Dev

Chickpea casting day #5

Day #5 Gummy bears

Recipe Jello + gellatin

For this new tests we are going to use gelatin following this gummy bear recipe.

100ml of water, 43gr Jello and 12 gr powder gelatin. Mix gelatin into the cold water and put into low mid fire for 5 to 10 minutes stirring.

For this test we are using a negative glass shot like mould. After pouring the mix looks like:

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This recipe is way more flexible as expected, but we should compare to get a sense of hardness, the mould was not that great to clean. Since the shape did not have an opening the inner chickpea was more tedious to release.

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Chickpea casting day #4

Day #4 Agar agar + gellatin

Using 8mm walls, lets try to get a agar agar + gelatin design. Procedure pour gelatin and agar agar and put the mould in the freezer directly. Prechill the mould in the freezer before pouring.

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Recipe mix, 50gr of water 1gr of agar agar  + 1 gr of gelatin for elasticity.

We printed two moulds: one was pre chilled in the freezer, mixed poured at 45ºC, not chilled 40ºC.

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After that both moulds go to the freezer for 20 minutes.

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It is way easier to clean (compare to day#3), since the chickpea did not had time to frozen, even washing it with water removes all of it EASILY.

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There were still some air bubbles trapped. But the molded mixed even has the layers pattern!

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Cleaning the not pre chilled mould, feels harder. A water bath chickpea cleans it. Some tiny chickpea parts got embedded into the gelatin mix, so the surface looks dirtier, pretty sure this is because the mould was not pre chilled. Gelatin mixed feels more elastic than plain agar agar, but still brittle. More research aka internet browsing needed to fine tune the recipe.

Wall thickness for the shapes is 8mm and 12mm, a better hydrocolloid mix needs to be found to allow thinner walls without breaking the results during unmoulding.

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Happy for the results.

Chickpea casting day #3

Day #3 chocolate

Using thinner walls we tested pouring melted chocolate. The wall being < 2mm holds the shape, but  seems to be too thin to hold the pressure from the molten chocolate.

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After letting the chocolate to set we removed the chickpea using a paper towel, maybe a toothbrush would be better in this case. We did two tests, one of them we kept it in the freezer, which was impossible to clean. The frozen test (oval) after 30 minutes out of the freezer, the chickpea puree thaws so since it has more water in eat is easier to clean, also the design is simpler too.

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Chocolate 101 water and chocolate do not play together well, and the moisture from the chickpea puree aint here to help; great that this is just a test. Finished cleaning using tweezers. This feels like jurassic park. Chickpea looks like cookie crumbles.

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LESSON, next time better to print on top of baking paper to be able to release the part easily, it got stocked to the tile.

There were air bubbles trapped during chocolate pouring, that got part of the design broken.

There is quite a need for post processing but eventually the design was released.

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First half positive results!

Chickpea casting day #2

Day #2 First molds and materials tests

Experiment day one:

1.30h to puree the chickpeas + half a lemon, sieve it and load the capsule. 570gr checkpeas = 1.5 cartridges.

1h to get the right airflow.

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Molds are easy to create. Candy melt is too thick. Agar agar might be cooled otherwise melts the chickpea.

A water issue or heating issue?

After testing with water, wall thickness of 2 mm can not hold. Until here we have been using Curves with just one perimeter. Pumping up the air pressure we could manage to get thicker walls but seems not enough.

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Using 8mm walls, and pouring water into them gave us around 4 minutes window to hold the shape before it collapsed. We tested with plain water. Some chickpea from the walls gets “melts” and gets into the water during the process, weird way to do chickpea infusion 😉

AEP: Air Extruder Parser

Air Extruder Parser (AEP) is a design tool that allows to take any regular slicer and convert a stepper extruder output into an air extruder on/off control.

What it does?

AEP goes through your gcode file, finds the points where the extruder is not printing and adds lines to control the air extruder on/off state and adds possible start or stop delays.

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How to use?

Click on “select file” button, and browse for your GCode. Once selected the tool generates and downloads automatically the parsed GCode.

Options?

AE on and off  GCode commands can be edited for custom preferences. Also delays after on or off commands can be add to adapt to the properties of the material being printed.

Conclusions

This is a very simple tool, that does a simple job. We have been using it for our Lost chickpea casting experiments (coming soon). We are thinking on implementing a new feature that allows to decide how many millimetres we want the extruder stop printing before reaching a printing line. This is targeted to be used for materials tendency to ooze after AE Off, what do you think? it would be useful?

References:

Chickpea casting day #1

Casting is a really cool manufacturing/rapid prototyping technique where molten material is poured into a mould. Once the material solidifies the original is released. The mould is normally destructed in the release process and not reused.

In our new set of experiments we decided to give a try to chickpea purée as a casting mould material. The pros for chickpea purée is that is cheap, easy to print (if the right precaution are taken) and has enough consistency to print high enough 3d structures that allow us to get bigger moulds. worthy to try, right?

