Wednesday, April 22, 2009


Wedgewood X Assembly, Thumbnail Edition

Having drilled my left thumb and nail for M3, I'm now back in the workshop once again and working on Wedgewood. I promised the guys in the #reprap chartoom on IRC (Chatzilla or similar needed) that I'd give a quick update. As you can see from the photo my good camera is broken too, other than that there is a railcar-like X carriage and on the right a contrivance to dangle it all from the Z axis.

The wheels are made from two skate bearings with a washer between that is thinner than the rail. This causes the bevelled edge of each of the bearings to run on the corner of the top of the rail and self-centre. Runs nice and smoothly, should also be robust enough to dampen oscillations of the drive rod. Yes, that is a Ponoko lasercut extruder (from an old extruder kit) plugged into the X Carriage - both the MDF carriage and lasercut extruder are compatible with the Darwin exchangable head holder. I love standards :)

The stepper will be screwed to the block on the far right and coupled to the horizontal threaded rod. Probably put a bearing in there to reduce play too as I'm using cheap stepper motors.

Oh, I can also report that brazing thermocouple wire doesn't work - it melts way before the brass. I'll have to locate some silver or 95/5 solder. Flash-welding the stuff is looking more convenient by the day.

Vik :v)

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Calling it 'Flash-welding' reminded me of a technique for DIY spot welding using a disposable camera.

Relatively thick wires are connected to the capacitor in the camera. One of the wires would go to the barrel and the other would be clipped on to the thermocouple wire near the end to be welded. Once the camera's flash is charged touch/press the wire against the barrel and one spark latter it's attached, well that's the theory.

In reality it will probably take a few goes to get the right sized contact area between the wire and the barrel to get a strong weld without vaporize the end of the wire.

Finally if you can't workout why this is potentially very dangerous/lethal go find a better disclaimer ;-}>
Looks funky... any chance of a vid of front and back when it's running or would that be a good-camera thing?
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Quick question.

As the Wedgwood uses two X Carriage rails (of what ever type) and spare/alternative heads could be stored above the carriage rather than off to one side or the other.

Is it worth while considering putting the tool head between the rails rather than at one side or the other.

This should help reduce torsional stress, particularly if someone wanted to later try fitting a milling tool head ?????

Just thoughts for what they are worth.


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