Swaging, crimping and peening

My Smiths catalogue lists CZ106 as rolled brass i.e sheet.

When I used to modify lamp fittings for someone in the dim distant past I used CZ131 which I could buy as round bar.

Keith

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I have used the 'spinning' technique on small work, Dave; using a single ball-ended hand-tool, but remembered having read "somewhere" about Laurie Penman's idea ... surprisingly; if you know that something is out there, it's usually possible to find the right words [deep in the subconcious?] to successfully search for it.

I would be wary of using my good chuck for such work, but have several small Jacobs drill-chucks [bought very cheaply] tucked away for future abuse.

MichaelG.

Attached pic of drawing supplied to me by a tubular rivet manufacturer giving correct proportions for a swaging tool.

I have made several of these in the past from silver steel. They need to be hardened, preferably dead hard and with a well polished finish.

For brass rivets up to about 3/16" dia. I used the tool in my drill press running at a slow speed and with lubrication. I have successfully closed a 1/4" dia. tubular steel rivet with a short tool in the bench vise.

It looks to me the problem is the correct material, even if you anneal the brass normaly used in machining it will crack if you try to deform it that much. Why Mr. Penman makes use of a extra bush for fitting a wheel on to a pinion is me not clear. If everyting is supported and lined up correctly you can force the pinion direct into the wheel. This for small and thin wheels or for larger wheels. An old way to fit wheels onto pinions is to force the brass of the wheel into the pinion teeth, but for that method the modern brass is also to hard. Niko.

Edited By speelwerk on 07/09/2017 14:41:52

More disappointments. I get fairly close before the cookie crumbles, which is frustrating. Never mind, I'm learning lots of new tricks.

Here's the lathe method ready to go:

I modified the boss so that the swaged section was about 0.4mm thick. Without annealing it flattened fairly well as the lathe turned but, just as the edge of the swage pinched the pulley, it disintegrated. The die/punch approach does the same. The brass gets very brittle the more it's pushed.

I made another boss and tried to anneal it.

Oh dear. I overdid the heat and the thin part crumbled in front of my eyes.

I'm going to try a few more times with the brass rod I've got. Glad for comments on my annealing technique as it may be faulty. Using a blowlamp:

• Method 1 - brass heated until it goes blue and immediately plunged into cold water.
• Method 2 - brass heated until it glows red and immediately plunged into cold water. (The ruined example went bright orange after I accidentally moved it into the hottest part of the flame. I wish I had steady hands. )

I'll try Michael_w's repeat annealing suggestion later : it's not ideal in this case because the pulley I'm using has been painted.

At the moment I'm pinning my hopes on getting a more ductile brass, so thanks to Clive and Keith for providing the CZ numbers. I feel I'm probably asking too much of the brass I've got. Although it machines well it sure don't like bending!

Dave

Hi Dave,

You're right, you are asking too much of the brass you have it's probably wrought brass which seems to hate being deformed. (Been there,done that). You'd be surprised at the difference it makes if you use the right stuff.

And you wont have to anneal it!

Keith

Edited By Keith Rogers 2 on 07/09/2017 15:01:02

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I'm never happy trying to heat-treat brass ... too much risk of the zinc evaporating, methinks.

I'm sure you will get there when you get some more ductile material

... and maybe soften a few sharp corners ?

MichaelG.

Success! (Much to my surprise!)

Despite a few imperfections this boss is a solid fit on the pulley with no splitting. On the downside making it was labour intensive. After countersinking the 4.1mm meccano shaft for 2mm using an 8mm slotting mill, I turned the boss down to 8.4mm over a length of 3mm to fit the pulley tightly. Before attempting the swage, I warmed the end of the boss with a pencil torch until the brass went blue and I quenched it. Then with the pulley spinning at 150rpm in the lathe plus a squirt of cutting fluid I used the tail-stock and the 60° punch to take the fold half way. Then I reheated the swage part of the boss to blue heat and quenched again. Once recovered from breathing burnt pain fumes, I finished the swage off with the flat punch in my vice. The brass folded and gripped the pulley without splitting. (I would have finished in the lathe but the punch I made is too short to fit the chuck. Doh.)

With a more ductile brass it might be possible to do the squeeze in two steps using a 60° punch and a flat one to finish off. I'd expect the tool shown in Keith's drawing to do an even better job - it starts gently before completely turning the swage over.

Whilst not a perfected process, I'm happy that this can be done. With a bit more work, a Keith style punch, and the right brass, I think these could be knocked out at speed with just a lathe.

Many thanks for all the help! You chaps sure know your stuff.

Dave

Been doing a bit of 'research' on my 'bus journey:

**LINK**

http://www.dalefield.com/nzfmm/tips/loosebosses2.html

MichaelG.

Another good find Michael - I might have guessed someone's been at the problem before. The bit where he says "The tool used was like a shouldered screwdriver" and "spun at high-speed" is interesting. Got to be worth a try.

The photos of various Meccano parts sans boss are revealing too.

Thanks,

Dave

Dave, Thanks again for the interest you have taken and the work you have done. Chris

Good stuff!

Andrew

A bit more information fro New Zealand http://www.nzmeccano.com/AboutBosses.php