The Core

ABOUT THE VIDEO

In this video, I will go over the core of the machine. The notes to follow are how I build it.

1) Platform



The height including the board is 16.5". I had to adjust this height a few times to make it match the chairs I used, so you may want to go a little taller and adjust later. Nothing special about the platform, just some 2"x4"'s to hold everything up.

2) Case


On top of the platform is a box made by 2"x6"'s. This is tall enough for the stepper motors to be vertical, and roomy enough for everything else needed. I attached the case with door hinges for easy access.

3) Platform layer


As mentioned in Woodworking 101 this is the layer used for the stepper motors, bearings, and roller chain.


Each 1/2 circle begins 15" from the end of the board. The tracks are 2" in from the sides, and 1.5" apart from eachother. Bearing holes are cut to the exact size of the bearings, and 2 bearings deep. Sprocket holes are cut through the board at a size slightly bigger than the sprocket itself.

4) Roller chain


I never really went over the roller chain, so I will now. I used #25 bike chain and purchased 10' off ebay. You will also need:

Chain connection links (5)
Offset chain connection links (5)
This is where I connect the wire from the carriage.
You may want to buy a few extra of these incase you cut a chain too small.
A chain breaker may come in handy for making the chain the right size. Sometimes I used the chain breaker, but most of the time I just used a die grinder. There are a ton of youtube videos about breaking chain if you need help.

5) Sprockets


Two things to pay attention to with the sprockets are:
1) Core size - be sure the core size matches the shaft of your stepper motor
2) Tooth size - be sure you get the right size for your chain (my case was #25)

6) Bearings


Nothing special needed for inline skate bearings. I purchased an old pair of skate from a thrift store and used those. If possible it is better to have sealed bearings like the ones in the photo.

7) Stepper motors


The motors I used are Nema 24, around 425oz/in. Probably overkill, but it's what I had so I used them. It you cut down on the size you may be able to reduce some noise, but I dont know how low of power you can go.

8) Switch Layer


First you need to router out a groove wide enough and deep enough to fit the switches. Then router out the ovals just as you did in the platform layer, but all the way through the board.

9) Switches


Lever switches will be mounted in the routed out groove on the switch board. A hole will need to be drilled through both the platform board, and the switch board for the wires. You may need to bend the lever on the switch to make sure the carriage bolt depresses the button. The switch should also be nailed down so it doesn't move.

10) Horse Carriage


This horse carriage started off as a 3"x 1/2" block. I used a belt sander to curve the edges so it will wobble as it is pulled. I drilled holes on both sides and used 1/4 threaded rod and a lock nut on each side for stability, and to hit the lever switches. An eye hook is used to attach a wire from the roller chain to the carriage. Two small threaded rods are also attached for the horse to sit on.