various questions

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Yoderby
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various questions

Post by Yoderby »

I have the COG at about 1" in front of the rear axles and centered side to side. I'm planning on having a raised wheel for less friction. It seems to me that there will be an imbalance as the car goes down the track. Is this mind trick and as long as I test that it runs straight on a table there won't be a problem leaning to one side with 3 wheels? Rules state that wheels must run flat but one raised wheel is acceptable. Or am I better off with no raised wheel?

I drilled axles holes. It seems like if I hammer the nails in it will be solidly in. Is it necessary to drill tiny holes through the bottom to add glue or is this not really necessary?

After I hammer the nails in to the drilled axle holes, if I test it and it doesn't run straight how can I adjust the axles so it does run straight? I can see how one could adjust them using the default axle slots not not when it's drilled holes. Rules state that bent axles are not permitted.

I involved my kid in making the car at a basic level but I was the one who read the articles about weights, COG, raised wheel, polishing axles etc. I explained the reasoning for everything and had him use the tools to guide him but I did most of the work since physically he's not really able to do it. Is this ethical?
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Re: various questions

Post by gpraceman »

:welcome:
Yoderby wrote:I have the COG at about 1" in front of the rear axles and centered side to side. I'm planning on having a raised wheel for less friction. It seems to me that there will be an imbalance as the car goes down the track. Is this mind trick and as long as I test that it runs straight on a table there won't be a problem leaning to one side with 3 wheels? Rules state that wheels must run flat but one raised wheel is acceptable. Or am I better off with no raised wheel?
No, it is not a Jedi mind trick. As long as your COG is not too far forward, then the raised wheel will not touch (and barring a bump in the track).
Yoderby wrote:I drilled axles holes. It seems like if I hammer the nails in it will be solidly in. Is it necessary to drill tiny holes through the bottom to add glue or is this not really necessary?
It is not necessary unless the axles fit loosely in the holes.
Yoderby wrote:After I hammer the nails in to the drilled axle holes, if I test it and it doesn't run straight how can I adjust the axles so it does run straight? I can see how one could adjust them using the default axle slots not not when it's drilled holes. Rules state that bent axles are not permitted.
You might want to check out some of the discussions on rail riding.
Yoderby wrote:I involved my kid in making the car at a basic level but I was the one who read the articles about weights, COG, raised wheel, polishing axles etc. I explained the reasoning for everything and had him use the tools to guide him but I did most of the work since physically he's not really able to do it. Is this ethical?
As long as your son is doing what he is capable of, then there is no ethical dilemma. However, I would be a bit careful in thinking a kid is not capable of something, unless there is a handicap involved. When done in small chunks of time, even the youngest kids can do quite a bit of the car build.
Randy Lisano
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Re: various questions

Post by Yoderby »

gpraceman wrote: You might want to check out some of the discussions on rail riding.
As per the rules, rail riding is not permitted so I can't do that. Thanks for the feedback.
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Re: various questions

Post by gpraceman »

Yoderby wrote:
gpraceman wrote: You might want to check out some of the discussions on rail riding.
As per the rules, rail riding is not permitted so I can't do that. Thanks for the feedback.
I was referring to discussions on how to steer the car. You can affect steer without having bent axles or canted wheels.
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Re: various questions

Post by Yoderby »

I did a search but don't seem to be able to find that discussion. I would have thought one of those things be necessary. Can you point me to a link to check out?
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Re: various questions

Post by Yoderby »

I found a rail riding faq here:
http://www.maximum-velocity.com/railridingqa.htm

Since I don't know if there is a center bar or just side dividers I guess I'll just try to make it run straight this time.
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Re: various questions

Post by knotthed »

Yoderby wrote: Since I don't know if there is a center bar or just side dividers I guess I'll just try to make it run straight this time.
Why not ask you race organizer what the track configuration is?

Do the rules say rail riding is not allowed? This would be a doozey for the books.... Someone should compile a list of absurd and bad rules into a pinewood comedy.

As a former race organizer, I am shocked at how much or lack thereof effort that people put into the derby. You are here asking questions so your already headed in a good direction.

I was able to go and observe 3 other local derbies this year since my organizer duties are over. I was shocked to find that current organizers had not even taken the time to familiarize themselves with the rule updates from council.

The moral of the story here is that the best thing you can do is ask questions - and ask them to the people in charge. Then people can help you to the fullest extent.
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Re: various questions

Post by Yoderby »

I rechecked the rules and I was wrong. It says:
"So that the car can clear the track's center guide strip, there must be min .375" underside, and min 1.75" wheel to wheel clearance"

"wheels must run flat"

It doesn't say that axles can't be bent. So it looks like I cannot cantilever the wheels but I can bend the axle. So based on that faq I guess I want the back wheels to be straight and flat.

