Fine or coarse.


#1

So I am getting some spiked acorn nuts for a hayabusa I am getting in the mail and they have two options, coarse threads and fine, witch one should I buy?


#2

I would suggest the coarse thread option. I am not 100% sure how these are used on a hayabusa since I am new to yoyo stuff and I am pretty sure that you know that the coarse thread nut only matches a coarse thread screw.

But from the engineering background here is when to use coarse vs fine

Coarse:
Always use coarse threads by default, unless you have a reason to use fine thread.
Typically cheaper and more commonly availible.
Easier to install.
Less likely to cross thread or have damages threads.
Much easier to hand thread a hole for a coarse thread.

Fine
They are slightly highter clamping load and tensile strength. (About 10 to 15%)
They allow for a finer degree of control if you are using them for adjustments.
They are more resistant to vibrating loose.

Additionally, if you are working with thin material a fine thread will allow you to get more threads engaged. Typically, the minimum thread engagement is 3 full threads. A lot of people also use the diameter of the screw as a guide. So if your screw is .25" in diameter it should have .25" of thread engagement.

Based on all of that stuff, I would say you don’t need the clamping strength or the fine adjustment. The vibration benefit is tiny, and out weighed by the cross-threading risk of fine thread.

Just my opinion.
Josh


#3

To follow up on what jupdyke said, the Hyabusa uses a course thread M4 bolt and nut axle. Since you are using spiked acorn nuts, I would suggest getting those in the same specification as the stock axle and then using a setscrew to thread between them and act as the new axle.


#4

The acorn nuts are the same specifications in width but it does not say anything about the threads per inch. I think i will go for it! Thanks Jupdyke and Mrcnja!