Flattening a sole

[Rob Matarazzo]

I've been trying to flatten the sole of a Stanley No. 80 cabinet scraper, using silicon carbide wet/dry paper on a granite tile. I've used this procedure several times before on planes and chisels, with no issues. On this project though, I seem to be getting nowhere fast.

I'm starting with 100 grit paper. The sole is just not getting flat. There's a bit of a hollow around the mouth opening and I want to get rid of that. I'm using a forward and back motion, but there are left-to-right scratches in the sole that are just not disappearing, in spite of the significant effort that I've put in so far. I'm not sure what is going on. Is the iron in these tools extra hard?

[Patrick Chase]

I've been trying to flatten the sole of a Stanley No. 80 cabinet scraper, using silicon carbide wet/dry paper on a granite tile. I've used this procedure several times before on planes and chisels, with no issues. On this project though, I seem to be getting nowhere fast.

I'm starting with 100 grit paper. The sole is just not getting flat. There's a bit of a hollow around the mouth opening and I want to get rid of that. I'm using a forward and back motion, but there are left-to-right scratches in the sole that are just not disappearing, in spite of the significant effort that I've put in so far. I'm not sure what is going on. Is the iron in these tools extra hard?

Based on some engineering knowledge and a big of guesswork, I would expect the #80 with its fairly complex casting geometry to be more susceptible to warping than an ordinary bench plane or chisel. That's easy enough to verify with a known-good straightedge and some shim stock, but first a question:

Why does it need to be flat? You don't need sole engagement ahead of the mouth to prevent tearout (a properly honed scraper does that all on its own), so that eliminates the usual justification for focussing on that area. The #80's sole is so short that you can't really rely on it to fatten anything, so that eliminates much of the justification for trying to achieve overall flatness.

It's basically just a scraper holder, after all.

[Rob Matarazzo]

I suppose you're right about the need for flatness. But just the same, why am I having so much trouble removing metal?

[Juan Hovey]

Rob - If your granite tile is like the tile sold at Home Depot and elsewhere, it's quite capable of flexing if you've got it on an uneven surface, making it pretty much impossible to flatten the base of even a small plane. My experience in making hand planes tells me there's no substitute for a surface plate, and the good news is that a small Grade B plate won't set you back a month's wages.

[Robert Hazelwood]

Sometimes it just takes a while. If you have a straightedge and feeler gauges you can get an idea of how extensive the hollows are, and gauge your progress.

My only other recommendation is to keep the sandpaper fresh. A roll of sandpaper is nice to have for this. Good luck.

[Robert Engel]

Explain why would a scraper base need to be that flat?

[Rob Matarazzo]

...

It's basically just a scraper holder, after all.

By the same reasoning, a plane is just a chisel holder. Yet we seem to think that a plane sole needs to be flattened.

[Patrick Chase]

By the same reasoning, a plane is just a chisel holder. Yet we seem to think that a plane sole needs to be flattened.

If you had quoted my entire post instead of just cherry picking a single line, the answers would have been obvious. To recap:

- [Some] planes need the sole ahead of the mouth engaged to prevent tearout. Scrapers don't.

- Planes are used for flattening work and need a reasonably flat sole for that purpose. The #80 is too short for flattening regardless of sole conditions (though scraper planes like the 112 make for a more interesting discussion in that regard).

[Tom Bussey]

Contrary to popular belief, cast iron does not sand like wood. And I know most people will disagree because one can get some scratches on a bottom and think they got it flat. If one takes a bolt in the 1/2 inch range, puts it in a drill chuck and runs it at around chuck 250 RPM and see how long it takes to reduce the diameter be .003. One would need at lease a mike or dial caliper to measure it. I think it will surprise you. And Iron sands slower.

Most hand planes I have had the experience to deal with are high in the middle and low at the ends and have a total indicator run-out of about .015 It is called TIR. 80's on the other hand tend to be low in the middle because the were machine ground and even with coolant the wheel will heat up the metal in the metal in the middle so it ends up low in the middle. The way one gets around that is to redress the wheel and take like a half thousands at a time until it goes flat, usually about .002-.003. Most companies won't take the time for that.

