Quality of Parts

Hi,

I'm new to reprap and 3D printing and am keen to get started, but have a few questions about the the quality of the actual prints.

I'm part of a small model club and we build all kinds of scale models, ranging from working vehicles with gears to figures and objects. Mostly handcrafted using various methods, we sometimes use resin casting/moulds which gives good surface finish.

What is the quality of reprap prints:
-Surface: Is it consistent or porous and does it need sanding?
-Strength: If appropriate materials are used, are gears etc durable enough for repeated use?

Many thanks!

Edited 1 time(s). Last edit at 02/23/2011 02:11PM by johnjkjk.

The reprap makes parts by squooshing a string of pastic on top of previously squooshed plastic. That string is nominally .5mm across and is squooshed to between .5mm and .3mm tall.

Thus the surface finish if you look at it closely it's made of squooshed plastic strings.

And you can't make details smaller than 1 piece of string.

And the geared extruders (both Adrian's, Wade's, and herringbone designs) are printed using a reprap, and those plastic gears are in service for long periods of time without apparent difficulty.

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I'm building it with Baling Wire

I like to show this sequence of photos to people who ask about print quality.

if you just need gears to make something move, and the gears are going to be hidden, then they can be used as-is. if you want to print something like a train car, and make it realistic, you'll need to work it quite a bit.

but printing itself it a bit of an art, and it takes a lot of calibration and refining your machine in order to print at it's very best.

another great example: Gothic Cathedral play set

jgilmore, Buback,

Thanks for your reply!

I'm looking mostly to print small scale model parts, such as those for a train car or aeroplane (1:72 being a common scale), which need to be very accurate, with small lines, markings tubings and bits here and there. Everything is for display, including gears- so they won't be hidden either. Of exterior surfaces will get painted over eventually, but if the surface is not smooth or lacking in accuracy in lines and markings and bits then it becomes difficult to get a good finish.

Do you think that with enough calibration and good printing technique I'd be able to achieve this using a reprap?

Thanks!

Richie

Richie,

Imagine stuffing .3 mm or .5 mm flexible mechanical pencil lead into a mold. That's the sort of tool marks that you'd have on your pieces.

So, it may not be appropriate for your use. But you should build one anyway, because it's fun, and because the world's not going to take over itself!

And, at some point, this
http://reprap.org/wiki/A5_Powder_bed_printer
will become real.

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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!

I'm curious how you would make the models regularly? are you assembling kits? Current reprap prints are not going to be as good as injection molded plastic parts.

here's a u-boat model skimbal uploaded to thingiverse.

the printer won't output a finished model, but it will produce good quality blanks.

I don't have a reprap - I've got a makerbot cupcake with a bunch of upgrades. Though reprap seems to have a reputation for being able to put out better quality, I think +90% of it is how much time you invest in learning how these machines work and calibrating it. They're not exactly plug-n-play and the software can take a bit of getting used to.

Here's a picture (along with my index finger for scale) of about the best I can do for horizontal resolution. Vertical resolution is 0.20mm in this picture but you can get it down to 0.10mm with some work. That's getting close to the limits of the machine though and as you get closer to those limits, it gets a fair amount harder to keep the machine happy.

[www.flickr.com]

(also, that's black ABS which is notoriously hard to photograph and shows up every little defect in painful detail.. the print looks pretty good in person)

Quote

-Surface: Is it consistent or porous and does it need sanding?

It's not porous.. Consistent depends on your definition.. Sanding, too..

Quote

-Strength: If appropriate materials are used, are gears etc durable enough for repeated use?

Again depends on your definition.. In a car engine, a printed gear would last about 2 seconds. Maybe. If you're lucky. Low load against parts of similar material will be ok for a while but ABS is the same stuff that Legos are made from - it'll wear and break if you abuse it. That's ok, though - just print more.

Thank you all for your replies.

Buback- yes it's kits- plastic parts to assemble into scale model. Either we buy ready made kits or for custom stuff, for which kits are not available, we handcraft a master and use resin casting. The latter is a very tedious process, but the results are usually very good.

Might build one anyways just for fun!

Thanks again for the information,

Richie

Powder based 3d printing would be better for your use. See [open3dp.me.washington.edu]

Might build one anyways just for fun!
It's compulsory.

Powder based 3d printing would be better for your use. See [open3dp.me.washington.edu]
And the
http://reprap.org/wiki/A5_Powder_bed_printer
which folk are doing up.

---

-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!

SebastienBailard Wrote:
-------------------------------------------------------
> Might build one anyways just for fun!
> It's compulsory.
>
> Powder based 3d printing would be better for your
> use. See
> And the
> [reprap.org]
> which folk are doing up.


That's great I didn't know about it but was it ever finished? The wiki isn't complete.

Actually this is a brand new project. development just started, so it is one to watch closely.