Spark

The Autodesk Spark team has done something quite unusual in the world of commercial 3D printing companies (3D Systems and Stratasys, please take note).  The Spark team has brought out a DLP style printer called the Ember which employs photo-resin technology.

lemoncurry

{from lemoncurry group}

The Ember system is a bit on the high end in terms of cost (coming in at about $6000).   It is a bit out of the price league for home consumers but possibly within the scope of prosumers and small companies.  Unlike almost all 3D printing companies, Autodesk promised that they would not use the “razor blade model” for consumables (according to Duann Scott).     They have come through!   Autodesk released PR48 under CC-SA.

Thank you!

To get all the details, please check out their post on the spark blog:

http://spark.autodesk.com/blog/embers-resin-now-open-source

autodesk_resin

 

ganter on March 6th, 2015

by Kat Steele

Seattle Handathon

Students join forces to hack 3D-printed prosthetic hands

 Seattle’s first-ever “Handathon” brought together students, faculty, and clinicians last weekend for a 24-hour, hackathon-style challenge to build better 3-D printed prosthetic hands.  The event included two dozen participants from the engineering and prosthetics & orthotics (P&O) programs at UW-Seattle, UW-Bothell, and Seattle Pacific University.

 TheBeginning  The Beginning

 Teams were challenged to improve the latest open-source 3D-printed hand design, the Raptor Hand – from functional improvements to crazy design ideas. All teams had access to a CAD lab, 3D-printers, tools, actuators, electronics (Arduino, electromyography, etc.), and enough pizza, coffee, and treats to keep them energized for 24 hours.

 At the end of 24 hours we were amazed at the designs and improvements the students had developed.

The winning team, Dexterity, had two P&O students on the team and focused on function and comfort. They modified the thumb to provide more degrees of freedom and allow multiple types of grasps. To improve comfort, they incorporated a neoprene sleeve.

TeamDexterity Team Dexterity

 The second place team, Myo, used an Arduino with electromyography to create a locking mechanism for the hand. The current hand design lets users open and close the hand by flexing and extending their wrist. However, if you want to hold onto something for a long period, you have to keep flexing your wrist. To reduce fatigue, Myo created a simple mechanism that could lock the hand into a specific position triggered by electromyography.

Congratulations to all the participants! Over the next few weeks designs will be uploaded to the E-nable community to let others continue to build and innovate on the open-source designs. From Seattle, we challenge more groups to take hackathons from programming to physical devices!

The Handathon was organized by Dr. Kat Steele, a UW assistant professor in mechanical engineering and students in her Ability & Innovation Lab, along with Mark Ganter, a UW professor of mechanical engineering; Sue Spaulding, a UW teaching associate in rehabilitation medicine; Pierre Mourad and Ivan Owen at UW Bothell; and Adam Arabian at Seattle Pacific University.

Handathon3

 Karla Vega incorporates the actuator for Myo’s locking mechanism.

ganter on January 27th, 2015

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{Prequel update:  the UW press team produced a nice version of this story that is a little less technical}

http://www.washington.edu/news/2015/02/09/3-d-printing-with-custom-molecules-creates-low-cost-mechanical-sensor/

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We would like to take a moment to share with you some very exciting news on our research front.    When different research teams partner together amazing things can and do happen.    This research paper is available free for about a year compliments of A.J. Boydston.     Click on the paper title below to read the paper.

We promise more AM related details and results soon.

