Crank Balancing DIY

[KiwiGF]

Interesting read as I am looking at balancing my SR crank.  Not having any "knife edges" I am considering mounting the crank between live/rotating centres on my lathe.  Has anyone tried this?  Just concerned about the amount of resistance in the bearings in the centres.  I've tried two centres and the difference in how free they run is considerable.

For knife edges I just used some nails on a portable work bench, a pic of the set up is on the first page of this thread.

I think trying to use a lathe whilst more elegant will not work as well as the nails 

[KeithJ]

Interesting read as I am looking at balancing my SR crank.  Not having any "knife edges" I am considering mounting the crank between live/rotating centres on my lathe.  Has anyone tried this?  Just concerned about the amount of resistance in the bearings in the centres.  I've tried two centres and the difference in how free they run is considerable.

For knife edges I just used some nails on a portable work bench, a pic of the set up is on the first page of this thread.

I think trying to use a lathe whilst more elegant will not work as well as the nails 

Thanks, will try a variation on a nail solution.

[Rocket Racer]

a friend passed me this, thought of relevance

[muskrat]

G'day RR.
That's exactly (only taller) that I use. I made an adjustable one for height and width mainly for balancing wheels. Used the little rollers for sliding doors. As little as 1/2 gram will make it spin.
Which ever method you use they must be level and true both sides.
The lathe method with the crank between two live centers isn't good enough as the clamping force (as little as it needs to be) will create drag.
Cheers

[chaterlea25]

Hi All,
I modified a wheel balancing jig by replacing the crappy bearings with skateboard low friction bearings
I was balancing an Indian Chief crank that was made up from bits and I needed  to balance it
Their method is to hang one complete piston from a rod as the weight required
I tested the method on a BSA V twin crank as well and found it good with the same method
One of the days I will check the crank SRM balanced for the MAP rods and Wisco pistons to see what factor they used ?

John