You don’t see the plumbers tape once the axle is in place, so it will still look clean and one piece.
That’s right. It may get loose down the line if you are constantly taking it apart. Then you can use the plumber’s tape.
You really should hardly need to take the yoyo apart anyway.
I would probably feel better with that scenario. I imagine it could also happen because of the wood drying.
Still think the silicone pads could work. the magnets would squeeze the pads against the wood.
Then you have a force working against the magnet.
So it might come apart instead of just slipping…
Possibly. It would open up other problems that would need troubleshooting.
So this idea is difficult because the axle is one piece?
Yes. Also drilling into end grain can be problematic.
What if you made a jig that held a piece of wood with a hole for the axle? Then you could drill all the way through both sides of the axle, and into the first yoyo halve. Insert the axle into the second yoyo half and follow the hole to drill that half.
How about you use plumber’s tape. 
When proposing a solution to the slipping problem, everyone needs to bear in mind that it needs to remain simple, repeatable and able to be produced quickly and accurately. None of the proposed solutions pass those tests.
This wasn’t meant to be a thread where everyone troubleshoots for me. Every proposed solution here I had already considered yesterday.
I’m not sure why some people are turning their noses up at the possibility of having to use plumber’s tape. You use lubricant and solvents in your yoyos and wouldn’t complain about using them, so what is the real problem with using plumber’s tape?
While not viable, most of your solutions posted here would work, though. 
For what it’s worth…
Plumbers tape was a standard tuning item a dozen years ago with some Dif’s and AntiYos (probably others too). We used it to exactly center the axle between the two yoyo halves. Wasn’t a big deal to me or anyone I ever heard of using it. My two cents.
Yeah, but that addressed design flaws that have since been resolved.
Yeah but did you think about making the axle three pieces, so you could easily make the dowel notch? 
Even though I voted I wouldn’t want to bother with the tape, I think I’d buy one. The whole magnet thing is just too cool!
Try not to think of having to use the plumber’s tape a design flaw. I don’t think it is.
Steel bearings need to be cleaned, is that a flaw? No.
Steel bearings need lubricant. Is this a design flaw? No.
These things are maintenance required for proper operation. That’s exactly what the plumbers tape is for my system.
I personally would rather not have to apply plumber’s tape. While yes, all yoyos require some form of maintenance, whether that be cleaning bearing, or changing the pads. The thing is, I don’t like cleaning bearings or taking apart yoyos, I do it only when there’s no other option. While the plumbers tape is synonymous with yoyo maintenance, if it can be avoided, I would personally prefer not to have yet another material that I would need to have/purchase to keep my yoyos spinning.
I admit to not being a wood worker, but I don’t understand how a simple block of wood with a hole in it for the axle, to guide the drill bit, wouldn’t pass the test of allowing you to easily create the dowel key system…
I’ll take your word for it though. No need to explain.
I look forward to seeing how this develops. If you’re happy with the plumbers tape, and are considering it as actually part of the design, then I will too! Changed my vote. 
Plumber’s tape is a fine solution. It’s not a deal breaker for most people I’ll bet.
I don’t think plumbers tape is any more of a design flaw than needing to crank down the caps on a TMBR or being able to adjust the response on a No Jive by adding a sticker. It seems the take apart feature is more for the pain in the neck axle knots that the toothpick, dental pick, whatever aren’t able to remove
i’ve been trying to avoid this thread, but as an engineer i feel i can provide some insight. i’m not trying to hurt feelings, just help
by creating the fine tuning and take apart system, you’ve created a problem that only needs one permanent solution. the magnet is obviously not that, as you still have to use the plumbers tape to lock it in. the plumbers tape can solely serve as that solution, because it will be locking the axle system into place anyway. you can account for the couple gram difference in weight anywhere.
i will not speak to the effectiveness of the overall design, design aspects, use or carrying around of plumbers tape, etc. i think the community is doing a great job of providing constructive feedback.
edit: mass
This is actually where the tape would be superior to any kind of key locking, as the locking wouldn’t allow for as much tuning. Tuning is one of the benefits of a take apart system. This magnet system without a locking device, offers greater tuning than other options I know of, at least for tuning out vibe.
Also the key locking systems, would be be extra difficult to pull off in a way that would allow an easy swapping out of axles, and without introducing vibe.
The more I think about it, the more I’m embracing the idea of the design as it is, and using tape if necessary.
Another cool prospect with this design is the possibility of plastic halves to go with the wood axle!