Opinions Wanted: Critique my Rail-riding explanation

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Vitamin K
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Opinions Wanted: Critique my Rail-riding explanation

Post by Vitamin K »

Hey folks,

So I'm writing up an introduction to rail-riding for the uninitiated (primarily, dads in our pack), and I thought I'd ask for some opinions on it.

You can view it here: https://docs.google.com/document/d/1af1 ... sp=sharing

I'd like feedback on:

- Correctness of the information
- Clarity of my explanations
- Quality of writing
- Usefulness of diagrams

This is just an intro, and does not go into actually construction techniques. I plan to write that up at a later date. Feel free to leave feedback on this thread, or using the GDocs comments.
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Re: Opinions Wanted: Critique my Rail-riding explanation

Post by Speedster »

VK, that is a very detailed, and I think, very accurate description of rail riding. My experience for many, many years has been folks want a quick fix and it's hard for people to picture something when they're hearing a lot of words. I have learned to keep my words to a minimum and show them a lot of visuals. This works really well with scouts because it gets them out of their seats and involved. I realize you're teaching Dad's. Troy Thorne's latest book, " Build a Winning PINEWOOD DERBY CAR" , Chapter 7, Pages 86 and 87, has pictures and very few words describing Railriding. If you keep even one book it can be passed around and everyone can read it. I keep a stock of 10 of the books in case someone wants to buy one which I think would work well if every Dad had one to look at. After the Dads take a few moments to look at the two pages you can then get on with the actual construction of the car and the Dads will have the books in front of them. I think it is true, One picture is worth a thousand words.
I wish you well in your workshop.
Last edited by Speedster on Fri Jan 15, 2016 5:16 am, edited 1 time in total.
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Darin McGrew
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Re: Opinions Wanted: Critique my Rail-riding explanation

Post by Darin McGrew »

Vitamin K wrote:This is just an intro
I think it goes well past being "just an intro".

Who is your target audience?
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Vitamin K
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Re: Opinions Wanted: Critique my Rail-riding explanation

Post by Vitamin K »

Darin McGrew wrote:
Vitamin K wrote:This is just an intro
I think it goes well past being "just an intro".

Who is your target audience?
I consider it an intro, because I do not go into implementation details.

The target audience is the dads from my Pack, in order to help them better assist their kids.
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Re: Opinions Wanted: Critique my Rail-riding explanation

Post by birddog »

I like it. Good write up!

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Re: Opinions Wanted: Critique my Rail-riding explanation

Post by DaringRacer »

Hey - question for you guys on rail riding.

Why such a huge drift? I've been reading on RR and most are saying 3-5" over 8 feet. Thats huge, basically as soon as it leave the block it runs into the rail I'd think at that amount.

Why not like .5" over 8 feet so it has time to build up speed first? I mean, the more you are on the rail the more friction there is.
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Re: Opinions Wanted: Critique my Rail-riding explanation

Post by Vitamin K »

DaringRacer wrote:Hey - question for you guys on rail riding.

Why such a huge drift? I've been reading on RR and most are saying 3-5" over 8 feet. Thats huge, basically as soon as it leave the block it runs into the rail I'd think at that amount.

Why not like .5" over 8 feet so it has time to build up speed first? I mean, the more you are on the rail the more friction there is.
It could be a factor of more aggressive COM weighting. As Pinewood Derby technology has progressed, folks keep pushing the COM closer to the rear axle. Usually, the lower the COM, the more steer you need on the car to prevent any wiggles.
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Stan Pope
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Re: Opinions Wanted: Critique my Rail-riding explanation

Post by Stan Pope »

DaringRacer wrote:Hey - question for you guys on rail riding.

Why such a huge drift? I've been reading on RR and most are saying 3-5" over 8 feet. Thats huge, basically as soon as it leave the block it runs into the rail I'd think at that amount.

Why not like .5" over 8 feet so it has time to build up speed first? I mean, the more you are on the rail the more friction there is.
Toe-in of 0.5" in 8' might work IF the track were perfectly smooth and the wheels were perfect. Even the best section joints are prone to cause the DFW to pop away from the rail a bit, and, depending on the track set-up on race day, enough toe-in is required (1) to keep the opposite side from crashing the rail and, better, (2) to keep the DFW "glued to the rail." The rougher the track and the more extreme the CM location, the more toe-in is needed.

On the other hand, too much toe-in does create some excess friction losses, so it helps if you have an opportunity to tune the toe-in to the track, perhaps during a "test and tune" session prior to race day.
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Re: Opinions Wanted: Critique my Rail-riding explanation

Post by Scrollsawer »

VK,

I think that's an outstanding write-up. I don't think it's too wordy, but then again, I like a lot of detail. Considering that your target audience is folks who have no idea what rail riding is, or any of the 'steering' principles required to set up a rail rider, I think the amount of detail is spot on.

