Why is it taking hours to flatten a plane sole?

[dave hunt]

I need some help. I have a few old planes that I picked up recently and I am having a hard time flattening them. I have tried this in the past only to get so-so results. It seems like the plane are convex (high in the center) and it takes me a few hours and a few blisters to get them flat.
I have been using sand paper on granite tiles and sandpaper glued to my table saw or jointer. I have tried all kinds of different types of sand paper ranging from 60 grit to 180. I have tried it dry and by wet sanding. I have read tons of blogs and posts on how to do it and watched some videos. Any ideas what I might be doing wrong?

The planes that I have completed turned out great and cut nice thin shavings it just takes so long to get there.

Any help would be great.

[Andrew Gibson]

I would say you are doing it right, It just takes a long time to remove the material to make the soles flat. I have found that I usually use 80 grit belt sander belts cut open and glued to my jointer bed.

The other thing you can do is start with a corrugated sole ...
that's what I did and all my bench planes are corrugated... well accept for my dedicated #5 scrub. Thanks Great Grandpa for starting me with a #7c.

[John Coloccia]

Two reasons:

1) you're sanding metal. Metal is really really hard!
2) you're probably wobbling on the high point. Eventually, you establish a flat somewhere, and then whatever angle you happen to be at is the angle you'll ride. You're probably taking a lot more off than you have to. At this point, see #1.

To confirm this, take a marker and mark up the bottom of the plane. You'll probably notice that you're wearing off the marker in the middle and at the ends.

This is the same reason why when you're trying to joint a board that is high in the middle, the tendency is to plane and plane and plane, turning it into a narrower board that's high in the middle.

[george wilson]

It can take a long time to remove just a few thousanths by hand. The more you grind,the bigger your flattened surface gets,and the longer it takes to get that last little bit flat because you must remove an ever larger surface.

I was in the cabinet maker's shop in Wmsbg. years ago,before Jon and I made all those saws. The Garlick saws they were using some of,had the COARSEST ground surfaces on them I've ever seen. Marcus Hansen was trying to polish off the grinding marks. He was using a fairly fine whetstone. I knew he'd NEVER get to the bottom of the myriad of deeper marks,because as he went,he had ever more metal to remove.

[Fred Herrington]

I just finished doing this with two planes for the first time, and even using 60 grit, I definitely spent a significant amount of time before I had the soles flat. I'm going to find a machine shop to lap the things next time.

[Marv Werner]

Dave,

One of the problems that is common, you can easily be sanding more than just the high middle area. Try doing it the other way.....

Put the poor sole in a vise upside down and use a sanding block so you can see exactly where you are sanding. Sand length ways for awhile, then in a circle for awhile, then length ways, then in a circle and keep doing this until the surface is nearly flat. Once it looks flat to you, go back to sanding with sandpaper on your granite. When you do that, try to sand in a figure 8. This prevents uneven sanding. Finish up with only sanding length ways using a light oil or mineral spirits. Mineral spirits does a pretty good job of cleaning your sandpaper. Oil tends to clog it up. The best and fastest cutting sandpaper I've found is a 3M product that is black in color. I buy it at Walmart. You don't need a mirror finish, just flat.

Good luck.
Marv

[Wes Grass]

As John noted, if you're tipping it up at one end, there's a lot more material to remove before you get it flat. As an example, if you had a 12" long plane with a .002" crown to it, you'd have to take .008" off one end to clean it up at the other. You'd be better off deliberately grinding it a bit hollow first.

[James Taglienti]

You could try not flattening the planes. The only planes I have that are dead flat are a smoother, a #7, and a block plane. They all went to the machine shop. I have about a dozen others that i have not even put a straightedge on the sole and they work great.

to think that all of a sudden after so many years we JUST came up with the epiphany that only flat soled planes will work...

[dave hunt]

Wes,
am glad you suggested that. I was thinking about grinding a hollow in the sole and then it should be a lot faster to bring the sides down. Does that sound right?

[Peter Evans]

Convex soles are very hard to flatten because very hard to avoid rocking the plane as you run it back and forth.

As said above, concentrate on the centre section first to get that down to the toe and heel level. No need to flatten the whole sole, just toe - heel - and in front of mouth at same level.

You could grind a very slight concavity on a belt sander, and then flatten on the plate. Remember to use all the sandpaper and take the sides of the plane over the edge on each side and ends; people usually do not wear the sandpaper equally.

Peter in Sydney

[Jim Koepke]

If you do the math for a #5 plane that needs 0.003" removed, you will find that you will need to remove about one tenth of a cubic inch of material.

Especially with a convex sole you will find that your abrasive paper is not wearing evenly and can compound your problem by wearing in the middle, causing the sole to be lapping convex.

Others have mentioned using a machine shop. I wish they would post how much they have had to pay for the service. I can imagine it could cost quite a bit just for the set up.

jtk

[Klaus Kretschmar]

Dave,

recently I got a vintage Stanley #5 (Type 17, war production). There was the problem too, that the sole was not really flat. I´ve an old stroke belt sander which helped to create a flat sole square to the sides in short time. Some pics to get the idea. The following both pics show the plane as I received it. Sides and sole had been laquered in former times, the tote had a crack.





I made a jig for the stroke sander using a flat granite plate and a square MPX fence.







