I recently bought a molded reprap prusa mendel kit from Metrix create space. They are a hacker space in Seattle, Wa. The molded kits cost anywhere from a third to half of what a set of printed parts cost because they take far less time to produce. One downside of the printing method is that parts will end up sloppier and require some more post processing.
Here is what the base looked like as it arrived.
Here is the other three parts, unprocessed.
The next picture is where you can start to see the disadvantages of this method. There is a lot of plastic on the bearing holder (purple) that needs to be cut away, and you can see the way that the miniscus on the big gear has made the entire gear cupped. I want to clearly state: none of those are deal breakers. This is a great deal, and even the RP parts require a fair bit of processing. I was surprised when these parts came in, but after thinking about it I don’t think I should be. They appear to be functional, and that’s all that really matters to me. As long as they last long enough to print their replacements, I’ll be happy!
Hit the jump for how to build it!
After breaking my makerbot extruder head I decided I wanted to try my hand at making one from scratch. It’s a brass m6 tube with a nozzle screwed onto one end. How hard can it be!
It turns out it’s really hard, but I ended up having luck with a technique called the “afghan lathe”
Before I get too far into it I need to explain that most bolts are made of hardened steel. To de-hardened them all you need to do is to get them red hot with a blowtorch and let them cool slowly. Here is a pic of me doing just that to two m6 bolts.
After your bolt has cooled, it should look something like this.
Start out with a drill press, a vice, some c clamps and a drill bit. Put the drill bit lightly into the drill chuck backwards. Lower the drill press until you can grip the drill bit in the vice (which should be sitting on the drill press table) Clamp the bit in the vice, and the vice to the table VERY securely. Release the chuck on the drill press. Now you are going to take the bolt that you de-tempered and put it in the chuck. I left the head poking out. That will make it easier to get a good straight grip on it. Tighten everything down and grab some machining oil.