Re: [CAD_CAM_EDM_DRO] Re: 3D printer fun with powder

Hi Graham

I'm following this very interesting thread since a while ,thanks
Graham to try to remove overload zeros after the coma ($)
to afford such a project !

Did you ever test some alginate powder stuff then just "print" over it
some colored water ,i'm very curious about the result...??

Alginate is too souple for make some solid prototyping models but
maybe ,adding some percent of an hardener other kind of powder ,
could make a more solid state proto ?

I have no idea about the transparency ,just this powder is white
when it's dry ,and green for the dentist quality (menthol adding)
the Alginate dentist quality is better ,and the percent of water is
different :
1 water/5 powder
standard is :5 water/1 powder

this is a link for some differents Alginate flavours

http://www.accu-cast.us/prod_liqui-stone.html

it's a very affordable material , the drying time is very short ,more
for thin layers, and seems compatable with very little amount of
wet (close to fog) printer head spraying , ajusting the setting of
the ""paper" in the printer config
allow to adjust the amount of wetting (wet.fogging ?..sorry
about the bad wording !)

I have no idea about how to sweep the powder ,maybe the
copier option as describe Mark is not too far from the truth.
just ,it's very closed with an electrostatic process ,thing which is
not very comfortable for DIY unspecialized devellopers.

If this alginate powder stuff was yet discuted then ignored or
didn't permit to get some optimists result ...sorry , forget
this message..!

thanks again ,(Graham,all),

thierry

----- Original Message -----
From: "Graham Stabler" <grezmos@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Friday, June 22, 2007 12:55 AM
Subject: [CAD_CAM_EDM_DRO] Re: 3D printer fun with powder


> Well I tried with a bigger roller on its own and that didn't help.
>
> Then I baked the powder and pushed it through a finer sieve using a
> rubber spatula.
>
> That has definitely improved things, of course I should have tried
> just sieving and then baking and sieving but heck, sue me. Dryness is
> definately a good thing anyway.
>
> I added a strip of acetate as a squeegee for the roller to prevent
> lots of powder getting thrown back, this also helps and is better than
> the rubber one I was using yesterday.
>
> Then I played around with speeds and feeds, its filling the gaps in
> the build area better but only if I really move the gantry fast,
> otherwise I get the sausages.
>
> Then I remembered an experiment I tried yesterday, basically I tried
> pushing the gantry by hand while rotating the roller by hand very
> slowly, basically fast enough such that the linear speed of the roller
> surface was just faster than the linear speed of the gantry.
> Yesterday I saw the lovely clean surface left behind the roller but
> the powder coated the roller and eventually it came over the top and
> made a mess, today I have the squeegee reinstalled and improved.
>
> The corn flour is strange stuff, I don't know anything about powder
> science (if there is such a thing) but I'm getting a feel for it. If
> you try and push the powder with a straight edge it tends to dig in to
> the layers beneath and sort of tear the surface but if you push it
> with a rotating roller, that will tend to lift the powder preventing
> it from digging in, it stands to reason that it only needs to spin
> just fast enough to do this. At least I think it might, I need to
> experiment further, my motor does not go slow enough. Ideally I would
> sync the gantry and roller, I may try that if it seems like a winner.
>
> I'm covered in powder :) A drugs bust is probably imminent if the
> neighbours spot me.
>
> Graham
>
>
>
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