3D-Printed Mechanochromic Materials

Department of Chemistry and Department of Mechanical Engineering, University of Washington, Seattle, Washington 98195 United States
ACS Appl. Mater. Interfaces, 2015, 7 (1), pp 577–583
DOI: 10.1021/am506745m
Abstract
We describe the preparation and characterization of photo- and mechanochromic 3D-printed structures using a commercial fused filament fabrication printer. Three spiropyran-containing poly(ε-caprolactone) (PCL) polymers were each filamentized and used to print single- and multicomponent tensile testing specimens that would be difficult, if not impossible, to prepare using traditional manufacturing techniques. It was determined that the filament production and printing process did not degrade the spiropyran units or polymer chains and that the mechanical properties of the specimens prepared with the custom filament were in good agreement with those from commercial PCL filament. In addition to printing photochromic and dual photo- and mechanochromic PCL materials, we also prepare PCL containing a spiropyran unit that is selectively activated by mechanical impetus. Multicomponent specimens containing two different responsive spiropyrans enabled selective activation of different regions within the specimen depending on the stimulus applied to the material. By taking advantage of the unique capabilities of 3D printing, we also demonstrate rapid modification of a prototype force sensor that enables the assessment of peak load by simple visual assessment of mechanochromism.

 

 

For those not familiar with the field of chemistry and the ACS journal, when you see “Supporting Information” in the text click it for another paper’s worth of research result details.
bowman on January 17th, 2015

When a part takes 15 hours to print and it breaks, a little chemistry can come in handy. Besides, who doesn’t want take two parts and want to stick them together. Want to know if/how to solvate a polymer? Skip the gnarly home cocktails of ABS & turpentine and learn how to make a good chemical bond below.

 

Chemical Bonding:  Adhesives to English description

[Acrylic] =>Super Glue [Cyanoacrylate]-  water [a weak base] on the surface of the part neutralizes the stabilizer [a weak acid] in the super glue and causing to set quickly [aka anionic polymerization]

When to use Super Glue [cyanoacrylate] generally if it has the word acrylic in the name. Cyanoacrylate and acrylic [PMMA, MMA, etc]  based polymers can get good bonding at the molecular level.

 

[ABS, PVC, HIPS] => Acetone and Methyl Ethyl Ketone [MEK aka 2-Butanone] will dissolve both ABS and PVC and chemically rebuild the joint in a less ordered manner as the solvents dries. It essentially adds enough chemical energy to allow the polymer to move around an re-order itself for several minutes before the polymer runs out of energy and sets.

More explanation here: ABS plastic & Solvents: 4 good ideas

Sidenote: Acetone can often instantaneously dissolve polymers with lots of styrene. Styrene [Benzene] groups are prone to ring opening. This is when the benzene ring breaks open and releases a fair amount of energy. ABS will not have this behavior, but it is good to do a test piece before address other styrene polymer eg. “High Impact PolyStyrene”[HIPS]

 

Flexible Materials

Silicone

Bonds to other silicones.

Rubber and Latex

Both rubber and latex are important for 3D printing allow parts to be designed with flexible joints, gaskets, sleeves etc. Rubber cement can work surprisingly well.  However latex and many robust rubbers need to be primed or dissolve with N- heptane is a good solvent for latex and most rubbers.  Bestine makes a good rubber (with N-Heptane)  cement that can bond to both.

Polyurethane [PU]

Ninjaflex is a good example of a flexible polyurethane. Polyurethane based adhesive can bond on a molecular level with polyurethane parts. Gorilla glue is cheap effective and readily available, flooring and wood finishes offer a mixture for finer applications.

Polypropelyene [PP]

PP [#5] will fuse to most of the polyethylenes. It is fairly solvent resistant, but polyurethanes will interact with the polymer.

 

It is best to avoid these polymer solvents

Nalgene /Poly Carbonate[PC] – Methylene Chloride dissolves this along with a long list on MeCl based cocktails. [Which means use gloves, goggles, proper ventilation and/or a good respirator] A better alternative for polycarbonate friction fusion. PC has a pretty good friction/heat fusion like PLA.

PolyLactic Acid [PLA] can be dissolved in Bases like, weak concentrations of Lye and Isopropyl Alcohol … however this mix can cause damage to the nervous system. [Which means use gloves, goggles, proper ventilation and/or a good respirator]

 

These polymers just don’t dissolve. [except with superacids and other complex chemistry.

