So am am creating a low Q-Factor BB for my Quad build.[ This is the non lathe version ]
For 2 reasons :-
a) it will allow the chassis to be narrower at the front which for a given front track should allow a tighter turning circle ?
b) in turn a) allows for narrower body work at the front
This combined with short cranks as low as possible should help to reduce the shear size of the quad , especially compared to the current pedal car
First thing you need to do is start with a one piece cartridge BB with the narrowest axle you can find , as the extra length is outside the 2 bearings mine was 110mm the easiest to buy although some places list a 107mm one. No one I found had it in stock [ cheap ]
Taking it apart we get this :-
Top row we have the 2 cartridge retainers and the 2 bearings now removed , the lone item is 10mm cut from between the inner bearing stops [ you could try for more [ if brave ]] next we have the 2 drive stubs and below a fairly thick wall piece of tube to join the axle back together.
I had two relatively straight steel crank arms [ helps dissipate the heat ], a substantial clamp at the BB axle end and some M12 threaded rod at the bottom.
So the fight now it to get both axle stubs in the tube with the gaps looking even all the way around both [ in this version don't expect it to be easy ! ]
So it is now down to around 100mm +- it was very hard to weld there was a very bright yellow ball sat over the weld pool stopping you seeing it properly and one/both of the metals to be welded were providing a firework display of molten steel balls most intimidating.
Oddly I was able to weld around both ends and put a weld in a M6 hole I cut into the tubing without needing to sharpen or clean the Tungsten ?
The pedal car measures 4" between the outer crank pedal face and the centre of the chassis.
This one measures 2.5" between the outer crank pedal face and the centre of the chassis.
Next up we need a modified BB shell to mount this in .......
The left threaded end has a large flange so could weld to the shell easily so the shell was cut at that end , I afterwards found out the threads did not need grinding off as it fit without. This has made it less positively located at that end , will it work ?
So I have done my best to get the cut end square and using a socket and the tool for screwing these ends in and out we are clamped up for welding.
However we do not look well as holding one bearing there appears to be a visible wobble on tother one ?
All we can do is press on ....
DannyC will be along shortly to show you how to make the lathe boy version with undreamt accuracy I am sure.
Paul
For 2 reasons :-
a) it will allow the chassis to be narrower at the front which for a given front track should allow a tighter turning circle ?
b) in turn a) allows for narrower body work at the front
This combined with short cranks as low as possible should help to reduce the shear size of the quad , especially compared to the current pedal car
First thing you need to do is start with a one piece cartridge BB with the narrowest axle you can find , as the extra length is outside the 2 bearings mine was 110mm the easiest to buy although some places list a 107mm one. No one I found had it in stock [ cheap
]Taking it apart we get this :-
Top row we have the 2 cartridge retainers and the 2 bearings now removed , the lone item is 10mm cut from between the inner bearing stops [ you could try for more [ if brave ]] next we have the 2 drive stubs and below a fairly thick wall piece of tube to join the axle back together.
I had two relatively straight steel crank arms [ helps dissipate the heat ], a substantial clamp at the BB axle end and some M12 threaded rod at the bottom.
So the fight now it to get both axle stubs in the tube with the gaps looking even all the way around both [ in this version don't expect it to be easy ! ]
So it is now down to around 100mm +- it was very hard to weld there was a very bright yellow ball sat over the weld pool stopping you seeing it properly and one/both of the metals to be welded were providing a firework display of molten steel balls most intimidating.
Oddly I was able to weld around both ends and put a weld in a M6 hole I cut into the tubing without needing to sharpen or clean the Tungsten ?
The pedal car measures 4" between the outer crank pedal face and the centre of the chassis.
This one measures 2.5" between the outer crank pedal face and the centre of the chassis.
Next up we need a modified BB shell to mount this in .......
The left threaded end has a large flange so could weld to the shell easily so the shell was cut at that end , I afterwards found out the threads did not need grinding off as it fit without. This has made it less positively located at that end , will it work ?
So I have done my best to get the cut end square and using a socket and the tool for screwing these ends in and out we are clamped up for welding.
However we do not look well as holding one bearing there appears to be a visible wobble on tother one ?
All we can do is press on ....
DannyC will be along shortly to show you how to make the lathe boy version with undreamt accuracy I am sure.
Paul
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