Bent Axles vs. Canted Drilled Holes?

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davidwilkie
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Bent Axles vs. Canted Drilled Holes?

Post by davidwilkie » Sun Jan 25, 2015 9:15 pm

I guess there is a pre-question here which is whether rear axles should be canted at any angle at all? I seem to recall 2.5 degree cants on the rear axles being in vogue to keep the wheels riding against the axle heads. And a 1.5 degree cant on the DFW (can't recall if bent up or down). Is that still the case?

If so, then two methods as best I know:

1. Put bent axles in straight holes

< or >

2. Put straight axles in canted holes

I have been using the canted holes method, using Stan Hope's method:

Image

But I recently watched this video...



...and noticed the tunability of the bent axle method

I guess I could still drill canted holes at less of an angle and use axles bent at less of an angle, but that seems more trouble than it is worth.

So, the question is:

0. Should axles be canted at all, or at least should the rear axles be?

1. Bend axles so you can tune them by turning them?

2. Drill canted holes and use straight axles?

or 3. Is there yet a mother better way that is neither of the above?

Greatly appreciate any thoughts or opinions! (and if different front / back, please elaborate)



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Re: Bent Axles vs. Canted Drilled Holes?

Post by Vitamin K » Sun Jan 25, 2015 9:29 pm

I elected for bent rear axles for our family's builds this year, primarily because of the 'tunability' aspect. My luck in both drilling and evaluating drilled cant has been spotty, at best.

I used Stan Pope's cantilever weight technique, and I found it very easy to test and tune with: http://stanpope.net/bentaxlealign.htm

That said, a lot of people use drilled cant with very good results. Lightninboy's testing method looks very good, also: http://www.derbytalk.com/viewtopic.php? ... t=0#p75671

I think that good results can be had with both methods. One difference to note is that with drilled cant, you do your alignment first thing before anything else, and with bent axles, alignment is your final step. Depending on your processes, one may appeal more than the other.



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Re: Bent Axles vs. Canted Drilled Holes?

Post by sporty » Sun Jan 25, 2015 9:48 pm

There our two views.
some say. A faster car. Is more finely tuned thru bent axles.
and the other is drilling cant. Using straight and true axles.
keep in mind. Rears are the reference on that.
the front . Railriding. Well . I have drilled a can't and mild toe.
I do this to use a smaller bend in my axle. Easier to tune.

A smaller bend. Gives a bit more give and ease of tuning with a wider range of ease of adjustment.
Where a axle that has allot of bend in it.
it's really touchy and has less range of the ability to adjust and tune.
It's super sensitive to touch.
the bend can be great enough also to not fit the wheel. Causeing the axle to scrape the wheel bore. Or not fit in at all.
so some grind or reduce the diameter there. So the axle will fit.
and the bend can be great enough that it causes rub in the bore. Or when the wheel for a brief millisecond goes to the body. During the slope/transition to the flat of the track. Can cause issues of binding with a axle very bent.
many would rather drill canted and check with pin gage or the few different options to check the cant/ angle is the same and even on both sides.
with bent axles in strait holes. It's a bit more sticky to check and gage the angle and even height.
Factors of two axles having the exact same bend/cant. And both in the same spot.
so that the height is the same also where the wheels will be at on the axle.
Derbyworx newer pro axle bender is costly but provides much more accuracy over the earlier less costly version.
Some feel it's easier to toss a few dollar piece of wood. When a mistake is made and easier to check and confirm. That the cant is the same and height the same. Over trying to get two axles bent the same.
the time to prep axles and extra ones. To get a few that are identical is in some people view. A little harder and more time consuming.
Then just tossing bad drilled canted wood.

Often we do forget. The o.d. of the wheels need to be the same in the rears and the wheel bore size also. As this also is a factor. In the real and overall can't and level Ness of the rear.
but a super tuned car should be faster over just a finely tuned car.



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Re: Bent Axles vs. Canted Drilled Holes?

Post by Stan Pope » Mon Jan 26, 2015 12:33 am

Vitamin K wrote:I elected for bent rear axles for our family's builds this year, primarily because of the 'tunability' aspect. My luck in both drilling and evaluating drilled cant has been spotty, at best.

I used Stan Pope's cantilever weight technique, and I found it very easy to test and tune with: http://stanpope.net/bentaxlealign.htm

That said, a lot of people use drilled cant with very good results. Lightninboy's testing method looks very good, also: http://www.derbytalk.com/viewtopic.php? ... t=0#p75671

I think that good results can be had with both methods. One difference to note is that with drilled cant, you do your alignment first thing before anything else, and with bent axles, alignment is your final step. Depending on your processes, one may appeal more than the other.
You can use more than 2.5 degr rear camber but alignment via the "wheels to the axle head on forward & reverse roll" test loses accuracy. Alignment accuracy of the biased weight technique is still excellent.

You can mix drilled camber and bent axles to accommodate your lack of drilling precision. For instance if you can only drill to +/-0.5 degrees, then you could drill at about 2 degr and use 0.5 degr bend in axles to get room to correct the toe angle on the rears. (If you have to Dog Trot, then you should add about 1 degree to the axle bend.)

