Universal Paste Extruder

Printing with other materials -

This particular 3D printing adventure started last August (2011) after seeing a few news reports on 3D Chocolate printing, it had always been on my list of things to try, after reading the reports and looking at the rather over marketed video of a machine doing essentially nothing… I was really frustrated that the technology didn’t seem that accessible or even that revolutionary considering they described it as the “worlds first Chocolate printer”

It looked like the University of Exeter had decided not to show any videos of the printer actually doing anything to do with the printing process. – See the PR page and video Here. It does make a reasonable point about the end user specifying the custom design for themselves, much as we already see with 3D printing.

So they were giving no clues to how fast they had it running, or how long they cooled between layers etc. Just what you can see in the pictures. I decided not to go down that route of molten chambers of chocolate being pumped to a nozzle, it seemed overly complicated and limiting of what foods you could print with. It could be fine for industrial scale custom manufacture or a more adventurous Chocolate shop, but not that great for people with 3D printers to experiment with – and that was my angle.

Various paste extruders existed for RepRap, Makerbot and Fab@Home and both peristaltic pumps and moineau pumps were being experimented for paste extrusions, I looked at some of these, but went a different route.

I was quite aware that paste printing and especially Real molten Chocolate was a very difficult material to print with and I also didn’t want to have to use a Air compressor or other types of valves to achieve my food printing.

I decided on two development paths, both of which I’m still working on for different reasons you will see below.

1) – The Universal Paste Extruder

Chocolate was not the only Goal, I really wanted to be able to experiment with lots of pastes, foods and especially Ceramic materials.

So I designed this mechanical paste extruder, it is designed to fit on any RepRap or most 3D printers, you only need a normal Extruder motor connection, that’s all ( I know I have other wires in this Photo, that’s for part 2 – the heated paste extruder)

A short introduction video is shown here and also on my YouTube page in HD here

It uses my Quick-Fit X carriage mounting, so can be swapped over in seconds, you can also fit it to a normal Greg/Prusa style X carriage and most other designs.

It’s geared and uses a driven belt to press down on the Syringe. The main reason for this arrangement is to keep the height to a minimum and as the carriage goes higher the syringe goes lower so you get maximum build height.

Slightly out of data photo, but here are all the printed parts.
It uses normal 10ml Syringes – Either Luer lock or centre depending on what nozzle size you want.
Centre slip type
Assembly - 

Assembly video -

A full assembly video is shown here and also on my YouTube page in HD here
The motor is a normal NEMA17 type and small drive gear.
The Large gear is secured by using a modified M4 PCB stand-off to lock to the M4 threaded bar.
You can also fix it with an M4 Wingnut.
A standard 16tooth T5 metal gear is used to drive the belt.
 Trapped M3 nuts for the idler, 608 bearing.
Middle gear, fit this last.
The middle gear M4 shaft also clamps the end of the T5 belt in one of it’s groves, it will be a tight fit.
The other end of the belt gets fed under the metal gear and is compressed by the idler bearing.
The Syringe is supported well around the flange, and is deliberately loose, you can fit a strip of card, plastic, PTFE or some other material if needed, the M4 bolt and pressure block can also be used if you want to clamp in the Syringe,  but it does not really need it.
Insert a loaded syringe, fit the Cap with bearing and extrude until tight.
At this point you need to have a sensible figure in your firmware for the Estep value, you can calibrate steps per mm in the same way as you would with a plastic extruder, see here for help on that.
It’s also possible to leave it the same value as your normal extruder and then just alter the packing density / extrusion multiplier in your slicer.
I’m using Slic3r V0.7 and using 570 for the Esteps (8x microsteps) or 1140 for 16x Microsteps.
Slic3r profiles for various materials are up on the thingiverse page
Below are my initial efforts over one weekend with as many materials I had on hand, the kids really enjoyed helping me with this experiment.
I’m hooked on Ceramic printing now, so I’ll be doing a lot more of that along with more chocolate experiments. Some of the chocolate things didn’t exist long enough for a photo.

