A $20 hackable extruder for your artbot or 3D printer

Tuesday, April 17 2007 @ 01:30 PM PDT

Contributed by Lenore

Fused deposition machines are an interesting class of rapid prototyping and art robots, capable of extruding paint onto a canvas or extruding to build up complex, three-dimensional objects one layer at a time. Naturally, one of the challenging parts of designing machines like these is designing and building a system for dispensing the printing medium. So, imagine how surprised we were when we were walking through the aisles of our local Michaels craft store and saw a pre-built extruder on the shelf for $20! Naturally, we picked one up because an extruder head might make a nice accessory for our own three dimensional printer.
So, what is it? It's an inexpensive kit that can be used for developing your 2D or 3D printer extruder with an air-powered delivery system. For the price you can get a small air pump, tubing, syringes, tips, and dispenser. The components are simple and easily hackable, and it looks like a good set of tools for starting to build a simple extruder head for an art bot of some sort.
Quite mysteriously, this kit is not actually advertised as an arbitrary material extruder kit, but rather as "the ultimate fabric painter." This is very strange because not only does the kit not include any fabric paint, but it's not obvious that there's any advantage whatsoever to painting fabric with this method. (Actually, if the picture on the front of the box is any indication, there may even be disadvantages!)

The pump uses two 'D' cell batteries, which means there is plenty of room to put in a small 3V power supply. There is even a small screw hole in the case that could be used for feeding wires in. You can add a little relay or transistor to control your airflow and you're in business.

The kit has several foam stoppers with a hole to admit air to the syringes when they are in the applicator. There are also rubber stoppers and various tips and caps.

The instruction booklet is generally terrible (throw it out and substitute common sense), but the box does suggest that the kit can be used for things other than paint, including glue.
While you could probably get most of the parts for about the same amount of money, the applicator is not readily available and it is awfully nice that it is all together in one kit.
And what the heck does "contents may vary" mean?

The applicator works with a finger valve. When the finger valve is open, the paint doesn't flow.
For use in your robot, plug the hole permanently with silicone and pulse the pump power instead.

When your finger covers the hole, the paint flows.

Just to show some potential for this machine, we tried it out with frosting, and it worked reasonably well. (Even the reprap folks seem to be interested in sculpting frosting.)

Finding the right rate to move the tip at is tricky, but once you program your robot to do it for you, you won't have to worry about the shortcomings of human beings.

Update: We tried swapping out the rather weak pump that was included with a $10 (still inexpensive) aquarium pump and had good results. The tubing fit nicely and the air pressure increased significantly.

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Comments (7)

Evil Mad Scientist Laboratories
http://www.evilmadscientist.com/article.php/fabricpainter

	The instruction booklet is generally terrible (throw it out and substitute common sense), but the box does suggest that the kit can be used for things other than paint, including glue. While you could probably get most of the parts for about the same amount of money, the applicator is not readily available and it is awfully nice that it is all together in one kit. And what the heck does "contents may vary" mean?

	The applicator works with a finger valve. When the finger valve is open, the paint doesn't flow. For use in your robot, plug the hole permanently with silicone and pulse the pump power instead.

	When your finger covers the hole, the paint flows.

	Just to show some potential for this machine, we tried it out with frosting, and it worked reasonably well. (Even the reprap folks seem to be interested in sculpting frosting.)

	Finding the right rate to move the tip at is tricky, but once you program your robot to do it for you, you won't have to worry about the shortcomings of human beings.

Update: We tried swapping out the rather weak pump that was included with a $10 (still inexpensive) aquarium pump and had good results. The tubing fit nicely and the air pressure increased significantly.