Lie-Nielsen Butt-Mortise Plane Question

[Craig J Brain]

Hi Everyone!

I've picked up a L-N Butt-Mortise Plane and for the life of me can't find where it suggests the best angle for sharpening the blade.
I can't see it in the instructions or on the web site. Any suggestions?

Thanks,

Craig J. Brain
Australia

[Mike Brady]

Since it does not specify and the work is light duty, I would go with the standard 25 degrees. You can put a small micro bevel on top of that if desired. E-mail Lie-Nielsen if you have doubts.

[Craig J Brain]

Thanks! I'll do that.

Craig J. Brain
Canberra

[Mike Henderson]

If I recall, the butt mortise plane is a bevel down plane and the bed angle is relatively high. The only thing you have to worry about is the clearance angle so you can put a 30 to 35 degree bevel on the iron. I wouldn't recommend a 25 degree bevel because it makes the edge a bit too fragile and doesn't buy you anything. When you use a blade in the bevel up position, such as a paring chisel or a block plane, a low bevel angle is an advantage. But on a plane with the bevel down, the cutting angle is set by the bed angle and the only thing that determines the limit of your bevel angle is the clearance angle.

All of this is the same as any other bevel down plane, such as a Stanley bench plane.

Mike

[And just a comment, I have a butt mortise plane but when I cut hinge mortises, I tend to use a router plane. I just find it easier.]

[Mike Brady]

I agree with your reasoning, Mike, but that goes counter to what the general practice is at Lie-Nielsen for all of their planes, bevel up or down. I can't think of a plane that they make in a bench or block configuration that doesn't ship with a 25 degree bevel. Their instructions for the butt mortise plane do not say how it was sharpened from the factory. Personally I would want the keenness of the lower angle bevel since you are only taking a few strokes with this plane anyway. It is basically a paring cut.

I also agree that a router plane is going to be a better tool for the job of hinge mortising.

[Mike Henderson]

I agree with your reasoning, Mike, but that goes counter to what the general practice is at Lie-Nielsen for all of their planes, bevel up or down. I can't think of a plane that they make in a bench or block configuration that doesn't ship with a 25 degree bevel. Their instructions for the butt mortise plane do not say how it was sharpened from the factory. Personally I would want the keenness of the lower angle bevel since you are only taking a few strokes with this plane anyway. It is basically a paring cut.

I also agree that a router plane is going to be a better tool for the job of hinge mortising.
Let me clarify a bit. You can put a 25 degree primary bevel on the blade but use a microbevel of a steeper angle, maybe 30 to 35 degrees. That will give you a longer lasting edge. You won't get a keener edge by using a 25 degree bevel.

Mike

[I believe LN ships their blades with a 25 degree bevel so that you can put a steeper micro bevel on the blade. If they shipped it to you with a 35 degree bevel angle, you'd have to hone the whole bevel to sharpen the blade. For a bevel up plane, the bevel angle makes a difference and most bevel up planes use a 25 degree bevel angle.]