

Pwdr - an open source powder 3d printer - kephra
http://pwdr.github.com/

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ChuckMcM
This is awesome, I had forgotten the kickstarter to make an inkshield,
apparently the guy pulled it off and made 'em [1]. Way to go. I apologize in
advance for killing his web site.

[1] <http://nicholasclewis.com/projects/inkshield/>

~~~
wetterhorn
Indeed, I've used an earlier version of Nicolas' inkshield for the Pwdr
machine, it works great!

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angusgr
My initial reaction was this might be a hoax, or at least vapourware, on
account of the lack of any print pictures or videos, just the very nice glossy
shots of the machine sitting idle.

However I did find one video: <http://www.youtube.com/watch?v=bzX5x1A1AMg>

And one photo: <http://www.thingiverse.com/image:161441>

So, seems the results may lag a bit behind the presentation, but this is still
really exciting to see. Fair enough for something they're calling v0.1, as
well.

~~~
wetterhorn
The focus was mainly on the machine and not the results, as they can still be
improved. But i've added a section on the Github website with pictures of
print results. Hopefully this proves that it isn't a hoax ;)

~~~
angusgr
Very nice, thank you!

Didn't mean to be too cruel about it, it's just that with a new 3d printer
announced almost every day I always look to see what the achievable print
quality is like.

It's a great project you're working on, I'm sure many people (me included)
will be watching closely.

~~~
wetterhorn
Oh no, I totally understand your first reaction. Hopefully, others will pick
up the project too and start experimenting and improving the machine. And one
of the reasons to get people's interest is to make it all nice and shiny. As
you've mentioned, a new 3D printer is announced almost every day, but 90% just
looks crap

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brntn
It's very superficial of me, but I wish more open source hardware projects
went to this much effort to "sell" their product.

Beautiful page design, well written copy, nice photography and a great looking
device.

~~~
schmrz
While I do agree that the page design is nice I don't consider this a good
presentation of the end product or an open source project. The first thing
that you should show if you are selling the product—doesn't matter if it's to
fellow open source developers or customers—is that it works. And the best way
to show that is with a simple and short video.

It could be of course that the presentation is not yet finished completely.
Nevertheless, the idea is really nice and I would love to see the project take
off.

~~~
wetterhorn
Thanks for your feedback. Meanwhile, I've added some pictures and a video of
the printer. A more extensive video should follow soon.

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Pirate-of-SV
Am I the only one waiting for a 3D printer which parts can be created with a
3D printer?

~~~
brntn
Isn't that the whole point of the reprap projects?

You're going to be waiting a while if you're hoping for a 3D printer that you
can buil at home and can churn out steel rods, bolts and belts.

~~~
kephra
Pwdr can do aluminum oxide and likely also other sinter metals.

~~~
Wingman4l7
A step in the right direction. I've always felt that home 3D printers will
truly become a game changer only when they can make _metal_ items, like
DMLS[1] does.

[1]: <http://en.wikipedia.org/wiki/Direct_metal_laser_sintering>

~~~
itmag
A machine that can make metal parts from a blueprint can also make all kinds
of weapon. Do you think such a 3d printer would be legally available to the
general public?

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Wingman4l7
Actually, there was a big kerfuffle on Thingiverse when someone published, as
proof of concept, a design for a plastic rifle magazine:
<http://www.thingiverse.com/thing:11636>

~~~
Wingman4l7
People have also done the lower receivers for the same rifle (an AR-15):
<http://www.thingiverse.com/thing:11770>

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tocomment
So how does this compare to the quality of the rep rap? Is this a better
approach?

~~~
ChuckMcM
It will compare badly at first.

RepRap/Mendal/Prnrbot/Makerbot all use a plastic extrusion mechansim (think
robo-spider) which can make a lot of cool things but cannot make a bunch of
other things. In particular 'spinning' machines (as I tend to think of these)
cannot make large overhangs because the material they are using has no
structural stability while being extruded. [1] The "Dual 'struder" on the
Makerbot Replicator opens the possibility of a 'support' material that can be
removed, this requires filling in with the support material to support the
non-support material being extruded over it. The support material is later
removed with a solvent.

In powder based machines the 'unbound' powder it its own support. So overhangs
are not an issue. The challenge with powder machines has always been that the
materials have relatively poor structural stability (in the cornstarch
variety) or require a precise (and) delicate sintering process, or a 'firing'
type process. In all cases having both bound and unbound material present can
challenge the finishing stages.

[1] These machines melt ABS plastic to the weak/sticky stage as they push it
out (typically 220 - 240 degrees). At that temperature a strand cannot hold
its own weight.

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tocomment
I'm not understanding how it works. Can someone explain?

~~~
printer
1: A very thin layer of powder (plastic) is evenly spread. Then the print head
prints a binder on the places where you want to create a slice of your 3D
model. Then another layer of powder is layered on top of it and GOTO 1. When
all slices are printed your 3D model will be covered in powder which is also
the support material for overhanging slices.

It's very hard to make this up from the photos but I think you can see the
container for the powder and model with a movable bottom.

-EDIT- This printer uses a binder, but other models melt the powder with a laser (Selective Laser Sintering).

~~~
tocomment
Thanks. A couple follow up questions:

So does the user sprinkle the powder after each slice, or does the machine
somehow do it? How would the machine make an even layer of powder?

Why doesn't the powder stick to the print head, or get pushed around unevenly
by the print head?

Why doesn't the powder fall out during printing?

~~~
printer
_So does the user sprinkle the powder after each slice, or does the machine
somehow do it? How would the machine make an even layer of powder?_

I can't make it up from the pictures, but most printers just trow a pile of
powder on top of the last layer and flatten this with an arm. But I think this
video will show it much more clear: <http://www.youtube.com/watch?v=wD9-QEo-
qDk> (take a look from 1:50).

 _Why doesn't the powder stick to the print head, or get pushed around
unevenly by the print head?_

Because the print head never touches the powder. Just like it doesn't touch
the paper in your inkjet printer.

 _Why doesn't the powder fall out during printing?_

Check the video ;)

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wetterhorn
Well, you've covered pretty much all questions, but here is a reply from the
builder :)

 _So does the user sprinkle the powder after each slice, or does the machine
somehow do it? How would the machine make an even layer of powder?_

The storage bin moves up a little and the build bin down, and then a counter-
rotating roller (mounted on the XY-carriage) deposites the powder from one to
the other bin.

 _Why doesn't the powder stick to the print head, or get pushed around
unevenly by the print head?_

Indeed, the printer head is mounted ±4mm above the powder bed and can never
touch the powder. See the printer head moving across the powder bed in this
video: <http://www.youtube.com/watch?v=bzX5x1A1AMg>

_Why doesn't the powder fall out during printing?_

Because the pistons form a seal and don't let the powder fall through.

