Redeeming Slots?

[Vitamin K]

So, I know that for most pineheads (myself included), slots aren't very popular. Usually the first thing we do is flip the block over and drill holes for axles, ignoring those annoying, janky slots. I am fortunate enough to own a precision-made axle drilling jig with hardened bushings for this purpose. It works great.

However, as many of you know, I sort of have this mild obsession with trying to find inexpensive ways to go about building for the Derby. A $100 drill jig is not inexpensive for a family who has just received a block of wood and is all "now what?"

One option is to use bent rear axles, and people like Stan Pope have demonstrated that this is very workable. However, despite techniques to streamline the process, it is arguably a lot more labor intensive than just drilling a set of angled rear holes with a jig.

So now I am wondering...are slots as horrible as we imagine? The biggest challenge in rear wheels is getting the axles parallel and, by design, a slot is perfectly parallel. To that end, it stands to reason that if we were able to insert axles at a repeatable angle into the rear slots, we could get canted rear axles that were always going to be parallel with each other.

My thinking was for some kind of triangular piece (3d printed) that would fit down into the slot, that would then act as a guide to adjust the insertion angle of the axle as it was pushed in. Ideally some kind of sacrificial axle would be used for the initial insertion to form the grooves in the slot that the actual axles would go into.

What do y'all think of this line of thinking? Completely loopy, or maybe workable?

[FatSebastian]

My thinking was for some kind of triangular piece (3d printed) that would fit down into the slot, that would then act as a guide...

Would this tool be placed in center of the slot pointing up, so that the pointed tip rides up on / along it when the axle is inserted?

If so, when you insert the axle from one direction, the nail might push the piece out the other side. It might need to be long enough to reach all the way to the other end, then the block can be placed on its side and it won't push out. The tool can be turned around to go the other direction?

If the metal axle is riding on it, it may need to be made of a material as hard or harder than the axle, such as steel or ceramic. The "sacrificial" axle could be replaced by pointed tool (like an awl or bead threader) and could be supplied with the tool.

What about speed axles or hinge-pin style axles that aren't pointed... would those be compatible with the openings made by this tool?

[Vitamin K]

Would this tool be placed in center of the slot pointing up, so that the pointed tip rides up on / along it when the axle is inserted?

If so, when you insert the axle from one direction, the nail might push the piece out the other side. It might need to be long enough to reach all the way to the other end, then the block can be placed on its side and it won't push out. The tool can be turned around to go the other direction?

So in my mind, the insert is the entire length of the slot. providing a sloped guide on both ends. If it's really cheap (e.g. plastic or 3D printed) perhaps it would be superglued in place before use. I think it would be advantageous for the top edge of the triangle (the side the nail would push against) to be slightly concave rather than flat.

If the metal axle is riding on it, it may need to be made of a material as hard or harder than the axle, such as steel or ceramic. The "sacrificial" axle could be replaced by pointed tool (like an awl or bead threader) and could be supplied with the tool.

I'm not certain it would need to be *that* hard. It just has to be solid enough to "train" the direction of the insertion through the already provided gap. So, that is, harder to push through than the existing slot. I do sort of like the idea of a dedicated "gap-making" tool, though. Of course, the advantage to using a sacrificial axle is that it means that the channel you create is always the right size for the axle you use.

What about speed axles or hinge-pin style axles that aren't pointed... would those be compatible with the openings made by this tool?

Once you've pushed a channel through slots, you've essentially made yourself a "hole", just one that's got a gap in it. I feel like it shouldn't matter once you've made the initial channel.

[whodathunkit]

So, I know that for most pineheads (myself included), slots aren't very popular. Usually the first thing we do is flip the block over and drill holes for axles, ignoring those annoying, janky slots. I am fortunate enough to own a precision-made axle drilling jig with hardened bushings for this purpose. It works great.

However, as many of you know, I sort of have this mild obsession with trying to find inexpensive ways to go about building for the Derby. A $100 drill jig is not inexpensive for a family who has just received a block of wood and is all "now what?"

One option is to use bent rear axles, and people like Stan Pope have demonstrated that this is very workable. However, despite techniques to streamline the process, it is arguably a lot more labor intensive than just drilling a set of angled rear holes with a jig.

VK, I know what your saying these pinewood derby jig tools.. they are not cheep for those starting out! or for us that have been in the hobby for a while.

And i know what your saying about the axle slots and how frustrating they can be from time to time..
Plus the use of axle drilling jig tools just to drill axle holes in car body's.. with no view of the axle.

If the intent of the axle slot rule.. is no drilled axle holes to where axles can not be in view in a slot.
( now if you allow a scout to just drill new holes with no view of the axle in a slot!)
Then it is not fare to every other scout who has encountered a bad slot and had to find a way to use it.. instead of just flipping the block and using a jig drilling holes for the axles.

