We took the Cubscout Bear Book Elective 7 "Things That Go" and built these Cubmobiles (cheap version of a soapbox) and raced them as a district event. Although our derby was a smashing success, it still has room for alot of improvement. Anybody else done it ? Looking for some ideas on timing the runs (we used stop watches last year). I would definitely recmd this to any pack looking to boost summer scout involvement.
- Darin McGrew
- Pine Head Legend
- Posts: 1736
- Joined: Fri Jul 18, 2003 1:23 pm
- Location: Mountain View, CA
My friends and I built them back when I was a cub scout, but we didn't do it as part of scouting. We just took them to the dirt roads just outside of town and had fun. One lesson I remember, is that a narrow wheelbase is bad, especially when there's a turn at the bottom of a hill.KLenort wrote:Anybody else done it ?
From your photos, it looks like your cub scouts don't have that problem. But I'm curious--how does the starting gate work? It looks like the board blocking the rear wheels drops down into a slot, but the rear wheels don't look big enough to clear the slot cleanly.
The parent that came up with the ramp did an excellent job without having any sort of plans to follow. The gal holding the pipe in the middle starts the cars. That pipe holds up the 2x4 in front of the wheels, when she pushes it forward it drops the board down flush letting the cars both go simultaneously. The only proble (as you can see) was that the ramp wasn't large enough to give the cars enough kick, hence the loose plywood. We thought that our hill was big enough and we didn't want the cars going too fast so the ramp was built with only the back tires on the ramp (big mistake). We will be rebuilding the ramp, just need to design it larger and able to disassemble for storage.darin_mcgrew wrote:From your photos, it looks like your cub scouts don't have that problem. But I'm curious--how does the starting gate work? It looks like the board blocking the rear wheels drops down into a slot, but the rear wheels don't look big enough to clear the slot cleanly.
I'm like Darin and was wondering how the start gate worked. I looked over the link that Randy gave and assumed that it worked as the one described. I know now that it works opposite. I'm thinking that this is the better set-up.
Also like Darin, we used to build these when younger as we had street with a great slope and a 90 degree turn at the bottom. Too bad we didn't make cubmobiles - the brakes sure would have come in handy!
One of our Pack leaders and I have been discussing a cubmobile race for our Pack but have not been able to get the local Police or State Park to let us have a road to use. We are in the (very) early stages of discussing a cub push-mobile race. Now I'm wondering how high we would have to build a ramp to get a little speed on a flat parking area...
Before I forget: Randy thanks for adding this section to Derby Talk!
Da Graphite Kid
- Master Pine Head
- Posts: 357
- Joined: Tue Oct 14, 2003 9:31 am
- Location: somewhere, north carolina
Thanks for posting this thread and pics! Our Cub Scout Bear Den is building one of these for our district Scout Show! But we don't have hills where we are so no racing YET!KLenort wrote:
We took the Cubscout Bear Book Elective 7 "Things That Go" and built these Cubmobiles (cheap version of a soapbox) and raced them as a district event.
Our den leader was thrilled when I told her about seeing these on the forum! Our Scout Show is March 20 and I'll post pics when we get it built!
We're working on an electronic timing setup for this year's District site, but it's too early to make a posting for it. Will advise.
Definately let us all know about the electronic timing system that you come up with.
Why not allow "smooth axles with pins" (cotter type)?
What sort of racing format was used - double elimination?
Was this a team/Den effort or were these individual Cub Scouts that competed?
Some thoughts that we had (they are so few nowadays... ):
- The Pack would buy and own the wheels and seatbelts used. This way it would make it more affordable for all to participate and not give any one team a racing edge by using some 'special' wheels/bearings.
- Competition would be between Dens. This makes it a Den project and would involve all of the boys who would each have to race at least once.
- Pack Leaders would race (that was my idea ).
Da Graphite Kid
We had a Pack that thought that the solid axles were an advantage, so we eventually went to mandatory lag bolts. Solid axles are much stronger and can be strapped to the bottom of the wood - instead of weakening it with a hole. If a hole is bored, you can put another 2X4 on top. In fact, the "top plate" can be used to bear against... so that there's less chance of a foot slipping into the wheel.
With a lot of racers, it works best to have everyone run once in each lane and average the times. May want to consider having the stopwatch stopped upon crash - starting back up once he's underway. This doesn't ruin his chance to place well.
If you can do a free-for-all lineup at starting line (maybe by "all W2's" then "all Tigers" ...) it will flow much better than calling racers to the line. Stack 'em up for the starting line (all straped-in) and lift them onto the ramp. Better yet, have the ramp slope on each side!
The wheels shown below are VERY reasonable (and fast). Wheels are the most difficult to even-up... everyone's looking for an edge.
Problem was that a lot of the boys could not keep them running. Our road had a slight bend, and they would get into this oscillation, or just flat out over turn the car. Result was that about 25 - 50% ended up falling over.
Anyone have this problem?
I will share that we pretty much followed the spec's to a tee. Nothing overly done with the wood and shapes.
I spent a great deal of time, ensuring that the angle was right with the wheels and that it was squared well. I used 12 inch wheels from farm-n-fleet. Used break cleaner to clean the bearings and wd-40.
Steering to me is the bigest issue, next to first coming off the ramp. That little bounce and how your child deals with it, is everything. I kept the blocks close and the lag bolt fairly tight. I found that i did have to tighten it up after every other race.
Anti-vibration is a key also. When I mounted thr 5/16 lag bolts. I used a washer in front and beghind. Now i seen people insert the bolt into the wood or use blocks in between the lag bolt. I used metal clamps with hard rubber. To dampen vibration.
I saw no difference in the 10 inch or 12 inch wheels. Speed wise.
My son was the lightest kid on the track, I did use oak wood for added weight versus pine. Btw Oak has not gotten any cheaper in it's day.
I am very curious to the people who have used the wheel chair wheels and how they faired in the races. I would consider trying them. If i felt they were a better whee.
And if slick wheels over treaded wheels make much a differance. Ours were treaded.
- Master Pine Head
- Posts: 189
- Joined: Wed Sep 22, 2004 2:42 pm
- Location: South Carolina
Cub Scout Pack 215 in Anderson SC had a video of a cubmobile raceranman106 wrote:[Thanks for posting this thread and pics! Our Cub Scout Bear Den is building one of these for our district Scout Show! But we don't have hills where we are so no racing YET!
in a flat parking lot or almost flat parking lot on there website.
They use push bars to get the car started. 2 boys push from behind.
I tried googling it and its down right now.