CEB Day 4

It’s Monday, and back to work on CEB. First, I must say that the entire device follows Design for Disassembly (DfD), as well as lifetime design. This is beneficial for prototyping, as changes may be made readily without having to start over. This is accomplished by bolting where appropriate. It’s more work than welding, but it is absolutely worthwhile from the standpoint of serviceability and lifetime of use.

The key existing challenges for successful completion are several:

*Perfect alignment and vertical motion of compression assembly within chamber: Assembly cannot grind into the sides of chamber, or the plate will wear out the liner. The liner is a 1/8″ thick sheet of wear-resistent nylon 6/6 from McMaster Carr, part #8555K14. Tolerance here is 1/32″ for the allowable gap, and hopefully it will be down to direct, light contact throughout the compression stroke.

*Stroke limit of cylinder matches the ejection surface height perfectly, or to within 1/16″. This is necessary for automatic ejection of the finished block by a sideways push of the hopper assembly. I am designing the stroke limit to be 1/16″ lower in case there is any misalignment, as the difference can be made up by beveling the compression compartment edges, so the block can still be ejected without being chipped against the edge of the compression chamber. Another strategy here is to use a spacer to fill in the gap if necessary.

*Limit switches: While the ejection stroke limit is determined by the physical extension limit of the cylinder, block compression size will be determined by a limit switch. This way, all blocks will be identical in thickness, a precondition for laying level walls.

*Replaceability of the compression chamber nylon liner: the liner is wedged firmly under the side of the compression chamber on the big side, and it is held by small bolts for the short side of the compression chamber. Easy replacement is done by removing 4 bolts for the large side. Given that the rubbing against the liner will be forceful, the short side holding mechanism should be changed to a holding plate, not just small bolts, so the liner won’t simply rip through the bolt holes.

*20 ton pressing strength: currently, 8 1/2″ grade 8 bolts provide structural strength against compression where applicable. This is approximately 100 ton holding strength, which is a safety factor of 5. If the device shows any sign of weakness, I will weld on stop blocks where applicable. This will still retain full DfD features of all other parts.

Today, I will test the expansion of the cylinder, and subsequently begin mounting the cylinder in the frame, using the extended distance as a guide to attachment locations. Cylinder and spool valve prior to testing:


  1. Rebecca

    David returned your call only for you to never return his. However, if you are still interested in his advice, he’d be willing to speak with you. In the interum, he was looking at your progress, and says good luck and keep on plugging.
    “David says: you will regret not holding the press foot ridged with the press cylinder and to reevaluate your press tonage, unless of course you are pressing from the end and/or have a rather long press foot. Bravo on discovering 6/6 nylon, it’s amazing stuff.”
    I am relating his words to you, something I’m not comfortable doing. However, he is not comfortable with computers. Actually he says they hate him! He’s 69 years old and feels no need to learn them. If you have further questions or are just curious return his call. He’ll not chase after you.
    Be good to yourself,

  2. Mauro

    Dear frien I amwriting from Chile South america
    I am also building a CEB machine but I dont know how much pressure needs to be applied in to the cilinder Can you help me with that information.

    PD. your design is much better and simpler than mine

    best regards,

    Mauro Cuevas

    From Marcin:

    Hello Mauro,

    See for all the details.

Leave a Comment

Your email address will not be published. Required fields are marked *