RepRap acrylic extrusion using hotbed

[Nophead] started the year off by successfully extruding acrylic using a RepRap machine. The problem when working with this material is that when the hot ooze hits the cold air the printed material tends to warp, badly. [Nophead] raised the ambient air temperature around the part being extruded by replacing the bed of the RepRap machine with a heated aluminum plate.

We took at look at his build details for the hotbed. The plate itself is aluminum that he had milled by a machinist friend of his. It looks like the heat is produced by a network of power resistors bolted and soldered to the bottom of the plate. The original idea was to produce a controllable SMT soldering platform. Unfortunately this heating method doesn’t have the power needed to raise the temp quickly but that failure turned out to be a RepRap success.

Comments

  1. The Moogle says:

    hmmm I wonder how long it will be before someone takes CD case plastic grinds it into dust then melts it into something new :)

  2. stunmonkey says:

    Cool, with the help of a machinist and a milling machine, a Rep Rap came closer to doing something marginally useful.
    Actually at failed at attempting something useful, as opposed to failing at something useless, but that is still a step up.

  3. loans says:

    he describes his problems not as warping, but rather of material adhesion. He writes that the acrylic wouldn’t stick to anything (I guess meaning as it was extruded it refused to hold its shape on the bed.)

  4. andrew says:

    Fascinating read here too: http://hydraraptor.blogspot.com/2010/01/hot-bed.html

    He discussing warping there too but the more interesting bit is how he figured out how to control the temperature of the plate.

  5. nave.notnilc says:

    calling this a reprap machine is rather inaccurate, it doesn’t use any of the electronics or hardware that are part of mendel, the official design.

  6. stunmonkey says:

    Nave is correct, this is just a CNC extruder-based system, a general classification of machine, of which there are hundreds of designs, RepRap being one of the least evolved or functional.

    This is NOT based on the ‘one true’ extruder-based system that has become an object of worship.

    I keep forgetting there is an “official” design and set of religious canon around this subject.

  7. casainho says:

    I just made my heated build platform after seeing NopHeap message. It works very well on plastic sticking to build platform and at same time avois almost the warp!

    And my is a RepStrap, also a CNC, controlled using EMC2 on GNU/Linux Ubuntu.

    Here pictures and more info about my heated build platform:

    http://casainho-emcrepstrap.blogspot.com/2010/01/perfect-build-platform.html

  8. Charles says:

    @stunmonkey

    You are wrong sir. The Mendel version (official version of RepRap) is the most evolved open source 3d printer on the net. Some people are just angry that RepRap succeeded at bring 3d printing to the masses @ less than $1000USD whereas other designs out there are running at the $2k-$3k price range. Makerbot’s Cupcake, Bits from bytes printer and Rapman are all children of the RepRap project. All are capable of resolutions of 0.1mm or less depending on fine tuning. Not to mention the other hundreds of RepStrap designs out there that all spawned from the RepRap project.

    Furthermore iirc Nophead is a member of the reprap core team. Nophead’s experiments have been very beneficial to the reprap project. His blog is one of the first I check every day for updates.

  9. I like the “jeweling” done on the tabletop. It makes it look like the bolt of a firearm or the insides of a watch. Because of the “jeweling” I’m guessing the plastic sticks better and warps less.

    There’s plenty of space on the underside of that table, so I see no reason why he can’t add more resistors to get a faster warm-up. It would sure be neat to see a toolhead mill a pcb, dispense solder paste, pick and place parts, and finally heat to the reflow point to create a circuit board.

  10. Colecoman1982 says:

    Hey look everybody, Stunmonkey is back. It’s been a while since I’ve seen anything from him. For those of you who don’t know him, Stunmonkey doesn’t seem to post anything that isn’t an anti-reprap troll. I’ve even seen him follow reprap news posts from here onto Makezine blog. Personally, I question whether he’s actually capable of posting a constructive/positive post on anything.

  11. jproach says:

    @Standard Mischief: they actually print on a piece of acrylic that sits on top of the aluminum. The aluminum is just a good way to get an even temperature across most of the build platform. I agree that it looks great though.

    Here is another similar design: http://pleasantsoftware.com/developer/3d/2009/11/12/canned-heat/

  12. Brian Aday says:

    Next step, put a reprap in an oven. We have an extruder type commercial machine which builds in an oven and cools the finished product slowly.

  13. stunmonkey says:

    Nah, you are just pissed because I have positive, useful contributions to every subject BUT the RepRap. Of course, thats likely because it is stupid and misguided in the extreme, and generally supported by religious zealots.

    Charles is my favorite, can’t make a logical rebuttal, so he opens up with that old lie that RepRaps are somehow at the top of the heap development-wise, and the old straw man about how opponents to this idiocy are just somehow part of a larger “conspiracy” to keep cheap machines out of peoples hands. Um, yeah. put the tinfoil hat away moron.

  14. stunmonkey says:

    Yes, you have indeed uncovered the conspiracy.

    I am actually THE MAN, and I am, personally, keeping you down.

    I am currently sitting atop an egregiously expensive CNC machine and a pile of suppressed patents, smoking a cigar and laughing at my evil plan of WORLD DOMINATION to keep defective plastic spewing tinkertoy sets from the hands of the proletariat, in order to starve the poor and to prevent them from somehow saving the world with RepRaps.

  15. ladz says:

    I’ve been looking at RepRap for years. It seems neat, but nobody is actually making any of them. It’s nearly impossible to find anybody selling the funky plastic parts necessary, and they are quite difficult to machine. It’s a long way off from “find a friend who has one to make them for you.”

    Seems cheaper and more effective to scrounge the parts to make a more normal cnc router out of eba* stuff: 8020, commercial linear slides, old servos with Gecko or UHU drives, etc.

  16. w33d says:

    Would it be possible to use hot glue at specified temperature and freeze it with a breeze pumped to?

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