Any Bicycle guys? Chinese rotor brakes for lathe question.

[woodchucker]

I bought a while back some offshore brake rotors to setup as an emergency brake on the lathe, along with adding a relay to disable power.
I made a new pulley for the motor and was trying to align the bolt hole pattern. I scratched it out and wanted to make sure I had the program setup.
Well, I could not get the bolt hole pattern to align with my scratches. I decided to put the rotor back on and it doesn't align, turn it , still not. turn it again, now it's aligning. Are bicycle hubs not symmetrically drilled?

 

[mattthemuppet2]

not as far as I'm aware, never had that issue mounting or remounting disks on my bikes. Shame I didn't know, i have a couple of old but useable disks you could have had for postage.

 

[woodchucker]

not as far as I'm aware, never had that issue mounting or remounting disks on my bikes. Shame I didn't know, i have a couple of old but useable disks you could have had for postage.

well I needed the brakes too. so I ordered a kit for cheap. Am sure surprised. I was scratching my head becoming very frustrated. I am still raging with Covid, so my patience was getting tried.

 

[erikmannie]

I bought a while back some offshore brake rotors to setup as an emergency brake on the lathe, along with adding a relay to disable power.
I made a new pulley for the motor and was trying to align the bolt hole pattern. I scratched it out and wanted to make sure I had the program setup.
Well, I could not get the bolt hole pattern to align with my scratches. I decided to put the rotor back on and it doesn't align, turn it , still not. turn it again, now it's aligning. Are bicycle hubs not symmetrically drilled?

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I am quite sure that that all hubs are engineered to be symmetrically drilled to within some tolerance which I would estimate to be around +/- .005”.

I do believe that I have those same rotors.

 

[DavidR8]

In all my bicycle building days have never encountered a hub that wasn't symmetrically drilled.

 

[derf]

They are not drilled.....they're are stamped.

 

[woodchucker]

stamped or laser cut.
So I had picked that rotor as being better finished than the other which had many ugly spots on the faces. Well I picked up the other one and found that where the holes align, the area that rests on the boss is out. So it was pushing the rotor off center.
The top is the good one, the bottom is the one I was working with that would not do a bolt hole pattern.

 

[mksj]

They should be a standard ISO Standard 6-bolt Disc Rotors, they are symmetrical, the disc should fit in any indexed rotation of the disc brake with the 6 bolt hole pattern. Also the mounting screws use some form of Loctite that is preapplied to the mounting screws.

ISO Standard 6-bolt Disc Rotors

 

[woodchucker]

thanks, I did it the old fashioned way. Drilled one, screwed it, drilled the next. A pain since I had to keep removing the rotor, but it's done.

 

[Charles scozzari]

I bought a while back some offshore brake rotors to setup as an emergency brake on the lathe, along with adding a relay to disable power.
I made a new pulley for the motor and was trying to align the bolt hole pattern. I scratched it out and wanted to make sure I had the program setup.
Well, I could not get the bolt hole pattern to align with my scratches. I decided to put the rotor back on and it doesn't align, turn it , still not. turn it again, now it's aligning. Are bicycle hubs not symmetrically drilled?

View attachment 437768View attachment 437769View attachment 437770

Nice idea.