Posted By Cap'nBill on 02/27/2009 3:01 PM
In looking at Harris' book on 'Boilermaking', I notice drawings for various valves-such as safety valves. I have a small lathe, drill press and various other tools. While drawings are interesting they're not very descriptive in the 'How to' department. One of things that puzzles me is how to cut a good, or proper shoulder, or 'seat'. Are there any tutorials out there dealing with the subject. [edited]
Cap:
If you have the dwgs, you have the info to build the item in question. If, OTOH, all you have are undimensioned
line dwgs ... you have a bit of a problem. Are you a machinist? If not, get a copy of Machinery's Handbook, or the Machinist's Handbook. They are often available used, you sure don't want to pay new price for one.
To answer your question about seats/shoulders: so long as the mating surfaces are the same angle and all that, that's basically what you need. The ugly term 'standardization' rears up about here. If you're handbuilding 'one-offs', that is, one for your own use, I think you can neglect standards--just make 'em so they work and suit you.
I know nothing of 'standard practices' as applied to steam locomotives. Someone else will have to chime in. Be aware that, in the case of most valves, you'll need to 'lap' those seats and shoulders for a good mechanical seal.
Don't feel lonesome: I've been paging thru line dwgs of early steam locos, and I swear, the artist/draftsman who drew them didn't know what he was looking at. I can read blueprints. Problem is, very little in the books are dimensioned. If you're lucky, you can find a mention in the text of wheel diameter, then go from there. For your projects, I have to assume there're a lot of blueprints out there on specific items.
You should ask of someone who knows regarding safety valves, because
they may have specs--after all, at a meet, you don't want someone's loco blowing up just as it reaches your adult beverage.
That would be awful.
I read where the boilers must be pressure-tested, but nothing is ever said about the valving, including safety valves. I'm really not the one to answer more than the machining issue.
Les