Nicker profile?

[Jarviser]

I have searched around the forums to try and find the best profile for a three lobed nicker such as on a #78 or L-N #140N. I slipped in a query in another post but it got lost in the thread.
I can find info about length, and Bugbear has provided a great little design for a holder, but what shape should the cutting point be?
a) Just put a bevel on the existing rounded shape? or
b) Flat Chisel shape? or
c) Pointed or V shape, like the nicker on a #50c?

"Planecraft" says they should be filed "straight, like a plane blade" which suggests a chisel edge, so why make them round in the first place?

Any suggestions or URLs would be appreciated.

 

[Derek Cohen (Perth Oz)]

I prefer the nicker to be rounded in profile, and then bevelled flat across the back. I feel that the rounded edge slices into the wood fibres more gently and progressively, rather than tearing them as a sqare edge can when it catches.

As a example, below is a nicker I added to a sliding dovetail plane I made.

Regards from Perth

Derek

 

[bugbear]

but what shape should the cutting point be?
a) Just put a bevel on the existing rounded shape?

Yeah - same as the blade in a cutting gauge.

BugBear