Fab@Home:Assembly Tips

Step 1: Orientation - The threaded brass inserts have a slightly tapered shape (right) to guide it into the hole. The direction of insertion for the insert on the right of the photo would be toward the bottom of the image (the receiving hole would be below the insert).

Step 2: Place in hole - The inserts should fit slightly into the appropriate holes.

Step 3: Position the part and soldering iron - Hold or clamp the part such that the hole for the insert is overhanging the edge of your workbench, and insert the tip of a hot soldering iron into the insert.

Step 4: Insertion - Use gentle pressure from the soldering iron to push the insert straight downward into the acrylic part.

Step 5: Steering - Use the soldering iron to steer the insert to keep it straight in the hole as you insert it.

Step 6: Depth (front) - Continue pushing the insert until it is just flush with the upward facing surface of the acrylic. There will be a small ridge of melted acrylic which rises slightly above the insert.

Step 7: Depth (rear) - Ensure that the insert does not protrude beyond the back side of the acrylic - the back surface must remain flat to align correctly against other parts.

Step 8: Check Angle - Use a screw of the proper size to see how well your threaded insert is positioned. If crooked (like the one showne), take the screw out and use the soldering iron to adjust the insert (alternatively, the insert may still be hot enough that you can use the screw to push it into the proper position).

Step 1: Cutting the sheath - Using your wire stripper, or a knife, gently cut partially into the outer sheath (gray in photo) of the cable about 1 inch (25mm) from the end. Be careful to not cut too deeply - we want to avoid damaging the (red/black in photo) insulation on the individual conductors inside!

Step 2: Removing sheath - Bend the cable sharply at the location of your cut to break the sheath, and pull it off. This can take a bit of effort and some slight additional cutting of the sheath.

Step 3: Stripping wire - Using your wire stripper, wire cutters, or a knife, gently cut into the conductor insulation about 1/4 inch (6.4mm) from the end. Be careful not to cut too deeply because slight cuts into the copper conductors will cause them to break off. As you cut into the insulation, you should feel a slight change in firmness when you reach the copper.

Step 4: Removing insulation - Pull the insulation off of the wire and look closely for nicks (cuts) into the copper. If you cut the copper, you should cut off the wire before the nick, and strip the insulation back further. If you are working with multi-strand wire, twist the exposed copper strands tightly together.

Step 1: Apply flux - Apply a small amount of soldering flux to the bare copper. We recommend using a no-clean flux.

Step 2: Apply solder - With your soldering iron, heat the stripped copper for a 3-5 seconds. Touch the solder wire to the hot copper, and let the solder flow to cover the copper.

Step 1: Prepare motor extension cable- Using the lengths recommended for your fabber model, cut a length of 4-conductor cable to extend the motor leads for each motor. Strip the cable and conductors on both ends of each extension, and tin the stripped conductors on both ends (see Stripping Cable and Wire and Tinning Stripped Conductors).

Step 2: Prepare and secure motor leads - The HSI motor leads are pre-stripped to about 1 inch (25.4mm). Twist the conductors of each lead wire tightly together, and cut them off to about 1/4" (6.35mm). Apply flux and tin them. Find heat shrink tubing (yellow in photo) with a slightly larger diameter than the motor leads (we recommend 0.076" to 0.093" ID tubing). Cut four pieces about 1" long, and thread them on the motor leads. Secure the motor leads to block of wood as shown in the order red, red-white, green, green-white. Laying them out in this order will simplify connecting the motor to an amplifier, and taping them down to a wood block frees your hands for soldering.

Step 3: Position and secure the extensions - Secure the tinned conductors of the extension right next to the tinned motor leads. Pay attention to the color sequence you choose to use (write it down!) so that you know which color in the extension corresponds to which motor lead color - this will simplify connecting the motor to the amplifier. We recommend red=red, red-white=black, green=green, green-white=white.

Step 4: Solder the conductors - Using the side of the tip of your soldering iron, press the tinned ends of the conductors against each other until the solder on them from tinning begins to melt. Add a small amount of solder to make a nice smooth connection. W To prevent the wires springing apart when you remove the soldering iron, you may need to hold them down with a finger (caution - they will be hot!) or a tool. Blowing on them will freeze the solder quickly.

Step 5: Slide the shrink tube - Once the solder joints are all made and have cooled, slide the heat shrink tube pieces up over the solder joints.

Step 6: Shrink the shrink tube - Using a heat gun or a hair-dryer, heat up the shrink tube until it contracts uniformly onto the solder joint. This protects the joints from corrosion and shorting with each other.

Step 7: Examine your work - Take a moment to examine the joints for quality. There should be no sharp solder points poking through the shrink tube, and the tube should be tight, and not free to slide around on the wire. Being careful at steps like these will make for a much more reliable machine later, saving a lot of time and trouble in repairs.

Step 1: Gather parts - Using sharp scissors, cut the ribbon cable straight across to the length recommended by the assembly instructions for your fabber model. Look at the cut end to ensure that the conductor strands are cleanly cut, and have not been pulled out or made to touch each other. The IDC connector will usually consist of 3 parts - the connector front, the connector back, and a strain relief clip (see photo).