Printing with Sugar paste (Icing sugar)

Printing with Sugar paste video is shown here and also on my YouTube page in HD here


I highly recommend using a centre syringe with a big nozzle for first testing and also using a sugar paste as the first material to experiment with. This nozzle is 2.4mm.
I’m printing on mirror-glass (Not heated) but you could warm it up to help things dry out (Apart from Ceramic, don’t use any heat at all, any time printing with Ceramic before or after printing.
(See below for more on Ceramic printing)
This was my first print result, not bad, not good, too fast and the paste was a little runny, you are looking for about the consistency of cream cheese or Nutella (chocolate spread).
Second print , slower, need to adjust the fill and maybe use lift.
After a while I found really nice print settings for Slicer ( I put them up on thingiverse too)
I did quite a bit of Sugar printing, but as it’s slow to dry most of them were wiped off and put back into the Syringe, so it’s the ideal first paste material to experiment with in that respect.
If you use the other type of Syringe (Luer lock) you can fit removable needles of different sizes (Blunt or cut-down) to give very fine printing, this picture above is sugar paste with a 0.6mm needle (pink).
They have different gauges and colours as a guide – There are many more available than listed below -
Amber = Gauge 15 = 1.36mm internal nozzle
Pink= Gauge 20 = 0.61mm internal nozzle
Blue Gauge 22 = 0.41mm internal nozzle
Red Gauge 25 = 0.25mm internal nozzle
Yellow Gauge 32 = 0.1mm internal nozzle
TopTip – It’s a good idea to cut-down the length of the needles, even the blunt ended ones -
I used Pink and Blue and snipped the needle with cutters and then filed down and sanded the end until it was nice and round, see in the above photo how much I cut it down from the normal length, you could go even shorter and would need too for the really smaller sized needles.
Normal length needles.

Printing with melted Chocolate, Yum, Yum…

Printing with Chocolate and Muffin Mix video is shown here and also on my YouTube page in HD here

Chocolate is a tricky material, quality dark Chocolate is harder to print with than white Chocolate, I didn’t try milk Chocolate yet.

65% Dark Chocolate
The easiest way to melt it is in a Microwave for 30 seconds, then stir it and let it melt, don’t heat again unless it won’t all melt after many minutes.
Mix it all really well and check the temperature, don’t go over 35 degrees C.
Most dark chocolates stay very runny at around 33-35 degrees C
You want to be loading your syringes (Suck it up) at about 30-33 degrees C
White Chocolate is usually a thicker consistency at these temperatures, making it slightly easier to print with.
You can load white Chocolate at 31 – 36 degrees C
You should have plenty of printing time ~ 15+ minutes and you can always put the loaded syringe in a cup of warm water to keep it at a stable temperature.
I’m using Luer lock without needle as the hole is slightly smaller (2.1mm), a normal centre syringe is (2.4mm)


Dark chocolate outline, with a poured white chocolate inside.
White Chocolate – printed a little too cool in this picture.
Chocolate printing would benefit from a cold-bed to help freeze the layers quickly, so a future idea will be to use some Thermoelectric cooler (peltier) modules and Aluminium plate for the chocolate bed.

Printing with Masa (Corn chips), Crunch, Crunch, Crunch…

Printing with Masa Harina video is shown here and also on my YouTube page in HD here


Masa Harina flour is finely ground dried corn, used in lots of Mexican dishes.
Follow the instructions, mix with water, you are looking for a play-doh type consistency.
It’s a perfect 3D printing material as the dough is not sticky and extrudes very well indeed.
I decided to design the RepRap Crisp shown above to test this material.
I think a touch more water in the mix would have helped.
I’m printing on a Silicon baking sheet (so I can pop them straight in the oven).
They printed a little too fast, you need some time for the layers to stick before moving, but not bad.
A monster RepRap corn chip 
Baked to perfection in about 18 mins
And yes, they tasted really good! You can hear me crunching them on the video.

Printing with Chocolate muffin Mix and sponge cake , spongy…

Well I did say it was what I had around the house, this was a little bonkers, but good fun.

Muffin Mix, worked quite well.
Cooked top
Sponge cake mix (on the left) not recommended (too many bubbles and easy to burn)
I’m thinking Cookie dough would be the ultimate 3D printing Food material, I’ll have to try that soon.

Printing with Ceramic porcelain clay, Arty and Crafty…


Printing with Porcelain clay video is shown here and also on my YouTube page in HD here

I’m using porcelain clay for this experiment, slightly watered down to form the consistency of toothpaste.

And I’m thinking that it needs to be slightly thicker next time around.

Clay sticks to most things, but unless you can remove it, your part will be stuck to your print table.

If you leave a printed ceramic object on the bed it will warp as it dries and usually break up.

Do NOT be tempted to use the heated bed to dry the clay, it will ruin the print.

The best way I found to print clay objects is on a piece of aluminium foil taped down, this can be removed and the part dries slowly.

If you use anything with an absorbing surface (like paper, card or baking paper) the part will warp.

I have tried both Blue and pink nozzles (0.6mm and 0.4mm) with a 0.2mm one to try next time.

