Tugboat's 3D Printer Build

As some of you are aware, I'm building a 3D printer. The one I'm building is from RepRapPro.com and it is the Mendel Tricolour (hey, they're British). It comes as a fairly heavy box with all the parts in it, lots of assembly required. And lots of attention to detail. A digital caliper is very useful in this! The kit comes with a lasercut measuring dingus that is also very helpful. Once assembled, the Mendel can print in several different plastics, like PLA, ABS, and polycarbonate (yeah, the stuff bulletproof glass is made from). ABS is good for boat battling as it takes hits very well. I've used 1/8" thick ABS for SS and details and it's never cracked and doesn't even dent much. The cranes on Lil Scharnie are unsupported 1/2" wide strips of 1/8" and they've been abused mightily without signs of distress. There are also other plastics that will work. One cool trick is to use a plastic called SIL to support overhangs that are too extreme to print in free space, or for the insides of complicated parts, printing the object itself in ABS. After it's printed, you dunk the part in a chemical called Limonene, which dissolves away the SIL, leaving the ABS unharmed. Pretty slick!
Being a 'Tricolour' means that this version of the Mendel has 3 extruders. This means that I can print in 3 colors, or in 3 different types of plastic, without stopping the print. A picture of where my Mendel is at (progress-wise) is below, taken 2 days ago. Since this one was taken, a lot of wiring has been routed. It takes time because you have to make sure that no wiring bundles will interfere with the moving parts, and to make sure that you're going to the right connector! Some of the wires require soldering, but the instructions are pretty good, step by step walking you through the assembly. I've also used the RepRapPro forums and the RepRap.org forums for help when I had questions. The open source community is really good about advice and sharing best practices.

The nice thing about buying this kit (of an open-source design) is that you can do cool things like download the file for the parts, and print yourself a full set of spare parts for the printable pieces! Totally legal and actually, the company tells you that that's something that they recommend, so that if one of the printed parts breaks, you don't have to wait for support to mail one to you.
I'm getting closer to printing my calibration runs, and after that, I have been sent files for turrets and other parts, and I've got superstructures drawn up for SMS Scharnhorst and HMS Queen Elizabeth (1943). Photos will be posted here as I make progress.

 

A 1kg spool of filament costs from $30-40. Doesn't sound like a lot, but it is. A 12"x36" piece of 1/8" ABS doesn't weight nearly that much, and it's plenty of material. The big advantage for superstructures is that you can print them with things like doors, portholes, platforms and splinter shields as part of the SS. 3D printing tends to leave little lines on the surface from all the layers, but there are some tricks to remove those. Show and tell will be fun.

 

Heh. Not sure I'd want it, as with my printer, I would only be able to print her in 8" x 8" x 5" sections... ew!

When I get home, I'll post a pic of where the Mendel is at this point, and a few renderings of objects that I've drawn in Sketchup to try printing.

 

Updates are late, but I got a lot done! As of bedtime last night, there remained only 8 wires to hook up: 2 wires for each of 3 end stops (X, Y,and Z axis), and the temperature sensor for the heated bed. Before I leave for work this morning, there will be 4 or less remaining

You can see that I organized the wire bundles a little with cannon barrel armor black Radio Shack wire loom. This also helps make sure that none of the wires get caught in moving parts. The Z-axis moves up and down, the extruder head (on the X axis) moves side to side, and the whole heated bed (on the Y axis) moves front to back. So organizing the wires is important. I was very happy with how the instructions broke this down into single-step endeavours, with bright pink lines tracing where each wire bundle should be routed along the frame. You can see one wire bundle looped waaaay out to the side... that's the wires for the X-axis motor, which have to have enough extra wire to allow full travel ont he Z-axis. Down lower, the white wire (and for people with young eyes, the little tiny orange and white wires) that loop out a bit less are for the power to the heated bed, and the temp sensor thereof. Need enough loose wire to let the bed travel unimpeded. The wierd-looking loop of ribbon cable and white plastic tube at the top are wires from the extruder to the hot end, and the Bowden tube to the hot end. Class: the Bowden Tube is what carries the plastic filament from the extruder (which pushes the filament) to the hot end (which melts it and deposits it).
Tonight, we plug it in and see what happens!

 

Woo! It took longer htan I thought to finish the build. Lots of wires and things that took time after the actual mechanical assembly was complete. So last night, I took the power supply out of the box and WHAT!?! I have to wire that, too!?!? So, I did not get the printer printing last night, for want of a power supply. The PS is almost done being wired, so hopefully tonight I will get some plastic melting in pleasing shapes.

 

I am ready to connect the power supply to the Mendel, but my stupid multimeter died. Since I wired the power supply, I will not connect it until tomorrow when I have a new multimeter to make sure that I didn't do anything that would blow up the Mendel...

 

Nah, had to stop for a few weeks because of the carpal tunnel surgery. Getting back to it this weekend! I have to check the voltage output of the power supply, and connect it, and I'll be printing

 

Actually, last night, I completed the final voltage checks on the power supply (20A at 12V, don't want THAT going wrong) and it's hooked up and ready to fire up. Tonight, we print!

A few calibration shapes, and then turrets and other fun things!

 

I have been wondering this myself, ABS _should_ be able to hold the pressure if it's done right (thick enough walls, etc), and that leads to some VERY interesting cannon stuff. Early on, just new magazine shapes (nice tight helical feed mag has been proposed; Brian and I tried one many years ago but it never got ready for prime time), later, entire cannons, apart from barrels and magazine caps. IF and only IF they can be done safely. Hope so, though, it'd go a long way towards the cheap entry-boat project reaching fruition, along with the printed hulls.

 

Have to print some stuff to compare. But printing it with support structures built in should save weight. I did some quick measuring and I can print a Gearing in 2 print runs.