Plane Blade Edge - How much Radius?

[Bob Jones]

I am about to sharpen the blade for my new LN #7 plane. I was wondering if I should grind a small, tight radius to smooth the corners? That is what Hack apperars to do in his book.

On the blade to my #4 smoother I used the advice here and put a very gradual radius on the sides by just putting pressure on the cormers while honing the final edge. This makes it easier for me to get a smooth surface than the tight corner radius I was using.

I just don't want to screw up this great new blade!
Thanks!

[Ron Brese]

I would do it the same way as the iron for the #4. You may be cutting glue joints with the number 7 so you don't want the radius pronounced. Typically just a little pressure toward the corners while honing will do. A Lie-Nielsen 7, Man I been wanting one of those for years now!

Ron

[Mike Henderson]

Normally, you would not put a radius on a #7 plane iron. The #7 is generally used for jointing where you want a flat, straight cut. Most commonly, you would not even cut with the outside ends of the blade

The edge of a #4 is radiused slightly because it's generally used as a smoother and you want to avoid the ridges left by the end of the blade when smoothing.

Mike

[Ruston Hughes]

I concur with Mike and don't camber the blade on my #7 since I use it for jointing edges. When I do use it on the board face it's always followed by a smoother or scraper so any lines that may be left by the blade edge are removed in the smoothing process.

[Mark Singer]

Keep it square....

[Bob Jones]

Thanks for the advice, this will be my jointer - not smoother - so i will try square for now.
I bought the LN because I got sick of watching old planes on ebay sell for way to much for it to be worth the risk of buying old equipment - based only on pictures. I did buy an old #4 & #5 for good prices - but the 7's and 8's are not good values in my eyes.

[Alice Frampton]

It might be worth pointing out that just because a jointer is only going to be used for jointing it doesn't necessarily mean the blade edge should be straight. It rather depends on which jointing method you prefer.

Cheers, Alf

[Pam Niedermayer]

And to reinforce what Alf said, take a look at this page by Jeff Gorman: http://www.amgron.clara.net/planingpoints/edgeplaning/squareedgeindex.htm

Pam

[Andrew Homan]

It might be worth pointing out that just because a jointer is only going to be used for jointing it doesn't necessarily mean the blade edge should be straight. It rather depends on which jointing method you prefer.


And just to confirm what both Alf and Pam noted, David Charlesworth also advocates a cambered edge for jointing edges -- check out his books and his planing DVDs.

The basic idea is to center the protruding part of the blade on the high spots. With a pencil, mark the high spots, then follow this path with the "low" part of the blade.

-Andy