Pinewood Derby (2 Viewers)

[gameday]

For my car (heavyweight division) I decided to make it look like I just stuck two blocks together and put some wheels on it.

But it weighs about 3 and a half pounds. Here's why.

"She may not look like much, but she's got it where it counts, kid." -Han Solo

Can't wait to hear how the pig does. I recall reading on either derbytalk or max-velocity that there is a point where performance degrades because the car weighs too much. It might be around 10 ounces. Apparently the weight causes the wheels/axles to bind. Good luck.

 

[shuke]

How do recommend aligning? I checked out video where you make a mark on the nail and then rotate it but that hasn't worked out so well. Widest base as possible or is that shtick?

I don't think we're going to mess with the axles this year. That's how we splintered the axle slot last year. I've seen what you're referring to about rotating the axle, but I can't imaging that helping much if the axles are not out-of-round, which would have been obvious if you chucked them in a Dremel or drill for polishing.

OK, so we actually did the axle rotation thing tonight for the first time. Was extremely easy and my son was super pumped about fine tuning it.

 

[Mr. Pickles]

Freaks

 

[Disco Stu]

For my car (heavyweight division) I decided to make it look like I just stuck two blocks together and put some wheels on it.

But it weighs about 3 and a half pounds. Here's why.

"She may not look like much, but she's got it where it counts, kid." -Han Solo

Can't wait to hear how the pig does. I recall reading on either derbytalk or max-velocity that there is a point where performance degrades because the car weighs too much. It might be around 10 ounces. Apparently the weight causes the wheels/axles to bind. Good luck.

There very well could be a tipping point, but it's got to be higher than 10 ounces. Last year I ran my outlaw car at 29oz, 15oz, and 5oz. Heavier was better in that case at least.

 

[St. Louis Bob]

How do recommend aligning? I checked out video where you make a mark on the nail and then rotate it but that hasn't worked out so well. Widest base as possible or is that shtick?

I don't think we're going to mess with the axles this year. That's how we splintered the axle slot last year. I've seen what you're referring to about rotating the axle, but I can't imaging that helping much if the axles are not out-of-round, which would have been obvious if you chucked them in a Dremel or drill for polishing.

OK, so we actually did the axle rotation thing tonight for the first time. Was extremely easy and my son was super pumped about fine tuning it.

:finger: Glad it worked out for you. It was easy to rotate but just like the goggles, they did nothing. Until I bent the axles a little, then I could fine tune it.

 

[St. Louis Bob]

Freaks

Scouts has helped Cal with social matters tremendously, so I'll props to them for that. However the PWD is like going to church for 5-6 hours. I don't understand why they make you watch kids that you don't associate with at all the rest of the year. Stagger the thing already so it lasts an hour or so and might actually be fun.

Camping in frigid, wet, conditions WITHOUT BOOZE*, is just wrong. Lots of people just staring at each other and their phones.

I'm sure the fact that I'm older than most of the other dads by 10-15 years doesn't help my Tanneresque views of these things.

I always bring a little booze.

 

[shuke]

I've got a good feeling about this one.

 

[Mr. Pickles]

I've got a good feeling about this one.

Needs more graphite.

 

[St. Louis Bob]

I've got a good feeling about this one.

Needs more graphite.

Cal's car kind of sucked but he did better than last year so he was happy. I say was because his little brother took 2nd place in his den and 4th overall. Cal was happy for him to that little ######## Dylan started taunting him.

Thanks again for the help gentlemen. I actually feel like I know WTF I'm doing now.

 

[Mr. Pickles]

I say, if you're not using multi-walled carbon nanotubes, you're not trying.

 

[shuke]

I've got a good feeling about this one.

Needs more graphite.

Cal's car kind of sucked but he did better than last year so he was happy. I say was because his little brother took 2nd place in his den and 4th overall. Cal was happy for him to that little ######## Dylan started taunting him.

Thanks again for the help gentleman. I actually feel like I know WTF I'm doing now.

 

[St. Louis Bob]

I say, if you're not using multi-walled carbon nanotubes, you're not trying.

I'm calling some of my uranium miners next year for samples.

 

[Disco Stu]

Pack races were today. I was the "car runner" which got a little old after a couple hours, but we had a good time. The cars we made lived up to the considerable hype given to two time champs by the MC.

Stu Jr and I both won fairly handily (relatively speaking). Mine did cross over into the "too heavy" category, as it was only slightly faster than son's car. The axle angles are more extreme than they were this morning. They might not have held up to many more heats.

