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

Fabric painter kit from craft store
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!)



Cheap-o air pump
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.


syringe system for painting/printing
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.


Contents may vary 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?




Finger valve open 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.




Finger valve closed When your finger covers the hole, the paint flows.



Writing 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.)



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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A $20 hackable extruder for your artbot or 3D printer | 7 comments | Create New Account
The following comments are owned by whomever posted them. This site is not responsible for what they say.
A $20 disposable microdispenser - just a remarkable!
From: Anonymous on Tuesday, April 17 2007 @ 10:24 PM PDT
This is a terrific find. An air powered, finger-controlled microdispenser for glue or solder paste, at a disposable price. Throw away the cheesy pump and hook it to your lab air.
Very nice find.
Finger valve vs. pulsed power
From: Wikkit on Wednesday, April 18 2007 @ 03:54 AM PDT
Pulsing the power supply will create significant lag when you want to stop the flow, as the pressure in the line will have to dissipate. Retrofitting the existing control with some sort of solenoid valve would offer better control and simplify the programming on an automated device, though it would be very easy to spend more on a solenoid valve than you did on the extruder.

I think the ultimate best use for this device would be to take it apart and see exactly how everything works, and see if there are any clever bits. Then build a new one with lessons learned that will run on the aforementioned shop air.
A $20 hackable extruder for your artbot or 3D printer
From: Forrest Higgs on Wednesday, April 18 2007 @ 09:16 AM PDT
Aquarium pump... perfect. That's just what Adrian Bowyer's support material extruder prototype needs to get rid of that big recycled plastic soda pop bottle.
A $20 hackable extruder for your artbot or 3D printer
From: Anonymous on Wednesday, April 18 2007 @ 01:38 PM PDT
The parts list here could be purchased all for less than the initial $20 that you invested.

Syringes of various sizes are available at your local drug store. They also have tips ranging from extremely small to just up over 1/32 of an inch. Possibly bigger, if you order online.

Tubing is available at any aquarium/pet store. Also hobby stores have silicon tubing, which is chemical resistant and very pliable.

The aquarium pump you already solved. Much higher pressure, as well as long-term reliability.

It's a great idea, but at the same time the parts were already readily available from various sources.

I'm not saying this isn’t a good starting point--but at the same time, you make it out to be that this is the only solution. I will have an instructable online sometime in the next couple of weeks on how to make an extremely accurate extruder from two syringes, and an aquarium pump.