This is the fourth design of my marble machines. This was a collaboration between busted bricks and myself, he originally came up with the design and I have modified, improved and added a motor to it. The machine is cut from 3.2mm laser mdf,
I sell the kits through my own website and I share most of my files on thingiverse.

This instructable will take you through the complete process of assembling this little marble machine. Any comments, questions, clarifications and improvements will then be shared with the world and hopefully save myself a lot of effort in the future. If this works I'll add my other marble machines too.

Step 1: Preparing the Pieces

Start by removing all the excess pieces from the panels. Cutting on these low power lasers (40W) can be a slightly temperamental process that is affected greatly by blemishes in the material it's cutting. Every effort is made to ensure that the parts cut cleanly but you may occasionally need to run a scalpel around the edges of the cuts. Leave the centre of the track in place.

Take the two semi circular track pieces and glue them on to the underside of the track, there are notches in the edge of the track to show where they should go. Once the glue has dried, remove the central spacer and you are left with 2 rails evenly spaced which the marbles will run over.

Step 2: Making the Steps

There are 4 steps in the staircase design, each one is made from three pieces of mdf and held together with a bar through the middle. Each layer is marginally taller than the last so the three pieces form a step with a slope on the top.

Repeat this for all 4 steps. The 4 bars are all slightly different sizes and will only fit through the corresponding steps.

It is worth noting that the top layer of the largest step has a little notch in the bottom, this side should be placed against the highest end of the staircase.

Step 3: Making the Camst

The steps are lifted up and down by a series of cams under the staircase. A long flat section of mdf forms the axle and rectanglur holes in each of the spacers helps ensure that the cams are all aligned correctly. There should be two spacers between each cam.

The notched end of the axle should go into the spacers with the non rectangular holes, this provide a recess for the the optional motor upgrade. The axle should be built up with cams and spacers and care should be taken to ensure that the cams alternate above and below the axle.

The two handle pieces can be glued together at this stage but will be fixed to the shaft in a later step.

Step 4: Optional Motor Upgrade

The marble machine can be bought with an optional motor upgrade. If you have just a manual machine then skip this step and move onto the next one.

The motor upgrade provides a geared motor, a battery pack with switch and 2 screws. The battery pack connects directly to the motor and can be soldered in place. The machine works in either direction so it doesn't matter which way round the motor is connected.

Remove the tab on the bottom of the motor, this can be done with a pair of cutters or a sharp knife.

Attach the motor to the taller of the two upright panels using the screws provided.

Step 5: Putting It All Together

Take the longer of the two vertical panels and place the two side panels into it. There is a notch halfway down which should be secured tightly. It is easiest to align these first and then rotate the panel into place through the top two notches.

Place the axle with all the cams into the frame work, aligning the end of the axle with the motor shaft. When you rotate the axle the motor should turn.

Place the second vertical panel onto the sides, ensuring that the cam shaft fits through the hole in the middle. At this stage you can glue the handle on the cam shaft.

Mount the whole framework onto the base panel. There is a small fence piece which is also inserted onto the base plate, this is used to hold the battery box.

Insert the 4 steps onto the cam shaft, they should be free to rise and fall. If they are stiff then you may want to sand the sides of the steps slightly.

Starting at the top of the staircase, slot the two track pieces into their mating halves. This will leave the track pointing upwards. Gently bend the bottom of the track down towards the bottom of the staircase and hook them into the other slots. The machine should now be ready.

Step 6: Completed Machine

The marble machine is now complete. It works best with 3x 10mm marbles running round the track, this allows there to be 2 on the staircase and 1 running round the track.

So that's it. I'll be checking the comments regularly if anyone has any questions and don't forget, if you don't have access to your own laser cutter I do actually sell the full kit of parts cheaper than you could get them cut at one of the online cutting services.