A basic structure and mechansim Re: 3D printing, powder spreading

Graham -
You may not have to "worry" all that much about the "pits and bumps in
the road", or not at least for your feed section...ZCorp illustrates a
"particular" method of levelling, tamping, re-levelling, smoothing the
powder at the top of the build...they make it seem like it needs to be
perfect - it absolutely doesn't. The snowplow roller does an
incredible job of flicking the powder up and making the layer smooth.
I had completely done away with the tamping process in the feed bin,
and I believe, have more consistent models - certainly less mess and
wasted time. If there's a 1/8" divot in either side of the powder
surface at the beginning of the build I typically ignore it - the
excess powder fills it in fine. I do start the build on about a 1/16
to 1/8" of dry powder; this makes it a lot easier to depowder and
remove the part after the build, plus, it isn't "glued" to the build
plate.

The commercial unit uses a single pillar screw system, perhaps a 3/4"
to 1" coarse drive, IIRC.
My shortened version (still proof of concept) I rigged with 4 springs
and a center-point cable draw. That works (sort of), but is limited to
about a 1" build height.
Most of the bulk of the commercial unit is dedicated to having a space
for the build and feed platforms to disappear into.

Yes, pix are on the way when I can get back to it....sorry for the
anticipation!

Ted.


--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Graham Stabler" <grezmos@...>
wrote:

>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "ballendo" <ballendo@> wrote:
> >
> > Concern is for their round areas. The "snowplow" will be working
> > over an area (between the two) where no rise and fall can be
> > accomplished.
> > I'm visualising problems due to that with scatter, uneven layering
> > in the build area, and powder build up...
>
> I've thought about this and it won't cause a problem, the area will
> simply get a coating of powder at the same height as the roller, it
> can't build up because it gets ploughed as well.
>
> If I knew all of this was going to work I would build the machine
> proper but I don't, this will work or at least work well enough to
> check. Cutting the end off pumps, hole sawing some receptacles in the
> mdf base and adding a single threaded rod and nut in the already
> hollow handles is all that is required. That's 5min. All this
> cutting and gluing perspex is a big job in my workshop.
>
> Graham
>