Pumping melted wax for batik presents some problems as well as some positive
aspects.

• You only need to lay the wax down for absorption by the fabric, so exact
  dispensing of a volume is probably not as critical as for plastic
  deposition.
• But the wax will melt at a temperature depending on the wax you're using,
  beeswax, paraffin, microcrystalline.
  (Probably you are using paraffin as it is cheapest ?
  Melting point is between 46 and 68 °C (115 and 154 °F) depending on
  formulation.)

So you'll either need a pump design that:

• can be pumped clear,
• or a way to melt the wax in the head so that a cold pump can be rewarmed
  and work without damage.
• It will probably also need to be easy to take apart when warm, and clean.

The roots style pump might work but the wax is widely distributed in the
housing and you need good sealed bearings to prevent leakage.
The moineau (positive displacement pump) would be good but is hard to make.
Probably the best for your app is the peristaltic style pumps.
These do suffer from pulsing but the fabric absorption will probably
mitigate this and your flow rates are probably low enough to not make this a
big problem.

The tube which contains the wax, can be pumped (mostly) clear at the end of
a run, and can be enveloped in heat using a warm water jacket as well.
A stepper motor can drive the flow reasonably precisely for your
application, especially if geared down (you need a lot of force).

A design could be:

• Horizontally mounted with wax entry from reservoir above with a side entry
  tube and similar side exit at bottom.
• A water jacket around the entire pump which can be continuously fed with
  hot water to maintain the wax temp (and the wax reservoir above).
• When the wax is visually melted in the top reservoir then the printer is
  ready to go. A cap on the output would prevent dripping while heating.
• Silicon tubing is good to 200C so is ideal for wax and peristaltic flow.
• When finished make sure to pump the reservoir out and clear the tubing. So
  add a dump tank position on the printer.
• Failure of the heating does not require dismantling, just reheating to
  clear.
• But detecting a loss of water temp should stop the printer, to avoid gear
  failure when the wax solidifies.

Designs:
The pulsing is reduced by having more chambers. You need a tubing pump. See
here for design considerations:

• https://en.wikipedia.org/wiki/Peristaltic_pump
• http://www.coleparmer.com/TechLibraryArticle/579

You need a jacketed design but at least openscad can help you here. By using
the difference() function from a larger volume you can make an outer casing
to act as a water jacket.
There are a number of designs on thingiverse under peristaltic but many are
not parametric.
You will need a strong stepper motor and/or gearing reduction to add torque.
A stepper driving a planetary gearbox driving the pump might be ideal for
space purposes.
To start with:

• http://www.thingiverse.com/thing:8964
• http://www.thingiverse.com/thing:454702
  non scad
• http://www.thingiverse.com/thing:8652
• http://www.thingiverse.com/thing:254956

Good luck...

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Thank you all for your interesting posts.  As I noted in my second post of
the 23rd, I was considering a gear pump system like Nick Seidl's that can be
heated.  He designed it for molten chocolate so I only need to heat the
system another twenty or so degrees higher.  I am presently looking at
various nylons to use for the build and have come to realize that shrinkage
is going to be an issue with nylon. If these problems look too daunting, I
was considering an alternative where I adapted a metal syringe (Wilton
dessert decorator) to RichRap's paste extruder.  I could wrap the syringe
with a heated sheet. Dripping will happen but can be contained.  Again,
thanks for reading.

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I can't find Nick Seidl. Your second post is to a Vincent Li design.
If Nylon is not suitable - consider PET or PC
E.g.

• https://www.matterhackers.com/3d-printer-filament-compare

http://3dprintingfromscratch.com/common/3d-printer-filament-types-overview/#pett

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