LN block plane question

[joseph quijas]

Im wondering if theres any advantages to getting the 20 degree bedded block plane vs. the 12 degree?
Ive been looking at the Lie Nielsen website and it seems to me that you could get the same result by putting an 8 degree back bevel on the 20 degree, but that seems like complicating something that doesnt need to be complicated. Im having a hard time seeing why someone would order a 20 degree bedded block plane, but Im definately not all knowing/seeing in this department.
So Im wondering if some of you more experienced in planes than me could enlighten me on the differences between the two, if one might be more versatile than the other etc.
Thanks for the advice and I look forward to reading all of the responses.
Joe

[Brian Kent]

Low angle for end grain and ease in straight grain.
High angle for twisty grain.

You can put a higher bevel on a low angle plane but can't put a lower angle on the blade of a high angle plane.

Hence the low angle block with an extra blade for higher angles if needed = best of all possible worlds.

[joseph quijas]

thanks for your response; I have one more question.
What about putting a back bevel on the 20 degree bed? is this good/bad? just asking because i overheard someone mentioning this at one of the previous shows.
Thanks
Joseph

[Rob Fisher]

thanks for your response; I have one more question.
What about putting a back bevel on the 20 degree bed? is this good/bad? just asking because i overheard someone mentioning this at one of the previous shows.
Thanks
Joseph

On a bevel up plane this will do nothing to effect the cutting angle.

The cutting angle is the bedding angle (20 in this case) plus the angle of the main bevel (typically somewhere around 25 degrees). For a regular block plane the effective cutting angle is around 45 degrees (20 + 25 =45). For a low angle block plane the effective cutting angle is around 37 degrees (12 degree bed angle + 25 degree bevel = 37 degree cutting angle)

Back bevels work on bevel down planes (typical bench planes), but that's another story.

Rob

[James Taglienti]

I was just asking similar questions in a different thread. Everyone told me that a low angle block plane is simply better.

Strange that we go out of our way to get high angle smoothers and use the ruler trick, etc, but when it comes to a block plane the lower the better. :confused:

Personally I prefer a standard angle block plane (20*) with a 30* ground blade for anything but end grain. Resistance really isn't an issue when the cutter is around 1 1/2" wide, and it gives a better finish- I don't have to worry about grain changes as much.

But it looks like i'm in the minority!!

[Sam Takeuchi]

Of course if you only use 25 degree blade in an low angle plane, it'll limit face grain performance. People recommend low angle block plane because you can use higher angle by using micro bevel or spare blade and perform on face grain equally well as standard angle block pane.

If you leave 25 degree blade in a low angle block plane and try to tackle anything other than soft straight grained material, of course it'll perform poorly. Advantage of it is it provides wider cutting option than standard angle block plane. That's all. A standard block plane with 25 degree blade (45 degree cutting angle) and a low angle block plane with 33 degree blade will perform about the same if these are of similar quality. 30 degree blade on standard angle block plane isn't going to work any better than 38 degree blade in an low angle plane. The difference is that 25 degree blade in a low angle block plane cuts and works better than 25 degree blade in a standard angle block plane.

If you have a fleet of block planes setup for different tasks, then this bit of versatility isn't really a concern, but if only one or two block planes are available, this versatility comes very handy. The difference is, low angle planes can be setup to go low cutting angle to do the end grain work easier than a standard angle plane.

It's not any different from smoothers with high angle frog. I don't know how much emphasis people put on smooth planes to be able perform end grain tasks, but when they want high angle frog, I don't think their priority for that particular plane has to do with end grain work. Same thing, if you have a, say, 50 degree blade in an low angle block plane, you know it's not setup for end grain.

[michael osadchuk]

On a bevel up plane this will do nothing to effect the cutting angle.

The cutting angle is the bedding angle (20 in this case) plus the angle of the main bevel (typically somewhere around 25 degrees). For a regular block plane the effective cutting angle is around 45 degrees (20 + 25 =45). For a low angle block plane the effective cutting angle is around 37 degrees (12 degree bed angle + 25 degree bevel = 37 degree cutting angle)

Back bevels work on bevel down planes (typical bench planes), but that's another story.

Rob

Rob

I'm not sure that I completely understand what you mean by back bevel (to the blade, I assume) or cutting angle, but both Clarence Lee in his Sharpening book and Garrett Hack in his Handplane Book in their sections on block planes (with bevel up blades) say you can put a five degree back bevel to the blade to further lower "the effective cutting angle" to cut softwood endgrain with the lowest cutting angle.
I haven't tried this myself.

thanks

michael

[Chris Friesen]

both Clarence Lee in his Sharpening book and Garrett Hack in his Handplane Book in their sections on block planes (with bevel up blades) say you can put a five degree back bevel to the blade to further lower "the effective cutting angle" to cut softwood endgrain with the lowest cutting angle.

The idea here is that you trade off some clearance angle in order to reduce the cutting angle. So instead of a 25 degree bevel you make it 20 degrees and then add a 5 degree back bevel.

The edge durability will be similar since it's a total included angle of 25 degrees, but you've now got 7 degrees of clearance angle and an effective cutting angle of 32 degrees.

[Pedro Reyes]

Back bevels on bevel up planes can close the mouth, not change the cutting angle. I did this on an old 103. Word of caution, there is a minimal cleareance angle needed (maybe 10 deg) for a plane to work properly, or so I've heard. Also for edge retention a minimal (maybe 20) is recomended. So on a 12 deg bed there is little room to play with.

/p

[Rob Fisher]

Rob

I'm not sure that I completely understand what you mean by back bevel (to the blade, I assume) or cutting angle, but both Clarence Lee in his Sharpening book and Garrett Hack in his Handplane Book in their sections on block planes (with bevel up blades) say you can put a five degree back bevel to the blade to further lower "the effective cutting angle" to cut softwood endgrain with the lowest cutting angle.
I haven't tried this myself.

thanks

michael

I haven't read either of those books completely, although I have both and I am about half way through both, but I have not read the sections in reference. That said what Chris said is probably what they are talking about. I am certainly not an expert on this but I do think I have a good grasp of the geometry.

As for what I mean by "back bevel". In my experience a back bevel is when a bevel is placed on the flat or back or the blade (ie not the side that already has a bevel). When you flatten the back of a blade, this is the same side that gets a back bevel.

I hope this makes sense.

Rob

[Rob Fisher]

Rob

I'm not sure that I completely understand what you mean by back bevel (to the blade, I assume) or cutting angle, but both Clarence Lee in his Sharpening book and Garrett Hack in his Handplane Book in their sections on block planes (with bevel up blades) say you can put a five degree back bevel to the blade to further lower "the effective cutting angle" to cut softwood endgrain with the lowest cutting angle.
I haven't tried this myself.

thanks

michael

Micheal,

After reading the aforementioned section in Leonard Lee's sharpening book I think Chris has nailed it on the head.

The five degree back bevel does nothing to change the cutting angle of the plane. It does increase the included angle of the blade which will increase durability. Increasing the included angle allows you to lower the main bevel angle and therefore lower the cutting angle of the plane. The main bevel still dictates the cutting angle of the plane, the back bevel just helps to increase edge durability by increasing the included angle of the blade.

Leonard Lee does a much better job of explaining this, as well he has some nice diagrams.

Rob

[Andrew Pitonyak]

I created a graphic that shows that the back bevel does not affect the pitch angle for a bevel up (block plane) configuration.

http://www.pitonyak.org/wood/images/Pitch_Angle_Bevel_Up.jpg