3d printer without access to a 3d printer

Hello RepRapers, I've encountered a problem which I seem to require assitance with.

So I've designed my own printer. I'm starting off big in more ways than one. This printer is the first I've ever owned. I've bought myself RAMPS, as well as a j-head hotend which I have mostly assembled (Kapton tape is hard to come by, but I heard muffler cement works for the Thermistor and the Heater, but I'm not sure) and Nema 17s. Anyway the printer I've designed has a steel chassis and a 30x60x30 cm print area. Talk about starting off big. But I've lost access to the printer I planned to build the peices on. So my current goal is to get it working using duct-tape, hot glue, and hope, long enough to print out new peices for itself.

I've got most of it worked out, but my current problem is I need to make a bowden extruder using as little as possible. I can easily make most of it out of wood, but when it comes to the extruder I'm coming up blank. Wood seems to be the ideal material *Shudders at the thought of subtractive manufacturing* but I'm not sure how you would make the extruder work. If anyone has any ideas that would be fantastic, I've scanned the internet to the best of my ability and am coming up blank.

- Coatduck

Here is a bowden extruder made out of wood.
Here is an extruder made out of junked printers and computer cases.

That was fantastic! I took some of the ideas from that (I'm looking to build a Direct Drive extruder) and I've designed my own off of it.

Now my only big issue is to assemble the J-head. Does anyone have any ideas about something a little more solid than Kapton? I think that Muffler cement is looking pretty good, but I would like something like Glue or Cement, I feel like Kapton tape is a little less . . . Permenant, and a little flimsy. It's also very difficult to come across.

I have seen a production bowden extruder that appeared to be nothing more than a NEMA 17 geared motor and mount plate, a knurled brass pulley on the stepper motor, a lever, small bearing for a pressure roller, and a spring to hold tension. Nothing that anybody couldn't slap together with a hand drill and some flat "L" brackets from a hardware store if they were desperate.

Let me serve as a warning beacon for securing your thermistor in a J-head. I didn't have mine seated with full contact to the metal of the heated block. It popped out slightly. The electronics compensated for the falling temperature reading by raising the temperature. By the time that I smelled the PEEK tube melting, the brass had already fallen free from the black goop and onto the build platform. The sad part is that I was doing a PID auto-tune run at the time, and that poor J-head never even saw filament before it met an untimely demise.....

If you want a professional-looking thermistor mount and not a kapton tape job, this not-so-popular option is out there:

http://www.ebay.com/itm/Modular-Screw-on-M3-Stud-Thermistor-for-Reprap-Prusa-3D-Printer-Hot-End-Hotend-/221312429218?pt=LH_DefaultDomain_0&var=&hash=item33873faca2

I cannot comment on if/how the extra mass of the threaded adapter will delay the temperature readings, but there must be some reason why they aren't in common use.....

I just use furnace cement - the stuff that is used for repairing cracks in a brick fireplace - for securing the thermistor and resistor into the heater block of the J-Head. Holds up well and no worry about the thermistor falling out and the hot end melting. However, if the thermistor leads break, it makes it more difficult to replace.

My Thermistor has some slop in the thermistor hole of the J-head. Do you think the Furnace Cement will conduct enough heat to get an accurate reading?

Can you post drawings for your Bowden extruder? Pics or it didn't happen

Edited 2 time(s). Last edit at 03/08/2014 05:07AM by Svdharma.

I had the same problem, I threw this extruder together in an hour or two using random bits I had lying around. Instead of an air fitting I just threaded a hex nut over the tube and cut a V in the end so it can get close to the bearing and gear. The gear is supposed to drive a belt but till I get something better it will have to do. Use the smallest gear you got so it has more torque. If it can't push hard enough I'll add another spring or some weight to the bearing arm. It ain't pretty but it pushes plastic. I'm building everything out of wood and whatever I got laying around. I'm waiting on a hot end... I tried building a hot end but I need some teflon tube. It's on the way.