The easiest way to load the clay is to push it down the syringe with a small spatula or spoon, if you keep on pushing it down any air gaps should be forced out.
Put the plunger in and the clay can sit in there for many hours just fine.
You get a 0.65mm bead out a pink nozzle.
This was the first print (on glass directly, just to get the flow correct)
I needed to tweak the Slic3r settings a little to get correct infill, I’m making them just slightly overstuffed as you get a little shrinking when the clay dries and this seems to help keep the objects together.
Single wall, it’s quite amazing to see it build up, don’t touch it, they are extremely fragile while wet.
This pot is quite tiny, only about 18mm across
Same pot, scaled up, builds well.
Close-up of the first layer – (frog)
Second layer – tiny frog print.
Check out the video, it gives a much better feel for the print than pictures alone.
Printing a small bunny.
Bonus points if you guess which version of the bunny this it?
Yes I stopped it just before the ears, the clay was too wet to attempt them.
I printed a few more bunnies, pots and frogs, they dry nicely on the aluminium foil, leave them in a cool place to dry out. I hope to get some first fired next week to see how they hold up at high temperature.
I had a few accidents where the pots flopped over as I was taking them off the bed, you need to be gentle in handling wet clay, after just a few hours they are quite firm.
I will be doing a lot more experimentation with clays, this was one of the most exciting tests for the universal paste extruder so far.

Just after I had my universal paste extruder running, a rather interesting Chocolate extruder also popped up on thingiverse, Created by ttsalo I have yet to try it as it needs warm air to keep the chocolate molten, but I’m going to try this out at some point. I can imagine a dedicated DIY Chocolate printer based around a design like this.

I had a lot of fun doing this, if you want to experiment with paste, you can print yourself a set from the Thingiverse files I posted here - 
The Slic3r configurations are also posted, use them as a starting point. And don’t forget to change your Esteps in your firmware.
I have printed sets of these extruder parts in Faberdashery PLA and also built up some of these experimental extruder’s, if you fancy buying one, they can be found up on the eMaker shop, all proceeds of sales will go towards more RepRap experiments and some well deserved beer :) If they are out of stock, just ask me, I’ll print you a set.
I also usually have sets of printed plastic’s Syringes and needles as a kit if you want to source the other parts yourself.
* – While I was uploading the video’s to YouTube, one of the first comments was from films4you suggesting that it could also be used for solder paste, I have no idea why I didn’t think of that! – Thanks, another one to try at some point soon I think.

Some time later… I had my Ceramic parts back from being Fired -

An update for May and some pictures of my first ceramic objects that have now been fired -

I had my first Porcelain ceramic prints back from being fired a few weeks back, they turned out well considering these were my very first prints using the universal paste extruder. And I didn’t really know what I was doing with Porcelain clay.

They have been both first and second fired, so are now very strong and hard, and a little smaller than when first printed.

During the two stage firing they have shrunk about 15 – 20% from the dried out size, and are now real solid little pots.

All the parts were printed with a 0.6mm nozzle, I now have 0.4 and 0.2mm nozzles working well, so much smaller and finer details should well be possible.

Many of the small features have fused together, giving a very nice and smooth finish, this bunny is partially hollow with just a small pin-prick hole in the bottom, I was expecting him to explode, but he looks fine.

None of these were glazed or altered during the firing process, next time I may try some glazes and some smaller pieces.

I’m also going to try to calculate how much they shrink for a given infill and water content next time around.

The only casualties were the Frogs, two were damaged in transit to the first firing so one didn’t get fired, the other one was first fired and some of the feet fell off… it was second fired along with the rest and didn’t suffer any further damage.

Even this one above was squashed on his head before firing, you can see his squashed eye :( so I’m not exactly sure if his feet were damaged before getting to the kiln. So I’m going to try more frogs next time.

I have a very friendly potter now with her own kiln close by, so I can get things first fired very easily, then the local college can provide the glazing and second firing process, so it’s going to be lots of fun experimenting with this aspect of 3D printing.


Clay Update Aug2012 -

I’m also looking into printing with Paper-clay, many thanks to everyone that has pointed me in that direction, looks very interesting indeed. I’m still reading about it and have some more people to contact, so I’ll try to do another update on that when I have done some printing with it.

I also ordered some Precious metal clay (copper) but have not yet had a chance to test it out, should work well, but has some special requirements to fire copper clay, so I’m still working on that. If it does I may even order some silver-clay (really expensive, but very nice for jewellery), that looks quite amazing when fired, again thanks for pointing me towards that.

I do have Metal clay to try and also Paperclay (very good for low warp – perfect 3D printing material)

Thanks again for all the great comments and feedback from my universal paste extruder, it’s great to know people like it and are using it to make awesome things.

This development was first posted up on my Blogger blog (Universal Paste extruder – Ceramic, Food and Real Chocolate 3D Printing…) 6th April 2012

Thanks for reading.

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