RepRap Build
Parts
- Frame corners and rods - using 5/16" rod.
- Extruder controller - [1]
Assembly
- $8 z axis from HydraRaptor
Notes
On Frame Rods
From Erik:
As long as they're about 8mm in diameter you're good. Everything is designed such that tight tolerances are not required. Part of assembling a machine is taking a series of measurement. You can get away with threaded rods for most of the structural parts, except for the elements that other parts should be able to slide over. Several parts of the frame double as a guide for an axis.
You can also use cheap rod for most of the frame, the sliding ones should be maximally stiff (hardened rod) and chrome coated is nice and shiny. I'm using only the cheap type of ground bars for my own second Darwin, currently. It works fine. You don't need a heavy CNC grade frame when doing additive manufacturing, it's just very inefficient.
On Parts Choices
From Chris Palmer:
We are planning on using the parts shown, including your $8 z axis.
Are the Mother Board v1.1 and Extruder Controller v2.2 the correct boards to use?
The motherboard has moved on to 1.2, but I think the changes are very minor, so 1.1 should work fine. Extruder controller V2.2 is current. You will also need three stepper motor drivers of course.
What do you recommend for the implementation of the extruder?
I would recommend Wade's design: http://reprap.org/wiki/Geared_Nema17_Extruder. You will probably need to make an adapter plate to mount in on the Darwin carriage, but that should be trivial.
You can either bootstrap using the extruder parts I sent you and then print Wade's or I can print you a set of parts for Wade's if you don't want the hassle.
You can make the standard hot end if you have a lathe, but I would recommend the PEEK / PTFE Hybrid from Brian Reifsnider. http://hydraraptor.blogspot.com/2010/05/plumbstruder.html He sells in the forums and on eBay for very reasonable prices.
I see you're selling Mendel parts on Ebay. Is Mendel achieving widespread replicability?
It hasn't achieved the utopian ideal of everybody printing two sets and passing them on for cost yet, but there are a lot more people printing them than ever printed a Darwin. I have printed about 20 sets since April and got prices from £226 to £460 on eBay. A lot of people have printed their own using Makerbots and Rapmans, so I think there will be 100's around already. The eBay prices provide strong motivation for people to print parts and I am staring to see competition driving the prices down.