Home-brewed plastic made from milk ...

I am not convinced that it is fully needed yet.

Ethanol being an alcohol has useful degreasing properties.

The initial idea is to have a paste that contains some water. enough to encourage initial crystallization but not enough to encourage the stuff to set solid in the feed line/syringe. Ie enough to have the crystallization process started but suspended due to lack of any more water. Crystals need seed crystals on which to grow and so on ad infinitum (the rhyme was flees but never mind)

The Ethanol (reasonably safe as chemicals go) is supposed to be a whetting agent/lubricant so that the granules in the paste (there wouldn't be enough water to do this job as we are attempting to keep it in a suspended state of crystallization) can flow.

The Epsom Salt is relatively insoluble in Ethanol. So the Ethanol as far as the salt is concerned is an inert liquid.

Ethanol has a very low boiling point (66 DegC I think, 60 is Methanol) This means that the Ethanol used as the particle lubricant (or we wouldn't be paste like) can evaporate off fairly rapidly and cause the paste to dry/set. Even quicker if the paste is warmed up to 40 or 50 degrees just prior to deposition ie by warming the stainless steel canula/needle.

In evaporating off the ethanol leaves behind an ever firmer paste that is resuming it's suspended state of crystallization.

What you have then deposited for your support material is something that is semi anhydrous highly hygroscopic and keen to absorb more water vapor out of the atmosphere and consolidate itself further in a crystallizing fashion. (The needed "water of crystallization", has to come from somewhere or no crystals)

The theory is that if it isn't stiff enough to support the next layer immediately it soon will be and will only get more so over time.

The vital variables and questions to be answered are:-

What is the best ratios of Anhydrous Epsom to Ethanol to Water ?
How stiff can the mix be and flow ?
How long a shelf life and tool life can we expect from the paste if we keep it relatively well sealed of from the atmosphere, that is as stiff as it can be and flow ?
How soon after we deposit it will it be strong enough to take another layer of either support or polymer ?

All in all a bunch of experimentation is needed, A microscope to see what is going on might be useful too.

The objectives for the paste are :-

1. To flow reasonably freely.
2. To be deposit able in the same proportions as our polymer.
3. To set up quickly enough after deposition to allow the next layers to be laid on without pause. (Polymer and support)
4. For each layer of support to stick to the previous layer of support.
5. For each layer of polymer to have something robust enough to stick to when printer over the support.

If when we do some experiments we find that Epsom salts won't do then I guess we could try other salts that might crystallize more quickly.

I guess I had better state the obvious (cos it might not be), it's the crystalline structure that locks the bits together to make a solid. Exactly like what happens in concrete, except we are just using the crystal bit here and no aggregate.

We might yet need to add some of this yet (very fine aggregate or micro spheres) as a seed material and to help with dimensional stability.

I don't think we can get it to go from paste to all crystallized in one go, so I was hoping for enough to proceed immediately followed by more as we got on with the rest.

Hope this helps, sorry if my explanations aren't that good.

Cheers

aka47

Edited 2 time(s). Last edit at 02/19/2008 12:47PM by Andy Kirby.

---

Necessity hopefully becomes the absentee parent of successfully invented children.

I think that doing this with an aggregate would be getting somewhere... it would also hugely reduce the amount of epsom salt and (more importantly) ethanol required, possibly leaving enough for drinking.

But introduces the spectre of irretrievable blockages in the fine bore of the nozzle.

Your support blocking up 11 hours into a 12 hour run is going to be something I think you might want to make so unlikely as not to be worried about.

I know I do.

If that happened I would need to go out for a couple more bottles to drown my sorrows.



aka47

---

Necessity hopefully becomes the absentee parent of successfully invented children.

only if you use a coarse aggregate...

*edit* having fluid inlets round the nozzle could also help.

*extra genius drunken edit* attach piezo transducers to the extruder to allow the aggregate to flow due to vibration at a resonant frequency defined (presumably) by the particle size and diameter of nozzle. (this was come up with after trying various ways of getting wet sand to extrude from a syringe, tapping it seems to help)

*further exremely drunken edit* pressing an NXT speaker against a syringe of water/sand mix, getting better results with Bob Dylan than I am with Del the Funky Homosapien, although this is at very low amplitude.. I am restricted in my experimentation due to the lateness of the hour. Will try a more thorough test in the morning with a wider range of frequencies and amplitudes

Edited 3 time(s). Last edit at 02/19/2008 08:19PM by deadgenome.

As for self life of the Epsom salt mixture, probably a while, especially in a closed container. It stays a past as long as the water doesn't evaporate.

