Plane blades: Radius - Camber

[Cliff Rohrabacher]

Any one grind the cutting edge so that it has an arc or radius along the edge (some folks call it "camber") on a BU plane?

If so, how do you like it and what radius do you prefer for what application?

I've never done it. I haven't figured out what exactly it does for the work.

[Frank Drew]

Cliff,

Scrub planes have rounded edges, allowing the tool to hog off more stock with less effort; not totally dissimilar to the principle of a skewed edge.

But for finish work the blade has to be quite straight or very nearly so, IMO, or else the work will have, in effect, the appearance of having shallow flutes; of course, you can bevel or round (camber) the corners of the plane blade. Any rounding of the main cutting edge has to be very subtle.

[Joel Goodman]

Search under Derek Cohen or look at his website "www.inthewoodshop.com" -- he discusses why the camber for Bu planes needs to be greater than for BD planes and how to do it.

[Chris Friesen]

The advantage of camber is that you don't get "plane tracks" from the blade corners when dealing with surfaces wider than the blade. There is also a technique using a cambered blade to joint edges...the idea is that you can position the plane over the edge such that it takes a thicker shaving where the edge is higher. This lets you follow the existing wood surface instead of trying to keep the plane perfectly perpendicular to the face of the wood.

The ideal amount of camber is so that at a typical shaving thickness for that plane the shaving tapers down to nothing at the edges of the blade.

For a jack this would be a noticeable curve, for a smooth plane it's measured in thousandths of an inch.

[Cliff Rohrabacher]

The advantage of camber is that you don't get "plane tracks" from the blade corners when dealing with surfaces wider than the blade. There is also a technique using a cambered blade to joint edges...the idea is that you can position the plane over the edge such that it takes a thicker shaving where the edge is higher. This lets you follow the existing wood surface instead of trying to keep the plane perfectly perpendicular to the face of the wood.

The ideal amount of camber is so that at a typical shaving thickness for that plane the shaving tapers down to nothing at the edges of the blade.

For a jack this would be a noticeable curve, for a smooth plane it's measured in thousandths of an inch.

Well now, that is more information in less space on the subject than I've found anywhere. Thanks.

I was on Derek's site. I read and read and all the while it seemed like he assumed the reader already understood this.

[David Wheeler]

I have found for a BU Smoother the camber you get from the Odate (http://www.japanwoodworker.com/dept.asp?s=JapanWoodworker&mimid=WVCR0FI6814UEX5OEHL81CQO1UFNMKS5&dept_id=13288) crowning plate is perfect for that final shaving with your smoother.

I just hollow grind a 23 to 25 deg bevel; then using the MKII from LV put the camber on the blade with the plate at the honing angle you want (i.e. 40 deg for the camber with the Odate; 41 deg at 1.2k and 8k Shapton stones; then 42 deg. at 15k Shapton stone).

This is very repeatable; when the blade dulls; start over at 40 deg with the Odate; hone away the previous 42 deg micro-bevel; and you are ready to re-hone. Takes all of 5 minutes or less. You can re-sharpen many times before you have to revisit the hollow-grind.

[Johnny Kleso]

Camber and Radius is different in my mind..

Camber is a large radius of about 8"+ on a blade some times much larger like I use on a Jack plane where I just push hard on the corners for several strokes..

Radius is when I put a 1/8"-1/4" radius each corner to stop plane tracks.. I do this on my Jet slow/wet grinder by leting the blade slowly drop off the edge of the wheel...

[Mark Koury]

Cambered Plane Blade

The best source for this that I’ve ever seen - how to sharpen it and how to use it - is David Charlesworth. Go to Lie Nielsen’s site and buy the DVD set Hand Tool Techniques Part 1: Plane Sharpening and Hand Tool Techniques Part 2: Hand Planing by David Charlesworth.

This for me opened up a totally new perspective on using a hand plane. Things learned years ago in high school wood shop that never made sense to me now clearly do seem wrong in view of his approach.

Mark