Fair Woodworking

February 12, 2012

How I flatten my stones

I guess this is part #4…

If you want to bury yourself in text, as I wax not so eloquently about the value of stone flattening, there is more than just this post!  Oh yes my dear friends there is more. Much, much more. You can start with “How do you flatten your stones?“. If that wets your appetite, move on to “How do you know your stones are flat? “. If that doesn’t gag you, you will be ready for “Lap a chisel back in 6 minutes“. When you regain conciseness, run for the hills!

Or, you can continue here for desert. Much of this post is from an old forum post I made.

Here you go!

Here is my sharpening station with the 3 Norton stones I use. From left to right my 1000/8000 (I’ll be calling this my “8”), 1000/4000 (AKA “4”), and finally my 1000 grit stone (AKA “1”).

You will notice some lines on all the stones. Those are areas I have recently sharpened. Once I have marked the full stone it is time to flatten it. On a side note I generally only use the “1” for 1000 grit sharpening as the 4 and 8 are more expensive stones, they also are best left flat so that they can flatten the 4000 or 8000 surface when they need it.

Here you can see in the second frame, I have flipped over the 8 and 4 and marked a bunch of lines so we can see the progress.

I start by taking the 8 and rubbing it’s 1000 side against the 1000 side of the 4. I rub up and down just at little overlapping ¼ to ½ of an inch about 10 times. I then move the 8 to the 1 and rub again. Then I return the 8 to its place.

I then take the 4 and rub it against the 8, move it across to the 1, and return it to its place.

This first frame here is the result, I repeated the steps using the 1 to get to the second frame.

I find that when the pencil marks are this faint you are pretty darned flat, but one more round would probably remove them completely.

So what is actually happening here? Its all about the rule that 3 is a crowd. Your stones will generally be either concave (dished) or convex (errr humped???). If you have 3 stones chances are one is one way and the other two are the other way. So let’s pretend you have to concave and one convex.

Rub #1 convex against #2 concave, and then #1 convex against #3 concave. Very little will change here, but then when you rub #2 and #3 against each other the high points (circled) will be removed first, and those two stones will relatively flatten out.

Now #2 and #3 gang up on #1. When you rub #1 against #2 (and then #3) only the center of #1 touches the center of #2 (and #3) removing the bulk of the hump in #1 and returns both #2 and #3 to a much less dramatic concave shape. #2 and #3 flatten each other out again, and go to work on #1 again.

And so on and so on. At some point they will all even out.

I know it’s a little hard to absorb, and it’s just as hard to explain, but it works. It really, really works. It’s also one of the more affordable options. You need stones already, so however you do it, you will have a 1000, 4000, and 8000 (I’m assuming). All you need is 2 additional 1000 stones, or in my case with the combo stones 1 more 1000. You just need 3 individual stones that have a 1000 grit surface (3 is the critical number. Not 2, not 4, not 6). Once the 1000 grit sides are flat, you can then use them to flatten the 4000 and 8000 grit sides of the stones. It was suggested to me a while ago that you could save some money and time by just using the 1000, 4000 and 8000 surfaces with this system. I got to thinking that this could be a great option if it only works. So I tried it…

It seemed fine for the first week. After a month or so, I had a new blade that needed lapping, and was very surprised at how much trouble I was having. Slowly over time, the stones were going out of flat. The 1000 had severely rounded off both the 4000, the 8000 because they couldn’t cut as fast. It took a while to get them all back to flat using my old method, but once done. Lapping the blade was amazingly fast again.

Continue to next segment?

Editors note – I’ve added a video demonstrating the 3 stone system in a new post. There is also some additional description that I think may be helpful.

The video may as well be on this post as well…

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