Part 2 assumes you have bought all of the parts request in Part 1 and have 3D printed the STLs required. We will start with the spool holder or “Bone” as I have chosen to call it.:
Insert the 4 608 bearings into the Bone. The fit should be snug.
Take two wheels and place the bolts through them. Then the Wheel Spacer.
Place the two wheel assemblies from step 2 and put them through the 2 bearing on each side of the Bone.
Place another Wheel Spacer and then Wheel on the end of each bolt.
Tighten a lock nut on each bolt. Do not over tighten, you need it to be loose enough that it still spins freely but not so loose it wobbles.
I recommend that you now connect wires to the color sensor. I chose to solder headers to the underside and wire wrap 5 connections (Everything except INT and VIN). Leave excess wire at this point, 8in should be plenty. Secure the color sensor to the bone using two M2 (Or similar) screws. Set the Bone aside.
The strain gauge will come with its wires preinstalled. Place them toward the back. Look at the strain gauge. On the front it will be labeled “5kg” and have an arrow. Orient the gauge so the arrow points DOWN. Then use 2 M3 bolts to secure the Base to the strain gauge. Note, the base has one layer of plastic over these hole. This is done to allow printing of an unsupported hole. Simply drill it out or use an exacto-blade. Secure the front and back electronics case to the base using M3 screws. After locating where the HX711 will go, cut the strain gauge wires to length and solder them to the HX711 (See the next post, Wiring for details). After soldering, the HX711 can be secured to the electronics case using M2 screws.
You should wire wrap or solder the connections to the LCD now. Route these wires through the hole in the front electronics cover and route it along the channel on the bottom side of the base. At the other end will be another hole that will allow the wires to route up into the rear electronics case. Before placing your D1 Mini, you should consider how you are wiring it. Again, I recommend wire wrapping. If this is the case, solder headers to the D1 with the pin pointed up, on the same side as the USB port / opposite side to the wifi antenna. I then took a small piece of double sided tape, applied it to the wifi antenna and secured the D1 into the recess in the case.
The Bone can now be placed on the strain gauge and secured using two M5 screws. Go ahead and dry fit the cover to make sure it printed well. Pretty slick, right? Lets move to the next section to see how we are wiring it all together.