So we ended up having the two fastest cars, which is fun. And we went out on top (at the pack level at least).

 

[17seconds]

I say, if you're not using multi-walled carbon nanotubes, you're not trying.

I'm calling some of my uranium miners next year for samples.

I've already booked time in the synchotron at the Hadron collider. Back off son.

 

[17seconds]

Kidding... I have the shape down now

 

[gameday]

Pack races were today. I was the "car runner" which got a little old after a couple hours, but we had a good time. The cars we made lived up to the considerable hype given to two time champs by the MC.

Stu Jr and I both won fairly handily (relatively speaking). Mine did cross over into the "too heavy" category, as it was only slightly faster than son's car. The axle angles are more extreme than they were this morning. They might not have held up to many more heats.

So we ended up having the two fastest cars, which is fun. And we went out on top (at the pack level at least).

Nice, is Stu Jr running his rig at Districts?

 

[shuke]

The Creeper didn't do so hot. My son won one heat but came in probably 4th or 5th out of his rank (about 12 racers).

Not sure what do going forward without getting into sophisticated jigs and wheel/axle polishing that I think are beyond the scope of what the race should be about. One thing is that his cars are never very aerodynamic because he likes putting the drivers in there. I'll see if he wants to go a different route next year, although I figured aerodynamic effects would be negligible at these speeds.

 

[St. Louis Bob]

Pack races were today. I was the "car runner" which got a little old after a couple hours, but we had a good time. The cars we made lived up to the considerable hype given to two time champs by the MC.

Stu Jr and I both won fairly handily (relatively speaking). Mine did cross over into the "too heavy" category, as it was only slightly faster than son's car. The axle angles are more extreme than they were this morning. They might not have held up to many more heats.

So we ended up having the two fastest cars, which is fun. And we went out on top (at the pack level at least).

The Creeper didn't do so hot. My son won one heat but came in probably 4th or 5th out of his rank (about 12 racers).

Not sure what do going forward without getting into sophisticated jigs and wheel/axle polishing that I think are beyond the scope of what the race should be about. One thing is that his cars are never very aerodynamic because he likes putting the drivers in there. I'll see if he wants to go a different route next year, although I figured aerodynamic effects would be negligible at these speeds.

:(

 

[Mr. Pickles]

The Creeper didn't do so hot. My son won one heat but came in probably 4th or 5th out of his rank (about 12 racers).

Not sure what do going forward without getting into sophisticated jigs and wheel/axle polishing that I think are beyond the scope of what the race should be about. One thing is that his cars are never very aerodynamic because he likes putting the drivers in there. I'll see if he wants to go a different route next year, although I figured aerodynamic effects would be negligible at these speeds.

My kid is only 2, but I've already started computational fluid dynamic modeling of some prospective designs. When you're trying to squeeze out precious milliseconds, you pretty much have to cover every angle.

Maybe you should just buy a car off eBay next year. You may not have what it takes.

 

[shuke]

The Creeper didn't do so hot. My son won one heat but came in probably 4th or 5th out of his rank (about 12 racers).

Not sure what do going forward without getting into sophisticated jigs and wheel/axle polishing that I think are beyond the scope of what the race should be about. One thing is that his cars are never very aerodynamic because he likes putting the drivers in there. I'll see if he wants to go a different route next year, although I figured aerodynamic effects would be negligible at these speeds.

My kid is only 2, but I've already started computational fluid dynamic modeling of some prospective designs. When you're trying to squeeze out precious milliseconds, you pretty much have to cover every angle.

You're probably right. One race separated yesterday by .001 seconds. No shtick.

 

[Mr. Pickles]

The Creeper didn't do so hot. My son won one heat but came in probably 4th or 5th out of his rank (about 12 racers).

Not sure what do going forward without getting into sophisticated jigs and wheel/axle polishing that I think are beyond the scope of what the race should be about. One thing is that his cars are never very aerodynamic because he likes putting the drivers in there. I'll see if he wants to go a different route next year, although I figured aerodynamic effects would be negligible at these speeds.

My kid is only 2, but I've already started computational fluid dynamic modeling of some prospective designs. When you're trying to squeeze out precious milliseconds, you pretty much have to cover every angle.

You're probably right. One race separated yesterday by .001 seconds. No shtick.

I would suggest a detailed gravity map of the venue. At least then you can optimize for local density fluctuations.