So the ideal process goes like:

  1. Prepare the design we want to cast (software)
  2. Create a mould design based on the previous point design (software)
  3. Print the mould design using chickpea purée
  4. Pour into the mould the material we want for our original design
  5. Clean casting mould and release the design

We do still have some questions in some the previous points, but that is what experiments are! to get answers.

Mould wall thickness? Pouring material? Chickpea purée cleanability? setting time? …

Hoping to get these answers and more in the upcoming experiments days!

Printing cookies day #6

Today a new war starts at 3DC 😉 We are not going to stop until we get a reliable 3d cookie dough that holds its shape once is cooked. Cookies 4 LIFE!!

We are going to start analysing our recipe to see what is the cause that makes our cookies to collapse in the oven.

But first lets learn more about what happens inside an oven baking cookies.

This are the ingredients of our first test cookie dough recipe:

  • Soft butter 250gr, confectionary sugar 250gr, 1 egg, flour 600gr and vanilla extract.

For our test we are going to be reducing the amount of ingridients to get less dough. 1/3.

  • Soft butter 84gr, confectionary sugar 84gr, 1/3 egg, flour 200gr and vanilla extract.

From all the ingredients butter is the one with lower melting point. And might be the reason why the cookie collapse. Probably not the only one. But the first that affects before the egg protein start tangling together giving more structural support, not sure if its enough, though. So first we are going to test a batch of cookies without butter.

Butter is approximately 16-17% water. Trying to balance the lack of butter’s water we are going to add a whole egg. Hoping the extra egg protein coagulation also helps holding the shape.

  • Confectionary sugar 84gr, 1 egg (57gr), flour 200gr, vanilla extract and salt 2gr.

To add extra toughness we are using bread making flour, hopefully the extra gluten will help too holding the shape. Also we are adding salt to strength the gluten network.

Ok. Lets prepare the dough and see the consistency.

After mixing for over 6 minutes the dough does not hold together (crumbles). Since we want to play safe instead of adding water, we are going to add and extra egg.

After the second egg the dough is too soft. Going to add flour one spoon at a time to get the right consistency. 5 spoons later the consistency is better. The dough is elastic but pretty hard.

Setting up to 6 bars the pressure, the extruder can not handle it at enough speed. TOO HARD. We frozen some samples and deepfried one of them it hold its shape properly. Taste more like a dense sweet bread. Another recipe would be needed to test this.

Even if the dough was to thick to print, we manually prepared some cookies to test the results in the oven.

First try. 180ºC for almost 20 minutes untils it was brown outside.

first cookie

first cookie result

Second try. 200ºC for 20 minutes. This one is more obvious that has collapsed, but did not had a complete base.

second cookie

second cookie

Second cookie result

Second cookie result

Cookie cut off

To us it feels almost like bread, with tough crust but with the sugar sweetness. Maybe we should try some bread. Maybe we sould try some breadsticks instead?

Another fail day and one day closer to the solution! More experiments coming soon!

References:

Agar Agar day #4

Fourth day for our agar agar tests. We are back after designing some modifications to have a decent heated syringe and nozzle. Hopefully this gives better results after day #3 disaster.

We are using a common 3d printing heated block, with a convenient air fit connector that has both threaded sides magically equal to our cartridge and heated block ODs.

heating block nozzle

heating block nozzle

Today we have two goals. First one test if the heated nozzle is enough to avoid clogging issues. Thus test to print a basic cylinder shape. To validate if the new heating design works we are going to run two tests. First load the cartridge with agar agar and see if after 30 minutes the tip is clogged or not. Later run an stalactite test. An hour dripping.

For this test we are using our first day#1 recipe: 100gr of water 2gr of Agar agar. Heating the capsule at 55ºC.

Experiment 1

First thing we wanted to try was to hold the liquid into the hot extruder. FAAAAAAAAAAIL. the liquid keeps running without any external force. Their might be some air leakage somewhere. Or maybe the nozzle is not properly screwed to the cartridge body.

Agar agar day 4 test

Agar agar day 4 test

Experiment 2

After the first experiment success we are going to run some sealing tests. Filling some cartridges to probe that water should not flow through an open nozzle. This is a similar experiment to the upside down glass of water. Definitely there is something wrong with the nozzle sealant. After tighten it, it stops dripping. Finally some good news.

Pressure test

Pressure test

Experiment 3

After the previous issues, we tested to run a basic print with awful results. Controlling the flow with AE is extremely inaccurate, specially for low viscosities. We decided to stop the experiments and pursue a better hardware control for extrusion.

Aweful agar agar print

Awful agar agar print

Conclusions

Agar agar is a cool material to experiment with. Adding temperature to work with it is pretty interesting too. But not having the right hardware to follow the experiments makes it pretty difficult. For that we will keep this experiments on-hold until we got a decent extruder tech that permits having a constant flow. Luckily we will be back to play with hydrocolloids sooner than later.

Resources:

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