Drilling Angled Holes in the Original Slots?

[philm63]

My pack's rules say bending the nails is a no-no, but they don't say the original slots must be used but I still have this nagging fear of getting there for check in, and having someone tell me otherwise.

I'd like to build a rail rider for next year's derby (this year's is only a few days away - car's already done and packed away for check in), and I'd like to drill angled holes in the rear slots to give the rear wheels sufficient negative cant to pin the hubs to the nails when rolled forward and backward as advised on this forum. I'd also like to drill the front slots, one for the DFW angled for sufficient positive cant and also angled to provide a little toe-in for steering so sort of a multi-angle thing, and just a deeper slot to raise the non-DFW.

Is this advisable seeing as I would be drilling in the slots? Of course I'd do my best to keep the drilled holes as tight as possible but I have a feeling that because they would be intersecting the existing slots, there would be potential for looseness when all is said and done. If I could get them to remain tight enough to get the car tuned, I'd apply CA to the axles where exposed in the slots to set them, but still, I gotta know, is this even a good idea?

[whodathunkit]

Hi and philm63!

I see no reason why you can't drill your axle holes:
If you're rules state nothing.. about the axle slots must be used.. ( However please do check with your race coordinator.. as I don't know your rules )

I'm not trying to sale you on any of the PWD axle drilling jig tools at all here... Just showing you that there are a few axle drilling jigs tools to help accomplish the task your asking about.
For drilling axle holes into the original slots / or for drilling your own axle holes.

Some of these axle drilling jigs are made with built in steer... so that you don't have to bend any of the axles at all.
( These drilling jigs are very pricey from the different PWD venders who sale them.)

A jig like this axle drilling tool seen in this older topic.. you could get with built in steer so you could run a car with out bent axles.
https://www.derbytalk.com/viewtopic.php?t=8463#p81013
( I don't know if this jig is still available or not.. or even if you can find one!)

Just to show you a different axle drilling jig that I know of right off hand with the built in steer so you don't have to bend axles.. ( very pricey!)
https://www.turboderby.com/product-page ... g-ultimate

This next axle drilling tool type that I can think of .. where you'll see in the video drilling into the axle slots for the rear.. and drilled holes for the front.
( however this tool type.. will not drill for the front axle steer.. like your wanting and so the front axle must be bent !)
https://www.youtube.com/watch?v=f6pMdieQOOI


Hope this help's you philm63,
Best of luck: Whoda.

[FatSebastian]

they don't say the original slots must be used but I still have this nagging fear...

Foremost, I would ask an inspector at the upcoming race whether the slots really must be used, or not. Though angled slot drilling can improve performance, you are already at a disadvantage if you are competing against cars that aren't constrained to using the slots.

I gotta know, is this even a good idea?

We have drilled out slots before, using a jig. The Clear Jig that Whoda references is no longer available as far as I have been able to discern, but I believe Whoda has the right idea in that one should use a drill guide / jig to drill out a slot at an angle. Otherwise, the drill bit is almost certainly going to wander. And it may flex a bit (pun intended) even if an angled drill guide / jig is used. Using the guide, drill out the slot slowly by hand with a pin vise.

there would be potential for looseness when all is said and done

The bigger issue, as you note, is that the axle will be very loose in a drilled-out slot. Because of this, a slightly narrower-than-usual bit can be used (e.g., #44 instead of the usual #43). Although you did not disclose the axle sizes being raced, most angled jigs out there are for #43 bits (BSA axle nails). Turbo Derby has the ability to manufacture a custom jig with a smaller bushing size by special request (that "off-menu" option may cost more) that includes the angled DFW. Even then, the results on open slots can be uneven and loose.

Other suggestions that we have heard about but not tried:

FILLING THEN DRILLING... Fill the slot with some drill-able material such as epoxy resin or wood filler, then drill as normal. That gives more even drilling results, but it may fail inspection depending on what the local rules say / imply. (We tried gluing matchstick wood into the slots once and then drilling; they popped out, so I don't recommend filling slots with those!)

NO DRILLING... Cut the head off of an axle nail and mount it in a drill press. Use the drill press to push the decapitated axle into the slot at an angle, then retract. That leaves a canted opening for the real axle to go, and doesn't remove any wood.

[philm63]

For giggles let's say I wouldn't be able to find one of those Clear Drill Jigs (looked for a bit, no luck...) what angle would I be looking at for the toe-in on the DFW? Might take a crack at making something that will align my drill for this one. I know, depends, but is there a ballpark figure here? 0.5 degrees? 1.0, 1.5...? I'm guessing it should be pretty small, but I do want to pin the car to the rail pretty good.

[FatSebastian]

is there a ballpark figure here?

Greater steer-in angle is needed for more aggressive CoM placement and poorer track conditions. Reading this recent topic might help? I have seen "six" or "seven" degrees thrown around (which may be a combination of toe and camber?), but that still sounds aggressive for kids' racing... back in the day my kids operated closer to about 1.5 or 2 degrees (~4" of drift over 4 rolling feet) racing on wooden tracks of questionable condition.

[Loud2ns]

Here are a couple of cheaper options from Brian for drill jigs with steer.

https://www.turboderby.com/product-page ... -xl-hybrid

https://www.turboderby.com/product-page ... jig-hybrid

As for holding the axles in loose holes/drilled slots, I would caution against ca glue. It has the potential to wick into the wheel......which is a disaster. I have been using Elmer's glue to hold my loose fitting axles for a few years, and it's worked well. It also allows the axle to be broken free if needed for tuning tweaks.

