Liberator 2 CEB Design

Over the past few days, Marcin and I have been working on the design of The Liberator 2 – the second prototype of our high-performance CEB press. The design is now up for review. The main changes are an enlarged, stationary hopper structure, guide rails that use cam followers, and an anti-bridging auger in the mouth of the hopper.

The main review point is the cam follower roller bearings that guide the motion of the soil-loading mechanism. We’re using the cam rollers to hold the soil loading mechanism in position to minimize friction. In the previous design there was plastic liner below the loader and in the compression chamber to protect the metal pieces from rubbing, but the liner was a failure mode. Rocks would get under the liner and it would pry off. Is there a better way to do this?

The hopper can be wheelbarrow loaded, or with a larger plywood hopper attached it can be tractor loaded.

Also I made an animation of the function, which will be automated with an Arduino-based controller. The controller will also be responsible for selecting uniform brick thickness.

You also download the blender file at the OSE wiki page. Blender is a multi-platform open source modeling program, so anyone can use it on almost any operating system.


  1. Nick

    Great blender model, but could you perhaps overlaw some arrows on the jpeg to point out the parts you describe. I am not clear on what you mean by cam roller follower.

    Secondly how is the issue of inconsistent brick height being addressed? Are the bricks going to be compressed from the sides?

  2. Marcin

    The brick height will now be adjustable by using limit switches and the Arduino controller. We will test the machine with a manual hydraulic control valve. When all works as it should, we’ll replace the manual hydraulic valve with an Arduino-programmable hydraulic solenoid valve. Open source, of course.

  3. Nick

    What about the inconsistent pressing pressure you develop by using the limit switch approach? Will this affect the bricks compressive strength significantly?

  4. Marcin

    That problem is addressed if 2 limit switches are used. One will be near the bottom of the compression stroke, and one at the end of the compression stroke.

  5. Nick

    Ahhh, very good thinking on the two limit switch idea, sounds like a winning design.

    As a very small point you may want to consider using field programmable gate array as opposed to the arduino to bring down the cost a small amount? I believe FPGA can be had for $5-$7.

  6. Jeremy

    The cam follower roller bearings are the round cylindrical rollers you can see on the sides of the second picture. Here’s a link to the ones we’re thinking of using:,-CFH-1-SB–,-NEW_W0QQitemZ370098481327QQcmdZViewItem

  7. scott

    How will the limit switches help in assuring the blocks are pressed to the required psi?

    I think the requirement should be from 900-1200 psi.

  8. Jeremy

    How are the FPGAs programmed? The arduino looks easier to do and there seems to be good documentation. Is there a place with good documentation of the FPGAs? Are the FPGAs open source like the arduino?

    It looks like pressing from the side is out because it would mean we need a complete redesign for more power, because pressing from the side has to press a larger mass to get the 12x6x4 bricks.

    Thanks for the feedback Nick!

  9. Rob

    To add to comment #7, I’ve heard that having enough pressure to reach a 97-99% compaction is important. Have you all come across any documentation on this? Have I got it correct that you are thinking about programming the compression stroke so it varies soil intake depending on hydraulic pressure in the previous stroke?

  10. Richard

    This is beautiful. Factor E hard at work. Getting into the nit and grit of it. OSE has really taken off lately. The site, the process, the attitude. Keep up the good work.

    The exciting thing about the extreme low material cost of this machine is that it leaves lots of room for slight cost increases for more fluid and streamlined functionality, as well as supplemental technologies to more quickly catalyze the process. I will gladly help put Liberator II into action this summer once im liberated from academia.

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  12. Lost Chief

    I saw a video the other day called Vaults & Domes that was building out of CEB bricks. They had a manual press that make 2 bricks at a time. Would any of you happen to know where i can get plans on how to build manual ceb presses for free? Ive searched the net for some time and have yet to find any. I would really like the plans to make a press like th eone in that video to press 2 bricks at a time.

    Any help would be great.

  13. Lost Chief

    Here is the video. Not sure if you guys have seen it but it shows allot of tec.

  14. Lost Chief

    Hell i guess i should have checked this link. Its not working for me anymore but i have a copy and i will upload it and post it later today..

  15. Lost Chief

    Ok i uploaded it and you can download it here..

  16. Jeremy

    Thanks Lost Chief, I’ll have to check it out later.

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