Derby Talk is a forum for Pinewood Derby, Awana Grand Prix, Kub Kar Rally, Shape N Race Derby, Space Derby, Raingutter Regatta and other similar races where a child and an adult work together to create a race vehicle and a lot of fun and memories
I recently bought a bandsaw and drill press. I was eager to get going on some cars when the real hot weather came in and I have not been out to the garage since. I wanted to practice some speedy cars so I asked my son for a design idea. He drew out a car that looked like a capital letter "I". So we cut one of with the band saw. This was when I realized that we could make at least two thin cars with the same block so we cut out another.
I sanded down each to create slightly different body shapes. One with standard slots is a bit thick, the other which I intend to drill axel holes for an extended wheel base is thinner. I bought by first fornester bit and drilled out a 1 1/8 hole for the 3 oz (thinner) tungsten disc. I liked this idea from the "son of a pickle" car. Man does that disc just drop in perfectly. The lighter disc is thinner allowing for a thinner build (but will require more added weight)
Is cool to see how much farther back the weight can go with an extended wheelbase. I aimed my COM for 1" as I have a rough wooden track. These cars weight about 4.3 oz with the disc. So I drilled some small midline hole on the bottom to fine tune the COM and final weight with tungsten putty.
This is all experimentation with saw, drill and cars. Any feedback appreciated.
Seth (noskills...but working on them)
"Nunchuk skills... bowhunting skills... pinewood derby skills... Girls only want boyfriends who have great skills!"
Napoleon Dynamite
I recently bought a bandsaw and drill press. I was eager to get going on some cars when the real hot weather came in and I have not been out to the garage since. I wanted to practice some speedy cars so I asked my son for a design idea.
This is all experimentation with saw, drill and cars. Any feedback appreciated.
Seth (noskills...but working on them)
Seth, if I could post a photo.. of a Coca Cola being poured into a tall glass of ice I would.
The cars & you're skills are looking HOT.
Whoda.
What type of automobile can be spelled the same forwards & backwards?
Seth - finally got to see the pics and the cars look very, very cool. Tell your son I think he's got a winning design there. When you get all that weight at the back it makes the cars feel so heavy - we had a couple of people question that the "Son Of A Pickle" met the 5oz limit - but they'll rocket out of the transition from the incline to the straight so much faster than the cars with more conservative weighting. The holes for the tungsten putty allowed us to really fine tune our weight - we went with a 3/4" COM and we had no problems on the Pack's bumpy wooden track, and we nailed the weight at 4.995oz at the District race. Keep us posted - can't wait to see the finished results.
I like the idea of making two cars - as you know, we did the same and it allowed us to pick the fastest car on our home made track (although to be honest there really wasn't anything between them). We made a display stand modeled on a short section of our Pack's blue and yellow track and mounted the spare car on it. My son presented it to the lady who's been instrumental in running our Pack for many years now - Mrs Wyatt is 98 this year and has put 50 years into Scouting, so it was the least we could do to show our appreciation. If I can, I'll post pics over on our "Son Of A Pickle" thread.
Seth - when do you think your cars will be finished?
Thanks for the feedback and for giving me the idea of putting a disc in flush. It was so easy I may convert over from cubes. Plus using the fornester drill bit is easier for me than routing out rectangular pockets. I am curious is anyone has "sunk" a disc into the car, covered it in bondo or other putty and painted over it? I like the idea of incorporating the tungsten into the design but its nice to know that I can cover it over too.
I will be moving soon so between getting the house ready and packing the cars might sit a while. At least is getting cooler. I will post photos as we progress. These cars are just for fun but if they tune well I might run one myself at the next derby in the parent division.
Seth
"Nunchuk skills... bowhunting skills... pinewood derby skills... Girls only want boyfriends who have great skills!"
