Re: ShopTalk: NBP-COG

[Corey Bailey]

Dear Shoptalkers,

With regards to your discussions about Spines & NBP:

First of all, with the shaft resting (settled, if you will) in a bent 
position in a bearing type spine finder, NBP is on top, spine is on the 
bottom........Period.

Mark the shaft in this position.

If it is a steel shaft, determine the residual bend in the shaft. Roll it 
on a flat surface, use V-blocks and a dial indicator, but come up with a 
method of noting the residual bend.

Note the correlation of residual bend and the location of the Spine and NBP.

You will find that with the vast majority of steel shafts there is a direct 
correlation between the curvature of the shaft (residual band) and the 
location of the two planes in question. It will nearly always be the same 
correlation. I say nearly because I come up with some exceptions from time 
to time that defy explanation.

Best,

CB