Tooling for turning brass?

I've been asked to make some decorative turnings out of brass. Can
someone point me to a FAQ or give me suggestions as to type of cutting
tools to use, fluids for a nice visually appealing surface, and cutting
angles? These will eventually be polished; I assume doing that while
it's on the lathe is easiest?
Also, for a brass door handle, should I coat it with something to try to
keep it bright, or just set their expectations that it will develop a
patina over time, or is there a way to get a bronze-ish patina started?
Not going for the green verdigris look, just maybe an antique-brass-
without-paint-airbrush look. If "wait" is the best technique, that's
fine, though.
Any suggestions are most welcome. I assume I have to turn with the
speed fairly high and to take light cuts, but I've never done this sort
of thing in brass before.
Thanks,
Dave Hinz
Reply to
Dave Hinz
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Brass is probably the easiest metal to turn. Put a nice radius on your tool bit and you can get a glass smooth finish. You don't really need cutting fluid but if you want to keep it cool kerosene works fine. Brownells gunsmithing catalog carries brass finishing liquids but I think most of them are for blackening the brass. Good luck with it. 73 Gary N9ZSV
Reply to
Gary
I turn a lot of brass at work. I don't know what sort of lathe you are using, or what tooling you have available. Dad has always been a huge proponent of neg rake tooling when using HSS Using carbide, I have gotten the best finishes with carbide inserts designed for Aluminum, very high positive rake. I use surface speeds from 200 to 400fpm.
Reply to
Jon Grimm
Depends on the alloy. There are copper based alloys that are a nightmare. Leaded phosphor bronze is the finest material to machine I've ever encountered, and I've cut one hell of a lot of materials in my day. Without lead, it's a totally different animal.
Put a nice radius on your
Also, check in Machinery's Handbook----there's several well detailed methods of coloring brass or bronze.
Harold
Reply to
Harold and Susan Vordos
Much depends on the machine you have at your disposal. Brass has a serious tendency to hog, but works well with positive rake when the lathe is robust enough. A small machine running positive rake is surely to yield problems, where a large machine could be very forgiving. What often works well is a cutter with a positive rake established by the chip breaker, such that the breaker itself tends to limit the ability of the cut to hog. A tool thus ground is generally well suited to a particular feed and depth of cut, so you may not achieve the results you desire without considerable experimenting if you're not familiar with grinding such tools.
The advice to use a reasonable radius is good, but avoid lubrication if possible. Most oils discolor brass/bronze quickly, especially if they have sulfur as an additive.
As I stated before, Machinery's Handbook has some good information in that regard. One thing to understand----items such as a door knob will start out with the desired patina, but will soon wear such that they are somewhat, if not fully, polished down to the base color, and shiny, but only where they get well handled. Depends on the traffic, and the exposure to the elements. I have oil rubbed fittings on my shop doors (commercial stuff--Sergeant) and that's what they have done.
Again, all depends on your machine, and the choice of material. Leaded phosphor bronze works beautifully, and cuts with a very nice chip, or if you can find some typical bearing brass, 85-5-5-5, it machines nicely, too. ------Other materials may not cut as well, and likely will not. If you have any trouble at all with hogging, reduce your rake angle. Don't worry about speed, you can run most of these materials pretty much flat out---but make sure they're free machining grades. Aluminum bronze, or manganese bronze, for example, are more difficult to machine than drill rod.
Sorry I'm not more help. Too many variables to be conclusive.
Harold
Reply to
Harold and Susan Vordos
Good information in the responses.
Be careful of the rake on your tooling. Brass tends to be very "grabby" and will tend to pull the tool in. Light / old lathes thend to have a lot of backlash and flex in the feeds which amplifies the problem. Manual with our Emco 10X24 suggests 5 to 8 degrees clearance and 0 degree rake for brass. Unless you are using leaded brass, long stringy chips may be a problem. Keep a chip hook and / or long needle nose pliers handy.
GmcD
Reply to
F. George McDuffee
If you live in a big city and want that door knob to stay shiny take it to a music store's brass instrument repair department. They will buff it up, degrease it, spray it with an epoxy finish and bake the finish on for you. Just as long as they throw it in with another lot it shouldn't cost much. You could do all this at home but the bake on epoxy finish is hard to find in small amounts.
This finish is about as good as you can get!
LB
Reply to
brassbend
That's what I've been finding over the last couple of evenings...
which implies light cuts, then? My lathe is a 12" Rockwell, which I wouldn't call "huge".
I think I see what you're saying here.
Good to know, and this also is something I noticed last night.
That's kind of the plan.
Any handling concerns with a leaded metal? I'm not paranoid but I'd hate to make something for someone else if it's a potential problem.
Well, if nothing else, you've showed me that I know more about what I don't know than I knew I didn't know before, you know?
Thanks, Dave Hinz
Reply to
Dave Hinz
No such animal. Rockwell made a 10, 11 and 14 inch lathes.
I have the 11 and it is more than adequate for turning brass. I suspect the 10 would be fine too.
chuck
Reply to
Chuck Sherwood
My mistake. It's an 11. Looks like a newer version of this:
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think mine is longer than the one pictured as well. But yeah.
Thanks!
Daev
Reply to
Dave Hinz
I've read you should turn brass with a zero-rake tool to avoid its being drawn into the work, so that's what I use on my home shop lathe.
Since we're told to grind in more rake for softer materials, it sounds like turning is a peeling operation. Zero or less rake would seem to crowd the material off.
