chatwin polygon box

Chatwin polygon box Any ideas on how this works, considering it is mounted in the turret? Google revealed nothing apart from one for sale.
Bob
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turret?
Yes I spotted that on eBay too and was wondering ! Let's hop someone can enlighten us !
AWEM
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On Sun, 17 Sep 2006 23:02:15 +0100, "Andrew Mawson"

Hmm, Maybe I'll let you know in six and a bit days time...
Mark Rand RTFM
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Here are some videos and examples. <http://www4.profilator.de/technologien/mehrkant.html It is more often used for "milling" a hex onto a shaft. And that on a lathe. But it requires a second driven axis.
You'll find more if you google for "polygon turning". Like this little scetch (way down on the page): <http://www.hanwhamachinery.com/slhpd-tool.html
But that Chatwin-thing seems to work different. I guess it is driven by a drive dog (nose on the front disk), and the tool is sliding back and forth on the guide you can see within the cage.
Nick
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wrote:

It is, apparently.........
"the process is quite simple, the toolbit holder is on a spring loaded slide which follows a cam plate which revolves when driven from a dog fixed to the collet chuck faceplate or one of the jaws of a chuck"
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On Mon, 18 Sep 2006 21:49:45 +0100, "Nospam"

When I was doing my City & Guilds one of the way-past-retirement-lecturers who spent nearly all his time pottering about in the mech. eng. workshops. at the Suffolk College built something like this. I'd forgotten all about until this thread!
He made it as a stand alone benchtop machine rather than a lathe attachment. It had the normal driven spindle (can't remember if it had a chuck or centre-drive dog) with the bar stock supported on a centre at t'other end, and another gear driven shaft with the drive taken from the spindle running parallel with the cutter mounted on it.
I can't remember how this was driven down along the bed, but what I do remember was that there were some very odd shaped cutters. There was a single edged one that looked like a comma, a double cutter that looked like a mirrored comma, and a 3-toothed cutter, again shaped like a triple comma with a 120 degree spacing. It was fascinating watching it turn round bar into squares or hexagon section. Wish I'd paid more attention to it now.
He was forever developing stuff, and another one I remember was a benchtop ultrasonic glass drilling machine he built. A very clever chap that we didn't really appreciate much back then, in those days he was just another old curmudgeon berating us for sloppy workshop practice.
Peter
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Sad that one has to become one of them to realize that you should have listend to them when you were younger. And then you try to tell that to the youngsters. They will call you just an old curmudgeon ... :-))
Nick
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On Mon, 18 Sep 2006 23:51:26 +0200, snipped-for-privacy@gmx.de (Nick Mller) wrote:

Sadly all too true!
Peter
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Nospam wrote:

The Chatwin box on Ebay is for a capstan lathe,although it could be used on a cnc with a bit of careful programming.You would have to make or have made the cams for it as it only appears to have what is fitted to it and the picture is not clear enough to see.You would not use one like this on an automatic or multispindle lathe as you would be engaging the drive dog at full spindle speed.Multis and autos use a shaft driven attachment which is geared to the machine spindle through a gearbox to keep it in time.These boxes will not give you sharp corners to the shape you machine and the flats of hexes,squares etc are always slightly concave.They are not used on modern cnc`s as most of them have the capability of polygon turning by moving the tool to generate the shape. Mark.
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