 

[St. Louis Bob]

The Creeper didn't do so hot. My son won one heat but came in probably 4th or 5th out of his rank (about 12 racers).

Not sure what do going forward without getting into sophisticated jigs and wheel/axle polishing that I think are beyond the scope of what the race should be about. One thing is that his cars are never very aerodynamic because he likes putting the drivers in there. I'll see if he wants to go a different route next year, although I figured aerodynamic effects would be negligible at these speeds.

My kid is only 2, but I've already started computational fluid dynamic modeling of some prospective designs. When you're trying to squeeze out precious milliseconds, you pretty much have to cover every angle.

You're probably right. One race separated yesterday by .001 seconds. No shtick.

I would suggest a detailed gravity map of the venue. At least then you can optimize for local density fluctuations.

 

[Disco Stu]

Pack races were today. I was the "car runner" which got a little old after a couple hours, but we had a good time. The cars we made lived up to the considerable hype given to two time champs by the MC.

Stu Jr and I both won fairly handily (relatively speaking). Mine did cross over into the "too heavy" category, as it was only slightly faster than son's car. The axle angles are more extreme than they were this morning. They might not have held up to many more heats.

So we ended up having the two fastest cars, which is fun. And we went out on top (at the pack level at least).

Nice, is Stu Jr running his rig at Districts?

Yep. March 22nd. Our district must not be too big, since this typically doesn't take any longer than the pack event.

 

[gameday]

Pack races were today. I was the "car runner" which got a little old after a couple hours, but we had a good time. The cars we made lived up to the considerable hype given to two time champs by the MC.

Stu Jr and I both won fairly handily (relatively speaking). Mine did cross over into the "too heavy" category, as it was only slightly faster than son's car. The axle angles are more extreme than they were this morning. They might not have held up to many more heats.

So we ended up having the two fastest cars, which is fun. And we went out on top (at the pack level at least).

Nice, is Stu Jr running his rig at Districts?

Yep. March 22nd. Our district must not be too big, since this typically doesn't take any longer than the pack event.

Good luck to Stu Jr. I ran our District Derby for several years and we normally had about 125 entries. It took about 3 hours from start to finish.

By the way, did you and Stu Jr spend much time aligning the car? My sons didn't spend much time on that for the Pack race, but they did focus on that between the Pack and Derby race. By the time it was properly aligned we really improved their car's speed.

You probably know this but, if not, here's a nice aplet to help do the job:

http://www.florian.org/Kids/Scouting/PineAlign/PineAlign.html

 

[Disco Stu]

By the way, did you and Stu Jr spend much time aligning the car? My sons didn't spend much time on that for the Pack race, but they did focus on that between the Pack and Derby race. By the time it was properly aligned we really improved their car's speed.

You probably know this but, if not, here's a nice aplet to help do the job:

http://www.florian.org/Kids/Scouting/PineAlign/PineAlign.html

Yep. We didn't have to do much though. Rear wheels stayed out, just had to dial in the front dominant. Quick and easy this year.We'll probably just add (and work-in) a little graphite before district. It's probably fine as-is for four more runs but maybe not for eight.

Side note: using a mirror like that makes it very easy to see what each wheel is doing.

 

[Disco Stu]

He also won the "out of the ordinary" design award this year. Lots of questions... Is it all metal? No? Then isn't it going to break? Is it really light? No? Then where is the weight?

 

[17seconds]

I spoke to a scout leader at our pack show last night who is also an old friend of mine. He gave me some tips. One was that you don't want the car to have "perfect" alignment. It's impossible for a car to never touch the inside rail of the track so cars with straight alignment actually lose more energy bouncing back and forth off the inside track vs. cars that are drift left or right. Those cars slide down the rail on one side and lose less energy. He said the ideal car is one that goes straight for several feet then rides one side of the track all the way down. I think he said it's best to do it on the raised front wheel side too. Is he right?

Also, our pack doesn't seem too strict on rules. The only thing they really enforce are the dimensions and weight. You can have a front wheel way off the track, make your own axle grooves, etc... they don't care.

 

[Disco Stu]

I spoke to a scout leader at our pack show last night who is also an old friend of mine. He gave me some tips. One was that you don't want the car to have "perfect" alignment. It's impossible for a car to never touch the inside rail of the track so cars with straight alignment actually lose more energy bouncing back and forth off the inside track vs. cars that are drift left or right. Those cars slide down the rail on one side and lose less energy. He said the ideal car is one that goes straight for several feet then rides one side of the track all the way down. I think he said it's best to do it on the raised front wheel side too. Is he right?