Kinetic bonding- polymers that can’t be chemically bonded easily, can be fused with ultrasonic welding or with high heat. Layer to layer fusion with heat is one of the main principles that many 3D printers  rely on.  The extrusion temperature for the polymer is also the welding/fusion temperature. Parts can be bonded manually with the appropriate application of heat.

These polymers are all extremely resistant to acids/bases and solvents.

#1 Poly Ethylene Terephthalate [PET]

#2 High Density Poly Ethylene [HDPE]

#4 Low Density Poly Ethylene [LDPE]

High Molecular Weight Poly Ethylene [HMWPE]

Teflon [PTFE]

 

 

Five rules to help a reader answer their own solvent questions.

There are some solvents you should avoid, teratomas [tumors] and liver toxicity are not worth it. Don’t risk your health and  don’t waste your time.

[Chemists out there… stop cringing at the gross generalizations… the DIY folks will be fine].

 

Rule 1: Read the back of the label… that is where the real information is.

Business often gets in the way of industry information by creating catchy buzz words and brand names.  On the back of any product there should be a list of ingredients. This will inform the reader about what family of polymer, adhesive, etc that a product belongs to. The if the warning labels and ingredients don’t explicitly tell the contents check the MSDS sheets for the product. Often the name of the solvent with sound similar to the material name…[Thank you scientific naming conventions]

e.g. cyanoacrylate (super glue) & methylmethylacrylate (acrylic)

 

Rule 2: Like dissolves Like… this is one of the universal axioms that holds our universe together.

Greasy things are solvated by greasy things, polar things are dissolved by polar things. Think oil and water, they don’t really dissolve each other, they create an emulsion. Where does your polymer lie on the greasy to polar spectrum.

 

The polar functional groups allow plastics to be solvated by polar solvents like acetone or MEK.

The polar functional groups allow plastics to be solvated by polar solvents like acetone or MEK.

 

http://commons.wikimedia.org/wiki/File%3APeriodic_table_large.png

Thanks again Wikipedia you are worth every penny.

 

Rule 3: Acid Base Chemistry Exists… Deal with it.

Things like PolyLactic Acid are dissolved in Bases like, weak concentrations of Lye and Isopropyl Alcohol.  Get cozy with the periodic table. The electronegativity arrangement and electron shell information comes in handy. Polar groups bond to polar solvents. Hydrogen bonding is the giant electromagnet of the polymer world. This means water [super polar] and alcohols [polar but greasy] are good at dissolving things. Why does acetone work well? It is so tiny it fits into most small polymeric crevices. It has a free proton due to resonance, but it is still greasy enough to hang out with the other cool polymers.

 

WaterLabeled

Water is extremely polar

AcetoneLabeled

Acetone is tiny carbon chain. It is known as a polar protic solvent. It can handle proton swapping because of its free electrons, it’s electronegative character.

EthanolLabeled

Alcohols refers to OH [the oxygen and hydrogen bonded] on a carbon chain. Alcohols tend to be bulkier and slower for solvation they are common in SN1 and SN2 reactions.

Rule 4: Wikipedia and Google images… Learn to love them

Rule 3 describes a substitution reaction. SN1 or SN2 reactions are chemistry “terms” that will help improve search-ability for the necessary solvents.  It will be important to be able to classify similar solvents and plausible way for chemistry to happen.

 

Rule 5:  Read the MSDS sheets…Methyl Chloride is not your friend … and neither is Toluene.

If toxicity is this obvious head the warnings,

If toxicity is this obvious heed the warnings.

 

Always check Section 3 for health factors

Always check Section 3 for health factors

 

 

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A special thanks to our friends over at the Het Nieuwe Instituut over in the Netherlands. They prompted us to pull out the frostruder, calibrate the machine and come up with some new recipes for open source cookie baking.  Details about the show can be found below.

