brass vs bronze for making a punch

What if any differences might I notice when making and more importantly using a 1/4" punch made of C360 brass vs C932 bearing bronze? The brass
will work harden, but I can only guess bearing material is not supposed to harden up under use.
The punch would be just that- 1/4" x 4", tapered and knurled and used for driving out stuck pins. I figure it's easy enough to make and will be useful.
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On Tue, 12 Apr 2016 16:27:51 +0000 (UTC), Cydrome Leader

Since you haven't yet gotten a specific answer, I'll just point out that C360 is a great deal harder and stronger than C932. The bearing bronzes are pretty soft and, in the case of C932, kind of "mushy." I don't know its work-hardening properties.
My guess is that C360 is a better material for your application. Some bearing bronzes would be similar to ordinary brass, but C932 is pretty soft.
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Thanks for the answer. This is the info I as looking for.
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Went ahead and made it in brass, on a Sherline lathe. The taper was guestimated with a compound attachment and blended with a file.
http://www.panix.com/~presence/brass-punch.jpg
Knurling got messed up on the left side, but only with one cutting wheel, it may have clogged up. It has this odd pattern, but whatever, it's a punch. Used it yesteday to knock pins out of a casting.
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On Thu, 21 Apr 2016 16:56:03 +0000 (UTC), Cydrome Leader

That's a beauty. If you don't bash it up too much, you could make a pendant out of it. <g>
Doncha love the way brass takes to knurling? It's beautiful.
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May try to make another one in a different size to get it right.

The only problem is how much it flakes and clogs up the knurling wheels. Cutting fluid like Relion seems to make cutting easier, but makes also binds the flakes into the teeth. May need to setup some tubes, old toothbrush heads and the shopvac to suck all the flakes out of the wheels as they rotate. The wheels I have are 25TPI and 1/2" dia so it doesn't take much material to fill them up.
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On Thu, 21 Apr 2016 18:32:07 +0000 (UTC), Cydrome Leader

I haven't done it for a long time, but when my uncle was teaching me how to run his (now my) lathe, he told me to use heavy machine oil, or even motor oil, on knurling tools. I always have, and I don't remember any clogging problems with brass. But that was decades ago. I don't think I've knurled brass for 25 years. Maybe I just forgot about it.
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    [ ... ]

    Looks pretty nice -- at least from this side.

    How were you holding it? A 4-jaw chuck by any chance? Slightly off center? With a push type knurler, that could result in one side being light or unknurled. A scissors style would tend to follow the workpiece, even if slightly off-center, since the force comes from a knurl above and one below the workpiece.
    Otherwise, knurling between centers makes sense -- and then turn the needed features (striking end and punch end) after the knurl is done nicely.
    And a Sherline seems rather lightweight for a push knurl. A scissors knurl would make the job easier on the machine.
    [ ... ]

    I knurl brass moderately often. I use Vactra No.2 Waylube during the knurling, and then spritz it with WD-40 to clean the lube and the flakes off.
    But I usually do it on a 12x24" Clausing with a BXA series knurler which has a pair of arms off a dovetail on the tool holder, and a knob which moves one arm up as the other goes down. Set it once lightly clamped on the top and bottom of the workpiece, and set the height nut on the tool holder block and then it is just a matter of adjusting for the diameter. Move it into place for the start of the knurl, crank down the knob which brings them together until you get a good bite, start the lathe spindle, and keep squirting Vactra No.2 onto the knurls.
    Beware of trying to lube with an acid brush, It will grab the bristles and pull them in. Makes a mess. :-)
    Good Luck,         DoN.
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It's symmetrical from all sides, just had the double tracking on the left side from one knurl.

I indicated 3/8" barstock to "close enough" of about 3 mils in a 3 jaw, centerdrilled and used a livecenter.
The OD was turned down to 0.369" (to give 29 multiples of 0.04" from the 25 TPI wheel). I did some test knurls on the punch side which was facing the livecenter. Seemed OK.
I turned that to 1/4, added the taper and then cut the groove by the striking side. It seems easier to cut knurls from a taper than just cranking down on the holder for the wheels and then trying to start the lathe.
The sherline knurling attachment is just two blocks with pins for the wheels that are clamped towards each other with two screws. Their bases are held into the crosslide T-slots but must be left loose so both sides can slide around and cut evenly.

Their attachment is more similar to the scissor type ones in that the cutting forces other than required torque are not put on the lathe itself.
The torque requirements seem to push the limits though.

