Originally Posted by
Rob Lee
Hi David -
You're close. The areas are machined to remove material that could interfere with proper seating of the blade (I'll get to that in a moment). Cast metal does strange things when it cools - any features you put into a casting cool differently from surrounding areas. Management of where material is drawn from when the metal shrinks when cooling, affects stability and porosity of the final casting. In some cases - metal can be in a specific location just to establish a desired center of gravity. And, machining is not always to to establish contact surfaces - it could be for the purpose of ensuring a known clearance...
As for blade bed.... well .... as I've written many times before (and it's often overlooked) we look for a blade/plane contact locus along the mouth of the plane, and a single area at the adjuster. We control the blade/bed contact areas precisely by design. Trying to do it by establishing two planes that contact each other fully is fraught with problems. In addition, loading the blade (or blade/cap iron combo) with the lever cap further ensures that we get the contact geometry we want.
Cheers -
Rob