Sent from my SM-G991U using Tapatalk

[exoray]

FILLING THEN DRILLING... Fill the slot with some drill-able material such as epoxy resin or wood filler, then drill as normal. That gives more even drilling results, but it may fail inspection depending on what the local rules say / imply. (We tried gluing matchstick wood into the slots once and then drilling; they popped out, so I don't recommend filling slots with those!)

I have not had any real issues with wood plugs popping out, the secret is to make it loose enough that when you put it in there is actually still some (wood) glue between the plug and slot sides vs it being entirely forced out of the joint, it's a fine balance... Another option is to put the plug in and saturate the entire area including the seam with a thin CA glue... I eyeball rip a bunch of fins into a board on the table saw then find the one that fits the slot best... Of course double check with the rules committee as they might not consider this 'using the slots' if that is a requirement...

Since I use bent axles, I put a 1/16" drill bit in the slot then push the plug in, this leaves a square pilot hole I can easily hand drill out, if you are drilling at an angle I would obviously plug it entirely, and even saturate the end with CA glue to give more uniform hardness so the drill doesn't drift as much...

As for holding the axles in loose holes/drilled slots, I would caution against ca glue. It has the potential to wick into the wheel......which is a disaster. I have been using Elmer's glue to hold my loose fitting axles for a few years, and it's worked well. It also allows the axle to be broken free if needed for tuning tweaks.

I agree, wood glue or generic Elmer's glue to hold the axles in, holds well enough for race day and can be broken loose if need be...

[whodathunkit]

Ran across this video Thought it would be of help about the clear jig.. and all.
https://www.youtube.com/watch?v=5XIdDSiRQy4

[philm63]

Awesome - something I can actually get my grubby paws on! So, between the two "available" jigs, which one represents the best bang for the buck - one is $95 and looks like you clamp it on and it will do the rears, and then you move it to the front and do those holes (I'm assuming the "Straights" are raised...), and the other is $125 and the wheelbase is selectable upon ordering, and the jig is longer lending (possibly?) to a more stable hold on the block. I'm leaning toward the one that has all the angled and straight raised hole guides I need but only costs $95. Opinions? Advantages/disadvantages of each?

[FatSebastian]

Opinions? Advantages/disadvantages of each?

There are six models of Turbo Jig available. The purpose of the longer jigs is mainly to replicate a precise wheelbase; one application of this feature would be to employ a set of pre-fab single-piece fenders needing an exact axle separation. Between the less expensive models - the shorter Turbo Jig ($85) and the Turbo Jig Hybrid ($95), the Hybrid is more versatile and worth the extra $10 IMO (our organization has one).

As mentioned above, you may be able to get one of these custom made with narrower bushings if you query the manufacturer directly; using a smaller bit helps when drilling out open slots, assuming that drilling original slots is the goal (the topic of this thread).

[FatSebastian]

(I'm assuming the "Straights" are raised...)

Instructions can be found here. I think the "ST" may stand for something like "STeer" rather than "Straight", while the "0" implies no angle (so those would really be "Straight"). If using the short Hybrid for affecting steer, the jig may need to be re-positioned three times (rears together @ 3, left front @ 0, right front @ ST).

[whodathunkit]

I think the "ST" may stand for something like "STeer" rather than "Straight",

Thanks for your help here FS.

ST.. is the built in steer in the jig drill bushing iv been trying to point out.. so that the car can steer to the rail with the use of a straight unbent axle.

The clear jig with the 5th drill bushing .. and the Turbo derby jigs , and one more i will not say.
Are just a few of jigs that i know of from venders that offer this drill bushing feature..( for the no bending of axle rule sets.)

As far as the Pinewood pro jig i also shared it will only do 2.5 for the rears.. then Derbyworx Jigs straight drill only!

In the video above the clear jig seen was the 4 bushing jig 3.0 rears 0.0 straight fronts ..
Where the use of a bent front axle was also needed to steer the car.. and showing the problems encountered with the rears toe angles due to a raised or lowered front.

[philm63]

Whoa... "...problems encountered with the rears toe angle due to a raised or lowered front." Never thought about that aspect. Is this effect large enough to require additional measures? Is this a topic for another thread?

Let's see, rears angled at 3 degrees in a vertical plane, car body angled up or down maybe 2 degrees due to modifications for steering, body is 7" long, wheelbase is about 4.5", resulting toe-in is...?

[whodathunkit]

Let's see, rears angled at 3 degrees in a vertical plane, car body angled up or down maybe 2 degrees due to modifications for steering, body is 7" long, wheelbase is about 4.5", resulting toe-in is...?

look at this way:
viewing the vertical plane of the car from a (side view front to back) --0---0-
If the front end of the car is raised higher .. you are lowering the back end .. ( toe out on rear wheels)
now if the front end of the car is lower.. you are raising the back.. ( toe in on the rear wheels)
And its all due to..? the 3 degrees of camber in the back axles and the car not setting level in a vertical plane front to back.

[philm63]

Either way - toe-in or toe-out - even if only to a very small degree, can result in an increase in friction, correct? Are we talking about enough friction to keep us up at night, or is this one of those "eek out every possible advantage, no matter how small" sort of things? If it is simple enough to do, I'm all in on all of those "small things to gain every advantage".

Edited to add: Toe-in or toe-out can also serve to steer the rear of the car to some degree, and if I recall from my many hours of reading on this forum, "steer from the rear" is not a good thing. To confirm if there is any significant toe-in or toe-out resulting from the car not being level when viewed from the side, could I just do a thumbtack test? No front wheels, just a single thumbtack in the center near where the front axles would go sufficient to bring the front of the car to its final height as if the wheels (well, at least the DFW...) were in place. Roll down an inclined plane and observe any horizontal drift. Tune until it rolls straight. Done. Well, maybe. I know perfect alignment is key, but am I chasing the dragon here?