So what's different about brass? And is Jon's lathe at work stiffer and faster than what we're likely to have at home? I'd be pressing pretty hard to hit those speeds.
Reply to
rohamm
It's pretty hard to have a home shop machinist understand the differences in machine tools unless they're run machines intended for industry. To many, a lathe is a lathe, but nothing is farther from the truth. For one, industrial machines are far more robust, so offer incredible rigidity, especially as compared to small, bench model machines. Further, they are typically powered by large motors, whereas the typical home shop lathe is powered by a fractional hp motor. Industrial lathes are intended to be run at proper speeds for the work at hand, therefore are usually geared (and powered) accordingly. Top speed on the typical 12" machine should be 2,000 RPM, with some (Monarch EE, for example) going as high as 4,000, depending on the lathe. While I can't speak for Jon's machine, my hunch is he's running one that is industrially rated, and can do things that would be difficult, if not impossible, for the typical home shop machine.
Understand that none of these comments are intended to be negative in nature, and not intended to be insulting to the home shop machine, or machinist. It's just that their machines have little in common with industrial machines. It's much like comparing a half ton pickup with an 18 wheeler. Hardly the same critter, although both of them can drive down the highway.
Having said that, a robust machine will better tolerate positive rake in brass, due in part to the fact that the machine resists hogging by virtue of its mass. Takes more energy to move the machine, in other words. One goes to zero or very slight positive rake on small machines to overcome the problem, where a carriage may not weigh more than a few pounds. Needless to say, if the part is large and the cut is heavy, even large machines can be plagued with hogging.
Hogging is the quality one finds in free machining brass, but it is not restricted to those alloys. Even mild steel will hog if tool geometry is wrong. Because the material cuts easily, it pulls itself into the cut. That can be controlled by rake, or by clearance. The best solution is to work it out for your specific application, for what works well for your machine may not work well for another. We're back to the ability of the machine. There's too many variables to be specific.
Harold
Reply to
Harold and Susan Vordos
Not necessarily, although the lathe is not a heavy machine. They are considered a light duty machine, but might be found in industry under unusual circumstances. When you run light duty machines, you can still take a serious cut, particularly in free machining material, but tool geometry is very important. The lathe is not forgiving. You don't need much HP, for the brass you should be machining is quite free cutting. What you do have to have is geometry that prevents hogging. You'd be absolutely amazed at the cut you can take when you have the tool right. Fast feed (.015" easily) and deep cuts, say .200"/side. Setup must be proper, or you risk problems.
snip
Not as far as I'm concerned, but the world may not agree. They're doing just about anything and everything to eliminate lead from use, or so it seems. I'm sure anyone can make a health issue from this conversation----and they're likely right, but I can't help but wonder if maybe we've gone too far. How many years will it take to wear away a door knob? How much of that lost material is ingested? Dunno. I work with leaded materials, but wash my hands before handling food, and I'm not a finger licker kind of guy. YMMV.
Chuckle! Yeah. It's a stretch for me to even talk about it. I've been off the machines for a long time and have forgotten one hell of a lot. These conversations are helping bring some of it back.
And to you as well!
Harold
Reply to
Harold and Susan Vordos
I use a very small radius on a slightly negative rake tool. Seems to act as a wiper and burnisher when there is a slight forward but negative rake. Least for me..and I aint a machinist.
Gunner
"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.
Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner
Reply to
Gunner
Interesting perspective. I use to own a 12 inch craftsman/atlas. I now have a 11 inch rockwell which I consider far "heavier" that the atlas and can also remove metal much faster.
With a zero rake HSS tool bit, I can easily take 200 thou dept of cut in brass. Try that with some positive rake and things go sour very quickly. I think a little positive rack gives a better finish though (with a light cut).
It would be interesting to try using a "real" heavy duty machine.
chuck
Reply to
Chuck Sherwood
To put this in perspective, jump at the opportunity to run an Axelson lathe should it present itself. Or a Mori-Seiki, Monarch, or Pratt & Whitney---all of which are heavy duty industrial machines (there's more, too). Then you'll understand that you have a light duty machine. One of the benefits of such machines is you can run form tools, often large ones, without chatter. Try that on light duty machines. The advantages are far greater than that, but, for the home shop guy, may not be all that important.
The Craftsman isn't considered an industrial machine and lacks almost everything that would classify it as light duty. At the risk of insulting anyone (which is not my intention), they're hardly a lathe. I started machining on one and wouldn't be interested in owning one now, not even as a gift. Once you're operated proper machine tools, it's pretty hard to step back. You're constantly frustrated by the machine's limitations.
Harold
Reply to
Harold and Susan Vordos
Hmm. To do that, it would mean building an entire new house and shop to install the industrial machines.
Is that really *worth* it?
:^)
Jim
Reply to
jim rozen
So, do I go zero, or more? The above seem to contradict each other, unless I've gone completely dense?
That said, a few test cuts with a zero rake round cutter are, as suggested, producing very nice results. Dry.
Well, I've always thought of brass as 'chewy', which makes the rake of zero make sense now that it's pointed out.
Reply to
Dave Hinz
I'm a shooter and reloader, so I probably handle...wow. 100 pounds of lead per year, maybe? Probably more if I count the shotgun reloading. So I'm comfortable with it, but will probably choose an "unleaded" option for this work for someone else.
If nothing else, I've learned that the rake has to be either positive, zero, or negative, and I should try to see which works best for me. The zero rack rounded cutter is producing nice results on my test cuts so I'll probably stay with that. Now for the hard part - the artistic part of the job.
Reply to
Dave Hinz

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