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Thread: Turning brass on the lathe, dumb trick or not?

  1. #1
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    Turning brass on the lathe, dumb trick or not?

    I bought a used knock out bar for my lathe off the internet sometime back. It consists of a steel shaft with threads on the end and has a screwed on piece of brass on the threads. The brass end is a little to big to fit into the hole on my lathe so I want to turn it down a tad (take an 1/8" off). I have it chucked in my lathe, at slowest speed of 340 rpm (old Delta 12/36 wood lathe). I have never tried to turn brass, but I have read that it can be done on a wood lathe. I am a little hesitant to put tool to spinning brass without some guidance from this forum. I'm guessing that some folks here have turned brass at some point.... I have HSS turning tools. What do I need to know to do or not do? Thanks. Randy
    Randy Cox
    Lt Colonel, USAF (ret.)

  2. #2
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    I haven't turned it on a lathe, but I routinely machine brass with a router, cut it on a woodworking bandsaw and sand it with a belt sander. If you can take the piece of brass off and chuck it in a drill you can hold it up to a running belt sander and get a nice enough surface that way, but I don't know how big it is.

  3. #3
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    Quote Originally Posted by Randall J Cox View Post
    I bought a used knock out bar for my lathe off the internet sometime back. It consists of a steel shaft with threads on the end and has a screwed on piece of brass on the threads. The brass end is a little to big to fit into the hole on my lathe so I want to turn it down a tad (take an 1/8" off). I have it chucked in my lathe, at slowest speed of 340 rpm (old Delta 12/36 wood lathe). I have never tried to turn brass, but I have read that it can be done on a wood lathe. I am a little hesitant to put tool to spinning brass without some guidance from this forum. I'm guessing that some folks here have turned brass at some point.... I have HSS turning tools. What do I need to know to do or not do? Thanks. Randy
    Tu
    I've turned a lot of brass on the wood lathe using standard wood tools, spindle gouges, skew chisels, scrapers. Two things, if the brass is hardened or work hardened anneal it first by heating and quenching. Hardened brass is a pain. Besides brass I've also turned aluminum, bronze, and steel on the wood lathe with HSS tools.

    Second, if purchasing brass just for turning buy 360 free-machining brass. It contains a small amount of lead and machines easier than some types. This picture has a little finial I turned from brass. (I've made a number of finials and feet for small bowls and boxes.

    aluminum_brass_plastic.jpg

    For your knockout bar I'd probably chuck up the bar and let the brass protrude or find a large bolt with the same thread and use it to hold the brass. Turn at a moderate speed with sharp tools, no lube needed. You should get long curly "wires" from the cut, or you can use a scraper just below center or a negative rake scraper - these make more "chips" than long wires. This is an example of some of the waste that came from turning aluminum with a skew and spindle gouge. Aluminum easier to turn but not much:

    IMG_20150420_122415_440_se.jpg

    Remember these "shavings" are conductive so protect any electrical outlets you have behind the lathe.

    JKJ

  4. #4
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    How thick and long is the bar? If you have a lot sticking out of the chuck, you'll probably not be able to turn it because of the flex in the rod. What I would do is use a rasp or file with a handle and file it with the lathe turning. You can hold the back side of the bar with your free hand to maintain pressure and steady the bar. Sand after with the lathe running, Careful, that edge after you file it is sharp. A pass with the file at an angle will get that edge.
    You can sand the bar with fine sandpaper and steel wool and wax it. Make it look sexy. The brass will shine.

  5. #5
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    When I want to turn the end of a long narrow rod I use a set of pin jaws on my chuck and run the rod through the headstock, clamping it so that just the bit I want to turn is sticking out. That greatly reduces the vibration. One of the odd uses I put my lathe to is making brass couplers for organ pneumatics-- one end gets glued in the wood, the other gets a rubber tube slipped over it. I just run it through the headstock and cut off successive 1-1/2" pieces by the dozen. Much faster and easier than using a tubing cutter.

    When I started using gas pipe fittings as ferrules for tools I hated the way they looked and started turning them to more pleasant shapes. Works like a champ, brass cuts pretty easily with HSS tools. You can make it as shiny as you want going through the sandpaper grits and then buffing compounds.

  6. #6
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    I turned some brass parts for an Indonesian fire piston some years ago. I made a graver using 1/8 HSS mounted in a 6 brass handle.

    Just put the tool rest as close to the work as you can and hold the tooling tool at the back to maximize your mechanical advantage and take it slow.

  7. #7
    Isn't the brass knob a grip? I'm wondering why would you want it inside the spindle.

    But either way, I've done simple brass turnings using a scraper and the tool rest very close to the work.

