Advice on Workshop

[Jthompson]

We just finished our first year workshop and offered Scouts and parents several choices and examples on weighting cars. Almost universally, Parent/Scout teams opted for pennies because of convenience, cost (cheap!) and ease of cutting holes for the pennies.

IMHO here is the best solution the teams came up with. They cut out the car bodies on the band saw and saved the scrap piece of wood so they could use it as a brace. Parents and Scouts then used a small square that Scouts could handle to mark the centers of the penny holes just a little under one inch in from the sides of the bodies. Most cars had about one inch clearance between the rear axle and the rear of the car. This allowed for one row of pennies to be placed behind the rear axle. Lighter bodies, such as wedges, needed six penny slots cut from the bottom of the car.

Scouts took all thier wheels axles and body and placed them on the scale. They then added pennies until they got to approximately 5 oz. We found that the wedge shapes required about 36 pennies.

Scout/parent teams used a 3/4 inch forstner bit to cut the penny holes. They used the stop on the drill press and we found that putting 6, 7, or 8 pennies back-to-back provided a quick depth measurement for setting the drill press. Thin cars using this approach had a CG around 1 inch and a little over 1 ounce on the front wheels.

We offered epoxy and putty to hold the pennies in. Most opted for 5-minute epoxy. One car used sanding sealer alone to hold the pennies in. They fit tightly.

Getting the blocks cut and the cars weighted was one of our major challenges. Surprisingly to me, painting the cars was the next most challenging proposition for the workshops. We had a lot of parents who did not know how to paint wood.

[davem]

We just had our car construction day on Saturday and I too was very pleased with the Penny weight strategy.

A Forstner bit is required, but the concept is perfect for the kids...especially the younger ones.

Not sure who originally posted that idea...but it works great!

Thanks,
DaveM

[Pinewood Daddy]

We just had our car construction day on Saturday and I too was very pleased with the Penny weight strategy.

We'll have to try that next year. I got a bunch of carbide inserts from work (thrown away) this year. I had to mill pockets to put them in.

[Jthompson]

Math guy, I like your idea on standardizing weight slots. Of everything outer pack tried last year, we universally preferred using a 3/4 inch forstner's drill bit to create holes for pennies. We found we could place three rows of holes two wide toward the back of the car. Cars had anywhere from 32 to 42 pennies in them. We were able to get the center of mass back far enough on the cars so the weight on the rear wheels was about 4 ounces and the weight on the front wheels was about an ounce.

This year, parents and Scouts have told me that they only want to use pennies for weights. One of the fun parts about using this method is that the Scouts can use a drill press to drill all there weight slots. We set the depth on the slots by placing the drill bit on the bottom of the car body and adjusting the stop to the number of pennies the Scouts wanted to place in a particular hole. We used a caliper to measure multiple penny thickness so the hole would not break through the car body. This process was very fast.

Another time saving tip we are going to implement this year is to get rid of the requirement to use the slots. This caused some problems with Scouts forcing axles into the slots and having wood split. This year, we are going to use a commercial jig from Derby Works to drill axle holes. Several Scouts used this last year and were able to get good alignment without much additional work. We had Scouts use a square to make sure the jig was perpendicular to the car body. They then clamped the jig to the body and drilled holes at low speeds. This was a great tool and made car construction much easier.