PROJECT 4: Assembling the Parts

So far, you've cut out all the armor plates and drilled all the holes for your project robot. You're almost ready to bolt everything together. In this project, you will prepare the polycarbonate plates, axles, motors, and other drive system components for assembly and fasten them to the base. You'll get practice in preparing Lexan (no sharp edges, as mentioned in Chapter 4), as well as your first taste of soldering with the motor leads, and cutting steel for the axles.

Caution: Eye protection is required for all of these operations. Review all of the general power-tool safety protocols described in Chapter 5 of Kickin' Bot, as well as the sections that correspond to the specific tools used below.

Part 2: Installing the Side Panels

Assembling the side panels requires one more step, where you will have to mark a hole location using an existing hole, which is more convenient in some cases, and necessary if you don't happen to know all of the hole locations in advance. You'll put the panels together, mark the holes, and then pull them apart to do the actual drilling and tapping.

click on an image to enlarge it

Install the side panels on the base with 1/4"-20 x 3/4" long button head cap screws. As with any assembly operation, try to get all of the screws started before tightening any of them down all the way. [Note: Some of the screws may not go in. That's okay. Mark the holes on the base that miss. You'll need to use one of the techniques described in Chapter 8 (Fasteners - Holding It All Together) to open up the holes. Some of these techniques are shown in the Getting Holes to Line Up tip.] Once all of the screws are installed in the side panels, drill through the 1/4" holes in the front and rear panels to mark the hole positions. You're not drilling a new hole, just making a small divot to mark the hole center, like a center punch mark.

Remove the front and rear panels so you can drill and tap the remaining holes. In this picture, you can just see the divots created in the previous step, which mark the hole positions for drilling.

Make a block to help you line up the drill bit correctly. You can rough-cut a piece of scrap. It doesn't have to be perfectly straight on all sides, just flat. All that's important in the block is that the holes are straight. Use the drill press to drill both a #7 hole for the tap drill, and a 1/4" hole for the tap itself.

Set the depth of the tap drill using a shaft collar, or a piece of tape, or one of the other techniques described in Chapter 7 (Drilling and Tapping Holes). It's important to hold your block in place while you set the depth, or the hole will be too shallow by the thickness of the block.

Hold the block in place above the hole location that you marked in the first step. Align the drill tip on top of the divot and drill until you bottom out on the shaft collar. Make sure to use water or WD-40 to keep the plastic cool while you drill.

Use the 1/4" hole on the block to guide the tap into the hole straight. Again, make sure to use lubricant.

Chamfer the tapped holes with a countersink in a cordless drill. Re-install the front and rear polycarbonate panels. Re-install the front and rear polycarbonate panels. Use 1/4"-20 x 1" inch long button-head cap screws on the new holes. Optionally, you can install 1/4"-20 x 1" inch long socket-head cap screws on the upper holes only, leaving the button-head cap screws in the lower holes, which will prevent the robot from balancing on the front or rear panels, and make it fall back down onto its wheels, instead of becoming incapacitated.