Fast Way to Flatten Plane Irons?

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SteveHGraham
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Fast Way to Flatten Plane Irons?

Post by SteveHGraham »

Prove that machinists are smarter than woodworkers.

I have bought 4 planes (Okay, two were spokeshaves.) in the last month. Every one needed to have the back of the iron flattened, up by the edge. I have used a DMT extra coarse stone for this, and I have also resorted to 100-grit wet sandpaper resting on the stone. It's pretty slow. Yesterday I worked on a single new Stanley iron for two hours.

What's the fastest solution, short of buying a surface grinder?

I see a lot of lapping plates for sale out there, but the danged things are expensive.

Maybe I need to go to 60-grit.
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Frank Ford
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Re: Fast Way to Flatten Plane Irons?

Post by Frank Ford »

Maybe you don't have to stress out on the backside so much. Lotsa folks do a secondary bevel there, fairly eliminating the need to flatten the blade all the way to the cutting edge.


Do an internet search for "double bevel plane sharpening," where you may get some interesting ideas. . .
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Re: Fast Way to Flatten Plane Irons?

Post by Glenn Brooks »

Or, one alternative to a surface grinder is buy a second hand, bench mounted belt sander and put a metal cutting belt on it. They are made in 1", 2" and 4" belt widths. Works great for mild steel.

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SteveHGraham
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Re: Fast Way to Flatten Plane Irons?

Post by SteveHGraham »

Good ideas.

I do have a 2x72 belt grinder, and I have used it on the back of an iron. The annoying thing about belts is that they tend to remove more metal at the outer edges of plane irons even if you hold them as flat as you can.
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SteveHGraham
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Re: Fast Way to Flatten Plane Irons?

Post by SteveHGraham »

I'm wondering if I've screwed up my extra coarse diamond stone. I thought they lasted nearly forever, but I see people saying you can wear them out on plane irons.
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Re: Fast Way to Flatten Plane Irons?

Post by spro »

Steve G's belt sanders could do that. HF diamond hone plates could do that but I disagree with the concept. The blade thickness is already at the minimum thickness for planes without an adjustable throat. The sharp edge is nominally a combination presenting 45* to the work. A plane such as Steve's #4 size smoother, already has a large throat, so when the base is milled, it is slightly larger. I see no reason to grind the top of the blade, to meet some incorrect grind or wear at the end.
Also remember that the cap clamps the blade tightly to the flatness of the frog. You could lap/ grind the blade top flat but it may be sprung or becomes sprung if the frog isn't perfectly flat.
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SteveHGraham
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Re: Fast Way to Flatten Plane Irons?

Post by SteveHGraham »

I'm going to go get some coarser paper and fix the two irons I have in front of me. Then I'll consider the other ideas at leisure.

It's hard to argue with doing it correctly, the hard way. Then if I adopt other ways later, I can say it wasn't because I chickened out!
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Re: Fast Way to Flatten Plane Irons?

Post by spro »

Respectfully I say, you are doing it the hard way. I haven't read Frank's links to "double bevel" but most assuredly it relates to creating a small "chip breaker" into the rounded top edge. It isn't removing the whole surface of the blade.
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Re: Fast Way to Flatten Plane Irons?

Post by spro »

Are you ready for a rant ? Expect not. There were so many terrible metallic planes in the last 30 years.. I only look to see if they have improved. I have no reason to buy one, as I have many from when they really worked. Going back to holding a #4 in a vise that way, would have required an inside support between the bed rail/sides. That is because the metallic planes, for the most part, were built to be light and still work. Consider a tradesman or carpenter's tool chest and how heavy that became as iron fore planes, jointer planes were added.
The iron was fine grade of remarkable shapes, trued all round yet fragile if dropped on concrete.
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SteveHGraham
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Re: Fast Way to Flatten Plane Irons?

Post by SteveHGraham »

My first plane was a disco-era Stanley #4 I found in my dad's garage. It had a big crater in the bottom because someone let it rust. I fixed it up, just to have the experience of fettling a plane. It turned out to be magnificent. It was disturbing, because it destroyed my excuse to buy a nice Type 11 #4. Which I plan to do anyway.

I don't even have to point out that Stanleys from that time period (c. 1980) are regarded as crap. The fettling negated the crap factor.

As for putting the plane in a vise, the HF plane has no frog. It's one solid casting. That provided ample support for the sides when I clamped it. With my limited skills, I would be nervous about clamping a Stanley #4, but then a Stanley should not have to be milled.

I have had some other interesting bad-tool experiences today. Some Youtube guy raved about the new Chinese Irwin Marples chisels. I am having a hard time typing this because my parrot found the backspace key. Anyway, I got one from Amazon, and on a whim, I decided to try to scratch it with a Kershaw pocket knife made with Sandvik steel. I should not have been able to scratch the chisel, but I was. Disappointing. When I tried to scratch the knife with the chisel, the chisel slid on it like a butter knife on glass.

I decided to give the Irwin another chance. I tried to scratch it with an $8 Buck Bros. chisel from Home Depot. This is about as cheap as chisels get. Everyone makes fun of Buck Bros. It scratched the Irwin, and the Irwin could not scratch the Buck Bros.

I printed a return thing for the Irwin, and it goes back tomorrow. I hate bad steel. I'll bet the Harbor Freight plane iron is better.

I have never been able to find fault with Buck Bros. chisels, which is a mystery to me, since they get so much abuse on the Internet. The backs are shaped correctly when you buy them. They come with steel caps so you don't destroy them if you use a metal hammer. They take a great edge, and they hold it. Weird.
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spro
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Re: Fast Way to Flatten Plane Irons?

Post by spro »

We are just having a discussion but I understand dipping into very old concepts. The actions required the concepts work correctly. Many an old, Very old wooden plane still works to cut complex profiles. The blades were twice as thick and were completely supported by the angled bed of the throat. The beds wore and as that happened, the throat became wider. Picture the distance of an acute angle to a fixed point and reduce the base= wider distance. This is extremely important with wood for it is the choke point. It is the difference between gouging and slicing off.
Back to metal smoothers, a fixed frog is usually a bad thing.
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Re: Fast Way to Flatten Plane Irons?

Post by spro »

An adjustable frog allows the blade and its modern chip-breaker section to be positioned closer to the forward area of throat. These all work together. Even then, the lowest part of the blade has lost the firm bedding of the angled part of the base.
This is one other thing we don't see much in metal. Chip breakers are close. Wood plane ing requires a fixed aperture. The heavier wood or Iron defeats the tendency of another wood to split out. It is held within that aperture while cutting it by straight or scew.
Then the blade cap (which is really a chip breaker) is set right, then the cap.
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