The Stationary Engine List


| May/June 2000



Stationary Engine

The Stationary Engine List is an internet mailing list which specializes in worldwide computer 'conversations' about engines. It was decided sometime last year that the GEM readership would enjoy some of the discussions which take place, so I pick one of the many topics covered over the past month to pass on. This month starts with a query from New Zealand:

I've got a question for all you welding experts out there. I've had a 3 HP National for some time now, complete but with three broken spokes, so it's sat at the back of the shed. Just yesterday I was given a flywheel with one cracked spoke. I've tried for a long time to find a good one, but they all seem to be connected to complete engines. What's the best way to weld the spoke?

When I collected all the responses together, I had around 6,000 words to deal with, so I have disregarded all the tales of havoc wreaked by broken fly wheels on cars and tractors (this is, after all, an ENGINE magazine!) and tried to stick to the subject.

Clean up the flywheel real good. Vee out the crack real good, heat the fly wheel on a forge or in an oven and get it good and hot (around 600 degrees will work), braze it, put it back in the oven and cool it down slowly. Grind and file the braze job and put it to work. I have had a great deal of success so far with this method.

The other option is to use the best one as a pattern and get a new one cast. The reason for the preheat and cool down is sometimes if you localize the heat and just braze it you can make matters worse. The preheat dries out the iron and helps to prevent too much stress building up in the braze area.

If there is only a crack in one spoke, I would do nothing. Trying to weld it could stress other areas and actually you could end up with more than one crack. At 150 to 175 rpm, one cracked spoke shouldn't present a problem. Now, if you are planning on running this thing like a Maytag (5000 rpm!! Maybe not quite this fast but when the smoke's rolling they seem so) at a high rpm (400-450), I would possibly have second thoughts. For 'play' purposes, you should be fine. (This from a guy who has personally watched two single cylinders 'explode'!!)