HELP - Son wants to make a 50 Cal Bullet for a Derby Car

[krjpy]

My Webelos II son wants to make, with his father's help on the big tools, a 50 Cal bullet as his derby car. Does anyone have any ideas how to do this and what would be the best tools for them to use?

Thanks in advance for the help.
Kelly

[gpraceman]

Cylindrical objects can be a bit of a challenge. I think it is easiest to cut the top off the block, leaving a thin chassis that you mount the wheels to. Take the top of the block and start rounding it. A lathe would be ideal, but you can use a saw (band saw, scroll saw, coping saw, etc.) to cut off anything outside of a circle drawn on the end of the block and a sander to finish the rounding. When all done with shaping, glue it to the chassis.

[Darin McGrew]

For my first cylindrical design, I borrowed a friend's lathe. While using the lathe, I left the area of the block near the axle slots untouched. After removing the block from the lathe, I used hand tools and a Dremel tool to remove the corners on the top of the car (above the axle slots), but left the corners on the bottom of the car alone to avoid tampering with the axle slots.

Since then, I've learned to build cars, rather than carve them. I've attached pieces of dowel, wooden spheres, and various other decorations to a thin chassis cut from the original block. It's much easier to create a good-looking car this way.

[pwrd by tungsten]

I like the slab idea. 5/16" car with a real 50 cal on it. no powder... Bullet towards the back. Or fake bullet in shell going forward.

Important to keep the COM 3/4" or so from rear axle. this is main issue with bullet shaped cars. Nail the COM and you should be good...

[pwrd by tungsten]

Of course if it is in a school etc they may not allow even an empty bullet shell...

[Darin McGrew]

Of course if it is in a school etc they may not allow even an empty bullet shell...

Hey, some schools don't even allow "guns" made from Lego blocks. Try explaining that to a little kid whose dad is an avid hunter...

[andylester]

You can also take a small rocket nose cone and wooden dowel rods and see what you can come up with. There are all types and sizes of nose cones that will get you close to that bullet size and shape. Search the internet for that stuff and also ebay. You should be able to find the parts you need rather easily.

Good Luck!

[pwrd by tungsten]

Great idea on the rocket parts.

Oir school would not allow a lego gun either...

[ah8tk]

Here is a picture of a bullet car I grabbed off the internet in the last 5 years of collecting cool pinewood derby pictures. This IS NOT my car:



I think you could bring the block to a big box homecare center and test out some dowels for size. Then reduce the size of the front of the dowel and attach it to the slab car that was previously mentioned.

The car in the picture (with the axles attached to the bullet shape) would be very hard to align. I would just paint the slab car black and attach the casing (if you call it a casing car would that be better for schools?)

[FatSebastian]

I would just paint the slab car black and attach the casing

I agree with others on the use of a (dark) slab on which the bullet would ride. Without one, there may be problems with the car staying on the starting pin and/or tripping the finish line sensor, in addition to difficulty alignment.

[ah8tk]

Here is a plan I came up with using a 1” dowel:



This plan uses a 1/4" slab under the casing. Any additional weight will have to be placed in the slab to bring the car up to race weight. Is it pinewood derby season yet?

[FatSebastian]

Here is a plan I came up with using a 1” dowel:

Nice design, ah8tk. Without getting too far off topic, may we ask what software did you used to make it?

[ah8tk]

I use Microsoft Visio to create all of my car plans. It is something I use at work for making diagrams, I also have AutoCad available but I think Visio is easier to use.

Stan Pope hosts a Race Car Planning Sheet, it is a pdf I made a while back, in Visio, that can be used to draw pinewood derby plans on. It is also the basic car plan I use when drawing pinewood derby car plans.