 

Exhibition PLASTIC, Promises of a Home-made Future

At Het Nieuwe Instituut in The Netherlands

http://www.hetnieuweinstituut.nl/en/plastic

 

 

Working Specs

1 Syringe 60cc or ml  [they are the same unit folks].

Working pressure range 40-65 PSI depending on the thickness of dough mixture.

Cookie dough build plates: 1/4″ or 6mm thick aluminum plate. These should be pre-frozen before printing. Pull the build plate from the freezer just before printing to ensure good bed adhesion. [Think wet tongue on a frozen flag pole].

 

Layer Resolution [Initial Testing]

Layer Resolution [Initial Testing]

Recipes:

Vanilla Short Bread Cookies

1/2 Cup Flour

1/2 Cup butter

1/2 Brown Sugar

Teaspoon of Vanilla

 

Ginger Bread Cookies

1/2 Cup Flour

1/2 Cup butter

1/2 Brown Sugar

Teaspoon of Water

1/2 Teaspoon of Ginger

1/2 Teaspoon of Cloves and/or Cardamom

 

Chocolate Cookies

1/2 Cup Flour

1/2 Cup butter

1/2 Brown Sugar

Teaspoon of Water/or Vanilla

1-2 Teaspoon(s) of Cocoa Powder

The thicker cookies are hard to cook fast enough to harden without burning them.

The thicker cookies are tricky to cook fast enough to harden without burning them.

 

 

STLs

Frostruder Cap

The file below is the stronger version of the quick change cap, re-designed after the two failure mode were discovered.

http://www.thingiverse.com/thing:609952

 

Bunny Face Cookie

http://www.thingiverse.com/thing:609969

 

How the bot works

After sitting on the shelf for a year long break “little red” has been refurbished and is back at it again with more spunk and nothing to lose. This peppy little bot has Cupcake brains on a Prusa frame, we are talking some old school Gen3 Makerbot boards,  ReplicatorG  [GUI] and a python script called frostforge.  How does it work? the python script frost forge modifies the G-code  pulling out all the extruder commands and replacing them with commands to turn the fan on and off. A three way solenoid valve is wired where the fan would be. This solenoid now regulates the pressure to the syringe.

You run the python script in the Command Prompt [Terminal] It generally looks like this.

You run the python script in the Command Prompt [Terminal] It generally looks like this.

Solenoid ON [Cookie dough comes out]

Solenoid OFF [Residual pressure from the syringe gets vented]

Simple right…? Just ignore the colloidal substrates,  advanced fluid mechanics and food chemistry that is happening in realtime… as the pumping of the syringe kneads the cookie dough.

 

 

What you need to know is the pressure in your syringe should be below 65PSI, and generally the compression volumes will change 3-6  ml. What does that mean? If you have 10 ml left of cookies dough, then you have essentially Zero ml of cookie dough left. Now your laptop and bot are happily getting sprayed with cookie dough.

 

Frostrusion is not always the smoothest or cleanest process.

 

 

Troubleshooting

Common problems frostruding.

Clogging- Particulate is too large.

Solution- Sift ingredients more or use a finer powder.

 

Most common ingredient to clog the syringe is the brown sugar. It clumps more than most other ingredients other than fresh ground ginger

Most common ingredient to clog the syringe is the brown sugar. It clumps more than most other ingredients other than fresh ground ginger

 

Poor extrusion: Either the syringe is clogged or the cookie dough is mixed too thick.

Solution: Check the syringe for clogs… if no clogs, then add a 1/4 teaspoon of water to the dough and mix thoroughly.

Warning do not turn the pressure above 65 PSI

 

The clamp top and the syringe flange both fatigue quickly at ~70 PSI

1st failure mode: The clamp and the syringe flange both fatigue quickly at ~70 PSI

 

These polypropylene syringes can't handle 80 PSI chamber pressure

2nd failure mode: These polypropylene syringes can’t handle 80 PSI chamber pressure.

 

Poor Bed Adhesion: Z-axis should be one layer thickness from the bottom of the bed before extrusion.

