Tutorial: De-nubbing cranks with an angle grinder

Tutorial, Hope it helps.

Cool video, should be useful should someone need it.

Why you need to do this

As a former shop welder in the late 70’s, my theory is that they (the makers) needed that margin of metal to prevent melting as they welded the crank to the axle flange. IMHO, your tutorial is excellent. The uni makers did not do this themselves because of the extra cost (considerable) in labor. Grinding is labor expensive. This mod should save ankles and have no downsides. Great job.:slight_smile:

looks sweet:) good video!

Good work, what cranks are those?

I think there called Qu-ax ankle rapers

Im not sure exactly apart from that there made by Qu-ax

These Qu-ax cranks I think

btw: how much thread you have left for removing the crank?

You dont need to leave any thread to extract it if you use a berring puller or something like that. Thats what I use and it works nicely.

oh I’m gona get a bearing puller now

I have 100% of my extractor threads left.

why do they have nubs anyway?

to help 661 sell ankle protectors.

oh clever, how much of a cut do they get from 661?

“feel the light” or whatever his name is said that it was to make welding easier.

yer the nubs seem a bit overkill though.

anyway, yer all his extractor threads would be left as they dont start till the bolt cap thing in the crank (cant think of correct wording so make do with that) but as for me i like me kh moment cranks, no nubs, no grinding just more time rideing pain free.

are you out rideing your uni yet evan?

Yeah im riding a little bit, playing it safe.

I talked to Egon about it at Fluck and he said that they’re a necessary part of the manufacture process. You can’t weld the cranks without them if you’re using CroMo. Moments don’t have them, because they’re made of aluminium - different welding technique, I guess.

C’mon man, don’t be silly. KH cranks are made from solid stock, so there is no weld at all. Make sense now? Also, welding isn’t the same for all metals, so even if there were a weld, the nubs would be different (larger, I predict, since aluminum disperses heat more easily).

As one (former) welder has already said, the nubs are there because they are a necessary part of welding. I think that’s silly, since it’s really not a big deal to remove them, as Evan showed. In a production setting they would use a milling machine with whats called carbide tooling (i’d use an endmill or facemill) to do the job more precisely and quickly. It would take less than two minutes to do each crank once the machine was setup.

When doing the crank interface welds, if they didn’t have the nub, the heat of the weld concentrated on the edge of the crank would melt it away, leaving you with a crap weld and a messed up crank.

Nice tutorial Evan. I’m glad you even included deburring, which can also be done with a file, mind you.

Yeah bev, i hit mine with a file afterward. After doing that one crank for the video, i put the camera away and did the other side in like a minute in a half, I just did constant circles till the nub was gone.

kh cranks

are they cast or macined? If there is a diffrence :thinking: