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[ortwin]

https://www.youtube.com/channel/UCFgfsrioKAqbaTRBkl2gYKg/videos


Just now I found out that James has some newer endurance tops (Mk. 19 to Mk. 21) and videos about them that I did not know yet. He did not announce them in the forum so I make this post with the link to his youtube channel so we have a reference to that great work here.

[Iacopo]

James had a good idea with his new design, making the balance screws internal, instead of external like in my tops.
In this way the aerodynamics and the aesthetics are cleaner. Bravo, James !

[James]

Thank you! Yes I was always a bit concerned about the aero losses from using grub screws - happy with this little innovation haha

FYI I think my next top will use a spiked tip again as in my research I think that although harder to maintain, this will result is a slightly longer spin. Since I can edit a spike tip with diamond files quite easily, I am not planning on using grub screws. Also, hopefully it will use some 90-10 tungsten copper which will be exciting!

[Iacopo]

FYI I think my next top will use a spiked tip again as in my research I think that although harder to maintain, this will result is a slightly longer spin. Since I can edit a spike tip with diamond files quite easily, I am not planning on using grub screws. Also, hopefully it will use some 90-10 tungsten copper which will be exciting!

I can confirm that generally the top spins longer with a spiked tip. Another advantage of the spiked tip is that the top, especially if the tip is recessed, can precess in a more tilted position, which is beautiful to see. Also it can be spun at full speed without hulahooping. As for maintenance, I had wear out problems with ball tips, no less than with spiked tips, given the weight of my tops, but they are problems that can be managed anyway.

Good luck with that alloy, it must be very hard !

[James]

Thats good to hear. Yes, the 90-10 is hard but nothing compared to the cubic boron carbide I've been experimenting with!! This will likely be my next base material - it is harder than tungsten carbide so I'm hoping to avoid drilling holes. It should have the same/slightly lower coefficient of friction with a carbide tip compared to carbide on carbide. Not sure when I'll have the top and base ready to test but I will be sure to share the results

[Iacopo]

I never tried boron carbide.  I tried boron nitride, which was incredibly hard, so I had great expectations from it, but unluckily the piece I had was made of boron nitride in the polycrystalline form, (compressed powder of boron nitride), and it turned out to be abrasive for the tip of the top, with a poor coefficient of friction.  We need these super hard materials in the monocrystalline form, not polycrystalline.
It will be very interesting to see if you found a good material for spinning surfaces !   

[James]

Ah that is interesting and something I may have observed in initial testing. I haven't had the time to take the surface to a proper smooth finish yet so I am hopeful that this may help the problem. I'll let you know