Solution: Extrude a bead of cookie dough, and Zero the Z-axis to one bead width from the bed.

[See end of bloopers video for an example of poor bed adhesion.]

 

Baking Process

The baking process is a more complicated to maintain resolution. Remember butter melts… which can destroy the print resolution. The goal is to cook the outer shell to hold the cookie together as the inside cooks. The less water the better.

 

The cookies are kept in the freezer overnight to help remove the excess water.

The cookies are kept in the freezer overnight to help remove the excess water.

 

The cookies go on to the top rack under the broiler.

The cookies go on to the top rack under the broiler.

 

As the outside cooked fully the inside becomes molten.

As the outside cooked fully the inside becomes molten.

 

Once the surface starts to brown/harden remove the cookie from the oven.

Once the surface starts to brown/harden remove the cookie from the oven.

 

Cookies will have a light char or browning. And a re-freeze and re-bake may be necessary. Re-bake @ 400F on the lower rack to fully cook thicker cookies.

Cookies will have a light char or browning. And a re-freeze and re-bake may be necessary. Re-bake @ 400F on the lower rack to fully cook thicker cookies.

 

more on 3D printing cookie dough here

 

 

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Eamon McQuaide on December 17th, 2014

As the complexity of the part increased from our initial support design study : http://open3dp.me.washington.edu/2014/12/diy-support-study1/, the support we originally made was no longer suitable for use, as it would get trapped within the lattice structure we created, and be impossible to pull out. Now things are getting interesting..

100_3195

 

We noticed two things from our prior experiment:

1.  We wasted time and filament making solid support.  We needed to turn the support into a shell to reduce heat, and wasted material.  This will also make it easier to break out later.

2. We needed to add thin sections in the support to make it weak enough there to break apart to get it out.

Here is what the completed part looked like from the bottom:

100_3197

 

You can see now that the support was hollowed after it was designed in by using a “shell” command in Solidworks. We used a .5 MM shell thickness, which was a bit overkill.  It could have been done with .3 with equal success. The gaps between the part and it’s support was consistent with the last setup.  You can see in the foreground that there was a built in stress riser (thin spot about .05 MM thick) up the middle to aid in breakout, and the results were the support came out in two equal pieces.  The results were excellent!

100_3199100_3198

100_3200

Eamon McQuaide on December 17th, 2014

I don’t know.  But I do know that in practice I’m not all that impressed with the performance of blue painter’s tape either.  It doesn’t have a very strong adhesion with the print bed (it’s adhesive was designed to be easily removable), so there are two cases in which I have had issues:

1.  Long parts.  If you lay down plastic in a straight line on your print bed, a certain percentage of that length will be lost to linear contraction of the material as it cools.

2. Heated build beds.  Blue tape was designed to be put on walls and trim around your home as a mask that won’t leave behind a residue.  It was not designed to be stuck to a surface, and have that surface heated up to 100 degrees C while maintaining it’s full adhesive properties (common ABS plate temp).  Especially with our ABS builds, we have had problems not only with the plastic not sticking to the tape (wrong nozzle zero height setting) but with the part actually pulling the tape off of the bed under contraction.

I set out to find a solution to this problem, and found with a bit of searching, High temperature masking tape (MCMASTER PART # 7627A27).

The tape comes in 3″ X 60′ rolls, and costs about 18.50 a roll.  It claims to be stable up to 325 degrees F. It’s not cheap, but it’s also been very durable.  Our issues with part adhesion have gone away completely with the use of this tape, as well as the thermal degradation of the tape adhesive when used on a heated build plate.

NO WARP3

NO WARP1

 

 

The nice thing about masking tape, is it is not as sensitive to nozzle Z height adjustments as Kapton tape is. I’m guessing this is due to it’s slightly “fuzzy” texture that the liquid plastic bonds to kind of like velcro, or just the fact that it is not smooth, and therefore has more surface area for the plastic to adhere to.  This means with the many, many people who use our printers (with highly varying degrees of…..ehem….ability), we don’t have to re-level the beds constantly.

