My extruder is pretty much complete (except for the wiring):
I milled the gearmotor mounting holes as slots so that the pinch gap can be adjusted.
Unfortunately, I don’t have any plastic to run through it, and Makerbot is out of stock.
Drilling the extruder barrel was a bit of a challenge, but the first one I made worked out great. Here’s a pic of the drilling operation, using a 0.5mm drill bit held in a pin chuck on my mini-lathe:
Completed assembly of the major electronics components over the weekend. Soldering SMD parts was a new experience for me — very cool stuff! First, using a magnifing visor, I placed tiny dabs of solder paste on the pads. Then using fine tweezers, I placed the parts on the board. Once they are all in place, the board is placed on a hotplate until the solder melts.
I am amazed at how nice it turned out. Here’s a pic of some of the boards (and the USBtinyISP which uses conventional thru-hole assembly), along with the solder paste syringe I used:
And after fiddling with bootloaders for a bit… it all worked! Here’s a pic of the whole power supply/controller/drivers/steppers mess printing out a virtual minimug:
Got tired of waiting for the Makerbot extruders to come back in stock, so I’m working up a pinch wheel extruder design I can build on my mill. Hopefully, running the filament between a 0.5″ bearing and a 0.5″ brass bushing will do the trick. I’ll probably have to play with the knurling/tapping to get it right. This version uses the Makerbot Kysan gearmotor. Here’s a pic:
I just finished assembling the base/y-axis drive. A couple of pics:
Haven’t hooked up the stepper yet — gotta finish the electronics first.
Just some photos of the first parts to come off my assembly line.
First, a pile of frame brackets:
And then some drive brackets which will accept tiny ball bearings for the drive axles:
I’m making these using a small desktop mill setup for CNC. I’m a CNC novice, so I’m pretty happy with the results. Here is a photo of my setup:
I’ve been slowly building a CAD model of my RepStrap design. As you can see above, the basic mechanics of the X and Y axes are similar to the RepRap Darwin.
I’m trying to stick to easily available materials. Since I’m getting most of the materials from McMaster-Carr, I’ve started calling my machine the McMaster bot 
.
The main building block will be aluminum extrusions. This is an amazing building material. Strong, light, straight and true, machines very easily, and available from any neighborhood Home Depot. What’s not to like!
The erector set extrusions you can get from companies like 80/20 are even nicer, with a variety of well engineered ways to join them. But they aren’t cheap, and since I don’t like dealing with salesmen and waiting for parts, I’m sticking to the cheap stuff for now.
I’ve played around with a number of ways to join box sections, and I’ve settled on using a pair of small aluminum connector brackets pop riveted to the pieces. It forms a very strong connection, and if you drill the final holes in place, you get perfect alignment every time.
My latest project is to build a RepRap self-replicating 3D printer, and I’ve set up this blog to document the process.
Since building a real RepRap requires another 3D printer to print parts (which I don’t have), my initial goal to is to build a RepStrap machine using both the original RepRap and the McWire designs as inspiration.
More to come…