Also, our pack doesn't seem too strict on rules. The only thing they really enforce are the dimensions and weight. You can have a front wheel way off the track, make your own axle grooves, etc... they don't care.

No, he's not correct on that part. Ideally the only wheel to touch the rail will be the front dominant wheel (not the raised one). Avoid letting the back wheel on that side touch by narrowing the front end a bit (1/16" IIRC). Some will cut it, my son just sands more in that area.

Some negative camber on the rear wheels will also help keep them off the rail. Can see that in my son's car.

 

[17seconds]

I spoke to a scout leader at our pack show last night who is also an old friend of mine. He gave me some tips. One was that you don't want the car to have "perfect" alignment. It's impossible for a car to never touch the inside rail of the track so cars with straight alignment actually lose more energy bouncing back and forth off the inside track vs. cars that are drift left or right. Those cars slide down the rail on one side and lose less energy. He said the ideal car is one that goes straight for several feet then rides one side of the track all the way down. I think he said it's best to do it on the raised front wheel side too. Is he right?

Also, our pack doesn't seem too strict on rules. The only thing they really enforce are the dimensions and weight. You can have a front wheel way off the track, make your own axle grooves, etc... they don't care.

No, he's not correct on that part. Ideally the only wheel to touch the rail will be the front dominant wheel (not the raised one). Avoid letting the back wheel on that side touch by narrowing the front end a bit (1/16" IIRC). Some will cut it, my son just sands more in that area.

Some negative camber on the rear wheels will also help keep them off the rail. Can see that in my son's car.

How about the main idea that a straight alignment can be bad?

 

[IrishTwinkie]

I spoke to a scout leader at our pack show last night who is also an old friend of mine. He gave me some tips. One was that you don't want the car to have "perfect" alignment. It's impossible for a car to never touch the inside rail of the track so cars with straight alignment actually lose more energy bouncing back and forth off the inside track vs. cars that are drift left or right. Those cars slide down the rail on one side and lose less energy. He said the ideal car is one that goes straight for several feet then rides one side of the track all the way down. I think he said it's best to do it on the raised front wheel side too. Is he right?

Also, our pack doesn't seem too strict on rules. The only thing they really enforce are the dimensions and weight. You can have a front wheel way off the track, make your own axle grooves, etc... they don't care.

No, he's not correct on that part. Ideally the only wheel to touch the rail will be the front dominant wheel (not the raised one). Avoid letting the back wheel on that side touch by narrowing the front end a bit (1/16" IIRC). Some will cut it, my son just sands more in that area.

Some negative camber on the rear wheels will also help keep them off the rail. Can see that in my son's car.

How about the main idea that a straight alignment can be bad?

I'll be interested to hear what Stu says, but you do not want the car bouncing from one side to the the other of the rails. You don't want the raised wheel to spin. It the rotational energy will rob from the kinetic energy and slow the car down.

The track isn't perfect and car will likely turn anyway.

 

[Disco Stu]

I spoke to a scout leader at our pack show last night who is also an old friend of mine. He gave me some tips. One was that you don't want the car to have "perfect" alignment. It's impossible for a car to never touch the inside rail of the track so cars with straight alignment actually lose more energy bouncing back and forth off the inside track vs. cars that are drift left or right. Those cars slide down the rail on one side and lose less energy. He said the ideal car is one that goes straight for several feet then rides one side of the track all the way down. I think he said it's best to do it on the raised front wheel side too. Is he right?

Also, our pack doesn't seem too strict on rules. The only thing they really enforce are the dimensions and weight. You can have a front wheel way off the track, make your own axle grooves, etc... they don't care.

No, he's not correct on that part. Ideally the only wheel to touch the rail will be the front dominant wheel (not the raised one). Avoid letting the back wheel on that side touch by narrowing the front end a bit (1/16" IIRC). Some will cut it, my son just sands more in that area.

Some negative camber on the rear wheels will also help keep them off the rail. Can see that in my son's car.

How about the main idea that a straight alignment can be bad?

Yes, but alignment is still important. The car should be well aligned and balanced... just with a different goal than perfectly straight.

If the track was perfect, a car aligned to go perfectly straight would be ideal. But like IrishTwinkie said, the track isn't perfect.

