I don't but have thought about making one. You would just need to get a small piece of steel barstock (approx 1"wide), then drill a couple holes in it at the same spacing as the holes in the nut. Then put a couple screws through those holes and nuts on the screws to hold them in. You now have a little spanner wrench but you need a hex to drive it or just turn it by hand. You could tack weld on a nut in the middle that would allow you to put a socket on to drive it.
You're supposed to torque that nut to 20Nm.
Then back it off 30 degrees.
Then you tighten the clamp bolt.
This is important to put the proper preload on your bearings. You don't want to just crank it down, then tighten the clamp bolt. I usually just rig something up, snug it down, then back it off a little. I've never torqued it properly because I haven't made a tool yet
