Axle drilling success rate?

[Vitamin K]

Without giving away too many trade secrets, LightninBoy, do you have a suggested starting point for wheel prep? Assuming, that is, typical scout-level restrictions on what you can and can't do to wheels.

I have drilled a bunch of blocks now and they all pass my visual inspection (using drill bits, I dont have 5 in drill blanks) and the rolling back and forth test. They even race well at the pack and district level. Yet when my car (not my scouts) was up against stiffer competition it fell behind the PROs within 4-5 in of the starting pin. As my wheels were just as light as the competition I can only assume that my drilling is off my a visually imperceivable amount but its not perfect.

If your axle holes pass the typical visual and roll tests, then I would attribute the slow start to axle and wheel prep.

[LightninBoy]

Without giving away too many trade secrets, LightninBoy, do you have a suggested starting point for wheel prep? Assuming, that is, typical scout-level restrictions on what you can and can't do to wheels.

Check out the [no advertising for this vendor] videos on his website.

[Topspin.D]

I agree the table must be level before drilling... To test the alignment of my drill press table relative to the spindle. I like to use a bent piece of wire. You put two opposing 70 degree bends in a piece of coat hanger. Chuck one end in the spindle and then rotate it by hand around. This will show you where your table is high or low. Adjust the table until you get even gap or contact with the table all the way around.

[LightninBoy]

One thing I'll add to the conversation ...

Initially, my axle holes are spot on almost all the time. Where I've been having trouble lately, actually, is that the alignment goes bad during my build process. Keep in mind that my builds are pretty extreme in how much of the pine block I remove. So I've been looking for ways to delay the drill and/or lock in the alignment after the drill.

Point is, if you are cutting out a radical amount of pine - then make sure you are continually checking the alignment.

[Vitamin K]

One thing I'll add to the conversation ...

Initially, my axle holes are spot on almost all the time. Where I've been having trouble lately, actually, is that the alignment goes bad during my build process. Keep in mind that my builds are pretty extreme in how much of the pine block I remove. So I've been looking for ways to delay the drill and/or lock in the alignment after the drill.

Point is, if you are cutting out a radical amount of pine - then make sure you are continually checking the alignment.

This is actually another thing that's got me going towards bent axles for this year's crop of builds. I like the idea of being able to do my alignment post-build, as opposed to pre. I got kind of stung last year when I discovered my son's car wasn't rolling right, and I effectively was out of options for what I could do to help it (granted, I should have checked it much earlier than I did...fault's all on me!)

[LightninBoy]

One thing I'll add to the conversation ...

Initially, my axle holes are spot on almost all the time. Where I've been having trouble lately, actually, is that the alignment goes bad during my build process. Keep in mind that my builds are pretty extreme in how much of the pine block I remove. So I've been looking for ways to delay the drill and/or lock in the alignment after the drill.

Point is, if you are cutting out a radical amount of pine - then make sure you are continually checking the alignment.

This is actually another thing that's got me going towards bent axles for this year's crop of builds. I like the idea of being able to do my alignment post-build, as opposed to pre. I got kind of stung last year when I discovered my son's car wasn't rolling right, and I effectively was out of options for what I could do to help it (granted, I should have checked it much earlier than I did...fault's all on me!)

I wouldn't let this lead me towards bent axles versus angled axle holes. In my builds, I actually do two things that put a good alignment at risk:

1. I cut out fully open pockets and a lot of them.
2. I drill with a #43 bit, then ream to .091 (with a hand tool), to make the hole large enough to accept after market axles

I suspect I've had good alignments go bad due to both of these practices. And I'm making appropriate adjustments. But I doubt my troubles apply generally unless you are doing one of the two things above.

[Stan Pope]

An error of 0.1 degrees in drilling an axle hole amounts to a deviation of less than 0.0009" at the ends of a 1/2" deep axle hole. That error results in the affected wheel moving (or trying to move) more than 0.2" off its intended path in only 10 feet of travel. That is enough to drive a rear wheel into the rail. Or to (try to) drag the other rear wheel into the rail.

If I were inclined to drill camber and toe, I would still rely on "slightly bent" axles, maybe 1/4 to 1/2 degree bend. The reason is that I can verify that the final product is what I intended when I started drilling. Then, if I detect such small deviation from expectation, I can correct for that small error.

In fact, most of my interest in bent axle alignment arises from helping youngsters get more of what they hoped for when they built their car and then discovered that it dragged on rail. Consequently, I've put in the time and effort to develop and prove a method that works extremely well in that environment.

[LightninBoy]

An error of 0.1 degrees in drilling an axle hole amounts to a deviation of less than 0.0009" at the ends of a 1/2" deep axle hole. That error results in the affected wheel moving (or trying to move) more than 0.2" off its intended path in only 10 feet of travel. That is enough to drive a rear wheel into the rail. Or to (try to) drag the other rear wheel into the rail.

Based on a lot of personal experience, I can assure you that the rear wheel won't drag the rail in that situation. I've had cars with alignments that were visibly off, but they didn't drag the rail. They wiggled, required more steer, and weren't fast enough for the leagues - but they didn't drag the rail. One of those cars was still fast enough to win our very competitive district race.

If I were inclined to drill camber and toe, I would still rely on "slightly bent" axles, maybe 1/4 to 1/2 degree bend. The reason is that I can verify that the final product is what I intended when I started drilling. Then, if I detect such small deviation from expectation, I can correct for that small error.

Just to clarify that I'm only talking about drilling for camber, not toe. And in the above situation, I would only recommend bending the axles slightly only after the drilled holes proved to be off.

[Stan Pope]

Based on a lot of personal experience, I can assure you that the rear wheel won't drag the rail in that situation. I've had cars with alignments that were visibly off, but they didn't drag the rail. They wiggled, required more steer, and weren't fast enough for the leagues - but they didn't drag the rail. One of those cars was still fast enough to win our very competitive district race.

This is a case, then, where my "or tries to" phrase applies!

I don't disagree re delaying the decision to bend the axle ... very slightly ... provided that an excellent test of rear end alignment is used.