Before starting

BigFDM is a big machine, and therefore requires a large space were you can comfortably build it. This especially when you need to move around it, or to install big parts. Furthermore the build requires the use of common tools, including some power tools and bench tools. It is therefore recommended to build BigFDM in workshop space of at least 20sqm. Every step consists of the procurement of the required tools and the machine parts, and of some assembly. Steps are in a logic/convenient order to efficiently build the machine.

Here a video of a successfull BigFDM build, during a week-long workshop at Fab Lab ENIT, Tunisia:

Step 1: lower frame assembly

Tools required:

• DIN 875
• hex keys
• clamps
• rubber hammer

Machine parts required:

• 2 x aluminum Profile 60x60 1080mm
• 2 x aluminum Profile 60x60 1200mm
• 8 x 60x60 brackets

It is important to assembly the profiles onto a flat surface. First assembly only two profiles, using the DIN 875 and the clamps to make sure they are 90 degrees. Put the two profiles appromatively 90 degrees and close to each other. Screw without tighnething the brackets. Attach the DIN 875 to the profiles with the clamps. Small adjustment can be easily done with a rubber hammer. Then tight the brackets and remove the clamps. After this repeat the process with the other two profiles. Finally assemble all together, again making sure the joints are as much as possible 90 degrees.

Step 2: upper frame assembly

Tools required:

• DIN 875
• hex keys
• clamps
• rubber hammer
• caliper

Machine parts required:

• 2 x aluminum Profile 60x60 1080mm
• 2 x aluminum Profile 60x60 1200mm
• 4 x 30x30 brackets
• 2 x Hiwin linear guides 970mm
• 2 x Hiwin linear guides carriages
• 2 x X axis brackets

This step is similar as the previous one, with the difference that the brackets are different, and you need to install the X axis linear guides and carriages now to avoid much difficult assembly later on. On the front there are four 30x30 brackets, while in the back two custom X axis brackets.

Before assembling the frame, attach the two linear guides. It is recommended to attach bolts and T-Nuts beforehand to the linear guides, to then fit them slowly from the side. Before tighting the linear guides, use the caliper to adjust them as much as possible having the same distance from one border of the alumimum profile. Keep the linear guides at a distance of about 5mm from the X axis brackets. Last step of assembling the X axis linears guides, is to insert the carriages. Make sure they are blocked by something (eg some tape), to avoid them accindentally going out.

After attaching the linear guides, first assemble the two corners with the 30x30 brackets, and then the other two with the X axis brackets. This because the X brackets are quite flexible and their precision depends on the milling quality, therefore the metallic one will guide them to be square. The end result will be producing another square frame.

Step 3: main frame assembly

Tools required:

• hex keys
• rubber hammer
• 2 x flat pieces (MDF, Alu..)
• clamps

Machine parts required:

• 4 x aluminum Profile 60x60 1200mm
• 32 x 60x60 brackets
• 4 x machine wheels

This step objective is to assembly the complete main frame. Before starting is convienient to attach the wheels to the lower frame, to then be able to easily move the machine around. It is essential to make sure the vertical profiles are aligned with bottom and upper ones. To ensure this first assemble the vertical profiles on top of the bottom frame, without tighting the brackets. Use the clamps to fix two flat pieces on the sides, to align the vertical and the horizontal profiles. After being aligned you can tight the brackets. Then repeat the process, putting the upper frame on top, and align the vertical profiles with the upper frame.

Step 4: X axis assembly

Tools required:

• hex keys
• spanner keys
• rubber hammer

Machine parts required:

• 4 x GT2 40T Pulleys 12mm bore
• X axis motor holder
• X axis Nema 24 motor
• 2 x couplers 8-12mm
• 2 x X axis shaft holder
• 2 x 12mm shaft 468mm
• 12 x 637/8 ball bearings
• 4 x 61801 ball bearings
• 2 x 61901 ball bearings
• 2 x 30x30 brackets

Having assembled the X axis linear guides in the 2nd step, to be completed the X axis assembly now requires the motor and the supports for the pulleys. It is recommended to gently push the bearings to fit to CNC milled parts with a rubber hammer, to avoid damaging them. The Nema 24 motor must be installed first, and then slightly moved on the side when fitting the 12mm shafts. The shaft supports, can be pre-attached to the shafts, before attaching the shaft themselves. The pulleys on the front are attached using 30x30 brackets and closed with nut and bolt. Those are free running pulleys and each has 6 637/8 bearings inside to fit with an M6 bolt.