Where drilling alone may be a problem is if you are not allowed to indent the DFW. Then you either have to add wood to the opposite front side (if allowed) OR you have to align the rears to run Dog Trot, i.e. the rears are a bit off from the car's centerline. If Dog Trot is your option, then my weight bias alignment procedure with bent axles (or a combination of bent axle and drilled camber) are an excellent option.

Note: When drilling rear axle holes, assure that the table is perpendicular to the quill to better than 0.77 degrees. Excess error in the wrong direction will shift the wheel behind the DFW to track against the rail! (Of course, you can err a degree in the other direction and produce Dog Trot alignment!) -- This comment assumes that the drill press has an adjustable table angle and that the fence is perpendicular to the table axis ... which assures that the rear axles have equal and opposite toe.

Glad to see some folks are using some of my stuff! :)


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Re: Bent Axles vs. Canted Drilled Holes?

Post by davidwilkie » Mon Jan 26, 2015 5:56 am

Thanks for the responses!

I use the Stan Hope method above, e.g., using a drill bit to set angle rather than trying to adjust the drill press to such a small degree. But good point on making sure it's square to start. Not sure what "Dog Trot" is...I'll have to search that one!

QUESTION: how do you tune straight axles in canted holes? Do you just throw the wood out and start over?



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Re: Bent Axles vs. Canted Drilled Holes?

Post by Vitamin K » Mon Jan 26, 2015 7:02 am

davidwilkie wrote:I use the Stan Hope method above, e.g., using a drill bit to set angle rather than trying to adjust the drill press to such a small degree. But good point on making sure it's square to start. Not sure what "Dog Trot" is...I'll have to search that one!
It's "Pope," actually. Otherwise the alliteration for "Pope's Pinewood Pages Portal" doesn't work. :mrgreen:
davidwilkie wrote:QUESTION: how do you tune straight axles in canted holes? Do you just throw the wood out and start over?
You can toss the block and start on a new one. Or you can fill the hole with a round toothpick and epoxy and re-drill. Alternately, flip the block and re-drill the rears on the other side.



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Re: Bent Axles vs. Canted Drilled Holes?

Post by sporty » Mon Jan 26, 2015 9:54 am

Well the front drilled with the opposite cant. Railrider. Still gets a bent axle. To set the drift. Usually a mildly bent axle. Like 1 degree to 1.5 degree.
The rears. If using scout axles. Usually those axles. Even with looking straight have a little untrue Ness in them to still be able to rotate them some to fine tune.
if it's just a minor issue.

But many just use another block of wood. If you buy a full block of wood without the slots. Like from maxv.
then you can flip the block over and try again.
or fill the holes with glue and toothpick and try again.
sometimes this does not work tho. Due to the toothpick wood being softer or harder or not a tight enough fit in the axle hole. And it comes back out or creates the bend to wander why drilling. Or the difference in wood. One part of the wood drills easier then the other wood. Then it does not drill right.



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Re: Bent Axles vs. Canted Drilled Holes?

Post by Stan Pope » Mon Jan 26, 2015 12:42 pm

"Dog Trot" definition: The path followed by the rear wheels is offset from the path followed by the front wheels.

Watch a dog running sometime (or look at its tracks in the snow if you are lucky enough to get some snow) ... you will likely see that the rear feet come down on each side of ONE of the front feet.

If you are not allowed to narrow the front end and still want to guide by the center rail, then align the rear axles so that when the DFW slides on the rail, the rear wheels are both spaced away from the rail. The car will look a bit crooked ... if you look closely ... but the rears wont scrub energy against the rail!


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Re: Bent Axles vs. Canted Drilled Holes?

Post by ngyoung » Tue Jan 27, 2015 9:21 am

Lol. The big debate continues.

If you have access to a drill press I would really encourage you to use straight axles and drill the holes angled. Yes you have a lot of play using bent axles for tuning but that is a double edged sword. The biggest problem is also that you have a lot of play and it is hard to properly align. Stan's weight biasing method can help you get pretty close but personally I don't feel it gets you to the same point as getting the drill job done right. It is also pretty easy for one of the wheels to get knocked out of alignment during racing. It is usually bad enough having just that one DFW to worry about being bumped.

Both methods do take some bit of care. Drilling angled holes, your most important step is done early in the build with a blank block. Bending your axles you need to take more time tuning your alignment when your car is all done and you're likely less willing to redo anything. It is always good to check your work after every step regardless of the method before you get too far invested in the car body. With bent axles, every time you install the wheels you have to take time to re-align them, even if you have the axle positions marked. Drilling angled holes you can usually get multiple drill jobs in one block if you think the first one is not right, you don't have to chuck the whole block out. Using BSA parts you are still going to likely have some play in the axles since they are not usually perfectly straight.

In the end you really have to judge yourself and what you think you're more comfortable with.



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Re: Bent Axles vs. Canted Drilled Holes?

