Machinists usually express tapers of machined parts as so much per foot, like 1/16" per foot tapers on locomotive frame bolts or bolts holding on big ends or built-up siderods. Pipe fittings have a taper of 3/4" per foot (usually includes 12 or 14 thread washout plugs as well). 12-thread studs for boilers are 3/4" per foot.
The taper attachments I've seen on lathes have scales showing either degrees or so much per foot.

So what's with Baldwin? I've rebuilt a Heisler, Climax, Shay, Porter, Alco, and two Baldwins. Presently doing another Baldwin Mikado. Was supplied some Baldwin drawings for a similar locomotive to help with the curent project, and now I'm educated on some wierd tapers.

Taper on the wrist pin fit to the crosshead is 1/4" in 5". The taper on the end of the piston rod for its fit to the crosshead is the same. The key used to hold the piston rod to the crosshead is 3/16" in 8". The taper of the frame pedestals for the wedge is not the generally accepted (and published) 1" in 12", but 1 1/2" in 17".

What did Baldwin engineers know about these specific tapers being optimal for their purposes and why did they stray from the common terminology of "so much per foot"? These wierd tapers explain why I was not able to determine a specific, common taper per foot by actual measurement and simple algebra.



steamrr@mashell.com

I think the most likely answer to your question is that it's Baldwin.

I have, to date, not found a rational explanation of many of Baldwin's practices. In boilers I have been able to see a progression that indicates some experimentation but the reasons for a change in design philosophy are usually pretty difficult to unearth unless there is an obvious oops involved.

I have often thought that since Baldwin was around for so long as basically the same entity, that some of these interesting standards evolved from existing tooling, and rather than change from something that worked, they just stuck with it.


linnwm@supernet.com

Disclaimer: I don't own nor do I benefit from Little River publications, but they have recently reprinted the Baldwin, Lima and Alco standards and practices books which are a treasure trove of this kind of information. They will pay for themselves in the cost of the time not spent in trying to work out this data though other means. Why not give Ken a call and get a set?

Somewhere I have an old photocopy of Glovers - anybody out there got Porter?

Dave

I certainly agree with Linn, much like the common term for a Morse taper is 5/8" per foot, but the actual taper could be slightly off. The measurements taken from Morse's actual tapers are the ones published in Machinery's Handbook, and do vary a little.

I have been supplied with the Little River books
and find them to be quite helpful. The drawings I have showed so many different tapers on one page that I may have gone crazy had I not posted a message.

Thanks.

steamrr@mashell.com

I thought Harold was there for sanity reasons?

Best wishes and good to hear from you again.

dave