So you're going to come into contact with the rail. Might as well be on your terms. Contacting with the front wheel is much preferred since it's carrying a much smaller percentage of the car's weight.

The other rail riding benefit is that the shortest distance between two points is a straight line. If you're on the rail, you know you're following a straight line. If you're weaving back and forth, you're not.

 

[shuke]

So we screwed up by aligning the car? OH COME ON.

 

[17seconds]

So we screwed up by aligning the car? OH COME ON.

yeah

 

[Brony]

Doing this with my girls for the first time ever. I'm clueless. The good news is that as long as it's pink the girls will be content. I have about 3 weeks to get ready.

 

[Brony]

Finally figured out that COM is center of mass. After conquering that, I feel like anything is possible.

 

[17seconds]

Finished up the car late last night by doing the wheels and axles. You can tell it's our first car and my son did all the painting and decorating.

Starting out in the garage with a glass of 2007 Chateauneuf du Pape

You can see I got the Revell axle driller and a #44 bit. I kept the rear axle stock since I cut off some of the back anyway, and drilled new holes for the front.

Graphite fingerprints all over the paint job

Biggest problem I had was getting the axles in straight. Nobody told me how tough that would be. I ended up splitting the wood in 2 places and my the camber on my wheels is kind of wonky but it tested out OK.

Back wheels

Lifted front left wheel

I shaved off about 1/16" on the front right side of the body to make a rail rider. I was able to get it to drift left 1.5" per 4ft without much tweaking. No way I'm going to mess with full wheel alignment, I've messed up the axles enough already. It drifts properly and the raised wheel looks good so I'm done with adjustments.

Here's my test ramp. A 6ft long 2x6 that I managed to smash into my thumbnail with all its weight at the bottom. Black/blue thumb today and ibuprofen.

It seems the graphite is not as effective after testing the car a lot. Any techniques for applying graphite after the wheels are on?

 

[Disco Stu]

It seems the graphite is not as effective after testing the car a lot. Any techniques for applying graphite after the wheels are on?

It helps if you have a dispensing needle like this. How close are the wheels to the body of the car? I imagine it would be tough to get more graphite in if they're too close.

For next time... it's easier to drill straight axle holes if you do it prior to any cutting.

 

[17seconds]

It seems the graphite is not as effective after testing the car a lot. Any techniques for applying graphite after the wheels are on?

It helps if you have a dispensing needle like this. How close are the wheels to the body of the car? I imagine it would be tough to get more graphite in if they're too close.

For next time... it's easier to drill straight axle holes if you do it prior to any cutting.

That graphite is the stuff I have. The wheels were set with a caliper from maximum velocity, so normal distance i guess.

I think my holes were drilled ok, the issue was getting the nails to go in straight. The jig puts it right on the edge of the wood so the nail caused it to split. I had a bigger problem on the stock axle notches.

 

[Brony]

I've read much of the thread and I appreciate all the tips in here. The following questions will seem like they are straight from my kid, but alas, they're mine:

The contest rules state: The wheel-base (distance between the front and rear axles) may not be changed from the kit body distance of 4-1/4 inches.

Does this mean I should just use the pre-existing slots in the wood? Is drilling new holes going to make a huge difference or advantage?

I'm thinking that the general process is this:

1. Sketch what kind of car to make.

2. Cut the wood (I have hand coping saw, Dremel and power jigsaw). I wanted to do coping saw to get my kid more involved, but I'm open on this step. Will coping saw work OK for making detail work or should I use a Dremel for the detail here?

3. Cut out good place for weights underneath car and glue them in. Sorry - using Tungsten or lead seems like overkill here. What will most cars really use for weights? I saw coins referenced somewhere. Also, if my steps are right, how do you hit the right weight without wheels on car? just keep nails and wheels on the side of the scale?

4. Sand wood parts of car

5. Paint car, but cover up axle slot. Will I need primer here?

6. smooth the axle: Put nail in drill and then apply file, then rough sand paper, then progress with finer sand paper on the parts of the nail where the wheel will touch the axle. Do I really need 8 varieties of sand paper, or do about 4 levels of fineness work OK?

7. put wheel onto nail and then affix nail to car base. can I just push nail into the slot using thumb pressure? and how do you ensure that wheel is the right distance off of car wall?

8. squirt graphite into gap between wheel and nail. Work it in by spinning, rolling, treadmill, etc.

9. win, WIn WIN!!

Realistically, my girls will help paint the car at best and I'll be happy if they make a single cut with a saw on a test piece of wood. I'm only looking to enter a respectable car without the use of exotic lanthanide metals.

