Sharpening Round Bottom Plane

[KeithHowell]

Does anyone have a suitable technique for sharpening a round bottom plane blade?

Keith

[jmrentis]

Hmm, good question!! I know sometimes if you don't correct a stone you could get a curve going in the middle, but I doubt that would be a suitable way to sharpen a rounded edge. I know bainzy might have some good advice for you, plus there are plenty of experienced people here who like handplanes.

The type of planes that use this type of blade I believe are called scrub planes and are used to take off large amounts of wood quickly, rather than smooth anything. Here is a link to some general instructions on honing a radiused blade from Lie-Nielsen Scrub honing. Basically, it says that the radius can be done by hand, so no need for highly specialized equipment or anything. Just take your water stone or whatever and do as you normally would, but rock the blade back and forth from side to side as you go. That is, I believe the safest method they mention. It also says that the radius does not need to be exact or perfect and it will have some uneven spots, mainly because its just for bulk removal.

Anyhow, I would bet that the member Bainzy will have some good advice on how to go about this, since he got rid of all his other tools and replaced them with planes, , jk. He's always got good info on plane stuff.

My question to add on to this topic: Would it be better to have the whole thing evenly radiused or to have the edges heavily radiused leaving the middle with just a slight radius? It seems like it would be more efficient with the edges rounded and the middle only barely radiused, compared to an even radius across the whole blade edge. Thoughts?? J

Edited July 31, 2007 by jmrentis

[ihocky2]

I know that Veritas sells a seperate roller that is convex to use with their honing jig. This allows you to rock to the side and the more pressure and longer you work the blade on your stone the harder the radius. I have the standard honing jig and just skewed the blade in the holder to allow only one side to cut. I used a Ultra Fine sharpy to mark out the lines to line up on so as I moved through the grits I could reposition to the same place or at least close enough. If you have a bench grind with a tool holder, I would find something with the radius you want and trace that onto the flat side and just sharpen with a sweeping curved motion until you meet that line evenly and then go to the hand method for final honing.

Also I know that scrub planes have a heavy radius to the blade to really hog out material. But jack planes usually have a little less of a radius, but still have one so you can remove material quickly, but more neatly. You won't get the 1/8" to 1/4" cuts you can get with a scrub plane, but you'll still get heavier material removal and then hit it with a smoothing plane wit ha flat blade with the edges rounded off so you don't get the edge lines.

JM- I am not positive, but I think and even radius would be better so that you are taking a deep cut in only the center and taking less on the sides, creating less pressure on the blade and making it easier to plane.

[Bainzy]

For cambered plane blades I usually use a similar technique to straight edged blades. I got fed up with honing guides a while ago and found that if you ground the primary bevel fairly accurately, and on a rough stone shape the bevel to exactly how you want it (eg. straight with a honing guide, or cambered), when you resharpen you can just use your hand to guide the blade for a long time until you regrind the bevel.

You could go about it a few ways, such as with a Veritas roller as mentioned above, you could try find something called 'slip stones' which are like waterstones but are concave to allow you to sharpen tools with curved blades, or you could try do it freehand. I prefer to use the freehand method, after flattening the back of the blade I gently sharpen the blade by moving the area of the curve that's sharpened every few strokes from left to right until I'm happy that it's sharp all across the edge. Unless you're using very coarse stones, it'd take you a long time to wear the blade camber into an uneven shape, and if you end up using waterstones that long anyway you're using them wrong, waterstones should usually only require about 30 seconds of use for each grit at the most.