While sanding the planes (I fettled a few more), the plane was pressed against the fence to keep the sqareness. I did only short runs to avoid the heating of the cast iron.



The sanding was done on the machine with 4 grits. The fine lapping I did on the granite plate by hand. That was a piece of cake since the planes came really flat from the machine.



Having that done, the plane was cleaned up and it got new handles out of Bubinga.



The plane works like a charm. Full length and full width shavings with ease.





Of course I know that not every woodworker owns a long belt sander. But perhaps there is the possibility to use one from a friend or so. I just want to give the idea.

Klaus

[David Weaver]

If you do the math for a #5 plane that needs 0.003" removed, you will find that you will need to remove about one tenth of a cubic inch of material.

Especially with a convex sole you will find that your abrasive paper is not wearing evenly and can compound your problem by wearing in the middle, causing the sole to be lapping convex.

Others have mentioned using a machine shop. I wish they would post how much they have had to pay for the service. I can imagine it could cost quite a bit just for the set up.

jtk

I think it's about 40 bucks or a little more plus shipping both ways. For most planes, it's a complete waste of money. For one that you need to have a dead square side and bottom, you can (even then, you don't *need* a square bottom for anything other than a rebate plane if a side of the plane is flat and the iron can adjust laterally).

I don't have a plane in my inventory that can't be set up to take a 1/2 thousandth shaving (with the change of an iron in some cases), and the total cost of my flattening setup is $40 with a roll of 4" psa 80 grit al-ox paper. It's not necessary for very many planes to be that keen in use, but I have the time and the inclination to make them like that.

to the OP:

If this plane is proud in the center, I would not grind it hollow with any power tools. I would get a 2x3 inch block of hardwood and some 60 grit paper, scribe marker lines across the bottom of it, and run it across a reference surface being certain that every time you run it across the reference lap you hold it with pressure in the exact same spot. For proud in the center, I would hold it around the tail behind the tote and get your hand on the frog or under the frog in the center. One or two swipes. No pressure on the front.

That will tell you where you want to work when you turn the plane over and get after the bottom with a block with 60 grit on it. Turn it over and put it in a vise (don't overtighten it) and then work on the sole with the block.

As counter-intuitive as it may seem, you can remove metal a lot faster with a small block of sandpaper than by lapping the whole plane on a flat surface. You just can't replicate the ability to dig with a small surface of coarse paper when you have to spread your weight across the whole sole.

From time to time, you can go back to the reference lap (after each couple of minutes of digging work with your small block) and mark the sole of the plane with a marker again and check progress, moving the hollow forward as you work until you have the plane riding on the toe and heel, then you can just work it on your lapping plate until you have full width contact at the immediate front of the mouth. Don't be cheap with sandpaper - when you're lapping a larger plane, the paper is far more effective when it's new and keen. once it loses that initial bite, it cuts at a small fraction of what it does when it's fresh, and you can make this an hour job or a 5 hour job by being cheap with paper.

All of this work is in reference to a longer plane where it's hard to lap in the first place.

One other side comment from this, if you have a plane where the mouth is proud of the toe (i.e., the sole is convex), you don't really need to lap it. You'll develop the skill to use it as is very quickly unless it is comparable to a banana in shape.

The offenders that *need* lapping are the ones that are concave, twisted, or have a significant amount of wear in front of the mouth (even the last one is debatable).

I just did the soles of two #7s in the last three weeks, something I thought I would never do again. One was a T18 that I got that's a fairly nice plane, but it was proud in the center at least a hundredth. I probably burnt through about $6-8 of sandpaper lapping it, it took about an hour. If I'd have been cheap with the paper, I could've easily made it take 5 or 6 hours and just spent my time making my hands warm holding the casting rubbing it across dull paper.

[dave hunt]

Thanks guys for all the advise. I probably am being too cheap with the sand paper. When I say the plane is convex on the sole, I mean that it is high in the center form heel to toe, all the way down the middle of the plane sole. Do you guys see that often. I ask because it seems like most of the planes I have are this way.

[David Weaver]

Thanks guys for all the advise. I probably am being too cheap with the sand paper. When I say the plane is convex on the sole, I mean that it is high in the center form heel to toe, all the way down the middle of the plane sole. Do you guys see that often. I ask because it seems like most of the planes I have are this way.

Make sure your reference surface is flat. If you're using a TS, they are often hollow from front to back, especially if there is any weight on the middle of the table (like table mounted trunions on a hybrid ts).

Do you have a precision straight edge to check the bottom of the plane?

I have probably lapped 50 planes - they come in all manner of screw-ups. I have only two that are overlapped by someone else, though - most of the time they are untouched. Probably 80% have wear around the mouth, probably 20% have been hollow an appreciable amount like what you're saying, and probably another 20% have been a bit proud at the mouth (opposite of your issue). The rest are out of whack in some random way, like a little bit of twist, etc.

If you're batting 1.000 with all of the noses and toes being proud, it might be worthwhile to call a glass shop and see if they have any 1/2 inch thick float/plate glass cabinet shelves, and use it on a bench or somewhere away from the surface that may be hollow (since glass flexes some). My lap is an 8x42 piece of float glass that cost $20 from a glass shop, they even rounded the corners for me as a courtesy. I use it on a cheap sjoberg's bench that is very flat despite its cheapness. A precision 2-foot steel straight edge really helps to confirm what you're doing when you're working in thousandths.