 

[sho nuff]

I've read much of the thread and I appreciate all the tips in here. The following questions will seem like they are straight from my kid, but alas, they're mine:

The contest rules state: The wheel-base (distance between the front and rear axles) may not be changed from the kit body distance of 4-1/4 inches.

Does this mean I should just use the pre-existing slots in the wood? Is drilling new holes going to make a huge difference or advantage?

I'm thinking that the general process is this:

1. Sketch what kind of car to make.

2. Cut the wood (I have hand coping saw, Dremel and power jigsaw). I wanted to do coping saw to get my kid more involved, but I'm open on this step. Will coping saw work OK for making detail work or should I use a Dremel for the detail here?

3. Cut out good place for weights underneath car and glue them in. Sorry - using Tungsten or lead seems like overkill here. What will most cars really use for weights? I saw coins referenced somewhere. Also, if my steps are right, how do you hit the right weight without wheels on car? just keep nails and wheels on the side of the scale?

4. Sand wood parts of car

5. Paint car, but cover up axle slot. Will I need primer here?

6. smooth the axle: Put nail in drill and then apply file, then rough sand paper, then progress with finer sand paper on the parts of the nail where the wheel will touch the axle. Do I really need 8 varieties of sand paper, or do about 4 levels of fineness work OK?

7. put wheel onto nail and then affix nail to car base. can I just push nail into the slot using thumb pressure? and how do you ensure that wheel is the right distance off of car wall?

8. squirt graphite into gap between wheel and nail. Work it in by spinning, rolling, treadmill, etc.

9. win, WIn WIN!!

Realistically, my girls will help paint the car at best and I'll be happy if they make a single cut with a saw on a test piece of wood. I'm only looking to enter a respectable car without the use of exotic lanthanide metals.

Im not the expert that some here are...but my son has won his den every year and destroyed the rest of his pack last year.

2. Ive been lucky here getting to use the leader's woodshop as he holds a clinic every year for the kids and parents to come over...make sure the block is sketched out and then we cut it on his scroll saw. Its the one part most of the kids don't do much with at all. But then they do sit and sand their cars for a while. When we get home I get the power sander out and my son does that and then the painting. The most I do paint wise is the detailed work now. I used to do the extra coat to make sure it was smooth, but he has gotten good enough at it.

3. May seem like overkill...but all the stuff works. Yes, keep the wheels and nails on the scale to get the right weight. I usually have a good weight (have used the tungstun canopy last year)...have used the side rail weights one year and those worked very well also. And have drilled holes in the side of the car for the rounder lead weight things...those seemed good too. Last year's car was too thin for those. I like the putty though and was glad I had it last year. The scales at our pack race were not as precise as districts...and I had to scrape out some of the putty at districts to get him down the fraction of an ounce I needed. The putty made that so much easier. Also be careful weighting on the bottom and make sure you cut it out deep enough if that is what you are doing. Ive seen many people think they cut out enough and their cars don't have enough clearance on the track.

5. I have used primer yes. Works well and spraypaint makes things so easy for your son to help and do most of it...also a nice glossy clear coat makes it look great.

6. Ive never done too many types of sanding on those.

7/8 I have always squirted some graphite into the hole a little and then put the nail through. Ive done it with thumb pressure but then bought the little contraption from one of the web sites to drill the holes better. Will be doing that this year.

 

[Brony]

Thanks sho. Good info.

Do I have the general steps right? Someone probably has a good step by step for people like me, but this is one hobby where there's almost too much info out there.

You're probably right on the lead/ tungsten weight thing, just feels like too much at an event where there will be a prize for sparkliest car. (Actually true)

 

[shuke]

Biggest problem I had was getting the axles in straight. Nobody told me how tough that would be. I ended up splitting the wood in 2 places and my the camber on my wheels is kind of wonky but it tested out OK.

I'm surprised. My only guess is that your weird shape didn't allow the car to properly sit in the jig and put the holes too low.

It seems the graphite is not as effective after testing the car a lot. Any techniques for applying graphite after the wheels are on?

Put me in the camp that think any more than a squirt of graphite before assembly doesn't do a thing. If your axles are polished, and given the clearance between the wheel bores and axles, that graphite is just coming right back out.

 

[shuke]

I've read much of the thread and I appreciate all the tips in here. The following questions will seem like they are straight from my kid, but alas, they're mine:

The contest rules state: The wheel-base (distance between the front and rear axles) may not be changed from the kit body distance of 4-1/4 inches.

