Sunday, April 18, 2010
inexpensive, simple, acrylic makerbot-inspired 3d printer with heated table and build chamber
I thought I'd take a second to post some pictures from a design that my father and I have been working on for a while. Our goal, after making a 3d printer with a much larger bed size, was to make a smaller table-top one that I could keep with me in my apartment. Being a grad student (poor) who doesn't like the smell of heated plastic, but who also wants fantastic prints, we set out to design something inexpensive with a contained chamber, with a print size at least the size of a makerbot. In the end, my dad did a fantastic job designing and building the machine, and I think it has some neat features with respect to their simplicity and inexpensiveness that future designs might consider or adapt.
Overall, the design probably cost around $200-$300, all said and done (minus the 5lb spool of ABS plastic). We built 2 sets of makerbot electronics for about ~$225 (so, around $100 for one set), probably spent around $100 on extruder parts like the motor, barrels, and things (these have become pretty expensive as of late from makerbot... I think our first extruder using bits from the RRRF was probably only $20 or so :) ), and finally there's probably about $50 of acrylic for the sides and z-axis. We had some $5 steppers hanging around for the X and Y axes, where the slides were taken from matched sets of old inkjet printers, and the Z-axis stepper is from an old plotter.
Probably the neatest aspect of the design is the Z-axis. It's a "cigar box" design, and is almost entirely made out of acrylic. The essence of the design is that a large rectangular piece of acrylic moves up and down along the Z, sandwiched between several other pieces of acrylic. A single threaded rod is used as a lead screw (compared to four threaded rods with the Makerbot design), and the MK4 extruder mounts to the Z using a right-angle bracket. The advantages of this design compared to the traditional makerbot design are that it's likely far less expensive to produce and requires far less parts (no timing pulleys, belts, and one quarter of the lead screws and nuts), and as such is probably much easier to align, too. If you laser-cut the parts, you could probably have a simple design that would cut out on a single sheet, and end up with a complete Z-axis that you could bolt together fairly easily, as well. The disadvantages are that the design needs to be able twice as tall as your maximum build height, but that's not too bad at all if you only have 6-7 inches of Z travel -- infact, its probably about the same height as a makerbot right now).
Other bits of interest include the build chamber and the magnetic heated build platform. The build chamber currently isn't actively heated, but from the heated table and a fan on the variable voltage regulator, it gets up to around 40°C while building. The nichrome wire for the heater barrel is 8 ohms rather than 6 ohms, to give a bit larger heat zone, and we run it a bit higher than 12v. The table has four 2 ohm (25 watt, I think -- from memory) power resistors, and it's fed with about 18v, and heats up to 100°C in a couple of minutes (it's very fast).
I've included bunches of pictures below. As always we're happy to hear comments or questions.
The build was the 'tin-tin' rocket from thingiverse, which I figured would be a particularly challenging raftless build given that the only contact points between the table and the model are three ~2mm points. (I paused and added a little tape to the build at one point, and held it in place near the very top scared that it would fall off, but I really shouldn't have done this because it was doing fine and now the top is a bit funny... :) ).
(click on the thumbnails for larger pictures)
thanks for reading! :)
Major congratulations to you and your dad. :)
is there any chance you could put the designs/blueprints online?
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