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ernpchan
03-01-2014, 08:55 PM
I'm curious as to what would qualify as the strongest 3d printer. My recent guilty pleasure hobby is modding Nerf guns. Probably cuz the Nerf battles at work can get intense and I want to be on top of the arms race.

Adding after market springs puts an incredible amount of stress on parts so I'm curious if there's any printer out there that would be able to make parts up to the challenge. The few companies that make kits probably have access to manufacturing methods beyond the average diyer's budget but I'm curious how far one could get with LightWave and a consumer grade printer.

spherical
03-01-2014, 11:46 PM
Well, it's not the printer. It comes down to standard strength of materials and the contact patch between layers. The former is determined by the material itself. The latter can be modified by settings in the slicer. Generally, the more you widen the extrusion cross section (if your slicer supports that) or increase the temperature in order to increase the layer to layer bonding, the less small detail you'll get; but the stronger the part will be.

There are after-print operations that you can do in order to increase the bonding. ABS benefits from acetone vapor smoothing or painting directly on the surface where you want increased integrity. PLA works much the same way by applying tetrahydrofuran, usually in a vapor bath.

I have also coated parts with epoxy. If possible, apply to both sides. Helps to use an epoxy that is in the "Restoration Class". They are water-clear and stronger, but require long cure times and a bit more cash.

sami
03-02-2014, 12:06 AM
Sounds like you are talking about materials engineering and the strength of the material. Depending on the printer there is typically:



PC - Polycarbonate - $40/lb - Strong, tough, impact-resistant, prints clear. High melt temp requires special extruders. Recycle#7 other
NYLON - Aliphatic polymide blend - $20-$30/lb - Slippery & slightly pliable, Good for low-friction parts. Cheaper kind takes dye well, more expensive kind is stronger. Recycle#7 other
ABS - Acrylonitrile butadiene styrene - $20/lb - Most common printing plastic. Strong. Many colors available. Unpleasant (toxic?) odor while printing. Recycle#ABS
BENDLAY - Modified ABS formula - $20/lb - Highly flexible and clear with great layer adhesion. Moderate strength. Unknown if recyclable.
HIPS - High-impact polystyrene - $18 /lb - Like ABS but dissolves cleanly in limonene. Cheap support material alternative to PVA. Recycle#6
PET - Polyethylene terephthanlate - $30/lb - 100% recycled. No odor. High clarity. Manufactured from food-grade materials. Recycle#1PETE
PLA - Polylactic acid - $20-$30/lb - Easy printing. Plant derived & biodegradable. Many colors available. Comes in rigid & rubbery grades.
PVA - Polyvinyl Alcohol - $40/lb - Easily dissolved in cold water. Common support material.
PCL - Poly-caprolactone - $20/lb - Easily home-mixed with additives to form blends. Typically available as pellets.
+ Carbomorph - PCL + carbon - for conductive / capacitive output
+ Laywood Composite - 40% wood dust + plastic
+ Laybrick Composite - chalk + copolyester
+ Glow in the Dark ABS or PLA - with phosphorescent powders (strontium aluminate etc) mixed in
+ Metal Flake translucent PLA with aluminum flake like sparkles


See if you can find a copy of the actual paper magazine (or pdf) of the Winter 2014 edition of Make:

it has an "Ultimate Guide to 3D Printing" which reviews 23 printers from $300 to $3000 and is the most comprehensive shootout I've seen so far. They test all of them exactly the same and have photos of the exact same model printed on all of them so you can critique the subtlties. They also review substrates and printing materials and it seems like a really good guide to me. (the list above is taken from the mag)

I'm still using 3rd party companies at present because for me 3d printing is still too fiddly, too noisy, too smelly, and too time consuming. When they are as sturdy and painless to use as my laser printer copier I'll reconsider, but until then I'll just pay someone else to print since it seems like a time sink for me and I don't have the patience at the moment. That being said, it might be next year because a lot of 3D printing patents just expired in Feb so a lot of new stuff should be being released by the end of the year maybe.

ernpchan
03-02-2014, 12:17 AM
Thanks for the info!

JonW
03-02-2014, 08:13 AM
& Titanium powder printed with laser, but I imagine it would cost a fortune or more!

sublimationman
03-02-2014, 04:36 PM
With consumer printers the biggest issue with strength is layer adhesion. If parts are designed correctly you can minimize this pitfall to some degree by designing print direction to add strength in the direction most needed.

In the horizontal my ABS prints are very strong. I printed a 1mm thick X 10mm wide band and subjected it to a 75lb force (via fish scale) and it had no effect on the piece at all.

The issue is that hot layers are laid down on cool layers in a semi round form, there are gaps internally between each perimeter and infill. Think of it like rubber tubes laying side by side and then more on top in the same direction, there will always be gaps between them. Varpor bathing fixes this on the single outermost perimeter but that's all. Yes it helps but not a significant amount. Still it's strong, just avoid thin vertical parts where you can.

sublimationman
03-02-2014, 04:42 PM
These images are through a 50X microscope.

You can see on the broken part how there are gaps between each perimeter. This wall that I broke was 2.8mm wide.

The first image is just showing the outer wall of an average print again at 50X magnification.