Tuesday, 25 September 2012

Chuck-free lathe idea

We've been considering how to make a simple, but reliable chuck for a desktop lathe, but hitting a blank with both our Longworth and Spiral approaches.
After the recent BuildBrighton PCB making workshop, Matt came up with an idea. Like most half-baked ideas, we're still undecided as to whether it's a stroke of genius or a flash of madness.

What if we could do without a chuck?
To begin with, we're only going to be turning regular (round) shaped objects - mainly acrylic rod. So we don't necessarily need to grip an irregular shape and round it off, like many woodworkers do, when starting with square-section wood and turning it to make furniture legs and the like. We know we're starting off with a smooth, round shape.

So perhaps we could just have a couple of free-spinning wheels (shown in green below) and rest our stock in the "groove" formed by two wheels in close proximity:

The piece should now spin freely in place, without any need for gripping the stock. If the wheels are placed such that a drive wheel can be introduced immediately on top of the piece, to complete an equilateral triangle, there's nowhere for the spinning stock to go.

If we turn the drive wheel (orange wheel in the diagram above) and it's in constant contact with the stock, then the piece should spin and still be held in place by the "triangle of wheels".

By spacing the green wheels further apart, or bringing closer together, we can change the height of the centre of the stock being turned, allowing us to introduce a cutting head to the right of the wheels and carve shapes out of the stock. That's the idea anyway.
Will it work?
We'll hopefully soon find out!