The issue now is that I don't have equipment to bend the axle for the front wheel. And I'm confused about that as well since I drilled the axle hole. Any idea how I can bend the axle without a special tool? Thanks.
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Re: various questions

Post by Stan Pope »

Bend the axles with the "Armstrong" method ... i.e. pliers and a block of wood. Use your weight on the pliers and your strength to hold the nail at an angle to the wood block. Check angle with the chart at http://www.stanpope.net/pwaxlebend.htm

Or bend them with a hammer, screwdriver, and block of wood ... see http://www.derbytalk.com/viewtopic.php?f=11&t=8172

Or, use your imagination! :)

BTW, a small axle bend can allow the wheels to test flat and run cambered because of the loose fit between wheels and axles. So check the wording of the rule carefully.

A test often applied is to try to slide a piece of paper under the wheel from the side. Contact with the track / test surface stops the paper or causes the wheel to move. If the car is placed on a test surface, the wheels may be positioned to lie flat, but after rolling a few inches, they may ride up on the edges!
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Re: various questions

Post by Yoderby »

I checked the detailed rules and it says:
"Axle nails must be mounted parallel to the track surface. Tilted or canted axles that cause the car to run on the edge of the wheels are not allowed. Wheels must run flat on the track surface. At least three wheels must be in contact with the track surface at all times as the car rolls."

What does that mean? Does it mean bent axle is not permitted? I guess if the wheels run flat it would be allowed even if it wouldn't be exactly "parallel".
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Re: various questions

Post by Yoderby »

One more thing, can I use old credit card for spacer to hammer the axles?
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Re: various questions

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Yoderby wrote:I checked the detailed rules and it says:
"Axle nails must be mounted parallel to the track surface. Tilted or canted axles that cause the car to run on the edge of the wheels are not allowed. Wheels must run flat on the track surface. At least three wheels must be in contact with the track surface at all times as the car rolls."

What does that mean? Does it mean bent axle is not permitted? I guess if the wheels run flat it would be allowed even if it wouldn't be exactly "parallel".
That rule (the actual wording) needs some clarification and probable tweaking by the Pack race officials. Obviously, a very severely canted axle may cause the wheels to ride on the wheels inside edges, but that is not nearly what you'd want to do.

In this application, you'd only want an almost indiscernible amount of cant (or axle bend), which would keep the entire wheel tread 100% in contact with the track (which is what the race officials obviously want), and it would also allow the rear wheels to migrate out toward the inside of the nail head (versus bouncing back and forth between the nail head and the car body). In my opinion, you should be able to meet the Pack's requirement while also optimizing the 'outer wheel hub/inside nail head' contact surfaces.

Might need to explain to them what canting is, and why it's not a bad thing if done appropriately. Also should be easy enough to demonstrate to the race officials by building a car with adequate cant, and rolling the car in front of them so they can see what's going on.

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Re: various questions

Post by gpraceman »

Yoderby wrote:I checked the detailed rules and it says:
"Axle nails must be mounted parallel to the track surface. Tilted or canted axles that cause the car to run on the edge of the wheels are not allowed. Wheels must run flat on the track surface. At least three wheels must be in contact with the track surface at all times as the car rolls."
Personally, I think that is a crummy rule.

First off, it makes it harder for a novice racer to build a car. If the wheels are just slapped on the car, like many novice builders do, there is likely to be some cant to at least one of the axles. It is harder to get the axles in straight. So, the novice builder is already being put at a disadvantage.

Secondly, while a car may not have any axle cant at check-in, loose fitting axles, rough handing or rough stopping can easily cause the wheels to get a cant to them afterwards. So, what happens when a car is doing well and someone notices that the car has canted wheels? Accusations of cheating, of course. Even though it might not have been the fault of the racer that the wheels became canted after check-in. I personally saw this issue at one of our district races. The next year, the district rules were amended to allow canted wheels, for the exact reasons that I just listed.

So, the race coordinator should really look at that rule and consider changing it. If not for this year's race, then for the next.
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Re: various questions

Post by Yoderby »

This rule was buried in their official rules not the summary doc that they emailed out so I don't think they will care about this anyway especially if it's a minor tweak.

About the spacer, I see that a credit card is the perfect width:
http://www.derbytalk.com/viewtopic.php?t=4427
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Re: various questions

Post by Scrollsawer »

An old credit card or library card or grocery store loyalty card makes for a good spacer. I've also heard the rounded lid to a tub of margarine works well.

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