In my never ending quest to be the "favorite" uncle, I made my nearly three year-old nephew (who loves cars) this flip car track from walnut and birch plywood. It features four levels of track with six cars (three variants) giving three different weights and speeds.
Not working from any plans or blueprints, this seemingly simple project ended up being more difficult and time consuming than originally planned. That being said, it turned out looking and working as planned.
Step 1: Tools and Materials
This list of materials and tools are what I used for this project. It can easily be done with less tools. Use your own judgment and what you have.
- 1/4 in. Brass Rod
- 1/2 in. Steel Rod
- Large Coupling Nut ≈ 1/2 in.
- 1/4 in. Hardwood Dowel (I used oak)
- Hardwood - Walnut, Maple
- 3/4 in. Birch Plywood
- Wood Glue
- Painters Tape
- 5 Minute Epoxy
- Rubber Feet
- Spray Lacquer
Step 2: Car Body
For the car bodies I wanted to use two different colors of wood to draw attention to the fact that the cars were flipping as they rolled down the track. These pieces of scrap wood were taken from a rolling pin you can see here.
The car bodies measure 2 in. x 1 3/8 in. x 5/8in.
Step 3: Router Car Bodies
Run each end of the car through the router using a 1/4 in. round over bit. Hold the car securely with a wooden hand screw clamp or similar holder.
Step 4: Weight Car As You Like
I added different weights to each car to provide varying speeds of cars. See steps 21 and 22 for two other variants.
Drill a 1/2 in. hole in the middle of the car. Tape one side and fill the edges with two part epoxy. Press the 1/2 in. rod in the hole and let dry. Once dry, smooth each face using the disc sander.
Step 5: Wheels
I used both walnut and maple wheels for these cars. They were cut out using a 1 1/4 in. hole saw through 1/4 in. thick wood. Set the depth stop on your drill press to cut almost half way through your wood. Flip over and repeat. Cut away the remaining wood with the band saw.
You can sand the wheels by hand here, but I found that they fit nicely on the pen mandril of my lathe. The lathe made quick work of sanding the outside of many wheels at once.
Step 6: Lubricate and Instal Axles and Wheels
Cut axles an inch longer than needed. Glue wheel on one end of each axle. Using masking/painters tape mark the end of the car body. Place the axle in a hand drill and sand the axle and wheel smooth. While spinning the axle in the drill, press beeswax onto the axle. Using a heat gun melt the wax into the wood. Using a cotton rag, buff the wax smooth. This will be the lubricant that the car rolls on.
Make a simple clamp out of a short threaded rod and nuts, sand and round over the edges of the opposing wheels. Insert the axle in the car and glue on the opposing wheel leaving ≈ 3/32 of an inch of clearance (just eyeball it).
Cut off the remaining axle and sand smooth.
Step 7: Cut and Assemble Track
Now that the cars are assembled you can use them to decide on what size the track needs to be. Not knowing how long the finished track was to be, I cut four lengths of track 18 in. x 5 3/4 in. from a sheet of 3/4 in. plywood.
Cut edge walls for your track 18 in. x 1 1/4 in. x 1/4 in. and attach with glue. I used brad nails to attach them as well because I was rushing to get this project finished before Christmas.
Step 8: Make Center Stripe and Track Uprights
Cut strips 18 in. x 1/2 in. 1/4 in. that will fit down the center of the track to keep cars from crossing lanes. Glue and nail in place.
Using a table saw, cut the ends flat.
Using the same process as the previous step, make three uprights with the same measurements about 8 inches long.
Step 9: Clamp Up and Test
Using scrap wood from around the shop, I clamped everything up to see how big it was going to be and what angle each track should be at.
A height of 5 in. on the high end gave the desired grade.
Step 10: Cut Angles
Using a miter gauge or sled, cut one end of the track and one end of the upright at 36.8 degrees from square. This will ensure that the upright will be vertical at the desired slope.
If you are building this with any other measurements than what I have shown, you will need to break out your high school trig and calculate the angle that you need to cut this miter at.
Step 11: Cut Splines
To cut the splines in the uprights of the tracks, a makeshift holder is needed for the table saw. I made this out of scrap wood and secured it to my cross-cut sled. Cut two 1/8 in. slots 1 1/4 in. from each side of the track. Glue splines in place. Using a pull saw, cut the extra wood away once the glue is dried. Sand smooth.
Step 12: Trim Uprights and Cut Supports
Remove the spline cutting jig from the cross-cut sled and cut the uprights to 3 in. in length measured from the mitered corner.
Cut the supports measuring 3/4 in. x 1 3/8 in. x 28 in. for the longer supports and 24 in. for the shorter supports.
Step 13: Mark Support Locations
Setup the the whole track and supports holding everything in place using f-clamps. Once everything is where it should be, use a knife to mark the guides along the supports.
Step 14: Remove Sections of Guides
Using the marks from the previous step, attach a guide block and cut along the mark with a hand saw. Once cut, remove the section of the guides with a chisel. Do this for all the tracks. Clamp the track pieces and supports together to make sure that everything fits as it should. If anything isn't fitting, trim and test fit again.
Step 15: Cap Ends of Track Pieces
All four pieces of track need the exposed plywood edges covered. Cut eight pieces of 1/4 in. walnut that will fit on the ends of the track. Trace the profile of the track on the cap. Cut that profile using a bandsaw. Glue and nail the caps in place. Once dry, trim the caps down to the profile of the track. Use any sort of hand tool you have. I found small chisels and sanding blocks to be the most helpful.
Step 16: Drill Holes for Pins
Trim the top of the supports level with the rails of the top track. With the tracks clamped in place, mark the locations of the plywood portions of each track on the supports. Where the support and tracks intersect, drill a 1/4 in. hole 3 in. deep.
Step 17: Apply Finish
Disassemble the track and apply painters table along each interface between the tracks and the supports. This will ensure a clean glue location for assembly. Apply three coats of spray lacquer to the tracks and supports. Sand smooth between coats of lacquer.
Step 18: Assemble
Cut notches in each pin. This will give strength to each glue joint.
Assemble the track and clamp in place. Mix and apply two part epoxy into each hole. Press the pins in each hole until flush with the outside of each support. Let dry.
Apply lacquer to any un-finished wood at the glue/pin locations.
Step 19: Create Bottom
Create a bottom that will fit around the track between the supports. Apply the same lacquer finish and nail in place. Create a trim and nail in place. After the trim was in place, there was a gap between the track and front trim. I created a small piece of walnut the fit perfectly in place. Secure in place and glue until dry. Attach rubber feet.
Step 20: Alternate Car One
Draw lines from corner to corner and mark five equidistant points. Drill 1/4 in. holes at each point. Apply two part epoxy in each hole and insert brass rod. Once dry, sand smooth.
Step 21: Alternate Car Two
Cut a large coupling nut in half. Trace the profile of the nut in the center of a car. Cut the profile from the car using a jig saw. Cut notches in the nut and glue in place with two part epoxy.
Step 22: Polish and Finish Cars
Cover the cars with painters tape and cut the profiles of each metal insert with an exacto knife. Polish each insert until shiny. Remove painters tape and finish with lacquer.
Step 23: Play
This flip car track was a highlight of Christmas and will be great fun for years to come.