R&D: Frostruder MK2

Posted by on Monday, November 2, 2009 in Uncategorized

One of our goals when we started MakerBot and designed the CupCake CNC was to automate one of the most tedious things of all time: frosting cupcakes. This incredibly difficult task has plagued mankind for centuries, but at long last we have found a reliable way to automate the process.

Our original design for a frosting extruder followed in the footsteps of [email protected]’s paste extruder. They have a fairly elegant solution that uses linear actuators. Unfortunately, the linear actuators themselves cost more than our target price for the entire kit, so we attempted to come up with an emulated design that uses standard motors, lasercut gears, and some threaded rod to create a motorized plunger.

Well, this worked up until a point, but it was a pretty error prone and bulky solution. The gears were difficult to attach. The threaded rod based plunger required a design at least 2x the height of our desired syringe (60cc) and basically was heavy and didn’t work well. It was certainly an interesting design challenge for Bre, Will, and I that saw about 7-8 iterations and a failed appearance on TV, but ultimately it was fruitless. There’s a reason we never released the MK1 for sale. 🙂

Not only that, but the motorized piston based solution is an inherently flawed approach: The extrusion of a material is based primarily on the pressure, viscosity, and nozzle diameter. There’s not much you can do about viscosity and nozzle diameter, so we’re mucking with pressure. In the motorized piston approach, the pressure builds up gradually as you push the plunger down, and releases as the material either leaves the syringe or you back off the plunger. The result is that you either have extremely slow start/stop times or you have to deal with massive ooze problems.

Which brings us to the MK2. I was musing over the design failures one day when I had the idea that instead of trying to create the pressure in the syringe mechanically using a plunger, what if we directly applied pressure using air. I reasoned that we could use a commonly available air compressor and electrically controlled solenoid valves to push frosting out of a syringe tip. I had this idea for about 6 months, but it had to sit on the backburner for a while until I had a chance to work on it.

My first experiment was with some thick, chocolate frosting that you can find in nearly any grocery store. I simply wanted to see if it was possible to use air pressure to extrude frosting, so I wired up a solenoid to a switch and used that solenoid to turn the air pressure on and off to the syringe. I was using a 21GA (0.53mm) needle and a standard 60cc syringe. I hooked it up to the air pressure and opened the valve. Nothing happened right away, but I gradually turned the pressure up until about 50-60 PSI I started getting a frosting extrusion. I kept turning up the pressure to about 80 PSI where I got a really nice, very fast frosting extrusion that was about 0.5mm wide. Success!!!

Well, it wasn’t a total success: when I closed the valve, the syringe was still pressurized and continued to extrude. Obviously that is a problem, so I went back to the drawing board. I came up with the idea of adding a 2nd valve that would act as a relief valve and release the built-up pressure to the outside world. I grabbed a second valve and went back to the garage to experiment. The result was phenomenal! I was able to start and stop the extrusion at will, with zero oozing problems. This was excellent news. I soon had an Extruder controller wired up to the solenoids and a tester gcode script that would cycle the valves every 10 seconds. It was amazing to see a stream of frosting coming out and stopping every 10 seconds. I ran to get Bre and Adam to celebrate and we danced a frosting dance.

So: fast forward a few weeks and we’re gearing up for the Yahoo Hack Day in Times Square. We really didn’t have a solid game plan for what to do, but we knew we wanted to have fun and stay up all night hacking. I was really into the new frostruder design, so I brought it with us along with a portable air tank and a bike pump. We spent all night hacking on the frostruder and trying a variety of edible materials (frosting, peanut butter, and jelly). We ended up winning the Best Hardware Hack category with our New York Toast entry. It was a fun, fun hacking adventure.

For more info, check out Thingiverse and the MakerBot wiki.

Tagged with , , 18 comments

18 Comments so far

  • Cyrozap
    November 2, 2009 at 1:38 pm

    You meant “R&D: Frostruder MK2, right? LOL @ post name FAIL.

  • Zach Hoeken
    November 2, 2009 at 1:54 pm

    lol, yup.

  • Chris Norrick
    November 2, 2009 at 2:06 pm

    I just accuired one of these portable co2 systems for intended use with portable homebrewed beer dispensing (see link below). It’s a compact heavy duty co2 regulator to be used with air nailers, etc. It uses paintball co2 tanks so it is small and compact and should last quite awhile. Seems like a perfect way to supply air to the MK2. This is the Kobalt brand that is Lowe’s house brand. Another company makes these for them but I can’t recall the name at the moment.

