mY BEST SMOOTHERis my Mujingfang polishing plane which of all my planes is the
lightest. The plane is amazing, better than any of my smoothers -#4 w Hock blade, # 4
1/2 with L-N blade, Shephard Tool Spiers 7, St James Bay Norris-. That I think puts
the weight issue as Jeff G. said to rest.
Remember that the stanley bench planes are cast while the original (Spiers, Norris)
infills are dovetailed. Having built a dovetailed smoother and a cast infill
smoother, I believe that the infill was added not for mass but as a structural
component. Both the front and rear infills support the sides to prevent outward and
inward movement. Think of build a dovetailed drawer with no bottom or back, just
front and sides.
I feel that the infill bailey on the link you provide benefits from the Sorby blades
mass (less chatter, etc) AND the fact that the thicker blade provides for a tighter
regardless of bed type - adjustable frog or infill fixed- the last portion of the
blade in a bevel down plane is unsupported. So a thicker blade, as the infillshave
would, in addition to the thicker chipbreaker, provide a more stable (slightly)
In general the brittish infill smoothers may plane better, but as Jeff G said it may
just be folklore that exaggerates the difference.