Thread: Question about Infill Plane

Originally Posted by Jerryj

Hi
Please excuse my ignorance. The old Infill Planes do they have bevel down blades ?

Cheers Jerryj

Jerryj,
some do, and others don't...

Those with a low angle blade like the mitre plane are bevel up, and those with a high angle blade are bevel down. It is much the same as other types of planes.
Regards,
Peter

Depends... Traditional Infill Smoothers are bevel down, for some types like chariot and block planes they can be bevel up.

Regards
Ray

PS... Whoops... Cross posted with Peter...

Originally Posted by RayG

Depends... Traditional Infill Smoothers are bevel down, for some types like chariot and block planes they can be bevel up.

Regards
Ray

PS... Whoops... Cross posted with Peter...

Thanks Peter and Ray, I get the picture

Cheers Jerryj.

Jerry, you may by now have figured this out, but for others puzzling about plane blade geometery, it's very easy to work out if a plane blade is going to be bevel up or bevel down from the bedding angle of the blade.

To work properly, the cutting edge needs "relief", or clearance, immediately behind the edge. Because wood is a variably compressible material, the relief angle needs to be at least 10 degrees to cope with a wide variety of types. It's impractical to sharpen a metal blade to less than about 20 degrees (& even that is too acute for many) so the compromise is usually 25 degrees (usually in the form of a secondary bevel). Add 10 degrees for relief, and this sets the minimum bedding angle for a bevel-down blade at 35 degrees. That would be a minimum, and would be ok for some woods, but could cause problems in many others, which is one reason you just don't see planes with bedding angles between 30 & 40 degrees, they are either >40 or <30. Once you go below 30 degrees, the practical solution to the relief problem is to flip the blade over, in which case the bedding angle is now the relief angle, and the bevel angle becomes the 'cutting angle'. A 'standard' block plane has a bed angle of 22.5 degrees, which, with a bevel angle of 25 degres gives you a cutting angle of 47.5 degrees. Almost the same as the 'standard' 45 degrees of the most familiar bevel-down bench planes.

Of course there is a little more to the function of planes than cutting & relief angles, but these do set some important limits to design.

Cheers,