Heating up the epsom salt mixture won't necessarily dry it, but it might make the mixture flow easier. As temperature increases, more epsom salt dissolves in water making it easier for it to flow. As the temperature decreases, the epsom salt recrystallizes.

Umm the heating/warming up just before dispensing was to make the ethanol evaporate quicker....

Baking the Epsom Salts in the Oven at 210 DegC converts it into it's anhydrous state.

My plan when I get the ingredients is to pestle and mortar the stuff as it comes out of the packet , initially grade it with an icing sieve. Re grind anything that won't go through.

Bake the powder in the oven at 210 Deg C for an hour or so (shouldn't really need this long).

Let it cool with the top of the container stoppered with kitchen roll (prevent too much moisture creeping back in from the air) then when cool enough close of the container with an airtight seal.

Acquire cheap no name vodka.

Experiment with paste, making making trial batches by weight.

Gut feel tells me that we will need a mix that has more ethanol than water in it (2 parts Ethanol to 1 of water), where as standard spirit strengths are 35 to 40 percent by volume.

I have not figured out yet how to get purer ethanol other than buying Absolut (57 per cent by volume) or making a distilling rig. (time consuming and illegal in the UK)

The alternative I guess is to add smaller quantities of the anhydrous, encourage crystallization then separate by filtering leaving a higher percentage of Ethanol as water will be drawn into the Epsom Salts to make it crystallize. (V slow process)

Oh for a lab with pure ingredients, ball mill and microscope.......

aka47

---

Necessity hopefully becomes the absentee parent of successfully invented children.

BTW

Vibrating a mass of mixed sizes of powder grains, effectively compacts and sorts it a touch. Not necessarily what you want.

I am sure it does liquefy for the duration of the vibration (like patting damp sand and watching it flow into a puddle and away on the beach). But when you take away the vibration the fact that it's presence has "Sorted" the grains into the most dense formation is likely to be undesirable.

This technique is used when making concrete in moldings or form work they stick a motor driven poker into the mix.

The net effect is that the smaller particles drift downwards to fill all the spaces between the larger particles and some larger particles are left exposed on the surface.

You can try this with a jar of coffee grounds if you agitate it by hand the finer stuff concentrates towards the bottom and the bits that snuk through the grinder end up on top.

cheers

aka47

PS Could some artists be better for the flow because of the difference in bass levels produced by the differing sound spectra of their output ??

---

Necessity hopefully becomes the absentee parent of successfully invented children.

That probably explains why dylan worked better, nothing to do with the actual music playing, just the fact that it was the first tune I tried... so second time round, the grains have been sorted and virtually nothing comes out at all... hrumph.. oh well, was fun anyway

Hey I'd like to think it was Dylan too.

---

Necessity hopefully becomes the absentee parent of successfully invented children.

Andy,
I have heard you can strengthen Vodka by freezing the water out of it. I have not tried it so I don't know if it true.

---

[www.hydraraptor.blogspot.com]

regarding ethanol, there should be a ton of ordinary chemicals containing ethanol, more or less pure, but with some additions to make it undrinkable, at least for anyone not a serious enthusiast :-P

I have some 1/2 litre bottles to disolve ice-cloggings in the carburettor in our cold country, a lot cheaper than even cheap vodka...

oh and also they are peddling ethanol at the gas stations now aday, rather sympathic prices at slightly over $1 per liter...

I have tried freezing vodka down, years ago with very mixed results for experiments with extracting essential oils from plants ie Thyme and Rosemary.

V Low temperatures are needed (I used -18 DegC)

At higher water to ethanol ratios the ice tends to form a lattice rather than a layer and effectively traps a bunch of what you want out of it. Ethanol peculiarly seems to have an affinity for the water you want it separated from.

Out damn spot out.

There might be some mileage in Freezing, crushing and then filtering whilst still in the freezer though.

Most effective method I gather is a vacuum still, completely out of my league and desire to be kept by the state.

Overall I am hoping that luckily our finally required mix ratio can be met with off the shelf items (the 10 Dollar glop thing) that have low intrinsic toxicity.

Methanol and Glycol don't generally fit those characteristics, Good thinking though, we are heading along the right lines...

Question..... is there a clever something that will react with Methanol but not Ethanol and yield an easily separated (maybe filterable or precipitating solid) result ?????

And to think I agonized and then decided not to buy that cheap Microscope from Lidle last month..... ug

It even had a ccd/usb camera with it...... ug

aka47

---

Necessity hopefully becomes the absentee parent of successfully invented children.