There are some things to be careful about when using this tape:

1. Don’t heat the build plate above 25 degrees C with PLA!!!!!!!! You will never get your part unstuck without damaging the tape!

100_3139

2. Consistent with above, you may need to experiment with how close to set your Nozzle Z-zero height to get your desired release strength.  The plastics I have used tend to stick better to this tape than the blue tape.

NO WARP2

Creative Commons Attribution 3.0 Unported This work is licensed under a Creative Commons Attribution 3.0 Unported.

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Eamon McQuaide on December 4th, 2014

One of the most challenging things to do and maintain print quality with an extrusion style printer is to print a solid object (100% fill).
A student recently came into our shop to print some small parts in PLA. They were 15mm long with solid connecting tubes 4mm in diameter, and he insisted that they had to be solid.

hex_4mmDi_15mmL sidehex_4mmDi_15mmLfront

After a few attempts using support created in Makerware, it was obvious we were going to have to create our own solution.  The issue ultimately came down to cooling time. There was just no way to run the part slow enough to prevent warping, and permanent bonding of the support to the part.  We modeled in a solid support with a gap to the part of .3mm to start.  The part fused solid, so there was definitely not enough gap. We bumped it up to .4mm for the next print.  We saw positive results on the sloped surfaces, but the horizontal surfaces still fused solid.

On the left, first attempt with our own support.  Much improved, finish, but still fused solid.  On the right, another attempt With .1mm layer resolution.  This put way to much heat into the part.

On the left, first attempt with .2mm layer height, and our own support. Much improved, finish, but still fused solid.  On the right, another attempt With .1mm layer resolution. This put even more heat into the part, making things worse.

Eventually we found the equilibrium.  A gap of .6mm between support and part on horizontal surfaces, and .3mm on surfaces at an angle worked great.

The final settings were .2mm layer height minimum, 215 degree nozzle, 20mm/min print speed.  I accidentally left MW support on without any ill effects.  Support broke out cleanly, and parts were beautiful.

The final settings were .2mm layer height minimum, 215 degree nozzle, 20mm/min print speed. I accidentally left Makerware’s support on without any ill effects. Support broke out cleanly, and parts were beautiful.

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Eamon McQuaide on December 4th, 2014

I’ve noticed over time, that there are certain situations where slicing software has a hard time finding a solution to, or just completely ignores geometry that needs support built under it. This is usually due to a kind of loophole created by rules stated within the slicer. For instance:
There is a setting in every slicer that determines the maximum angle a feature in your model can be relative to the build plane. Imagine you build a standard pyramid shell with all sides 25 degrees from vertical. Most extrusion printers can build surfaces more than a 60 degree angle sans support without issue all the way to the top. Nothing amazing here.

tpvis 1 makerware
Now take the top of your pyramid and turn it back in on itself. Now you have an inverted pyramid pointing back down towards the build plane. This feature obviously needs support. Otherwise when the printer gets to the tip of the inverted pyramid hanging out in free space, it will have nothing to adhere to, and the print will fail.

tpvis vinverted1
But according to the slicer, this feature falls under the standard setting in most slicers of 45-62 degrees from vertical. The slicer ignores the feature, or creates an extremely thin support structure which is sure to move around and break off during printing. Think about the load applied to this structure by the extruder nozzle part way through printing:

tpvis inverted2
This is the point where adjusting your overhang angle settings can solve the issue. But that can waste a whole lot of material,  and be tedious if not impossible to remove. Another obvious solution is to rotate your part to print in a different orientation, but this write up is addressing the situations where there seems to be something wrong with every orientation you put your part in. At this point, with a little creativity, the best results are to be had by modeling in your own support.

Creative Commons Attribution 3.0 Unported This work is licensed under a Creative Commons Attribution 3.0 Unported.

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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]

[Read more about other 3D printing applications]

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