Questions about durability of repraped models

Hello all!

This is my first post and i am very excited to begin my quest for my very own 3d printer! I have read about the RepRap however i have one nagging question (or fear that is)... How durable are the parts created by the reprap machine? I have seen some close up images that show a distinctively "dotted" makeup of the parts created by this machine. This makes me wonder how well fused the polymer is and how such parts will react to stress. I would sure like to hold a part created with this machine in my hand and then subject it to all sorts of destructive tests with my trusty assortment of hammers . So finally i ask a real question or two...

1. How well fused is the thermoplastic parts made by this machine?

OR

2. How can i get a part made by a reprap machine sent to me so i can destroy it... opps i meant "test it"?

Thanks

Edited 2 time(s). Last edit at 12/16/2010 12:13AM by RantingRick.

Part durability depends partly upon your calibration settings in say, Skeinforge. For example, if you set the y layer height too high, the layers will be too far apart to bond together nicely. One other key aspect is the type of material you are using. PLA tends to be, from what I've heard, more brittle than ABS. Correct me if I'm wrong.

I have a bunch of scrap pieces (aborted builds, test pieces, leftovers from design iterations, etc). Most are pretty small but you could destroy them to your heart's content since they are not useful for anything. I'm only keeping them in hopes of having a recycling rig someday. If you can't find someone local, I could ship you a small pile of parts.

The simple answer is you have *some* control over the strength based on changing infill patterns, changing the infill density, and rotating the part to make the best use of the part's anisotropic strength. IE: if you load the part so that you are putting tension along the Z axis, the laminations will tend to separate, which makes it weaker in this direction. If you load it on the x or y axis, it will be stronger. I get the feeling that repraped parts will always be noticeably weaker than a part from a commercial molder, but you can probably adjust your print settings to get close.

1. How well fused is the thermoplastic parts made by this machine?
Good enough to make a 3D printer from them.

2. How can i get a part made by a reprap machine sent to me so i can destroy it... opps i meant "test it"?
a local reprap user group is the best way.

http://reprap.org/wiki/What_Tooling_Do_You_Have ?

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-Sebastien, RepRap.org library gnome.

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Remember, you're all RepRap developers (once you've joined the super-secret developer mailing list), and the wiki, RepRap.org, [reprap.org] is for everyone and everything!

Thanks for all the suggestions everyone. I will check these out!

There is some excellent work on the strength of parts here: [pleasantsoftware.com]

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[www.hydraraptor.blogspot.com]

There have also been a number of papers published on the topic (not specifically RepRap, but commercial machines) - here's one of them:

[citeseerx.ist.psu.edu]

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[haveblue.org]