Assembling Plan B

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With all the materials gathered it is time to assemble Plan B. This step will take around a day, depending on the amount of problems you will encounter. For assembly, you will need an assortment of wrenches, screwdrivers and allen keys. An electric screwdriver will cut down the assembly time by a ton. There currently isn’t a step by step picture assembly guide. All there is is a bunch of technical drawings and some pictures of the complete assemblies. If after this guide there are any questions left the can be asked in the contact me section. The questions will be answered as soon as possible and information might be added to the page if it seems to be missing. Low res versions of the drawings are displayed on this page, higher resolution images can be downloaded below.

download Drawings

Onward to the guide.

It’s best to start assembly with the pistons. The frame needs to adjusted to the sides and the axes of the pistons. Assemble the sub assemblies and mount these to the piston frames. At this point getting it exactly right doesn’t matter yet.

The spreader is easiest to mount to the frame while the frame is under construction, so it is next. It is best to assemble the bearing holders, but not yet join them with the 2 rods and the aluminum tube. This will be in the way of mounting it to the frame. Assemble these parts after the frame is assembled. Assembly of the spreader is pretty straight forward.

Now assemble the frame. First assemble the sheetmetal portion of the frame. All connections are made using T-slots. M3 nuts fit in the slots and a screw and a washer thread in to this nut. When the sheetmetal frame is assembled test fit the pistons. The frame needs to be as square as possible and all pistons need to have a gap smaller than 1mm to all sides on all heights. A consistent gap is more important here than a small gap, because a consistent gap can be filled with tape.

Fit the bearings for the pistons underneath the frame. Adjust these bearings until the pistons run smoothly. Also the bearings that run on the walls can be adjusted now to run on the sides of the hopper. At this point the endstops need to be mounted. Plan B functions perfectly well without these endstops, so this part can be skipped. They are just added safety.

Then assemble the plastic parts of the spreader axis. While assembling, mount the pre-assembled bearing holder of the spreader. When assembly is done you can joint both holders with the tube and threaded rods.

Assembling the carriage is fairly simple. The carrier for the cartridge is mounted with cable ties to the body of the carriage. The bearings are also mounted with cable ties. Don’t tighten the bearing ties too much, the bearings needs some freedom to adjust themselves to the rails.

Assemble the Y-axis. Assemble both bearing holders. Then fit the smooth rods in one holder and slide the carriage on (look at pictures to figure out the orientation). Then slide the other bearing holder on and adjust the carriage bearings (by simply pushing them) until the carriage runs smoothly across the Y-axis.

Assemble X-axis.

When all sub-assemblies are done, put everything together. Put the entire gantry on to of the printer. The pistons go in the frame after the printer is wired, there is no way to move the lead screws without power.

Make sure everything runs smooth. Move all axes by hand to check if they have any resistance. If there is too much resistance, Try moving the bearings by hand or loosen the screws a bit to give the bearing more space. When everything runs smoothly, the belts can be attached. The printer will need belts on the X, Y and S axes. These belts have been marked yellow in the schematic. The S and Y axis need a belt on either side, the X-axis runs through the entire printer. The belts are T2.5, 5mm wide and the pulleys have 16 teeth.

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  1. HI , I have some questions.
    Can we use other Keypad ? and Can you show the schematic of LCD Keypad that connect to board ?

    I’m little bit confused.

    Thank you.

  2. Hi,

    The drawing shows a part of Piston flag,but I do not understand what a Piston flag is. Can you tell me ?

    Thank you.

  3. Hi Great Project , I wanted to ask what printhead you are using with the HP C6602 Cartridge.We are doing something very similar but for sand casting puposes ( where we will make the mold itself).
    I would be very thankful to you for a reply.

  4. I just attached the rubber belts to the various axes and motors and noticed that when you move the y-axis assembly in the x-axis direction, it moves the carriage assembly along the y-axis due to the design of the belts, until it reaches the end of the axis, at which point the y-axis motor compensates by spinning. Is this an issue? How do you prevent the carriage from moving with the x-axis movement during a print?

  5. Hello,

    I was looking through the production drawings and noticed a lot of M5 Fender washers. I didn’t see any of these in the gathering materials page, so I didn’t order any. Is there a special reason I haven’t yet realized, or can I use a standard M4 washer?

    Thank you,

    • The M5 fender washers are used for retaining rings for the timing belts. They sit on either side of the idler bearings. They are important and cannot be replaced by normal M4 washers. M5 fender washers are already on the small side and M6 fender washer can be used if M5 is too small. I will add them to the list.

      • Im so sorry, i hadn’t looked the drawings,carefully,But, I’m confused about 2nd sheet of Piston Build Assembly(Full BOM), 2nd sheet of Piston Feed assembly,2nd sheet of X-axis assembly(full BOM). Are these continuation of previous page? I mean these second pages are just written for the list of unspecified parts on the first pages, aren’t they?
        And also could you specify the exact properties of Nema 17 stepper motor double shaft,please? because i fail to reach that link.

        • The order appears to be a bit messed up, but the pages are continuations of of drawings with the same name. In the bottom right corner there is sheet 2 of 2. The original link no longer exists. I have yet to find a new good supplier. Any Nema17 with around 4kgcm or more with a shaft coming out of both sides of the motor will do. The thickness of the motor is easily compensated with the 5mm shaft.

  6. I was looking at the solidworks assembly of Plan-B and am wondering how you ensure a seal between the pistons and chamber walls to prevent powder from falling through? Also, do the two supply pistons move up alternating once every two print layers, since the roller only goes across and not back with each print layer? Curious if that is what your firmware is designed to make them do.

    • Easy answer on how I ensure a seal is I do not. The tolerances are quite tight, but only within 0.5mm. The remaining gap can let some powder through, but most powders I used pack, meaning that when they compress, they solidify. The 2 pistons alternate as you said. That is designed in the firmware to be this way. It is a hardware solution to getting speed, but in retrospect all it did was add complexity.

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