    The CupCake CNC is the top item on this years christmast list!

  • Rick Pollack
    November 2, 2009 at 2:09 pm


  • Chris Norrick
    November 2, 2009 at 2:12 pm

    If you go to Product Demo, there is an action shot of it hooked up to a caulking gun = XXXL Frostruder!

  • Tox
    November 3, 2009 at 5:55 am

    Do you have spare MK1s left? Because if you less viscous liquids the Size of the thing does not matter, because you can connect it with tubes and have the device it self sitting ontop of CupCake

  • Zach Hoeken
    November 3, 2009 at 6:21 am

    Nope, no MK1s left. We do have a couple failed prototypes on the shelves, but trust me… you dont want those. We’ll have this kit out ASAP and it will rock.

  • Frostruder MK2 | Diy all the Way
    November 4, 2009 at 2:17 pm

    […] Hoeken wrote up a nice piece about the design of the MakerBot Frostruder MK2, currently in its second prototype. He talks about the challenges of designing a cheap, small […]

  • r bel
    November 5, 2009 at 11:42 pm

    have you tried printing with UV resin yet? it is probably too viscous just to push out the nozzle and harden with a UV led , but i think a “flashing chamber” before the needle where ‘some’ of the uv light passes through and increases viscosity would work. As im sure you are finding the only way to get a stream leaving the nozzle is either to increase the viscosity of the fluid so it will not coalesce into droplets at the tip or increasing the air pressure so the velocity of the fluid exiting can overcome the surface tension forces that cause droplets on the tip. This is the kind of toolhead im researching to build for my CNC and this frostruder could be an awesome place to start hacking. Go Makerbot!

  • Zach Hoeken
    November 6, 2009 at 1:24 pm

    r bel: we havent experimented with the UV curing stuff yet, but its a very interesting area we’d like to explore. from what i’ve heard the best way to do uv curing liquids is to spray them in a mist that will create a very fine, thin layer (see: super high resolution!) and then selectively cure with an LED or laser.


  • » Remainders – Stuff We Didn’t Post (and Why) [Remainders] Technology India
    December 9, 2009 at 1:07 am

    […] rather use the time saved to nibble on the “defective” inconsistently frosted treats. [Makerbot via […]

  • Unfold
    January 17, 2010 at 9:27 am

    I’ve build an extruder following the Frostruder MK2 design but with a single Solenoid and one that fits a Bits from Bytes Rapman. The goal is to extrude clay and build ceramic object.
    You can follow the progress here:

  • John Gomm
    February 28, 2010 at 11:50 pm

    I was looking at CandyFab today, which seems to have lost momentum, and it occurred to me that you might be able to combine a heated section at the bottom of the barrel of your frostruder to caramelize granular sugar (160’c) then use air to controllably lay it down like regular ABS. I will definitely be getting a frostruder when available, so if you don’t try it before then, I’ll experiment. Sugar is so cheap and sparks the imagination so readily that it’s a shame the candyfab project is not selling kits yet.

  • John Gomm
    February 28, 2010 at 11:55 pm

    Oh, you could also melt chocolate in a heated barrel and make sculptures, result! Might need a cooled stage rather than a heated one, for choccy.

  • Electric cupcakes « The tech telecom and all
    March 8, 2010 at 6:09 pm

    […] from days gone by. Designs like this would be neat to try with the Makerbot and its’ Frostruder […]

  • Claystruder parts | 3D Printer Parts
    July 3, 2010 at 1:50 pm

    […] for that one instead of losing time on the same thing. After talking with Bre Pettis about their Frostruder MK2 experiments I dived into it. Its a much simpler machine in terms of mechanics and has the advantage […]

  • Andrew
    August 19, 2010 at 12:18 pm

    You guys should google liquid dispensing – Controllers are cheap $350.00 syringes, pistons and a little compressor from home depot and you are in business.

    You guys are trying to develop something that already exists as a mature industry

  • Remainders – Stuff We Didn’t Post (and Why) [Video] | The KW Blog
    October 11, 2010 at 8:15 pm

    […] rather use the time saved to nibble on the “defective” inconsistently frosted treats. [Makerbot via […]


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