Cherry picked Planet Reprap - A RepRap blog aggregator

November 29, 2014

New reprap images on Photobucket

Thingiverse - Newest Things

RTFHawk tray for Hoverthings Flip


Holds the readytofly quads RTF Hawk and snaps in place on the Hoverthings Flip frame.

by evilbender at November 29, 2014 03:09 AM

Hinged Name


TinkerCAD being so simple, I just altered this for a 4-letter name instead, for my desk at work.

by SwimmingNaked at November 29, 2014 03:05 AM

November 28, 2014

Thingiverse - Newest Derivatives

Business Card Holder, Rounded, Blank, and Remix


The Nice biz card holder from:
thingiverse.com/thing:217074
But blanked out with no logo or name.
Plus a remixed version with a flat blank spot for a logo

by activezombie at November 28, 2014 11:33 PM

Serrated Knife Remix


Print vertically, support will be needed for the handle.

For a realistic looking knife, print blade with silver filament and handle in black or brown.

Attach with super glue or acetone.

by mb20music at November 28, 2014 11:10 PM

RepStrap.dk

Motor assemblies (mostly) built

Y Motor Assembly

The stepper motors do not have a flat part on their axes. I might want to come back and Dremel one. Also, the axes are a little short, the manual suggests 3mm axis should stick out from the pully, but even all the way in only 2.1mm is sticking out.

Ha! Guess what I forgot when bringing both parts and frame over to FabLab? The woods screws to mount the parts onto the frame:)

Y motor assembly is done except for mounting on the frame.

Z Motor Assemblies

Calls for 2 pieces of rubber tubing. I believe they came with the print, but I don't see them now. Ha - they were where I'd forgotten them last time.

The wires are supposed to be "towards the back". It's not clear what that means, but from where it'll be mounted and various images, I guess it means towards the mount, like this:


I'll get back to which hole is the "mouse hole" once I can mount them. Right now, they are done but for mounting.

X Motor Assembly

There's a much larger gap between the motor and the bracket than the +/- 1 mm tolerance indicates. Did I do something wrong? Or just get the wrong motors? They seem shorter. I will add some nuts.


The screw is thus also way too short if it doesn't let the head through the bracket hole, and none of my screws go through that easily.
Can't do more on this until I get the bits of electronics and a longer screw.

That's all I can do for tonight due to lack of little bits of electronics, print beds, rods, and polypropylene strips. I wonder where those are normally used, so I can find them?

by Lars Clausen (noreply@blogger.com) at November 28, 2014 09:50 PM

November 27, 2014

Open3DP (Open 3D Printing)

Printing with Jello: A cost effective way to calibrate for biomaterials

Every good calibration starts with a pile of new materials, a daunting task, a ridiculous timeline, and our favorite ingredient…caffeine.

 

The 3:00am breakfast of champions

The 3:00am breakfast of champions

 

How many of these ingredients are for the tester and how many for the printer? The gummy worms, sour straws and energy drinks were for the Humans. The jello, alginate, bone meal, laxatives, joint support powder, mystery tub, and ABS plastic were for the Bots. It seemed like a fair balance.

 

The task at hand was to come up with a reasonable recipe and calibration for a bone gelatin hybrid.

 Recipe:

Equal parts by weight

Bone Meal (extra fine)

PolyEthyleneGlycol (PEG) aka smoothLAX (coarse)

Jello (fine)… yes unfortunately you have to by the little packets. Royal (extra coarse)

 

Why the little packets?… because bulk pack Gelatin is a coarse grind, not a fine grind. You can either ball mill the stuff down to size or simply purchase the smaller more expensive name brand stuff.

 

Coarse grain/mesh size leads to a rough print. The flying particulate can jam the heads pretty quick

Coarse grain/mesh size leads to a rough print. The flying particulate can jam the heads pretty quick

 

Print resolution is dictated by the coarsest material in a batch. Variance in grain size can cause continuous failures in the print resolution as the layers perpetuate upwards. Long story short, try to get ingredients that are the same mesh size, or ball mill them all together until there is a homogenous consistency [Seen below].

 

Test batches are run in the small bins. Note the fine grain/mesh size of the printable media.

Test batches are run in the small bins.
Note the fine grain/mesh size of the printable media.

 

If calibration seems close, the next step is to test scalability.  Then do some more intensive troubleshooting.

 

The printer is laying down clean smooth sheets, and the head is drawing uniform bitmaps.

The printer is laying down clean smooth sheets, and the head is drawing uniformly.

 

1st Calibration depowdered.

1st Calibration depowdered.

 

Remember gelatin is a protein. Proteins take advantage of water to do some ridiculous tricks like folding, coiling, cross-linking, and hydrogen bonding. Normally we are used to seeing this happen in a warm pot of water…100 degrees C warm. The printer is unfortunately not that warm. In order to get to that kinetically favorable part of the jello [ie structural jello-y goodness] we must apply heat. Hence there is a take and bake aspect to the recipe.

 

The test bars should be square. This meant that the baking process was both time and temperature dependent.

The test bars should be square. This meant that the baking process was both time and temperature dependent.

 

After parts have been depowdered they are put into an oven. The oven is set at the lowest temperature possible, which measured by thermocouple was ~180-194F   or ~82-90C. Then parts were baked for 15 minute per inch or 25mm of thickness. Unfortunately nothing we print in real life is uniform in thickness… so as always… use your best judgement.

 

Like cooking anything… the baking specs. are dependent on thickness on the rate of heat transfer.

Like cooking anything… the baking specs are dependent on thickness on the rate of heat transfer.

 

After the prints have been baked there will be a diffusion gradient. A level where the prints absorbed some water but not enough to achieve full strength. This outer casing should flake/crumble off fairly quickly when compressed or picked. If the parts have been over cooked they will be darker, blistered, and it may not be possible for the casing to be removed.

 

Curing/Baking gradient on a real part.

Curing/Baking gradient on a real part. Blue is ideal… Red is burnt

 

The prints after desiccation will be rock hard, but will solvate in water, because 2/3 of the ingredients are gel-like substance.

 

Printed scaffolds calibrated and ready for testing

Printed scaffolds calibrated and ready for testing

 

What are the applications for printing in jello? This is the cheap way to test bone hybrids for tissue engineering. Jello, basic gelatin, and collagen have similar printing behavior but maintain different levels of biocompatibility. When it comes down cellular science the biocompatible materials are very expensive. The more preparation that can be done with ingredients that are similar, cheap,  and readily available… the more real science can be done with the expensive materials.

 

Printed Bone/Gel Hybrid [Fully Calibrated]

Printed Bone/Gel Hybrid [Fully Calibrated]

by bowman at November 27, 2014 04:16 PM

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2 × GT2 Timing Pulleys + 2M GT2 Timing Belt for RepRap Prusa Mendel

paulbulmer posted a photo:

2 × GT2 Timing Pulleys + 2M GT2 Timing Belt for RepRap Prusa Mendel

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paulbulmer posted a photo:

Reprap 12v 30W Ceramic Cartridge Wire Heater For Arduino 3D Printer Prusa Mendel

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