[tilemachos]

hello chaps. just made a custom thru axle for my bike, with professional help out of tennalum (7068 aluminium). first we thought about getting threads with forming taps since on paper they seem stronger than cut threads, but after a thorough discussion and reading , in real application cut threads behave much better than tapping threads. so we cut deep threads for extra strength and i've been using it for about 1,5 weeks now with no problem. since the thru axle doesn't actually support anything and it is just a screw that ties everything together(at the rear at least) i figured why not.
some pictures

 

[tilemachos]

and on the bike

 

[wayold]

Just curious - how did you cut the female hex socket on the end? Everything else looks pretty straightforward on a lathe, but that inside hex looks harder to get right.

 

[fmendes]

Congratulations, this is beautiful. I think skewer levers are things of the past if the rider carries tools (and the rider always should). How did you calculate the max torque?

Note that there is significant shear load applied to the axle if it's working fine. Your material should do ok. Now if your hub axle breaks while you are riding, the thru-axle will also be subjected to flexion.

 

[tilemachos]

deleted

 

[tilemachos]

Congratulations, this is beautiful. I think skewer levers are things of the past if the rider carries tools (and the rider always should). How did you calculate the max torque?

Note that there is significant shear load applied to the axle if it's working fine. Your material should do ok. Now if your hub axle breaks while you are riding, the thru-axle will also be subjected to flexion.

thank you!!!!
tennalum or 7068 is about 30% stronger than 7075 aluminium and about 60% than 6061 , that the old maxle thru axle was made from. While the maxle had an indication of 13.4nm of torgue , and with a lot less thread depths and from a softer material , i don't have an exact number for the torgue, but i guess , much more than the stock maxle.
also, this axle is solid not hollow, which means it can withstand almost double the load of a hollow maxle.
and all that with only 32 gramms more of weight penalty.

 

[tilemachos]

Just curious - how did you cut the female hex socket on the end? Everything else looks pretty straightforward on a lathe, but that inside hex looks harder to get right.

well , that is where the prfessional came in handy. he first drilled a hole to the head and then he put a forming tap with great pressure into the hole which formed the allen hole. for reference, the female hex has a 15mm depth.

 

[tilemachos]

final measurements.
lenght 178mm
head length 10.05mm
total length 18.85cm
head width 19.05mm
pitch thread 1.75mm
thread length 20mm
solid rod with 11.92 width. 12mm couldn't fit, so we made it exactly as much as the maxle was.

 

[plummet]

Awesome! The threads in axles are non critical as they are not wound up to high torque settings. So standard cut threads will be completely fine!

I would suggest you consider cutting a hex on the outside too. 6mm allen head internal hex's wear out over time.

Side note. I'm thinking of 3d printing some titanium axles. Oooooohhhhh.....Custom fruit is awesomer than off the shelf fruit!

 

[tilemachos]

Awesome! The threads in axles are non critical as they are not wound up to high torque settings. So standard cut threads will be completely fine!

I would suggest you consider cutting a hex on the outside too. 6mm allen head internal hex's wear out over time.

Side note. I'm thinking of 3d printing some titanium axles. Oooooohhhhh.....Custom fruit is awesomer than off the shelf fruit!

great idea. I was just thinking of that , but i may end up making a hole and putting a small metal rod to rotate it.
and i really agry to the diy. it is awesome , always , no matter how usefull or not , the thrill of your own component always gives you great fillings.

 

[Lone Rager]

... he first drilled a hole to the head and then he put a forming tap with great pressure into the hole which formed the allen hole. for reference, the female hex has a 15mm depth.

Formed as in swaged or broached?

 

[fmendes]

thank you!!!!
tennalum or 7068 is about 30% stronger than 7075 aluminium and about 60% than 6061 , that the old maxle thru axle was made from. While the maxle had an indication of 13.4nm of torgue , and with a lot less thread depths and from a softer material , i don't have an exact number for the torgue, but i guess , much more than the stock maxle.
also, this axle is solid not hollow, which means it can withstand almost double the load of a hollow maxle.

Strange that my previous comment disappeared...

As long as you satisfy the locking torque (that has to do with elasticity modulus), that should be fine.

 

[plummet]

Indeed.

 

[tilemachos]

Formed as in swaged or broached?

yes, that's it , rotary broaching