Does this mean I should just use the pre-existing slots in the wood? Is drilling new holes going to make a huge difference or advantage?

I'm thinking that the general process is this:

1. Sketch what kind of car to make.

2. Cut the wood (I have hand coping saw, Dremel and power jigsaw). I wanted to do coping saw to get my kid more involved, but I'm open on this step. Will coping saw work OK for making detail work or should I use a Dremel for the detail here?

3. Cut out good place for weights underneath car and glue them in. Sorry - using Tungsten or lead seems like overkill here. What will most cars really use for weights? I saw coins referenced somewhere. Also, if my steps are right, how do you hit the right weight without wheels on car? just keep nails and wheels on the side of the scale?

4. Sand wood parts of car

5. Paint car, but cover up axle slot. Will I need primer here?

6. smooth the axle: Put nail in drill and then apply file, then rough sand paper, then progress with finer sand paper on the parts of the nail where the wheel will touch the axle. Do I really need 8 varieties of sand paper, or do about 4 levels of fineness work OK?

7. put wheel onto nail and then affix nail to car base. can I just push nail into the slot using thumb pressure? and how do you ensure that wheel is the right distance off of car wall?

8. squirt graphite into gap between wheel and nail. Work it in by spinning, rolling, treadmill, etc.

9. win, WIn WIN!!

Realistically, my girls will help paint the car at best and I'll be happy if they make a single cut with a saw on a test piece of wood. I'm only looking to enter a respectable car without the use of exotic lanthanide metals.

1b. Drill axles holes.

3. Not overkill. Using lower density metals is fine, you'll just have to use more of it. Yes, just put everything on the scale.

5. Sanding sealer or primer, yes.

6. 2 or 3 grades of sandpaper is fine.

7. If you predrill it shouldn't be too difficult to push axle in. DO NOT FORCE IT. Push wheel in until there is a credit card size gap between wheel bore and body.

 

[Brony]

1b. Drill axles holes.

3. Not overkill. Using lower density metals is fine, you'll just have to use more of it. Yes, just put everything on the scale.

5. Sanding sealer or primer, yes.

6. 2 or 3 grades of sandpaper is fine.

7. If you predrill it shouldn't be too difficult to push axle in. DO NOT FORCE IT. Push wheel in until there is a credit card size gap between wheel bore and body.

thanks! I still feel like an ### hole spending $40 to 50 for a weight for an Indian Princess car, but it won't be the first or last time I have that feeling.

 

[shuke]

1b. Drill axles holes.

3. Not overkill. Using lower density metals is fine, you'll just have to use more of it. Yes, just put everything on the scale.

5. Sanding sealer or primer, yes.

6. 2 or 3 grades of sandpaper is fine.

7. If you predrill it shouldn't be too difficult to push axle in. DO NOT FORCE IT. Push wheel in until there is a credit card size gap between wheel bore and body.

thanks! I still feel like an ### hole spending $40 to 50 for a weight for an Indian Princess car, but it won't be the first or last time I have that feeling.

???

A small bag of lead fishing weights will run you about $2.

 

[17seconds]

1b. Drill axles holes.

3. Not overkill. Using lower density metals is fine, you'll just have to use more of it. Yes, just put everything on the scale.

5. Sanding sealer or primer, yes.

6. 2 or 3 grades of sandpaper is fine.

7. If you predrill it shouldn't be too difficult to push axle in. DO NOT FORCE IT. Push wheel in until there is a credit card size gap between wheel bore and body.

thanks! I still feel like an ### hole spending $40 to 50 for a weight for an Indian Princess car, but it won't be the first or last time I have that feeling.

I found a dude selling axles for $32 EACH. That's a polished nail, folks

 

[Brony]

1b. Drill axles holes.

3. Not overkill. Using lower density metals is fine, you'll just have to use more of it. Yes, just put everything on the scale.

5. Sanding sealer or primer, yes.

6. 2 or 3 grades of sandpaper is fine.

7. If you predrill it shouldn't be too difficult to push axle in. DO NOT FORCE IT. Push wheel in until there is a credit card size gap between wheel bore and body.

thanks! I still feel like an ### hole spending $40 to 50 for a weight for an Indian Princess car, but it won't be the first or last time I have that feeling.

???