Step 2: Orient correctly - For the Model 1, you need to orient the connectors carefully so that the connections between the microcontroller and other electronics can be made correctly - you will need to select certain individual conductors in the ribbon by counting from one edge, and that edge must oriented correctly to ensure that the conductors you select connect to the correct microcontroller pins. The photo shows the correct orientation for both connectors for the Model 1. Note the position of the notch in the connector front, and the red stripe on the ribbon cable.

Step 3: Expose connector back adhesive - Peel the paper off of the connector back, exposing the adhesive. Be careful to not peel the adhesive off. Note the scalloped surface beneath the adhesive, which is used to align the ribbon cable against the connector back.

Step 4: Attach the connector back to the ribbon cable - Place the end of the ribbon cable on the adhesive of the connector back. The ribbon should fit perfectly into the scalloped dents in the connector back - one dent per conductor. Orient the parts exactly as shown, noting the location of the stripe on the cable, and that the cable end should be flush with the side of the connector back.

Step 5: Mate the connector parts - Being careful to orient the parts as shown here and in prior photos, push the connector back evenly into the connector front. It should stay in place. The conductor barbs need to line up with each conductor in the ribbon.

Step 6: Press the connector parts together - Using a vice (ideally), squeeze the connector parts together until you hear two tabs in the connector snap into place. If your vice jaws are rough (knurled) or you are using pliers or vice-grips, protect the connector from the vice jaws with a stiff flat material like plastic, wood, cardboard, brass shim-stock, etc.

Step 7: Fold the ribbon back - If you are going to use a strain relief, fold the ribbon cable back over the finished connector.

Step 8: Add the strain relief - If you are using a strain relief, snap it into the connector back with the cable folded over underneath it as shown. It should snap into place on both sides of the connector.

Step 1: Gather the parts - Gather the 2 conductor cable, the limit switches, the crimp pins/sockets , and the connector bodies. Referring to the assembly instructions for your model, cut the 2-conductor cable into pieces of the appropriate length. Strip the sheath and conductor insulation, and tin the stripped copper on both ends of the cable (see Stripping Cable and Wire and Tinning Stripped Conductors).

Step 2: Secure the crimp pins/sockets - To simplify the soldering process, secure the crimp pins/sockets with tape to a block of wood.

Step 3: Flux the conductors - Apply a small amount of flux to the stripped/tinned conductors on one end of the cable.

Step 4: Position in pin/socket - Position the fluxed conductor ends into the back end of the pins/sockets as shown. The conductor should not go more than 1/2 of the way into the pin/socket. Ideally, (unlike in the photo) the insulation should extend past the tall flanges of the pin, and the stripped conductor should extend past the short flanges to roughly 1/2 the length of the pin/socket. The tall flanges are designed to be crimped onto the insulation, the short onto the conductor.

Step 5: Solder conductor - With the tip of your soldering iron, press the conductor down against the pin/socket for about 3 seconds, and apply a small amount of solder wire. You should see the solder flow smoothly over the conductor and the pin/socket. Do not apply too much solder, as it will clog the front half of the pin/socket, which must remain clear to connect to the limit switch (see inset).

Step 6: Detach pins/sockets from strip - Once your soldering is done, break or cut the pins/sockets you have soldered to off of the strip of crimps.

Step 7: Crimp pin/socket flanges - Using your needlenose pliers, fold the two sets of flanges of the pin/socket down onto the soldered area. Fold first one side down, then fold the other side down on top of the first. Do not bend the front end of the pin/socket, as its shape is important for connection to the limit switch.

Step 8: Insert pins/sockets into connector body - Noting closely the shape of the connector and pin/socket, push the pins/sockets into the back of the connector body. They should snap into place. You may need to use your needlenose pliers or a very small hex key to push the pin/socket fully into the connector body. Test your connector by pulling gently on the leads. The pins/sockets should stay inside of the connector body, and the conductors should stay inside of the pins/sockets. If you are not satisfied, fix the problem now to save yourself greater trouble later.

Step 9: Connect to limit switch - The connector should now simply snap into the limit switch

Step 10: Label your cable - Using a labelmaker or masking tape, label your cables by axis and direction according to the cable length specifications from the assembly instructions for the Fab@Home model you are building.

Step 1:Braid cutting and fraying - According to the assembly instructions for your Fab@Home model, cut lengths of braid for you cables and bundles. Note that the end of the braid will fray quite quickly after being cut.

Step 2: Melt cut end of braid - Using a small flame, heat the cut end of the braid to partially melt it to prevent it from fraying. Do not let it catch fire (unlike the photo).

Step 3: Wrap cable ends - To make threading cables through the braid easier, wrap some tape over the stripped ends. Tape bundles of cable together to keep them together during threading.

Step 4: Threading cable - The braid expands in diameter when you push on it, allowing you to push a bundle of cables through it. Simply push the cables in one end and inchworm the braid over the cable bundle until the bundle end comes out of the other end of the braid.

Step 5: Secure with Ziptie - Use a ziptie/cable tie to secure the braid to the cable.

Step 6: Finished Cable - Here you can see a motor with a cable extension and protective braid.