... my hint for the 'pure stuff' is freezing in a centrifuge

I knew that 'ice-beer' ('Eis-Bock' or doubled='Doppel-Eis-Bock' in german) is made by concentrating the alcohol, malt and solved aromatic additives by freesing the water out.

The container is freezed down to -30

[journeytoforever.org] - here's a load of resources on ways to produce and strengthen ethanol.

OK

Please find attached progress on the MgSO4 so far.

I got hold of a kilo and started experimenting, initially with the dessication to produce anhydrous. Note I don't in any way suggest that anyone follows my example the info is to tell folk what i have done.

Anhydrous, hygroscopic anything should be considered hazardous and not handled.

Had to relinquish custody of the oven to my wife for tea but I'll continue tomorrow.

There is a very big volume change, we might need to look at this.

cheers

aka47

---

Necessity hopefully becomes the absentee parent of successfully invented children.

I have prepared a MgSO4 paste, so far it has been about 2 days and it is fairly paste like(uncovered). I tried extruding it with syringe with no success, it jammed up rather fast. I have achieve varying degrees of sucess with fairly wet mixtures.


I prepared the paste simply by adding water to store bought MgSO4, kneading it and letting it sit.

Applying 10 watts of Bob Dylan or similar music to the syringe might yield promising results. Otherwise, I will try ball milling it or putting it in the blender if worst comes to worst.

... today i received another (finer) glass-powder from Schott for sealing-tests.

While the other types i used mixed with water behave like normal dust-paste, this type is more like starch-powder with water - when moving the stick slowly, it's fluid like milk or juice, but when moving faster, it's suddenly stiff and brakes like a solid, but went fluid again when released.

This type of paste would stiffen in the syringe, when applying force or loud music (vibrations) ...

Viktor

Ok this was state of play last thing yesterday (Had a day out today, reading:-

[www.antipope.org]

)

Still no steel balls.

Please see attached for that I have written here that doesn't make sense........

So I'm a slacker and want to read fiction now and then, tough teats, but I love you all and more so for messing with science et al (and alcohol).

Cheers

aka47

PS went to Lidle and bought a cheap bottle of 40 percent vodka, in preparation for the receipt of the aforesaid steel balls. Although most of it will be used in the experiment, some has already found it's way into my glass drinking implement.....

---

Necessity hopefully becomes the absentee parent of successfully invented children.

White Russian.

Ummm

Still no steel balls so I have spent some time messing with a spreadsheet (attached) in Open Office to give me some ball park weights and figures for experimentation.

Below is also the method I will be using to experiment.

If someone would be so kind as to check over my very poor chemistry and figures I would be most grateful.

Overall now I think I have a method for paste production, but need to complete a ball mill and get some marbles now as well as the steel balls.

This is my suggested route.

1. Take 500g Epsom Salts MgSO4.7H20 and reduce it to it's anhydrous version by baking it in the oven at 210+ Degrees Centigrade until the water has all gone. Rough guide as to when this has been achieved can be got by calculating how much the water weighs (Use figures from spreadsheet) and stopping when the mix has lost that much weight. All this can be done in a kitchen with kitchen implements.

2. Use a ball mill to fine grind the result of 1. to a powder sufficiently thin enough to go through the dispensing nozzle you want to use. (This because some may be left in the paste) Set aside the fine ground anhydrous powder in an airtight container. (Take sensible precautions. Don't handle or breathe in the powder etc it can't be good for you)

3. Grind a further 500g of Epsom Salts MgSO4.7H2O in the ball mill to a powder sufficiently thin enough to go through the dispensing nozzle you want to use. Set aside in a second airtight container. (Again be cautious the fine stuff can;t be good to accidentally breathe in etc)

4. Place your final glass milling vessel on the weighing scales and zero them.

5. Measure 100ml of your preferred vodka into the milling vessel.

6. add (by weight, this is why we are doing this on the scales) enough of the anhydrous powder to combine with the predicted water content of the vodka as it re crystallizes into it's heptahydrate form taking all the water from the vodka (may not actually be physically possible but it is a guide to quantity and can be worked out from the figures in the spreadsheet).

7. add 5% more of the anhydrous powder. This should make the result a bit thirsty ie hygroscopic.

8. add enough glass marbles to the mix to mix it and stop big crystals from forming. then place it on the ball mill on a low to moderate speed so it mixes continuously. (How long for I don't know yet, until it is done) what we are doing here is allowing micro crystals to form but disrupting them from forming up too big. A clever test to see how much water is left loose in the mix would be a good way to tell if it has finished but I don't know how. (Anybody help with this one ??).