I learned about the brush the hard way. Just had fun with a paper towel getting pulled onto a chain drive this week too. Will try the vactra 2, have a gallon of it anyways.
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0.003"
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wrote:

I hate to agree with you but I never heard the term "mil" until very recently and I worked in and around the business since I was in High School. It was always 3 thousandths (.003) or 3 tenths (.0003) for smaller dimensions.
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On Sun, 24 Apr 2016 14:21:47 +0700, Good Soldier Schweik

Before the late 1930s, "mil" was used commonly in machining, too.
Here's a little history of how we express "thousandth of an inch":
https://en.wikipedia.org/wiki/Thousandth_of_an_inch
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On Sun, 24 Apr 2016 06:43:15 -0400, Ed Huntress

Well, I wasn't around the shops in the "late 1930's" :-)
But I did for a couple of weeks run a lathe that the cross slide was calibrated in 1/128th of an inch. The owner of the shop reckoned it dated from "Civil War Days".

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wrote:

When they're that old, you should sell them to interior decorators for use as foliage planters. They look nice with a Wandering Jew twined around the bedways, standing between a miniature palm and a ficus tree. d8-)
In 1977, I was one of the writers for American Machinist's 100th Anniversary issue. For a year, we all poured through the old AM archives, going back 100 years. The term "mil," for thousandth, appeared all of the time in the old volumes, as a slangy shorthand, like the way we use the term "tenths" today.
Then, I'd say roughly in the late '30s, the term "mil" all but disappeared. Universal use of gage blocks, sub-thousandths accuracy, aircraft and military specs combined to add another decimal point to required accuracies. American Machinist adopted a style point of using numerical values to express accuracy, with a zero before the decimal point for metrics, and with no leading zero for inch-based dimensions. Written out in English, we used "thousandths," "ten-thousandths," and "microinches." Metrics were a problem child, as we first used "micron," and then, when SI came in vogue, "micro-meter."
Anyway, the point is that no one here is old enough to remember the use of "mil" for thousandths of an inch, but some of us who were deeply involved in metalworking history have seen it used a lot in the deep past.
BTW, don't get me started on "gage" versus "gauge." That one has a history, too. There used to be an important distinction, but that distinction has been lost in time.
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Ed Huntress

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On Sun, 24 Apr 2016 08:48:57 -0400, Ed Huntress

Well, this was when I was in High School and the shop was at least 2nd generation in the same building. It was owned and operated by two bachelor brothers who didn't talk to each other. The entire shop except for some bench grinders operated from a single electric motor "out back" driving an overhead shaft system. Strangely I don't remember thinking it was an odd place to work :-)
One of the brothers had an absolutely like new Henderson 4 cylinder motorcycle that he used to ride to work occasionally which certainly was interesting.
As a summer hire apprentice I wasn't doing any high tech stuff, they had me making nuts on the old lathe. Even then, making 50 cents an hour, I can't see how the finances worked. 12 ft of hex stock in an antique lathe, Drill, tap, part off, advance the stock a bit and do it again. Sort of a human screw machine :-)
But they paid every Friday afternoon at quitting time. Cash in the hand.

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John B.
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wrote:

At least he didn't have you start with round bar stock...

When I hear stories like that, I wonder how the United States, and the West in general, ever managed to produce anything that anyone could afford.
Just before wire EDM came into use, I started covering tool and diemaking, and visited a lot of t&d shops. I watched diemakers rough out blanking dies with a bandsaw, breaking the blade, threading it through the work (they milled out a really rough hole first, but it usually was nowhere near the final size), and then re-welding the blade back together. Then they'd break the blade to remove the die from the saw, and they'd go to work with diemaker's chisels, cutting close to the line and chiseling in some die relief. Then, possibly, on to the die-filer. Next, hand-filing with files down to jeweler-file size. After that, the die would go out for heat-treating.
When it came back, out came the slips and stones, trial-mating the die with a punch, re-stoning to fit, over and over.
That was for simple diesets. Anything complicated was likely to require a multi-part die, which had to be fitted together in pieces that were dowelled to the die base. My God...

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On Sun, 24 Apr 2016 09:53:34 -0400, Ed Huntress

When I was at Edwards AFB they had an "Electric Spark Machine". I was there for about a year and saw it used just once. A guy made a set of dies to punch out counterfeit quarters for the Coke Machine.
Interestingly he tried a number of alloys for his counterfeit quarters and the Coke Machine rejected them all :-)

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wrote:

I'm curious -- what year was that?

He was too early. Today, he probably could get away with any scrap metal. <g>

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On Sun, 24 Apr 2016 21:50:30 -0400

The machines I looked at several years ago only took bills. I guess they have them now that you can pay with your smart phone...
A different kind of counterfeiting required to bypass them :)
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Leon Fisk
Grand Rapids MI/Zone 5b
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On Mon, 25 Apr 2016 08:26:16 -0400, Leon Fisk

Once again, technology opens up endless entrepreneurial opportunities. d8-)
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