A small bag of lead fishing weights will run you about $2.

lots of chatter about tungsten putty and melting lead in the thread and I've seen that stuff running $10-15 per ounce. Fishing weights sound good to me. Now I'm glad I asked.

 

[Disco Stu]

Tungsten putty is just for the last couple tenths of an ounce. It's not a necessity, but it sure makes it easy to adjust at weigh-in.

You can buy one ounce at Hobby Lobby for $10 or so and have enough to last for a few years. And HL always has a 40% coupon you can print.

 

[Disco Stu]

OK, at the risk of being compared to a Trekkie, let me give this a shot. I am a cubmaster; one of my boys has moved on out of scouting; and my younger boy is a Webelo I.

As my boys progressed through scouting we did a lot of reseach and had a lot of success. Combined, they have over 30 Pack and District championship trophies. I am often invited to give seminars and workshops and I freely give out every single bit of advice I have. I have also hosted workshops at my house and over 60 boys have built their cars in my shop, and dozens of them have won Pack and District trophies.

There are many ways to build winning cars but here are the keys I stress:

1) your son needs to decide if he wants to build a cool looking car or a fast car. Rarely is a cool looking car fast. Fast cars are generally very basic and boring. Here is an example of a simple car.

2) note that my son did not use the pre-cut axle slots. It's much better to drill new axle holes as far forward and as far back as possible. Try and find a floor drill press to do that. Don't have the front wheel extend past the front of the car.

3) try and place your weight so that the center of mass is about 3/4th of an inch in front of the rear axle. You can measure that by placing the car on the edge of a ruler to see if it balances there. Another goal is to have 1 ounce of weight on the front wheels and 4 ounces on the back.

4) file and polish axles. An easy way to do this is to put the axle in a dremmel tool or drill and get it spinning. Use a fine file to file off the ridges on the axles. Dont' take off to much material. Less is better than more. Then use wet and dry sandpaper to progressively polish the axle. Start with 600 grit and work your way up to 2500 grit. You can then use a micro polish and to put on the finishing touch. Wash and dry the axle thoroughly after that.

5) BSA changed wheels 2 years ago and the new ones are pretty good. Prior to that the old wheels had a molding bump that had to be shaved off. I wouldn't suggest messing with the new wheels unless you have access to a lathe of some sort. As a side note, don't place wheels on axles and spin them until after you've filed the axles. Otherwise the unpolished axles will make tiny grooves in the bore of the wheels that are nearly impossible to identify and remove. You should verify all wheels spin freely and don't wobble. If they wobble go to the scout store and get new ones.

6) get some high quality graphite from one of the pinewood derby websites. Place the wheel on the axle, squirt graphite in, spin the wheel hard 10 times. Repeat the process 4 times for each wheel. Graphite consists of crytals that must be crushed to be effective. Do not squirt fresh graphite on the wheels unless there is time to break it in.

7) push the axles/wheels into the axle holes. The wheel should be the width of a credit card from the side of the car.

8) roll the ar on a clean, flat surface to make sure it rolls relatively straight. If it moves towards one side or the other more than an inch over a foot you need to make an adjustment. Pull the axle and wheel out of the front hole and try and place a very slight bend in the axle. Do not do that while it is in the car or you will break off some wood. Place the axle/wheel back in and re-roll it. Rotate the axle until it starts rolling straigher.

9) put the car away and do not mess with it again until the race. Most disasters happen during this time.

Here is a thread on building an outlaw car for the dad's race. Most of the concepts also apply to building a scout class car.

Bumping this again. This is still basically what we follow.

Main difference is step 8, since we do a rail-rider.

 

[shuke]

1b. Drill axles holes.

3. Not overkill. Using lower density metals is fine, you'll just have to use more of it. Yes, just put everything on the scale.

5. Sanding sealer or primer, yes.

6. 2 or 3 grades of sandpaper is fine.

7. If you predrill it shouldn't be too difficult to push axle in. DO NOT FORCE IT. Push wheel in until there is a credit card size gap between wheel bore and body.

thanks! I still feel like an ### hole spending $40 to 50 for a weight for an Indian Princess car, but it won't be the first or last time I have that feeling.

???

A small bag of lead fishing weights will run you about $2.

lots of chatter about tungsten putty and melting lead in the thread and I've seen that stuff running $10-15 per ounce. Fishing weights sound good to me. Now I'm glad I asked.

I melt the fishing weights. But you don't have to. You can buy some different sizes to get the right combination if you just want to glue them in/on the car.