This reveiew is based on 4 factors: rigidity, availabiltiy machinability, and cost.


8mm Thread Rod-- A-
Pros (rigidity availability cost): This is one of the basic building block for a number of 3d printers for obvious reason. It's very rigid in the lengths neccessary to construct a 3d printer. For basic reprap uses, it is one of the most usefull materials for a repraper to have. There are inumerable parts available that are based on the use of 8mm thread rod, so it's an esential material if your planning a build.

Cons (machinabilty): Unless you have an abrassive saw or other machinery to cut it into the right length, your dependent on retailers, who will sell hardware kits at a hefty mark up. if you have the ability to buy thread rod stock and cut it yourself, you'll save quite a bit of money and be able to build without constriction.


Aluminum Extrusion-- B+
Pros (rigidity cost): AKA T slot framing, aluminum extrusion offers great performance as a support structure for a reasonable price. Aluminum extrusions will continue to play an important role in several reprap projects, as aluminum is fairly inexpensive and offers a great deal of versatility with more convienient addons.

Cons (availabilty machinability): Where as thread rod is available at your local hardware store, aluminum extrusions are a specialty product, that often needs to be shipped for an industrial retailer. Also, as with any metal, a band saw or abrasive saw is needed to cut to size.


Laser cut acrylic or wood-- C
Pros (machinability cost): If you're lucky enough to own a laser cutter, know someone who does, or live in proximity to a fab lab, which offers machine time on a laser cutter at a cost, you will find a new world of options available to you. Laser cut parts can be fabricated in a fraction of the time that 3d printed parts take to make. The design process for these parts is also easier to master than the complex world of 3d CAD.

Cons (rigidity availability): Typical 40 watt laser cutters are limited it the thickness of material they are able to cut. 6mm (.236")
thick sheet acrylic may seem like an adequite support material, but for the purposes of building a 3d printer, you will find it is barely adequite, if it is adequite at all. While laser cutters are growing in popularity and availability, it's not an option for most builders.

3d printed parts-- C-
Pros (rigidity machinability): 3d printed parts can be your best friend. There is a growing number of ready made parts for you to use. while 3d printed parts take a while to fabricate, they ofer the complexity which is impossible by any other means besides casting or molding

Cons (rigidity machinability availability): The factors that determine whether or not your printed part will be durable long term are print quality, infill, and material. A quick and cheap print may seem like the way to go now, but you could be paying for it down the road, as your printer falls apart. If you're looking to build your own 3d printed parts, you have an uphill battle. though there are many free and open source resources avialable, they remain to complex for the general public. As 3d printers grow in popularity, 3d printed parts will grow in availability.

Just to add, 8mm threaded rod can be cut with a simple metal handsaw.

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http://www.marinusdebeer.nl/

I disagree with you about 3d printed parts. The principle of reprap is to have the ability to self-replicate your printer, the only way to fulfill that is through the use of printed parts to assemble your printer.
I have designed a couple of them and they perform as intended. Yes you can start with "cheap" parts and then print stronger ones (most of the people involved in reprap does just that).
Might be wrong, but I think people will be more willing to experiment with a printer that they can repair themselves with new printed parts or even improve upon than to start with a printer that is close source and not expandable.

I think a 3d printer should be like a microwave. You don't really worry about it breaking. It just does it's job without having to make improvements. Just my opinion.

^ ditto
I think there are two parts to RepRap. The innovators and the users. Innovators are the people who create new things, whether for themselves or RepRap as a whole. New designs, fix their own things and help others to also do their thing. Users are the receiving end of this. They are the post-war liberated citizens, "It ought to be celebrated by pomp and parade, with shows, games, sports, guns, bells, bonfires, and illuminations from one end of this continent to the other..." -John Adams. Should everyone who's a US citizen be a part of the military? No. Should everyone who uses a RepRap or RepRap based design contribute? No. If everyone followed that I believe we would start going backwards in improvements. Give them something that works, show them that we have in fact made good progress. Misplaced rant brought to you by MrDoctorDIV.
^{(Please keep replies to the OP, don't start a new discussion on this)}

Edited 3 time(s). Last edit at 10/23/2014 01:41PM by MrDoctorDIV.

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Realizer- One who realizes dreams by making them a reality either by possibility or by completion. Also creating or renewing hopes of dreams.
"keep in mind, even the best printer can not print with the best filament if the user is the problem." -Ohmarinus

You cannot create generalized ratings for these things. The best material to use depends on the needs, experience, resources and budget of the person building the machine.

Quote
Ralph.Hilton
You cannot create generalized ratings for these things. The best material to use depends on the needs, experience, resources and budget of the person building the machine.

I agree, it's a nice try though! (Don't want to be too discouraging). But I am not sure if this post is going anywhere.

Maybe it would be nice to mention 'real' important stuff. Saying you need an abrasive saw for 8mm threaded rod is just bs (sorry).

What would be more interesting, is to talk about the different alternatives. Like using galvanized steel, stainless steel or maybe a acme/leadscrew and the advantages and disadvantages on those. Then, after talk about extrusions, but also include the Tantillus 3D-printer that can be completely printed and doesn't use extrusions and then also tell about printers using just simple tubes instead of aluminum extrusions. Also there are different kind of extrusions, 10x10 Makerbeam, 15x15 Openbeam and 20x20 Misumi and other variants such as the V-slot extrusions that act as linear guides at the same time with delrin-lined bearings.

Laser cut acrylic or wood? Why not aluminum? Why not Dibond? There are so way much more materials that can be used. And why lasercut? I know a guy that made his printer entirely with a band-saw from pieces of wood and it prints beautifully! He re-printed the wooden parts with his all-wood printer now and piece by piece replaced the wood for printed parts (a shame if you ask me, that wooden thing looked awesome!).

Please appreciate this as feedback, I want to show there is much more available than is listed here, the list goes on and on. Maybe one day we'll have a good list with most available materials. And in the meantime more and more materials are being discovered. I am currently designing a secret production method for making molds for printer parts. Will be brought out one day, but it's currently in development with a secret fabricator of a new kind of plastic! (And no, not a thermoformer).

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http://www.marinusdebeer.nl/

Right on. I wanted to speak to what I have used before. It is an incomplete list that I've been thinking about for a while, but only spent about 15 mins on. Maybe it's a bit better suited as a wiki post than a forum post. I think Dibond is really interesting. Cuts like butter with the strength of aluminum. But pure aluminum is a bit harder to work with. I know thread rod can be cut with a coping saw, but never done so. I was talking more about the cost of buying pre cut kits vs. rod stock.