block plane mod

[george wilson]

My experimental plane was bevel UP. It just was at so low an angle it wouldn't cut.

[Greg Wease]

Speaking of too low to cut, this is a classic:

http://www.supertool.com/etcetera/deadends/look.htm

[bridger berdel]

My experimental plane was bevel UP. It just was at so low an angle it wouldn't cut.

OK, George, I'll bite. what was that plane? and why wouldn't it cut? I understand about needing clearance behind the edge, and that if you give it too little the wear bevel will quickly wipe it out, but won't a freshly sharpened paring chisel at least slice off a bump with the belly tight against the wood? of course, that is without having a mouth in front of it....

so yeah, too little clearance angle coupled with a very tight mouth is likely to produce an unworkable tool. I don't see how too low a cutting angle (front of blade to wood) can make a plane that won't cut, just one where the edge fails prematurely (which is entirely a function of grind angle, right?). so if I push the grind angle to near minimum (say 20 degrees) and put up with fussy edge retention, accept minimum clearance (Derek's 7 degrees sounds about right) I can achieve a cutting angle of 27 degrees. my current lowest is bedded at 13 and ground at about 18, so it is cutting at 31 degrees. I set it up that way for end grain, and it worked well for that. since grind angle plus clearance angle makes cutting angle, choosing bevel up or down is a trade off between bed fragility and needing to maintain a grind angle within tight failure boundaries (edge failure / bevel rub). besides, with this plane there is no reason I can't flip the blade over at any time.

[Jim Koepke]

The problem is when a plane blade is pushing into a cut the edge of the blade will make it tend to "dive" into the wood. In this case without enough of a relief angle the wood will push it back out.

Maybe someone can say it more eloquently.

jtk

[Jim Koepke]

Speaking of too low to cut, this is a classic:

http://www.supertool.com/etcetera/deadends/look.htm

Sometimes one has to do these things for themselves, but often we can temper our attempts by leaning on the experience of those who have failed before us.

jtk