Do grooved axles improve speed over regular axles? I know in theory, they are supposed to, but I'd like to hear from those that have tested them both. I will be using oil, so the "graphite reservoir" argument does not come into play here. I am about to place an order and I want some input before I finalize.
Grooved Axles
- Thread starter BlewBYu
- Start date
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Vitamin K
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BlewBYu said:
The fastest racers seem to support their efficiency, at least from what they tell us.
Mathematically, they shouldn't reduce friction, since surface area contact isn't a factor in that equation. However, since they reduce the actual area of contact, there's less space for surface irregularities to factor in.
Might also affect how the oil performs? I'm not sure on that. Would be interesting to know, though.
Okay... I may not have raced in a NPWDRL race yet, but I have tested grooved, and non grooved axles with graphite, and with oil....
Every time, grooved has been faster than non-grooved.... every time
Now, when it comes to gravity racing, any friction on these cars slows them down, whether it is in the surface contact from the wheels on the track to the contact of the axles on the wheel bores. This is why a needle axle will be a nail every time. there is more surface for friction. If you take away part of the nail that the bore will be touching, then you will have less friction... no matter how little that will be, it will still be less.
With oil, you don't use the reservoir, but you do have less bore riding on axle.
Every time, grooved has been faster than non-grooved.... every time
Now, when it comes to gravity racing, any friction on these cars slows them down, whether it is in the surface contact from the wheels on the track to the contact of the axles on the wheel bores. This is why a needle axle will be a nail every time. there is more surface for friction. If you take away part of the nail that the bore will be touching, then you will have less friction... no matter how little that will be, it will still be less.
With oil, you don't use the reservoir, but you do have less bore riding on axle.
Vitamin K said:
WTF are you talking about? Mathematically they shouldnt reduce friction? So, mathematically John is blowing smoke up everyone's butterhole by selling grooved axles and doing it to make money and it's false advertisement when he says they're the fastest axles on the planet? There was a thread post about a week ago with a picture of an axle inside a wheel bore. Without grooves, more of the axle would touch the wheel, which is more friction. The grooved axle in the picture clearly shows less contact with the axle which is less friction.
I personally use grooved axles, and it's not by he said, she said or whatever math equasion says is faster. Flat out grooved are faster. Where's my proof? I've raced in the NPWDRL.
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Vitamin K
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Obsessedderbydad said:
So...I didn't say that they weren't faster. In fact, I said that experience seems to show that they are faster.
I was just noting that surface contact area is NOT a component of friction, so the reasons for the speed increases probably lie elsewhere.
Sort of like how a lot of people mistakenly claim that raising a wheel makes you faster because of less friction. It does make you faster, but it isn't about the friction.
That's all.
I have tried to bend a stainless axle from John without a bend groove. The axle can be bent, but it is "rounded" at the bend point. The bend groove creates a "weak spot" in the axle, allowing it to be bent at a pre-determined spot, keeping the part of the axle in the bore absolutely straight. Without the bend groove and just bending the axle, I have found the car to be less stable. I would not bend an axle without a bend groove...
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Vitamin K
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BlewBYu said:
Couldn't you chuck the axle into a hand drill, put it into your vise and then make the notch with a file?
Are you actually saying that friction is not a component in this type of racing? And raising a wheel does not affect your speeds? Okay... maybe the tread, because it is not "skidding" on the track, is not causing "friction", but a 4th wheel touching the track does cause loss of energy... and the wheel bore of that 4th wheel contacting the axle is a point where there IS actual friction. There is NO getting around that. Every wheel that spins has friction... period.
And since this is a gravity race, once it hits the flat of the track, gravity leaves the equation, and it is all about weight and friction.... with a little aero thrown in there too.
Reducing the friction is done by reducing the contact area between the axles and the bores and the polish that can be attained on the axles and bores...
Good luck getting that 4 wheel car to run as fast as the 3 wheel cars out there.
Jay - Mojo
I have tried both ways, and basically ruined the non notched axles because the bend was rounded.... they are now my NDFW axles... You know... for the wheels that don't make my car any faster.
What I do is chuck up my axle in my drill press, then place my file on a block that is clamped next to my spinning axle... I use that as the rest to cut my groove... because a slipping file on my axle turns that axle into a NDFW axle also.... LOL
Since I started this process, I have had ZERO unplanned NDFW axles..... from this.
Jay - Mojo
Just a shout out to TXCHEMIST - Explain friction as it applies to this thread using words with three syllables or less. And go easy on the three syllable words...
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Vitamin K
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Mojo Racing said:
Guys, really. Reading comprehension. Please.
Obviously, friction matters. Otherwise we wouldn't bother with graphite or oil. Or polishing. But the point I'm trying to make is that some techniques that people view as "friction reduction" actually have nothing to do with friction. This doesn't mean that they don't work...it just means that they work for different reasons.
A car running on three wheels has the same friction as a car running on four. Why is the three wheeler faster? Because it has to invest a smaller amount of energy to get those wheels moving. It's the reason light wheels are better than heavy.
If you read the snippet that ngyoung linked from 5kids' piece on grooved axles, there's nothing about friction, but more about reducing contact irregularities.
I would second the call for txchemist to drop in and lay down some science.
This is good place to start, while waiting for txchemist. http://www.pinewoodderbyphysics.com/lectures.shtml
Reading Comprehension???? REALLY????
This quote about the mathematically the grooved axles shouldn't reduce the friction since the surface are contact isn't a factor in the equation is your statement...
Breaking it down, you are basically saying that the size of one non movable object against a rotating object has no factor for friction between the two. Really? How can that be?
Okay... Take the imperfections that are in all of the wheels and axles out of the equation... you are saying that the wheel with the non-grooved axle will spin for the same length of time as the wheel with the grooved axle if all other conditions are the same?
Here is a little experiment I want you to try... just for fun...
Take a pink rubber eraser... drag it down the length of a full sheet of paper... feel the drag of this eraser... that is friction...
Now cut the eraser in half and drag it down that same length of paper... It is the same principle... you are reducing the area where the potential for friction is...
If you tell me that you can't feel the difference in the two... you let me know... because I want to race against you!
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Vitamin K
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Vitamin K
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Mojo Racing said:
Yeah, man, please, just go read the lecture on the site HMH linked. Or go to the Wikipedia page on friction. Or heck, just ask Google.
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