Post by Stan Pope » Tue Jan 27, 2015 10:07 am

ngyoung wrote:...
Stan's weight biasing method can help you get pretty close but personally I don't feel it gets you to the same point as getting the drill job done right.
...
If only "pretty close" then I should be able to improve times by tweaking according to on-track tests. So far, I have not been able to do so.


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Re: Bent Axles vs. Canted Drilled Holes?

Post by Vitamin K » Tue Jan 27, 2015 10:28 am

ngyoung wrote:Yes you have a lot of play using bent axles for tuning but that is a double edged sword. The biggest problem is also that you have a lot of play and it is hard to properly align.
I really don't want to sound like a shill for Stan's work, but if you watch the application video, it takes all of 5 minutes. I really don't see that as "hard to properly align."
ngyoung wrote: Stan's weight biasing method can help you get pretty close but personally I don't feel it gets you to the same point as getting the drill job done right.
This seems a little hard to quantify, IMO. Either the wheels are aligned straight, or they are not. Very few people that I know of have actually tried both methods and done side-by-side testing, so I'm not really sure how I feel about statements like this. Over at [league racing forum], the first thing that they drill into your head is "DON'T EVER BEND YOUR REAR AXLES" (I'm not exaggerating), so I doubt many of them are experimenting with techniques to optimize bent axle alignment.
ngyoung wrote: It is also pretty easy for one of the wheels to get knocked out of alignment during racing. It is usually bad enough having just that one DFW to worry about being bumped.
I've heard this claim lots of times (often by folks interested in selling more Silver Bullets), but I am curious as to how true it is. I had to grip the nail head fairly well with the pliers and it took an appreciable amount of torque to rotate the axle heads (I really need to experiment with the K-House groove!). However, I just don't see a lot of forces that act on a typical pinewood derby car that are going to cause the rear axle rotation to change. :idk:
ngyoung wrote:In the end you really have to judge yourself and what you think you're more comfortable with.
This much, I whole-heartedly agree with. :thumbup:



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Re: Bent Axles vs. Canted Drilled Holes?

Post by gpraceman » Tue Jan 27, 2015 10:56 am

I sure hope this stays a civil discussion. Some people can really get their panties in a twist if people try to discuss using bent axles vs. angled holes. Unfortunately, there are underlying motives going on with some of the people that promote one over the other. (Please know, I am not calling out anyone in this thread.)

Some other forums stifle this type of debate, as they will criticize certain techniques or use of certain tools. In this forum, I hope that we can discuss such things and try to keep it objective, not subjective nor hearsay.


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Re: Bent Axles vs. Canted Drilled Holes?

Post by sporty » Tue Jan 27, 2015 11:22 am

Our we really helping david.
or has it turned into a side debate ?

Most scouts. Build 1 car a year. Spend less than 2 hours on it. It's highly unlikely most of what we share on here or talk about or do. Will ever appeal to the average scout or parent.
all we can do is try and help the ones who want to learn more and do more.

david.

I hope you were able to come up with a answer that was able to help you.

It's not a clear cut issue. In the end you have options. Try them both if you like. And find the one that you feel works best for you and your son.



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Re: Bent Axles vs. Canted Drilled Holes?

Post by Vitamin K » Tue Jan 27, 2015 11:32 am

Well, he did ask for thoughts and opinions. I don't see any harm in comparing and contrasting the benefits and/or drawbacks for each method. I think discourse is healthy, as long as it stays civil and objective.

Anyhow, if I've been less than civil, I apologize. Sometimes I can sound a little more pointed than I intend to be.
sporty wrote:Our we really helping david.
or has it turned into a side debate ?

Most scouts. Build 1 car a year. Spend less than 2 hours on it. It's highly unlikely most of what we share on here or talk about or do. Will ever appeal to the average scout or parent.
all we can do is try and help the ones who want to learn more and do more.

david.

I hope you were able to come up with a answer that was able to help you.

It's not a clear cut issue. In the end you have options. Try them both if you like. And find the one that you feel works best for you and your son.



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Re: Bent Axles vs. Canted Drilled Holes?

Post by ngyoung » Tue Jan 27, 2015 12:47 pm

I wasn't trying to knock Stan's weight biasing method and should have left my opinion out as to not let that take over the focus of what I was saying. :angel:

Like Sporty said, most people asking for help are only doing so to build one car a year. Just playing the odds, which ever method you go about doing will likely result in being very competitive if not the all out winner for the majority of scout pack derbies. For most packs, just getting the axle crimp marks/burs removed and polished is enough to smoke everyone else. If there are district and council derbies to advance to you will start to run into people that have likely put in some research to figure out how to build a fast car. Only then you'd really start to have a higher probability that some of these little intricacies become a factor.

Here on derbytalk I think I am among the minority encouraging to use the straight axle, angled hole approach. Especially if you already own a drill press. If you do not then I am all for going the other route. Sporty was doing an admirable job trying to stay neutral but other then my post, the discussion was pretty one sided though so thought I'd give it a shot to show the merits of the angled drilling. The biggest scout racing event, when it comes to national entries, that I know of is the Mid America. Although there are many factors in play, one of the things that I am willing to bet that is most common out of the open scout graphite and oil division finalists is that their using drilled canted rear holes.



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