Tuesday, June 28, 2005


Head mounts & sizes

Keith, Ash and myself have mated the 3D axis assembly with the frame and dangled an extruder over it for the first time, to size up the gantry that we'll need to hold the extrusion mechanism:

After some discussion we thought we might try mounting two parallel rails over the top of the linear axis, and allow the head units to suspend themselves there. By fitting the head assemblies with adjustable feet, we'll be able to reposition each head individually to align with the centre of the turntable at the apropriate height.

In short, this proposal will allow multiple heads to be integrated at an early stage, and define a method of implementing interchangeable heads that can be exchanged with other users.

I informally suggest a gap for the rail spacing of 100mm with enough error to accomodate people who like to think in terms of 4 inches :)

What do others suggest?

The photo shows my freshly-made example of Adrian's extruder clamped by the now obsolete pinch wheel assembly. It is at least serving as a space model!

Exceedingly nifty - looks like it's getting close :)

Now if I can just arrange to get materials to start mine, and learn the neccesary electronics...

Also, just a thought (and I think it's been brought up before), but it really would be nifty if it were possible to make a part out of either something that can stand high temperatures (read: incandescent), at least for a short period of time, or something that is easy to melt out of such of a material (say, wax and plaster of paris). Melting most metals is surprisingly easy to do, assuming the presence of some form of blowing device and charcoal, and casting is a wonderful thing :)...
So easy, in fact, that it's more of a challenge to avoid pulling a white-hot sparkler of burning steel out of a forge than it is to get it hot enough to work it.
If you want to get really hot, you have to go for ceramics, I think. Of course if you have wax (or any low melting point stuff) you've immediately got investment casting in the bag. But an RP machine that could directly deposit ceramic slip; there's an idea...
Not too different to depositing icing either. Just not so tasty :)

Vik :v)
Now I think of it, I've seen slip deposited before. I was at one point considering a RepRap-like project using just a slip printer and discovered that NASA had built one. They were inkjetting ceramic parts onto a hotplate. As they built up each layer, it dried due to the heat from below. They could graduate the material through the part, moving from a ceramic, through a creamic/metal composite to pure sintered metal at the other end.

Vik :v)
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