Serious CNC lathe...

Makes the spindle control on my lathe a bit pre-historic :-((

Amazing stuf

-- Myford Mat

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In article , Tony Jeffree writes

Indeed. Guess I will have to wait until my local second-hand dealer has them at a couple of thou though!

Would be interested to know what language the commentator thought he was speaking.

David

I noticed that too! I suppose he was a starving actor reading the script provided, as stranslated to english, by the engineer back in the "home" country.

Kinda interesting, but understandable for the most part.

Cheers Trevor Jones

What sort of rpm and feed rate do you think that was cutting at. Was it a steel component ... looked as if it might be?

Gentlemen,

As a service engineer on machine tools in the 80's I worked for a company in the UK who sold lathes that could turn external shapes better than it could machine round, the process was developed by a German company called WERA whose built machines to manufacture screwdriver, posidrive and philips hand tools but found a market outside of their world. We used to install machines in companies who used high speed sheet metal punching machines. The principal is actually very simple and you all did it at school in maths, take two gears of say 2:1 ratio and on the small mount the work piece, on the larger gear mount two cutters at 180 deg apart, spin the work piece and see what occurs. A square will appear. Under a precision measuring machine the flats have a very slight radius but to our eyes no problem. The video shows servo motors instead of gearing, it just needs to be timed correctly.

--Well that makes one of us! How the heck does that thing work? I'd love to see a slow-motion video of that process...

seems fairly simple. It's just a giant flycutter, with the rotation synchronised so that the work moves the necessary number of degrees i the period when the cutting bit isn't there.

if you rotate the cutter twice as fast as the work, the first strik would be on one side of the work and the second on the face 180 degree from the first. Or rotate work and tool at the same speed and have th same number of arms as you want flats, a tool with six arms woul produce six flats.

It's exactly the same principle as walking a pair of compasses roun the circumference of a circle.

You should be able to demonstrate the effect simply by mounting cutter in a powered toolholder on the crosslide and the work in th headstock with a calculated, controlled RPM.

But I still have trouble visualizing the actions of a wobble broach

-- rss

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Try this for size:

Cheers,

Garth

-- DR_

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had convinced myself that sort of motion would produce crescent-shaped cuts..

A bit off-topic, but one of the tests when I was learning was to make a

1" cube from a 1.25" length of off-square-cut 1.5" round bar - on a lathe. All sides, and squarenesses, had to be within one thou, and within a few tenths was better.

You could make a 0.900" cube if you messed up, or an 0.800" cube, and so on ...

-- Peter Fairbrother

The polygon turning? Search YouTube. I am almost certain that there is a company video on there with a slow-mo animation showing the process.

It is simply the coordination of the lathe spindle speed, and the cutter tip passing by. (Simply. There's a misuse of the word!)

Cheers Trevor Jones

On or around Wed, 28 Nov 2007 23:32:10 +0000, Peter Fairbrother enlightened us thusly:

I bet yer could. Chances are you need a 4-jaw chuck, an' all :-)

A few years ago there were similar vertical milling attachments to do things like hexagons on bolt heads.

A tipped cutter with a splined shaft through it went down to a gearbox on the table via a universal joint. This drove an offset collet head which held the workpiece.

All obsolete now though. These type of things eat up carbide inserts though due to the intermittent cutting action.

M_T

Professional Engineer.