Step 5: Y axis assembly

Tools required:

• hex keys
• spanner keys
• caliper
• ruler

Machine parts required:

• 1 x aluminum profile 40x40 932mm
• 1 x Hiwin lineas guide 900mm
• 1 x Hiwin linear guide carriage
• 1 x Y Axis Nema 23 motor
• 1 x Y axis motor plate
• 2 x Y axis connectors
• 1 x Y axis pulley holder
• 2 x Belt GT2 10mm about 2100mm
• 1 x GT2 40T Pulley 6.35mm bore
• 1 x GT2 40T Pulley 12mmm bore
• 6 x 637/8 ball bearings

The Y axis has to be mounted on the X axis. In a similar way for the step 2, it is recommended to first mount the Hiwin linear guide to the 40x40 profile, before doing anything else. Again fit the linear guide from the side, check it's alighment with the profile before tightining it, and put the carriage onto it. Next substep is to attach the connectors to X axis carriages. This becase later on there will not be space for the hex key to screw the carriage bolts. After attaching the connectors, it is recommended to attach the X GT2 belts to its bottom bolts (longer for this attachment purpose). Try to play with the front 30x30 bracket and the back pulleys, to align the belt to the connectors bolt attachment. Also try to give similar tension to the two belts. Once the belts are in place, it is possible to align the position of the connectors, by untightining the back pulleys, move the connectors to the same distance form the main frame (checking it with the rules), and then screw the back pulleys back. At this point is possible to attach the 40x40 profile to the connectors. Screw the bolts gently and a bit per each side, to avoid twist the Y axis position. Last substeps, attach the motor plate, the Nema 23 motor to it, and the right pulley with the pulley holder.

Step 6: head assembly

Tools required:

• hex keys
• spanner keys

Machine parts required:

• 1 x aluminum head plate
• 2 x dual Geeetech MK8 extruder heads

First attach the head plate to the Y carriage. The plate will also work as support in between the extruder motors and the extruders. The Nema 17 are mounted on the back, while the rest of the parts in the front of the plate. Leave the top holes free, as they will be used to attach wires/filament holders.

Step 7: Z axis assembly

Tools required:

• hex keys
• spanner keys

Machine parts required:

• 4 x lead screws 16mm, 4mm pitch
• 4 x linear rods 20mm
• 4 x brass nuts, 16mm, 4mm pitch
• 4 x linear bearing 20mm
• 1 x HTD M3 Belt 4698mm
• 1 x Nema 24 motor
• 1 x Z motor mount
• 5 x Z belt spacers
• 16 x 628 ball bearing
• 12 x 636 ball bearing
• 4 x linear rods bottom mounts
• 4 x lead screws bottom mounts
• 4 x linear rods top mounts
• 4 x lead screws top mounts
• 4 x bottom supports
• 4 x top supports
• 8 x top spacers
• 2 x 30x30 aluminum profile
• 2 x 30x30 brackets
• 4 x HTD 40T M3 pulleys, bore 8mm
• 1 x HTD 20T M3 pulley, bore 8mm
• 4 x aluminum bed plates

The Z axis of BigFDM consists of many parts. In a similar way to other steps, the order of assembly matters to successfully be able to assembly all. The first substep is to attach all the bottom parts to the main frame: Z motor mount and Nema 24 motor with pulley, the two 30x30 profiles, Z belt spacers, mottom supports, bottom mounts and the bottom 628 and 636 bearings. After this fit the rods and the lead screw into the bottom supports. Before you close the rods it necessary to install the aluminum bed plates, which will support the bed later on. To do this install first the brass nuts, the linear bearing and lastly the bed plates. Having the rods and the lead screws attached, with the bed supports attached in the middle, you now can start attaching the top parts. The lead screws and the rods mounts, have to to be first attached to the rods and screws directly, and then attached to the top supports. The top section is almost a mirror of the bottom one, so you need: top mounts, top supports, 628 bearings. Lastly attach the 4 pulleys to the bottom of the lead screws. The belt has to be carefully placed, avoiding to tension too much only one section. If you feel that is uniqual, untight a pulley close to it, and manually adjust the tension.

Step 8: bed Assembly

Tools required:

• hex keys
• spanner keys

Machine parts required:

• 1 x aluminum bed
• 5 x aluminum 20x20 profiles 1000mm
• 4 x aluminum 20x20 profiles 890mm
• 4 x aluminum 20x20 profiles 435mm
• 8 x lower bed corners
• 4 x upper bed corners
• 4 x bed corner supports
• 16 x 20x20 brackets

To be adjustable and to do not cause heat dissipation, the bed is divided in two sections, lower and upper bed. The two are connected just by 4 M8 bolts in the corners. The first substep is to assemble the lower bed, which will then support the upper one. The lower bed consists of 4 20x20 profiles, and some corner parts to allow the bed support bolts to move the upper bed up and down. After assembing the lower bed, it is recommended to assemble completely the upper bed on a table, and then just place on top of the lower one once ready. The upper bed is made in a similar way of the lower one, there are extra some 20x20 profiles in the center for mechanical stability. Because of the weight, is mandatory to be in two to place the upper bed.

Step 9: housing assembly

Tools required:

• hex keys
• spanner keys
• M6 tapping tools

Machine parts required:

• 2 x acrylic doors
• 3 x acrylic windows
• 1 x tablet acrylic support
• 1 x tablex aluminium composite cover
• 16 x aluminium composites corners

The assembly of the housing takes care of covering the all machine with a mix of aluminum composites and acrylic. It will still be possible to make a mechanical intervention in almost any part of the machine with it installed. The first to be installed have to be the aluminum composites corners, take care the front/back corners are 4mm wider from the side ones, and also some of them have predisposed holes for the main switch, tablet, emergency button, power sockets. Some corners requires to have threaded the inner holes of the 60x60 profiles with M6 tapping tools. After all the corners have been installed, is then possible to install the acrylic windows. Recommended to be in two, one person inside the machine under the bed holding the nuts, the other outside screwing the bolts.