Napoleon Dynamite
Hi Seth. In your 1st line you state "I wanted to practice some speedy cars". If I may offer a suggestion. Experts on DT recommend 2 ounces of weight behind the rear axle slot. Here is one way to achieve that . Four tungsten rounds measure just under 1 3/4" and weigh 2 ounces. These can be placed directly behind the rear axle slot by drilling a 25/64" hole through the body of the car. The other 4 cylinders can be placed where you need them to get the desired CM. You now have 5/16" of wood in the back (It's not helping you) that can be cut off and moved to the front to benefit from the FEE (Front End Extension) effect. This will move your CM higher up the arc and give you somewhat of a higher velocity. I need to have the rear of my car a bit higher because of the technique I use to set the camber on the rear wheels. I'm happy to describe this in an appropriate post. I buy MaxV's axles and I'm not going to sand them and remove the plating. I plan to polish them with #7 Clearcoat polish with the dremel and run them that way. We'll see what happens. If you decide to build a car this way I would be interested to know how it does against the tungsten round cars. Best of Luck.
NoSkills (current pictures demonstrate otherwise),
We started using some discs (lead) last year. Some people allowed the to stay up, others wanted flush.
We did use putty over the top and sanded down to smooth. After primer and paint, could just barely tell where the disc went.
My wife started a new support group... Widows of the Pinewood Derby.
Mark is that 5 oz? Mark, also I am not sure how to differentiate the effect of putting some weight behind the axel and some in front. It seems to me if I can put most if it in a single mass just above the axel to achieve the desired COM that should be just as good. When I said I was making a fast car, I meant in contrast to my fun pickle car and coke bottle car which we just "playing with the Dremel". These are both going to be set up a 3 wheel RR'ers. Already shaved the 1 /16 off the DFW body side.
Speedster, like the design. We're you required to use the standard axel distance for that build?
Thanks for all the advice. So far I am not very good at routing out pockets for tungsten cubes but the discs drops in well. Might switch to all discs if it works with my sons ideas.
Seth
"Nunchuk skills... bowhunting skills... pinewood derby skills... Girls only want boyfriends who have great skills!"
Napoleon Dynamite
Seth, we are required to use the standard axle slots. I no longer cut off the back and move it to the front. For a small fee, Max V will shift the slots in the block. I order 10 at a time. Who knows, maybe his slots are more true than comes in the box. If you are considering NOTHING but speed then probably there is only one way to build a car. The car must start out weighing 1/2 ounce or less, wheels and axles are going to weigh a certain amount, and then 4 ounces must be placed in a certain place. A car could be built with a 1" COM and not be very good. My cars are not the ultimate but I like the long front because I've seen so many nail biters. If you stick with all the laws of Physics, then Sporty's cars are probably the most perfect and with all his other skills is why he wins all the time. Since I don't know how to do it, perhaps FS will assist us in showing some of Sporty's cars and the weight placement. The most weight I've been able to add to my design is 3.88 ounces. My belief in the "Front End Extension" effect and the way I get Negative camber on the rear keeps me from building a car like Sporty, and lots of other things I don't have the skill to do. If I added 4 ounces of weight I'd have to drill the car full of holes and I don't want to do that. Any wood sticking out the back past the rear wheels can be used to help you if you move it to the front. This, of course, means that you are not using the area for weight placement. That is why I use 4 tungsten rounds. I don't need the extra wood to achieve my goal. Perhaps the true experts on DT will chime in. You are very enthusiastic and I know you will do well. Best of Luck.
Speedster,
I never quite understood the idea of cutting the back of the block off until now. So the extra length in the front allows you to put the weight farther back. And as you have less room you use the taller, smaller diameter rounds.
Thanks
Seth
"Nunchuk skills... bowhunting skills... pinewood derby skills... Girls only want boyfriends who have great skills!"
Napoleon Dynamite
Seth, Seems like the other factor for smaller rounds or cubes is that you can create a lower profile car. With cubes, cutting out like Sporty and others seem to do, you can get 2 rows of cubes behind the axel and 2 rows in front for about 4 oz total added weight to get your COM under 1".
This kind of reminds me of the old Coca-Cola commercial with..
Enjoy Seth..