Printing in 3D with RepRap Prusa!

So, things have been a little quiet here lately - the combination of work, Skyrim, and frankly, life, has been a total drag on my reality.  Loosing relatives always sucks, no doubt about it - but it's been one hell of a year - and I'm not alone in that I just want 2011 to be OVER!

On the good news side of things, my project for the last 3-4 months has finally produced some real outbound, rather than just being a tinkerers dream.  I got my RepRap printer going at last - and I've been now working on the next challenge - actually printing things!

Now this thing has been a challenge - at first I tried using my RAMPS 1.4 with the RepRap firmware - apparently most folks consider this a mistake - the Sprinter firmware is evidently much better - and I'd have to agree.  I'm glad I bought my RAMPS from Ultimachine - they're one of the two great American sources for bot parts I've found.  Lulzbot is the other, FYI.

As for the software controlling it - Pronterface is also the king of that realm in both PC and Mac - although it's no cakewalk to install - and then there's the entire mess of choosing how to perform your slicing - and it turns out that slic3r is the Mac best option there - the Skeinforge program does look good, but it's got a slew of defaults that just don't seem to count - and the latest versions insist on dragging the printhead around the for a few layers first, why, I have no clue.  Perhaps if I ever build a CNC or something...

So, here's the basic gist of what I'm up to - first, using Google Sketchup to create stuff in millimeters - then using a Sketchup plugin to export the models in STL format - then plugging those STL files into Slic3r, then finally loading those into Pronterface and letting the printer try and print.

And what a learning experience this has been - getting the Z-axis aligned is a total pain - and even worse is figuring out how to best adjust the extruder rate!  Right now, with the soft ABS that I got from Harout, I'm running the printhead at 240 C (need to recompile for the new printhead, so that temp might be off), and what's more, getting the first layer to stick is a REAL challenge with these.

I'm just glad I got the Budaschnozzle working nicely - it was the most trouble-free thing about this adventure.

So, just to share some experiences with folks, here's my first printhead design - using a 10watt resistor (resistance is too high - never got hot enough) - did melt some stuff with work, but not a good seal to prevent backflow!

As you can see in this pic, the backflow really got in there - no matter what plastic I used - and I clogged it with blue and green ABS as well as PLA.

A common beginners design flaw here - too much standoff between the heat and the output - by the time the hot plastic comes out of the mig welder tip here, it's too cold to stick to the print bed!

I got no decent output from this one - just some lumps of melted plastic.

Design #2 wasn't kept around, but well, it was .5 ohms of nichrome wire wrapped around a mig welder tip - and it lit up like a 40watt bulb for about 5 seconds too.

Design #3 was a pure Radio Shack version of the printhead - while I was waiting on a shipment of appropriate nichrome wire - I started building extruder head #3 - and that produced this one:

Now this one did have a fighting chance - it was six 10ohm 1watt resisters in 3 parallel strings of 2 resistors in series.  It heated up very nicely, and the JB Weld kept them on the aluminum heating block nicely too - however, once I tried using this with the green plastic, well, things got bad - the heat was too much for it, and it desoldered the resistors - and shorting out the circuit.  Once the resistance was out, it solidified, and then the pressure pushed it out of the teflon retaining tube.  On the controller side of things, the 10amp fuse never really protected the circuit so much - as did one of the traces on the RAMP's board! Fortunately, I was able to lay down some wire and solder and bring it back into workable shape!

Design #4 came into play once I got the nichrome wire that worked - it was 7.5 ohms for foot, and had insulation too - so it was perfect.  I immediately wrapped this up into a new single MIG tip once again, even put some insulation on it - and this sucker heated up FAST.  Once it was warmed up, I was able to get some action out of it - however, there was major backflow in this design too - so much that it even blew through the JB Weld holding it in place on my teflon tube.

I finally bit the bullet and bought the Budaschnozzle from Lulzbot and immediately found out that I needed a couple of 4x30 screws and wingnuts and washers so that I could attach the thing to my printer.

Their design was different, but actually works quite well - kudo's to the Budaschnozzle - I've printed plenty so far, and my biggest problem is Z calibration.

My first real prints were to get more endstop holders - the ones that came with my original printer were not nearly as durable as I'd liked, and so I set out to print more of them - except that the plastic I used at first was hard, and wouldn't flex nicely - I got these, but was still having troubles with lack of stick to the bed - that pesky Z axis..

Eventually I got things to stick better, then started working on the flow rates - and that's looking better now too.

I tried printing one of the BIG prusa sleds, but I gave up - too many parts, and still have not mastered the art of getting the first layer to work perfectly.

Now I'm a few parts in and having some real results.  Wowsa!

Thats all for now folks!