Practical Accuracy Flattening Tools

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24 Aug 2015
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The other thread has gone sideways with discussion about what's possible or practical from people who haven't done or measured anything.

Last year, I got an older plane out that I'd set aside because I dreaded the amount of physical work to fix it. IT was a very heavily worn (not defective, but worn into a twist, I guess by someone jointing edges with it on dirty wood), as well as toe and heel high.

This plane was expensive for me (it's uncommon - a norris no 13 that's 15 1/2 inches long). I didn't feel like addressing it right away but it couldn't be used for any kind of work that was close to smoothing or flattening.

Because this can be hard on fingers, I split the filing over a couple of sessions (if you do 20 minutes of the filing out of the center of a plane, you will remember it). It could've been done in one, but it's nice to make it pleasant and think vs. rushing through all in a row with blisters.

If I ever sell this plane, I may finish filing off another 2 thousandths of sole so that I can show pictures of it. The very tail of the the plane and a tip of the toe is 2 thousandths high. measured with a starrett 380 and a feeler. The rest of the plane doesn't come close to allowing my thinnest feeler - .0012" - no matter how you orient the straight edge - straight up and back from side to side, or on the diagonal or across it.

This is probably the worst plane for flatness that I ever bought, and twist and convexity is the most difficult combination.

There's no way the total time spent was greater than 2 hours, and I figure it's more likely to have been around an hour. I don't remember and would have to track down the post on another forum to remember.

If this were lapped, it probably wouldn't turn out well.

These files are $9, by the way, and the paper is just PSA roll. The only thing expensive is the straight edge (and the plane).

quite often, the smaller bailey-type cast planes take about 20 minutes to lap and they're very close to this. Sometimes it's 5.

If you think you'd like your common plane to work like an expensive plane in fine work, this is the part that's generally missing. Sloppy adjusters, blades not made of "a2" or whatever have nothing to do with it.
Quickest flattening is with 80 grit wet n dry, cheapest paper-backed, A4 size or similar, used wet (with white spirit or similar) on a flat impervious surface. I use my planer table but recycled toughened glass OK if it's on a flat base of something else such as several layers of MFC. Needs to be twice as long as the plane though you can get away with less. A long plane like a 7 you put down 2 sheets of wet n dry end to end. They stick down if wet enough in a pool of fluid. Then keep flooding the surface. Guide the plane with a batten for a straight edge and all the scratches are then length ways. No need to go to finer grit as the scratches soon lose their sharp edges. Thicker paper, dry, or fabric backed don't lie as flat and best avoided.
PS you could call it the quick and dirty method. It is quick and messy - but it does work. I've got a few rusty planes I might work up a demo.
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(what's the simpleton's version of what's going on above? If you lap a plane, you will generally lap a little more of the toe and heel away, so if the plane is already convex, then maybe you shouldn't lap a plane endlessly to get the convexity out.

So, you make a slight modification and take advantage of the fact that lapping "dubs the outside" a little bit by draw filing the center out of the work first, and then lapping until the hollow is gone.

That simple act, which can be done in phases, you don't have to file the entire center out at once and overdo it. Anyway, that simple act makes for a sole that is dead flat and will land into the "no passing light" category on a straight edge, just as a matter of compleletion, not as a matter of fiddling.

The no passing light category against a starrett straight edge is under 1.5 thousandths by quite a bit. Especially if you have a crisp edge on your straight edge and you're still at that.

you can clearly see on the back of this plane at the tip just how big of a gap 2 thousandths is. If such a thing existed going the opposite direction, it would absolutely have to be removed or the plane would take several shavings off of a board at the ends just to be able to cut the middle. 2 thousandths hollow over 13 inches in the center of a plane used on a 30 inch edge or panel becomes some multiple, and that becomes doubled on a matched edge. If you like 2 1/2 sheets of paper between the ends of your panels, especially on two wider boards being glued together, then good luck.

There are fibbers (people who say they can do more than they can and who oversimplify things) there are doers and problem solvers in a middle category, and there are naysayers. It's not hard for the naysayers to prove that they can't do something. I can prove to most people that if they're interested, they can do these types of things and maybe plane 1 will be a little bit more cumbersome, but by plane 2 or 3, you'll be working at visual tolerance as a matter of minimizing labor. It's physically involved to do some of this - not like sprinting, but in finger and hand pressure. You'll learn how to do what's necessary and that's it very quickly.
I found my recollection of the LN 62 -which was out to my feeler exactly 1.5 thousandths - hollow. It was obnoxious to use at that for fine work (again, planes the ends off of anything it meets before planing the middle).

The first is the picture of the sole (you need three hands to take this picture if you don't have a portable light in your shop. I had difficulty getting this one as the straight edge would fall over. I have marked the edges of my SE a little bit over the last 15 years in the shop, but never dropped it or dinged it hard - notlooking to drop it and the LN 62).

This plane is brand new - I bought it to do experiments with unicorn shopping (not a fan of the type). I knew I would sell it once I was done and while I could've sent this back to LN, that's not a nice thing to do when you can fix it. They could be turds and say that it's right at spec, but LN is LN and they would address it. I've had about 10 LN planes. Two have been hollow like this and the rest have been dead flat. And they did meet their spec, right at it.
Even though the picture is bad, look at the center until you can make out the mouth and you can see that even with the bad angle, the light coming through is considerable. First look will be that there's barely light coming through but about 1/3rd of the way through the length on the left side, you can see the mouth and if you look closely, you can get a better idea that it's slightly out of focus but the gap is very clear around the edges of the mouth.

I noted the process and showed pictures then, and timed this.
12 minutes. 12 minutes to remove 1 1/2 thousandths of hollowness and have something that probably isn't out anywhere on the sole a third of that. There's no passing light, even at the tips.

As many planes as I've addressed with processes like these, none of what I've learned or figured out has been a matter of "muscle memory" or "someone would have to do 15 before their first good one", it was figuring out how to address each issue without turning to machinists to make the problem overly complicated and maybe still come out with a bias in the wrong direction. The methods are easy, it's a matter of figuring out what they are.

If it cost $2 in PSA paper wear to do this, I'd be very surprised.

I sold this plane on ebay last week. Someone in france bought it for 15% more than the new retail price that LN sells here. The first jointer plane that I got from LN was hollow (it was actually just beyond spec). I didn't check it and find out that it was hollow, I had a hell of a time trying to match plane long boards with it and then bought a LN 7 that worked perfectly and then checked the 8 later. Hollow. A practical problem, not a theoretical problem. That was more than ten years ago, and I didn't have the confidence to fix the plane and had the tact to not send it back to LN and hassle them with it. I sold it to a willing buyer.

I was happy to be able to fix it this time instead.

12 minutes. If it had been two thousandths convex instead of 1.5 concave, I wouldn't have ever touched it.