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e-beach said:Dovetail groves, that's what I was thinking about.
Yep, dovetails. That's what I meant with 'negative angled grooves' in my earlier post.
e-beach said:Dovetail groves, that's what I was thinking about.
justin_le said:Even if the machining (not lasering, fwiw) was off and one tooth initially had most of the contact, that contact patch would almost immediately deform until other teeth or splines are making contact and things get distributed. And it does this well before actual shear failure of any tooth.
johnrobholmes said:........ I find it quite refreshing to see tests showing the torque arms doing what the final goal is, and yet there is still heavy discussion on why it won't work :lol: Love you guys!!
e-beach said:johnrobholmes said:........ I find it quite refreshing to see tests showing the torque arms doing what the final goal is, and yet there is still heavy discussion on why it won't work :lol: Love you guys!!
Aaahhhh, but the goal was 200Nm. Justin is not there yet. He's got it close though.
johnrobholmes said:.......The mild steel failed at 280Nm, page one.
It's only at 150 Nm that we noticed the arm not returning to the same zero point.
fechter said:I think Buk is on to something with the modulus though. A harder material that elongates less at the fail point should greatly improve things. I'd go for heat treated 4140 chromoly.
fechter said:Put torque arms on both sides 300nm should be enough for most motors.
I think Buk is on to something with the modulus though. A harder material that elongates less at the fail point should greatly improve things. I'd go for heat treated 4140 chromoly.
Chalo said:In this situation, I'm not sure how important modulus is. It seems to me that it almost wouldn't matter.
johnrobholmes said:If the clamping bolt gives enough preload, the two parts will bed into each other without any slop developing between the parts. This is why I believe Justin has chosen the splined interface to begin with.
justin_le said:What actually happens is that the metal yiels significantly at each corner, as you can see in these earlier tests with flat axles. There is no shearing failure, just significant deformation around the point of high stress.
justin_le said:I have my doubts that the square will be nearly as stiff at resisting initial axle rotation, and my bet it that it will show deflection of a few degrees at much lower torque than the splined version, but that the final failure torques may be similar. However, I could easily be wrong and will let evidence speak for itself one way or another.
Off to the milling maching to go make a square axle prototype!
justin_le said:Off to the milling maching to go make a square axle prototype!
Merlin said:I have also only 2 cents of an idea or it's more a question to the calculation professionals...
What's wrong with the(normal flat axle) clamping dropouts we are using on the "big bikes"?
... I mean we re pushing up to 20kw from a dead stop and if you're searching about sheared off axles you only find that historic crystalyte crap.
A single ta is nt that ideal at all.
Snapping an axle is more easy.
To be honest... Never saw a snapped axle when used 2 TA.
if I had a wish I would prefer an "update" about how the wires comes out of the motor. It's always shitty with the disc brake.
Always needing disc Spacers... Extend the brake bracket... Making it more flexing....
Buk___ said:..........
With the CAD design you've posted, with no taper to take up those manufacturing tolerances, the square split through the diagonal, and the pinch bolt 50mm away from the action; and so much of the corners 'knocked off', you've almost turned the square into an octagon and thrown away all of the squares benefits over flats; reducing the circumferential length resisting torque by almost 40% from almost 53mm to 33.31mm; and created (I think) pre-loaded stress point opposite the cable opening that is destined, almost designed, to fail.......
e-beach said:I was thinking similar thoughts when I was staring at the cads last night. So here is a early morning thought....
Get that bolt as close to the square as possible while still having some materiel to act as a 4th wall. If the cable is exiting at an angle anyway, it should go around the bolt and into the TA slot.