On old bench planes the bottom was milled and then the mill marks were sanded by hand on a big belt sander to remove the mill marks. At the turn of the century, 1880- when ever it was done by hand and that is why it is high in the center and 95% of the time it low diagonal corner to corner. It depends on if the person was right or left handed as well as what day of the week the plane was done. Monday and Fridays were not good days for precision work

[Tom Bussey]

If you are wondering I do it.DSC02422.JPGDSC02425.JPGand it take a couple of hours with a machine designed to do one thing remove metal

[Patrick Chase]

Contrary to popular belief, cast iron does not sand like wood. And I know most people will disagree because one can get some scratches on a bottom and think they got it flat.

If doesn't sand like wood, but you can steadily and reliably remove material (albeit slowly) with the right abrasive. It's not as intractable as, say, UHMW polyethylene. I also think that most people here are smarter than to just look at scratches. I use a known-good straightedge (edge flat to within 0.2 mils/foot) and shim stock to gauge flatness when I work, and I think I'm fairly typical.

Most hand planes I have had the experience to deal with are high in the middle and low at the ends and have a total indicator run-out of about .015 It is called TIR.

You should try an LN or LV some time. TIR consistently < 2 mils. Overkill for woodworking of course, but you have to admire their process control. They obviously must do the final grinding VERY SLOWLY, which no doubt contributes to the cost.

80's on the other hand tend to be low in the middle because the were machine ground and even with coolant the wheel will heat up the metal in the metal in the middle so it ends up low in the middle. The way one gets around that is to redress the wheel and take like a half thousands at a time until it goes flat, usually about .002-.003. Most companies won't take the time for that.

Yeah, that's what I was driving at when I said "I would expect the #80 with its fairly complex casting geometry to be more susceptible to warping than an ordinary bench plane or chisel" in the second post of the thread.

[david charlesworth]

Tom,

Can you confirm a story which I have heard often i e "that old cast iron is much harder than new. Indeed it is said to harden with age" ?

I have just been fettling a 5 1/2 from 1910 to 1918. It seems to be very hard.

Best wishes,
David

[Frederick Skelly]

Contrary to popular belief, cast iron does not sand like wood. And I know most people will disagree because one can get some scratches on a bottom and think they got it flat. If one takes a bolt in the 1/2 inch range, puts it in a drill chuck and runs it at around chuck 250 RPM and see how long it takes to reduce the diameter be .003. One would need at lease a mike or dial caliper to measure it. I think it will surprise you. And Iron sands slower.

Most hand planes I have had the experience to deal with are high in the middle and low at the ends and have a total indicator run-out of about .015 It is called TIR. 80's on the other hand tend to be low in the middle because the were machine ground and even with coolant the wheel will heat up the metal in the metal in the middle so it ends up low in the middle. The way one gets around that is to redress the wheel and take like a half thousands at a time until it goes flat, usually about .002-.003. Most companies won't take the time for that.

On old bench planes the bottom was milled and then the mill marks were sanded by hand on a big belt sander to remove the mill marks. At the turn of the century, 1880- when ever it was done by hand and that is why it is high in the center and 95% of the time it low diagonal corner to corner. It depends on if the person was right or left handed as well as what day of the week the plane was done. Monday and Fridays were not good days for precision work

Thanks for the lesson Tom. BTW, how many planes have you precision-ground for people over the years? One or two HUNDRED? Seems like you've been doing it a long time...
Fred

[Bill White]

Just what I have done in the past:
My "surface plate" is a sink cut out from a local granite fab shop. The price:::::FREE.
Plenty flat for any woodworking, and most machining that I'll ever need.
I mostly go blind and deaf when I see and hear woodworkers fretting over .001". Sharp is sharp, flat is flat (considering that the world is round).
I just don't think that the primo WWers of the ages worried about such trivia.
Blast away all ye who are so inclined.
Bill

[Rob Matarazzo]

If you had quoted my entire post instead of just cherry picking a single line, the answers would have been obvious.
...

A bit caustic no? I quoted the part of your post that I was commenting on. You're right, I should've paid more attention to the rest of it.