Love the illustrations, and also love the last two sentences of your second paragraph. I think it's always safer to go ahead and trim 1/16" off the DFW side of the car body, regardless of the positive camber on that wheel. Most folks won't be able to get their cars on a track to 'eyeball it' beforehand, so why not just tell them to go ahead and trim 1/16" off? (Just my humble opinion).

Again, great write-up!

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Re: Opinions Wanted: Critique my Rail-riding explanation

Post by Perry24 »

Great write up! Thank you. When do we get the advanced version that shows how to properly cant the wheels? ;)

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Re: Opinions Wanted: Critique my Rail-riding explanation

Post by Vitamin K »

Perry24 wrote:Great write up! Thank you. When do we get the advanced version that shows how to properly cant the wheels? ;)
Good question. That part is actually a lot more controversial, so I would probably want to do it in multiple parts, to address the different methods and explain the pros/cons of each.
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Re: Opinions Wanted: Critique my Rail-riding explanation

Post by Perry24 »

A little off topic, but is it better to bend axles or drill holes? I really want to try this, but would need to purchase tools to do so.

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Re: Opinions Wanted: Critique my Rail-riding explanation

Post by Vitamin K »

Perry24 wrote:A little off topic, but is it better to bend axles or drill holes? I really want to try this, but would need to purchase tools to do so.
Careful friend, for there lies the way unto madness... ;)

I jest, but I've gotten burned up at other Pinewood forums for even suggesting that bent axles were a viable way to do things. People have curiously strong opinions about these things...

First, I want to say that bending axles is not in opposition to drill holes for the axles. The difference is that you're not depending on the angle of the holes to set your cant and alignment. Just to be clear on that.

I think that both methods can yield a viable car with good alignment. There are some pros and cons to each. Here's how I see it:

Bent Axles

Pros:
- Very little in the way of special equipment required
- Not dependent upon perfectly straight axles
- Adjustable at any phase of the car build (for example, if your DFW raises the nose of the car unexpectedly and throws off the rear alignment)

Cons:
- Requires alignment of rear axles. Can be time consuming. (There are techniques to help this, though)
- Wheels must be realigned after being removed for cleaning or re-prep (or if wheel is removed for inspection!)
- "Professional" race stainless steel axles may require more work to bend than scout axles


Straight Axles w/ drilled cant

Pros:
- Almost universally preferred by league racers
- "Plug and play" once properly drilled. Wheels can be removed and re-inserted without issue
- No need to adjust rears, since alignment is pre-set

Cons:
- Requires use of some kind of machined jig (and possible a drill press) to guarantee that axle holes are at the proper angle and parallel
- "All or nothing" alignment. If alignment is off, block must be discarded or re-drilled. If alignment gets warped late into the build, no automatic way to correct.
- Requires very straight axles to be effective.
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Re: Opinions Wanted: Critique my Rail-riding explanation

Post by Perry24 »

Thank you, VK. It seems bent axles might be best for a beginner.

A few years ago, when my son was a Tiger, we built a crude car that ran good. He won districts for the Tiger/Wolf class. However, he got spanked by a RR for overall champ. That was the only time I've seen a RR at districts.

Unfortunately, he gave up Scouts this year to focus on soccer. However, there are a couple Scouts that asked for help to build cars. I would love to try a RR, but do not want to set them up for failure. The only test track I have access to is an old wood track. Not sure if that would skew the results. The Pack and District race will be run on a well-maintained wood Piantedosi track. We also must use the axle slots, so bent axles are probably the only option.
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Re: Opinions Wanted: Critique my Rail-riding explanation

Post by Vitamin K »

Perry24 wrote:Thank you, VK. It seems bent axles might be best for a beginner.

A few years ago, when my son was a Tiger, we built a crude car that ran good. He won districts for the Tiger/Wolf class. However, he got spanked by a RR for overall champ. That was the only time I've seen a RR at districts.

Unfortunately, he gave up Scouts this year to focus on soccer. However, there are a couple Scouts that asked for help to build cars. I would love to try a RR, but do not want to set them up for failure. The only test track I have access to is an old wood track. Not sure if that would skew the results. The Pack and District race will be run on a well-maintained wood Piantedosi track. We also must use the axle slots, so bent axles are probably the only option.
Regardless of whether you are running bent axles or straight axles, if you want to build a rail rider, you will need to build a tuning board. There are plenty of good resources for that, but I would not attempt to align a rail rider without one. You can build a simple one for probably $15 in parts from Home Depot.

If you go with bent axles, I would recommend you give Stan Pope's bias weight alignment system a look.
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