Introductions

[Tox]

Picked up @makerbot_97 and have it running in the East Bay. Took about
a month to get it working smoothly and correctly due to omissions (now
fixed) on the wiki. Been printing white ABS, with nut, with added heat
sink on heater barrel, no ceramic tape, onto acrylic base, at around
230 deg. Just got back from having it running most of the weekend at
the Hackers Conference, cranking out Reprap Mendel parts (and an award
base).

[Bob Hearn]

After seeing yours run over the weekend, I'm sorely tempted to get
one. One thing holding me back right now is hints on the website that
support material is coming. Most things I'd want to print (twisty-
puzzle pieces) have sections with > 45° overhang (though could
potentially be printed in two pieces, and snapped together...).

[Tox]

The last bit I saw suggested possible use of PLA as support material
since it dissolves in drain cleaner, leaving the ABS untouched. The
Makerbot doesn't really support dual extruders at the moment, and
support for dual extruders seems to be somewhere down the road for the
reprap mendel.

What might work, but I have not tested, is enabling "support" support
in skeinforge, then printing in abs with different temperature to aid
breakaway.

Scott

--
Scott Small

[Eric Smith]

> What might work, but I have not tested, is enabling "support" support
> in skeinforge, then printing in abs with different temperature to aid
> breakaway.

I wonder if that's how the Stratasys Dimension BST (e.g., the one at
TechShop) works, as it uses gray ABS for the support material. Or
possibly they have some additive in the gray ABS? Might be
interesting to buy some of the Stratasys support material and try
printing something partially out of regular black ABS and partially
out of the Stratasys support material, to see if it breaks away
easily. Expensive experiment, though, as the Stratasys cartridges are
fairly pricey. I think their filament diameter is closer to 2mm.

[Tox]

My understanding is that they were using a chemically different
material for the support, but I've not played with it.

--
Scott Small

[Eric Smith]

The soluble support material is obviously chemically different. What
I'm wondering about is the "breakaway" support material used in their
less expensive models. I was told that it was ABS, but there's
obviously something different about it.

[Tox]

Oh. Might be same material w/ different temp at boundaries too.

--
Scott Small

[Eric Smith]

Do you mean that they might just be extruding it at a different
temperature, preventing it from bonding as well? It would be great if
we could build breakaway support material that easily, by just using
two plastruders at different temperatures.

[Eric Smith]

A little research turned up what Stratasys uses for breakaway support
material. It's ABS with a filler of up to 80% polystyrene copolymer,
to reduce the surface energy of the ABS, producing a weak, breakable
bond. I'll see whether my plastics supplier can make me some filament
to test.

I know the motherboard was designed to handle it, but is there
physically room in the MakerBot for a second plastruder?

[Tox]

I believe that was the model and that you can do it with one head if
you accept thermal cycling time. That said, haven't tried it yet but
have a model that will need it so likely to test soon.

Tox

--
Scott Small

[Tox]

> I know the motherboard was designed to handle it, but is there
> physically room in the MakerBot for a second plastruder?

Not for multiples of the current plastruder design but there are
several ways I can think of to hack it together.

Tox

--
Scott Small