  8. #8
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    I finally took a pic to show what I am tryinIMG_5287.jpgg to do. Not doing to good posting pics. Thought I'd turn about 60 percent, then turn it around and turn the rest. Make sense? Randy
    Attached Images Attached Images
    Randy Cox
    Lt Colonel, USAF (ret.)

  9. #9
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    I make tapestry bobbins for my wife by turning hardwood that has a brass pin glued in one end, and then turned down to a sharp point. Works fine.

    Capture.PNG

  10. #10
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    I guess I was worried about a catch and then it goes flying or some other undesirable outcome.... Looks like keep the support close and take it very lightly. Learning curve again, seem to be in learning curves all the time... I always turn to this forum as lots have much more experience than me... Randy
    Randy Cox
    Lt Colonel, USAF (ret.)

  11. #11
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    A while back I had to turn off some material from a cast iron tool rest that wouldn't go low enough. I used a carbide tipped cutter made for a metal lathe (HF "cemented" carbide cutter) and attached it to the end of a 1/2" square bar. What I recall from the exercise included:
    - Keep the overhang to a minimum
    - Cut at or slightly below the centerline and keep the tool flat or slightly pointed down (if you have the tip up and above center (just like with wood) you can get a catch or self feed).
    - take small cuts. My cutter was only about 3/16" wide. But I tried to avoid full width cuts. The narrower the cut the more controlled the situation seemed. Also, I put a collar on my 1/2" bar so that I couldn't feed too deep. without the collar it tended to chatter and seemed to be close to "self feeding" or catching. So, I would advance the collar by perhaps 0.020 "
    - Because I was turning cast iron or cast steel, I found that cutting fluid seemed to help things. Typically cast iron is somewhat self lubricating and d/n need cutting fluid.
    - Because I was cutting cast iron or cast steel, I was getting miniscule metal needles coming off. I quickly figured out that a rubber glove kept the little needles from embedding themselves in my fingers.

    Cutting brass, bronze or aluminum is much easier and you might even get thin little curls of metal coming off.

    I do nearly all of my metal work on my old Atlas 12 x 36 engine lathe. But I used my G0766 for the 14" tool post because it would only fit my Griz lathe. It took me about 10 minutes to remove about 1/2" length of material from the tool rest. Scariest part was working so close to the 14" propeller. I worked slowly to avoid banging my fingers ... or worse.

  12. #12
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    I never thought it possible to turn brass or aluminum on my wood lathe! Makes me nervous to thing about sticking a turning tool into a spinning brass or aluminum blank.
    Thanks & Happy Wood Chips,
    Dennis -
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  13. #13
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    Tools for turning metals

    Quote Originally Posted by Dennis Peacock View Post
    I never thought it possible to turn brass or aluminum on my wood lathe! Makes me nervous to thing about sticking a turning tool into a spinning brass or aluminum blank.
    Dennis,

    I used standard Thompson tools, mostly a spindle gouge, a skew chisel, parting tool, and I tried a bowl gouge, for both brass and aluminum. I got nice curls from the tools, in fact the curls sometimes made a birdsnest that had to be removed, similar to turning acrylic but not as bad.

    IMG_20150420_115245_729_se.jpg IMG_20150420_115928_884_se.jpg IMG_20150420_121555_806_se.jpg

    In this case I was making inserts to hold tools in handles, this is the one from the above photos just before drilling and tapping for set screws:

    IMG_20150420_122415_440_se.jpg finished_small.jpg

    Since the metal is homogeneous and doesn't have any grain a catch is almost impossible (well I couldn't make it catch). You can't take off too much metal at once so the turning is slow. The metals sand and polish nicely.

    I actually had a demo scheduled at our woodturning club in July on turning metals on a wood lathe but like many things this summer, that got canceled.

    I also turned some steel chuck jaws to a precise diameter for a special purpose. In this case I used a standard scraper made from Thompson steel, ground with no rake and just a bit of relief angle. No burr. I didn't get curls of metal with the steel, but lots of extremely sharp needles of steel! I did get a little chatter if I didn't hold the tool firmly. I used a little oil for lube just as with a metal-cutting lathe. This tool is actually quite close to the type of tool normally used on the metal lathe for turning steel, except for the part where you hold it in the hands!

    turning-steel_IMG_20170605_081521_124.jpg

    Look up "graver", an age old method of using a hand-held tool for shaping metal, often used on a metal lathe.

    JKJ

  14. #14
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    Thanks John! I'll check it out.
    Thanks & Happy Wood Chips,
    Dennis -
    Get the Benefits of Being an SMC Contributor..!
    ....DEBT is nothing more than yesterday's spending taken from tomorrow's income.

  15. #15
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    OK!! I turned off maybe about 1/8" and it worked just fine, just like most of you said. Thanks much for the responses and technical knowledge. I got a little older (ouch) and wiser. Randy
    Randy Cox
    Lt Colonel, USAF (ret.)

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