Like all of my blog posts this article is not intended to be a how to tutorial but rather just my experience and observations in building a 3D printer.
A few months ago I decided that I wanted to have a 3D printer. There are a number of things I have in mind to make with the printer. One thing is to make patterns for metal casting. Both sand casting patterns and lost wax (plastic) patterns. Also some of my other future project could make use of printed parts and I will probably make some artistic things.
The prices for off the shelf printers are a bit more than I am willing to pay so I looked around for what is going on in DIY for 3D printers. I like building things anyway. After a lot of digging around on the WEB I decided on building a Prusa I3 which is in the reprap family of printers. This printer seems to be quite popular and there are lots of vendors selling parts for them. To get just what I wanted I ended ordering parts from quite a number of different vendors mostly on Ebay.
One of the concepts explored with the reprap printers is the idea of a self replicating printer so many of the parts for the printer are printed parts. Of course when starting out you don’t have a printer to make the parts so you have to buy them. As long as the printer does not completely break down you can then make spare parts or upgrades.
Surprisingly I had very little problems with parts not fitting or being defective. The metal frame had two holes that were not tapped for screws. That was an easy fix as I have to proper metric tap. The finish on the metal rods used for the carriage motion was not the best and the linear bearings fit a little tight. I mounted the rods in the lathe and sanded and polished them and got them to fit properly. I should have ordered chrome plated rods. I spotted two solder shorts on the electronics boards before I assembled them. Again an easy fix with a soldering iron. Another problem showed up when putting the X axis carriage together. The X axis guide rods tended to come out of the printed supports when the carriage moves back and forth. I drilled a hole in the support part and inserted a brass rod to retain the guide rods.
The rest of the problems I had were my own fault. I plugged the two circuit boards together wrong and burned up a trace on one of the boards, easily fixed with a jumper. Later on while testing the printer the carriage snagged a cable to a stepper motor and unplugged it. Unplugging a stepper motor with the power on almost always burns up the driver IC. Luckily I had a spare driver board.
I drilled and tapped a few more holes in the frame to mount the power supply and the processor board. After assembly it is necessary to make sure everything is square so that it will print correctly.
When I get it working I will gradually dress up the wiring so it looks a little better. I did not like the way the Z axis limit switches were supposed to mount so I made some metal brackets to hold them. They can be adjusted up and down by loosening a set screw. A metal bracket at the top holds the LCD at an appropriate angle. With the printer working I can print up a plastic case for the display. designs for several versions of a case can be found on Thingiverse.
It did not take too much to get it to print. Mostly fiddling around learning how to use the software. The cube was printed with PLA which is supposed to be the easiest to use.
After some test prints this is my first successful print using ABS plastic. It requires different setting for the printer and a heated bed. The bed had difficulty getting up to the 100° C temperature suggested for ABS so I bought a cork tile and glued it to the bottom of the heat bed. Since it was Christmas time some ornaments were appropriate to try out the printer. The default settings in the printer driver software are set up for printing PLA and I did not find any good suggested settings for ABS so it too some experimenting to get it right.
I decided this ornament would be a good “stress” test of the printer as it has a lot of “printing on thin air” going on. It is not prefect, there is still some tinkering to do. The first time I tried printing this the extruder jammed about half way through the 3 hour print.
There are all kinds of suggestions out there for what to use to get the object to stick to the printing bed while printing. I am using a borosilicate glass bed with Aqua Net hair spray. So far this seems to work well. The above ornament stayed stuck during printing even though it only has a small base and came right off after the bed cooled down.
Still to do is learning how to use the whole software tool chain to design and print a part. I did design a test disk and used it to try out printer setting. But for anything more complicated I will have to better learn the CAD tools. My collection of software consists of Repetier-Host, Meshmixer, slic3r, openscad, FreeCAD, 123D design, netfabb and InkScape.