9. When micro crystal formation is complete combine the result with the heptahydrate powder we ground up at 3. to get the consistency of paste you want. (It may need some more glass ball stiring, before use) Keep the result in an airtight container until needed or it is likely to set up too soon.

10. Post results/observations here for everyone to share.

Overall that is a route that should yield useful results if they are there to be yielded, Clearly there are still some how longs and how muches to work out here but that's down to experimentation.

A microscope and some clever tests for some of the stages would be great, but I don't have any.


Hope this is useful.

Cheers

aka47

Edited 1 time(s). Last edit at 02/25/2008 10:07AM by Andy Kirby.

---

Necessity hopefully becomes the absentee parent of successfully invented children.

You don't need steel balls, and in fact steel balls are not fit for the job. Steel corrodes, so use something that dosen't corrode, like bits of rock or ceramic.

I will post my ball mill design as soon as I get a chance.

Anyone got any simple ideas for sources of rubber tubing with an ID of 8mm.

I need some to go over the rods I will be using for the ball mill so that the milling container doesn't slip.

Most standard hose pipe etc is bigger than 8mm, but the bore of the bearings I am using is 8mm and I don't want to machine them if I can avoid it.

cheers

aka47

---

Necessity hopefully becomes the absentee parent of successfully invented children.

andy: checkout mcmaster.com they have a great part selector.

Ok

My Ball Mill Rollers are complete and are largley made up of the type of standard parts used for other Rep Rap stuff ie M8 threaded rod and Skate Bearings.

Just need to make a frame now.

Thanks for the tip Re McMaster, I have had painful experiences getting things in from the States to the UK though. Customs tend to open the parcels and leave them open for everything to fall out and get lost.

I put some pictures up of the construction for the rollers on my Blog.

[kirbyandco.blogspot.com]

Cheers

aka47

---

Necessity hopefully becomes the absentee parent of successfully invented children.

OK

Something i stumbled upon whilst rummaging around on t'internet.

[fab.cba.mit.edu]

Fabaroni

An RP machine that a group of folk at MIT have had a session trying to extrude things with that are essentialy foodbased.

There best extrudable from all that they experimented with (and some must have been just for fun) tuned out to be Pasta Dough.

The crazy thing is that now it has been mentioned you get one of those, why did'nt i think of that moments. (still going to play out the White Russian thread though to it's ultimate end)

I have made pasta so many times and those Indian noodles (spicy and fried then they go well crispy) that I can't understand why I did'nt think of that as something to try.

I have one of those brass things with a windy handle and perforated disks for making the noodles, and often make them along with onion Bhaji and Brinjal Fritters.

So both noodle dough (no egg) and past extrude fairly well and if heated slightly during extrusion should set up fairly readily afterwards. Getting the pasta dough off the piece afterwards is going to be fun because the egg acts as a binder. Indian Noodle dough though might be doable.

Hell how cheap can you get, flour, egg and water. Never mind 10 dollar bucket of glop how about 10 cent bucket.

cheers

aka47

---

Necessity hopefully becomes the absentee parent of successfully invented children.

OK

Ball Mill complete and ready for some action.

The construction details is anyone is interested can be found on my blog

[kirbyandco.blogspot.com]

Complete with step by step pictures, good for a chortle if nothing else.

I will do the actual milling for real (rather than testing it out) during the week when there are less people around to be disturbed by the noise.

Hopefully we should have some fine ground Anhydrous Magnesium Sulphate shortly to be quickly followed by some fine ground Magnesium Sulphate Heptahydrate (the usual stuff you get from the chemists)

aka47

---

Necessity hopefully becomes the absentee parent of successfully invented children.

Um, Andy, what is all this stuff for? I read through your blog and still can't fathom what you are doing. Are you into the epoxy stuff?

Demented

Demented sir

In a nutshell, messing with ideas for support pastes. Currently Magnesium Sulphate (Epsom Salts). The Ball mill is to ensure the paste constituents are fine enough to go through the relevant size of dispensing nozzle/needle.

To Ball mill these ingredients though you have to make a ball mill (I don't have one already), ergo some of the posts here and the details of the making on the Blog.

Pasta Dough might be the next one.... not sure yet.

I want a machine that will lay down removable support as well as polymer.

The Granite stuff is on another thread and is proving most interesting, whether I have an immediate use for it for RP machinery though is perhaps another question. It looks interesting enough for me to want to try and use it for a later generation of machine, probably only for the bed though, again not sure yet.

Does this help ??

Cheers

aka47

---

Necessity hopefully becomes the absentee parent of successfully invented children.

Most eluminating. Thank you, sir!

Demented