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introduction | platform | motors | batteries | third 'wheel' | second level
computer | sensors | interfacing | programming | parts & suppliers

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step 2. motors


Step 2.

Next, you mount the motors on the platform. Just so you know, you'll have to unmount the motors before going on to the next step - but do not fear! This is only so you have enought room to work with the other parts.

The original motors used for SmallBot were surplus gearhead motors, but I broke one of them so I'm now using hacked servo motors (servo hacking instructions coming soon.) Because I've used both motors, I've got two sets of mounting instructions.

Which set of instructions do you want?
- Gearhead Motors
- Servo Motors

Gearhead Motor Mounting Instructions

In order to make the gearhead motor mount, you'll need a piece of metal the length of 1/2 the circumference of the motor you're using + 1/2" to 3/4" on each side for the bolts. Note: the intended use of the metal is irrevelant. After you cut the metal, basically you take it and bend the strip in the center around a doweling rod the same size as the motor (you *could* use the motor but the process might harm the motor.) Next, you bend the flaps that will hold the bolts.


Be sure that when placed on the platform, the bracket lays flat, and parallel to the base. Align the motors so that the shaft is in the center of slots cut for the wheels. Mark this placement then remove the motors. Lay the brackets on the platform exactly where they will be holding the motors in place. Clamp them to the platform (by the brackets, not the semi-circle) and drill holes through the flaps (to accomodate the bolts.) Make sure you've done everything right by mounting the motors using the brackets, remove them and move on to the next step.

When you mount the motors on the platform, It should look similar to this:
Level 1



Servo Motor Mounting Instructions

The motor mounts for a servo motor are a deviation on the gearhead mount idea - or vice versa.. hmm.. The servo motors that I used are the Hitec/RCD HS-300J Standard Sport Servo Futaba available (along with any other R/C accessory,) at www.towerhobbies.com. For each wheel you'll need two rigid pieces of metal (I found metal at the hardware store that was 'intended' to bind two pieces of lumber together.. It was about a 6"x8" sheet of metal, with a lot of holes to drive nails through.), two bolts (just enough to go through the platform, past the servo motors, and into the nut,) 2 nuts, and a drill. What you will do is sandwich the servo motor in between the two pieces of metal, and bolt it all to the platform.

Why two pieces of metal? The piece on the top is to secure the motor to the platform. The piece on the bottom is to support the platform so it doesn't bend.

What size are the pieces of metal? You'll have to cut the metal to fit your specific needs, but it must be wide enough to accommodate the bolts and washers and long enough for the servo casing + the bolts and washers.
Servo Mount Diagram

The placement of the bolts is critical. They must be right up against, and touching, the servo motor. This is where it gets a little tricky. In order to drill the holes exactly where the sides of the motor are, you must epoxy the motor to the platform. Make sure that this is exactly where you want the motors to be. Also, make sure that the motor shaft is directly in the center of the wheel slots, and that the wheels can fit entirely inside them.
Motors Epoxied to the Platform

After the motors are epoxied, take the drill and drill a hole on each side of the motor (one towards the front of the bot, one towards the back of the bot.) Be careful that if a line was drawn from the first hole to the second hole, the line would be as close to parallel with the wheel well as you can make it.

Now you need to duplicate the exact placement of those holes onto the metal braces. Probably the easiest way to do this, would be to clamp the pieces of metal to the platform, directly underneath the mounting holes (either one at a time, or two at a time. One at a time would probably be better - just be careful.) To minimize slippage of the metal, you could put a rubber glove in between the platform and metal, and the clamp. After the holes are drilled, just thread the bolts through the platform, metal brace, through the second brace, and into the nut on top of the motor.

Clamping metal to platform

introduction | platform | motors | batteries | third 'wheel' | second level
computer | sensors | interfacing | programming | parts & suppliers




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