This isn't off-topic anymore! (was: Have YOU got a metal lathe and know how to use it?)
 

I have a specific need for a relatively simple yet precise couple pieces of brass (or aluminum, or steel... but prefer brass).

If anyone has a lathe and can turn it out, I'd be interested in talking to you about it.

• I need two identical-diameter metal rods. Each about 5-6" long. Diameter for the last half-inch at least at the "tips" (see below) must be 6.01-6.03mm. The rest of the shaft can be equal or smaller diameter.
• Tip of one rod is to be a cone-point. About a 45 degree slope for the cone.
• Tip of the other to be a matching, yet inverted cone (so like a "socket" reverse-cone instead of a point)

Not particularly complex geometry-wise but does need to be fairly precise.

If you can bang out this sort of thing and mail it to me, fire me a PM and I'll send you the additional details.

I only need one. The sooner the better.

If it works out, the rest of you will find out what it's for soon enough. if it doesn't, well then it goes into the "failures" bin and no one hears about it ever again. :lol:

Why yes...I do. Just a little hobby thing.

So 6.01-6.03 is the max diameter? I think my through spindle can handle that.

The shorter the better obviously...but I can try.

Send me a pm with the specifics...or call.

I have time this weekend. It's either repairs, working on one of my projects or this.

Tys

Well, that was fast. :)

sounds like it's going inside a barrel to me :P

PM sent.

5"-6" is too long to do in one setup. Since the middle diameter can be smaller, it would be easy to start with 1/4" rod and turn one end to your accurate 6.03mm diameter. Turn the rod around and work the other end so both ends would be fairly coaxial. Work the midsection in 1cm lengths sticking out of the headstock and step it along. Turn the last bit before the inside end (without chucking on that end, which might mar the end) and finish the midsection. I'm guessing it doesn't matter if the midsection is coaxial with the ends, but coaxiality at the two ends is important. Doing those ends on the as rolled bar (assuming that the bar is decently straight and round) before cutting the midsection would be more coaxial before you start cutting it down.

I think I may have 1/4" bar for you Tys if you take the job.

I'm sure Carl's lathe is hooked directly to his brain and he'd have it finished by the time I finish writing this post.

Don and I traded PM's, I've got some spare bits that I think will work. Gives me an excellent excuse to retreat to the workshop Sat morning with a hot cup of coffee.

Feel free to give'er a go...I quite often fail miserably.

getting the hang of it...my little steam engine is coming along nicely (2nd attempt!).

6" too long to work on at once? How small is your lathe? :eek:

Cut the bar long, turn a chucking seat. Then flip it and use the c'sunk end for the tail stock. Turn the whole shebang in one shot.

Edit: never mind, for some reason I ignored the part about being brass. Forget that noise, I hate brass and doubt we have any.

I mean that 6" is too long for a 1/4" dia which would be quite flexible. Unless you use a follow rest, you'd probably get some chatter.

Why do you hate brass? It machines like buttah.

DonP: if you're putting this part inside a barrel, try not to slide it around too much in a brass one. Brass has an annoying habit of sticking to itself and trading atoms. As a rule of thumb, I try not to slide like materials against each other with the exception of hardened steels.

Huh, learn something new every day. Well, thankfully this is just for a test-of-concept so no long-term durability requirement here. :P

It makes a mess.


Or maybe I'm thinking of bronze. It's been so long I can't remember. Nothing but aluminum, stainless, and high carbon steel these days.

I find myself being careful with my use of brass. It's decently strong and very easy to machine accurately. Unfortunately it's utter shite for long term sliding durability. It starts out nice and slippy (low friction) but at some point it's free machining charactaristics allow it to lose particles which make this terrible brass sanding dust which abrades more of the solid. Brass bushings rapidly turn oval as shafts start to slot them out.

I've gotten MUCH better wear from bronze or engineering plastics like acetal (POM) or nylon. Still, the stiffness and machinibility of brass makes for good short term prototyping mat'l.

If you want more wear resistance go for something like aluminum-nickel-bronze or copper-nickel-tin (Toughmet). You could use heat treated copper-beryllium but the machining dust is poisonous in large amounts.

I know a couple of guys with Swiss CNC's that would bang something like that out in a heartbeat.

Not bad for a first try. Hopefully good enough for prototyping. (I've got to take some photography courses....;))

http://i156.photobucket.com/albums/t...4/IMGP2272.jpg

Ze plot, she thickens.