
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Thank you, John.
“The Old Man of Kalihi”, a hidden treasure of Hawaii’s history that is poorly interpreted and little known, got my interest stoked in triple expansion engines. I wanted to design exhibits for the Board of Water Supply Fred Ohrt Museum here in Hawaii. I didn’t get the contract but got to see the beast up close and virtually meet you in the process of research. It is such a beautiful machine, I hope you get to see it someday.
I want to go to Cheyenne, Wyoming in May to see the Union Big Boy X4014 steam up. Fact is, we are planning to quit Hawaii to move back to New England. With a bit of luck it will be a stop on the way!
Looks awfully close to a 4ounce ball fishing sinker John.
Naaa probably not.
Has a hole through the centre too.
Nice mould John
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Bum! Wish that I had known.
Mine is 190g = 6.6oz. Good guess Tim!
I think your moulded lead sphere looks prettier than a fishing sinker.
I think your moullded lead sphere looks prettier than a sinker.
I think that Tim was having a joke at my expense!