I did some machinng of tires for a steam engine last year and again this March. I have an upcoming job to machine a number of boiler staybolts for a steam engine rebuild. Of course we are cheating... using a cnc lathe for the staybolts. The one engine has over 340 staybolts in its boiler. I would sure hate to do them on a manual lathe.
John
John,
Page 1056 has dimensions for regular and spindle staybolt taps. Does that help?
Wes
Thanks, I was just wondering what they said about them. I have a set of prints to work by. There are two different sets of them, one has straight v threads on both ends and the other has a tapered thread on one end and a straigh thread on the other.
John
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And FWIW, it is on page 1266 of my 15th edition (1957), so that table was carried on for a while.
Enjoy, DoN.
According to john :
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O.K. The information in the 15th edition suggests that the taps have both tapered and straight threads (presumably to get it started with the straight, and to seal when it bottoms on the tapered), *and* a reamer section as well. There is not a sketch, but I presume that it starts with the reamer section to set the ID of the hole to be tapped, then the straight section, and ending with the tapered threads -- though it may be straight, tapered, and reamer to clear the unthreaded section of the staybolts. I didn't take time while I had the book open to see whether the dimensions given would tell me which order they were in. :-)
Enjoy, DoN.
The one set we are doing has a tapered v thread on one end with the large end of the taper at the end of the shaft. The other end is a straight v thread with a stepdown turn about 3/4 inch long at the extreme end. The other set has a straight v thread at both ends with th3 3/4 inch turn on one end.
There are several lengths called for, the longest I think is 28 inches.
John
Those old editions make good reading if nothing else, but they do answer a lot of questions that come up in this group. I think there is some information on blacksmithing in the early editions as well as forging. I have a couple of large bolts from an early vertical boring mill manufactured in 1881. I had to replace them when I repaired the wear on the rail and ram. Those bolts looked as good as a new one except for the screw slot in the head rather than an allen socket head. The company still runs that old machine.
John
I just chanced into this with Google while trying to figure out why one end would have tapered threads and the other straight - Go Read It. You may be riding in that locomotive.
The problems have all been solved before, but it isn't in daily use, and it's in danger of being lost.
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That site you found seems to be from Railroad Man's Magazine, Vol.1.No.1. and Jim Skeevers' Object Lessons.
Got a lot of interesting information if you click to the site map at the bottom of the page. Also ' Tom Swift and his electric locomotive'
Our shop will machine the bolts to the spec. on the print supplied. The taper I believe is so the bolts self align when the boiler is pressurized. The spec calls for the thread gauge to make only two or three turns on the tapered thread. Some bolts that I have seen are set in half round balls that swivel to align the stays.
John
According to john :
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O.K. That one sounds difficult to handle with a die unless the shank of the stays is smaller than (or equal to) the minor diameter of the tapered thread.
It should be a cinch to cut on a CNC lathe, however.
That one sounds a lot easier to make.
Fun.
Good Luck, DoN.
Thanx Bruce. Nice link.
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