Choosing a printer and part durability?

Hello everyone!

I have been thinking for a long time stepping into the world of 3d printers. There is quite a little information about what the printers like reprap can really do and quality of prints seem to change a lot. Off course most of the bad quality prints are user errors.

At the moment the printer I'm mostly interested in is Tantillus which seems to be experimental at the moment. Quality and accuracy of it is what I'm after, some examples here [geometricobjectdepositiontool.blogspot.com] This is the quality I'm after, how easy it to achieve prints like in those examples? I wouldn't need better quality but I would need to know that I could get that quality when I need it and other times print at lower quality to print faster. I have a lot of time so it is not the problem. Required build area would be for 90% of prints definately less than 10x10cm but I might sometime require build area of 15cm.

The main question is also the part durability. This is the only article that I did find about durability of printed parts [pleasantsoftware.com]. Durability seems to be fine but one thing that makes me wonder is part construction. This video mentions that only the few first and last layers are solid and others not so solid [www.youtube.com] Is there a way to produce completely solid part using a 3d printer?

I would mostly like to produce R/C car parts. Off course printer won't achieve durability of injection molded part. I'm not after car parts surviving collisions against wall but part to withstand driving for example on the track jumps etc. For example suspension arm would need to last small rocks possibly colliding part and suspension shocks are quite strong these days. If I jump badly or collide and part breaks its ok but something that breaks without a reason is a no go. Off course if I would produce large amounts and I am sure that part is final design I would injection mold it. I would keep in the 1/10 scale so not heavy monsters.

Even though I'm after quality I am also after a low budget solution. A kit, building and finding parts is what I'm after. If something will be cheaper but requires more building it is not a problem. What 3d printer would you recommend and what electronics/software?

I'm sorry if text is hard to read but english is not official language in a country I live in.

Thanks already for replys!

You can build parts at 100% solid. Printing less than solid is common though as it slightly decreases build time and dramatically reduces the amount of plastic. Even sparsely filled parts can be quite strong as long as they are thick enough.

The issue that you'll likely run into though will not be solid vs non-solid fill, but the fact that parts are MUCH less strong in the direction normal to the layers regardless of fill. It really is nothing like injected molded strength along the weak direction especially for thin walls. Clever design can get around the issue, but there is a limit especially at the scale you'd be looking at for 1/10.

This video shows me destroying a thin part and might give you an idea about strength in various directions.
[www.youtube.com]

Thank you for your reply. This video seems to give a good view of part construction and weakness. Really helpful. Your part was quite thin but for sure this thin places can be found in many places of 10 scale car. Luckily thin and flat parts can be easily made out of aluminum or carbon fiber using simple tools.

For sure I need to have a clever design in part and maybe I should think about larger scale or making 1/10 cars using part thickness more common in 1/8 cars. Like some of the 1/10 Short Course trucks are built today.

billyzelsnack Wrote:
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> You can build parts at 100% solid. Printing less
> than solid is common though as it slightly
> decreases build time and dramatically reduces the
> amount of plastic. Even sparsely filled parts can
> be quite strong as long as they are thick enough.

Actually it dramatically reduces both the amount of plastic and the print time. Unless you're printing something with a lot of non-printing moves, the amount of plastic per second is more or less constant (depends on the speed and layer thickness settings of course).

Hollow or sparse constructions can be very strong and usually have the best strength-to-weight ratio. See bones or foam-core composite structures for example. Same amount of material formed into a hollow tube instead of a solid rod is mechanically much stronger.

> The issue that you'll likely run into though will
> not be solid vs non-solid fill, but the fact that
> parts are MUCH less strong in the direction normal
> to the layers regardless of fill.

The print should be about half as strong in the weak direction. (This is from some FDM paper from one of the commercial companies). If it's weaker than that, then there's a problem in the layer fusing (too cold, wrong flow, too fast or something else).

I would assume brushing an ABS part with acetone would help fusing the layers better together, making for a stronger part?

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-Nudel
Blog with RepRap Comic

Hey everyone,

Glad you like Tantillus and if you are not in the biggest of hurries it will be finished in the next month or so.

On to the topic at hand. I will be honest here and say you can get that quality out of any of the current RepRap designs but it will take some tuning and problem solving where Tantillus's mechanism requires very little tuning and should produce high quality parts right after assembly.

For strength I have to agree with the other opinions regarding layer direction and with ttsalo's comment on infill not being required to have strong parts.

Here is a video of a fully printed 4wheel drive 1/10th scale drift car Video be sure to have a look through his other videos. He has a few on the design and building of it. Its all in German but you will get the drift.

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