Infills have some popular features
First, they look cool.
Second, they feel great in your hand, though some may prefer the closed handle, others may feel the open handle has more space for large hands.
Third, they have a nice weight - heavy enough so they get some inertia going, but not so heavy that they are tiring to use, at least the smoothers.
Fourth, in terms of performance, they work really well. I don't have bedrocks, so I can't compare, but from what I have read, a well tuned Lee Valley, Lie Nielson, Stanley Bedrock, or Clifton with a sharp blade will perform as well as an infill with a sharp blade, but that as the blade edge looses its sharpness, the infill's performance will stay quite high while the others will start to decline quicker. There are a number of conflicting theories to justify the performance:
- Typically, an infill is equipped with a parallel ( or gauged ) iron that is many times thicker than a Stanley, and the cap iron likewise is much thicker than the stock Stanley leading to less chatter. Stanley blades that I have tend to run about .069 , some aftermarket irons are as thick as .090 inches, though they may not fit a Stanley plane without some modification. I just checked one Stanley chipbreaker and it was .062 inches. The standard parallel iron on a Norris is about .156 thick ( 5/32 ) postwar, .179 prewar, and the cap iron is just as thick making the overall combination around .312 or more which makes it much more rigid.
- Others suggest that the combination of wood and steel in the plane resists vibration much better than a plane made out of either one, allowing it to take chatter free cuts.
- The bedding angle for a Stanley is normally 45 degrees. While the Norris angle may not be as consistent from plane to plane as a steel body, using a Wixey digital angle box placed against the blade, I measured a Stanley at 44.2 degrees, and my Norris planes at 46.6 to 46.8. A higher angle will generally give a better finish on difficult woods.
Don't forget, they look cool.