Concern is this : what is to classify using a jig tool for drilling holes into the already existing axle slots.
If you are using the axle slot, and also drilling a hole do you consider this legal as the axle resides inside the slot even if the drilled hole just makes it easier to get the axle installed.

Like you VK, i wish there was a better way!

[FatSebastian]

So in my mind, the insert is the entire length of the slot...

Thanks for the response - very helpful to my understanding of what is being proposed.

What do y'all think of this line of thinking?

Assuming we have an isosceles triangle that is the length of the slot with sides sloping at about 3 degrees, the peak of the deflector would only be a little over 1 mm high (about half an axle diameter). This means that the guide will reside deep within the axle slot, and would seem to become very thin toward the wheel? Would it be so flimsy on the ends so as to crumple or break when a scraping side force from the nail is applied? If so, a deflector might need to be shorter than the width of the block to not deform under normal use. It might also help if it was anchored into the bottom of the slot without the need for superglue: I am imagining something like a tack with a narrowed head or a staple that penetrates the bottom of the slot, either of which is topped with a mild arch or triangular point that the nail tip rides upon after it is inserted a certain distance. The insert needs to be removable in case it is incorrectly positioned; CA glue in the slots is going to be unforgiving to mistakes. The guide will be hard to reach once installed, so maybe a toothpick-like protrusion or "handle" can be added to the high point, which can be snipped off after the axles are successfully installed.

Now, if a fully-inserted axle is straight, then in theory slots offer near-zero toe and camber is the primary variable in need of control. The Derby Car Axle Placement Guide (Hobby Lobby SKU: 889576), aka Derby Worx Pro-Axle Guide, helps insert axles straight-ish; it is not very expensive and often available locally off-the-shelf. But even with this tool, mild camber is still possible, even by accident. In fact, it is possible to induce or adjust negative camber by applying pressure to the axle from above with a slotted screwdriver; perhaps the question is whether an optimal angle can be had with this approach. However, if a racer is using slots, he already seems disadvantaged so perhaps lack of optimality is tolerable.

To adjust the camber of rear axles, I might also use a 3/4" Forstner bit to mill out a hole flush with the bottom of the slot and slightly pry with a screwdriver (see photo), but again there might be a question of whether the result is optimal. Perhaps this kind of hole could be filled with a thin 3D printed coin-shaped insert that is either tapered on top (like an upside down funnel) or with holes in the edges into which the axle tip would fit at the proper angle. This suggestion still wouldn't be an out-of-the-box solution because it requires drilling a large, flat recess, but it may avoid the need for fastening the guide because this shape shouldn't slide once the nail starts to push against it, and the axles will hold it in place after installation.

The image shows a conventional nail-style axle (pointed, such as BSA), and a hinge-pin style axle (such as comes with the Maximum Velocity kits, or some machined "speed axles"). The hinge-pin style can be "grabby" going in, so that might need to be considered.

[whodathunkit]

FS, I'm liking your idea hear I can see this working for the rears
If there were something to hold the axle tips down.. so that the weight of the car while resting on its wheels.. don't let the axles tip's slip back up in the top of slot even if glued with Elmers
Plus I wounder if one.. had a bad block to where the front axle slot was not cut square if it could be used to help steer to the car the rail with a straight axle.
And to make good use of a bad axle slot block with your method shown.

Seems that I can recall seeing a car that used set screw's or something along those lines to adjust the axles tips down and hold them in place..

( Somewhere back in the day! )

I know were it was now.. it was on the Coach's secret lube web site.. you know the maker of this stuff.
Older topic i found about it dates back to 2010.
https://www.derbytalk.com/viewtopic.php?t=5772


I'm thinking it's were seen the set screw's used and that it was on a Reese's milk chocolate car image on the site.. if memory serves me right.
Let me do some dig around and see if i cant pull up an image of the car .. or of one that looks like set screws are used.
Here it is.. however it's very hard to tell in the image if they are set screws or just holes drilled.

Man this car go's back a few day's .. maybe some here on DT may recall it!

Keep the cool ideas coming FS,

[Vitamin K]

I think NoSkills had a set-screw cambered car?

Edit: Looks like it's Speedster who shared the technique: https://www.derbytalk.com/viewtopic.php ... ews#p65229

If I can sneak some time, I'm going to try to 3D print a proof-of-concept for my "alignment triangle" and see how badly it ends up.

[Vitamin K]

Well, turns out that my 3D printer can't print small enough to properly do these little axle guides I have in mind. Maybe if I can find somebody who has a resin printer...hmm, I should check my lbrary's makerspace...

[exoray]

Maybe if I can find somebody who has a resin printer...hmm, I should check my lbrary's makerspace...

If you are into 3D printing get a resin printer, they are messy and annoying but the results are worth it, IMO...

My son that hates sanding, painting and pretty much every aspect of the pinewood derby except the race, decided to go simple on the wood and then use 3D printed parts to build it up... He even did a paper graphic wrap of the wood so he didn't have to paint