plane blade from old file?

[James Scheffler]

So I have this old rasp/file that I'm thinking about turning into plane blades (for single-iron wood body planes). I've read that you can reduce the hardness of an old file down to RC58-60 by putting it in a 428F oven for an hour. After that, you grind off the teeth by grinder or belt sander, cut it, shape the bevel, etc.

This is a pretty impressive piece of steel, being a full 5/16" thick at the haft end and tapering to 7/32" at the tip. It's about 1 5/8" wide, so I'm thinking block plane or scrub plane. It's about 12" long.

If I attempt this, it's clearly going to be a lot of work, but I could get up to three blades out of it. Similar-size new blades cost, say, $40 apiece to buy new. (Although the steel would likely be better in the new blades due to better alloys and more-precise tempering).

Any tips or pitfalls I should know about before attempting this?

Thanks!
Jim S.

[Michael Faurot]

Originally Posted by James Scheffler

I've read that you can reduce the hardness of an old file down to RC58-60 by putting it in a 428F oven for an hour.

If that works to anneal it, I'd like to hear back on your results. I've done it by heating the metal up with torches and then just letting it cool slowly to room temperature.

If I attempt this, it's clearly going to be a lot of work, but I could get up to three blades out of it.
[...]
Any tips or pitfalls I should know about before attempting this?

I've made some of my own blades out of O1 tool steel. The process isn't too difficult. I learned how by watching Tod Herrli's Hollows & Rounds video. I bought the video to learn how to make hollow and round type planes, but have not quite gotten to the point of doing that. However the video also goes into how to make the blades for these planes as well as how to make your own floats using O1 tool steel. So even if you don't want to make hollow and round planes--you may find the video useful for the metal working information.

If you are able to successfully anneal that file into something you can cut and shape, you'll have to harden and temper it again when you're done. For the hardening, I use two torches with one being propane and the other mapp gas. I then quench in used motor oil. To do the tempering, I use an old toaster oven. Basically the same technique as described in Tod Herrli's video.

If you can't get that file to anneal, take a look at getting some O1 from a vendor. It's not all that expensive and will still be less expensive than buying pre-made blades.

[Jim Koepke]

Originally Posted by James Scheffler

So I have this old rasp/file that I'm thinking about turning into plane blades (for single-iron wood body planes). I've read that you can reduce the hardness of an old file down to RC58-60 by putting it in a 428F oven for an hour. After that, you grind off the teeth by grinder or belt sander, cut it, shape the bevel, etc.

This is a pretty impressive piece of steel, being a full 5/16" thick at the haft end and tapering to 7/32" at the tip. It's about 1 5/8" wide, so I'm thinking block plane or scrub plane. It's about 12" long.

If I attempt this, it's clearly going to be a lot of work, but I could get up to three blades out of it. Similar-size new blades cost, say, $40 apiece to buy new. (Although the steel would likely be better in the new blades due to better alloys and more-precise tempering).

Any tips or pitfalls I should know about before attempting this?

Thanks!
Jim S.

Try searching for posts by Jake Darvall. He has not posted for awhile. Not sure if he is on the Australian woodworkers forum still, but he used to cross post between both forums.

Anyway, he made blades out of files and old engine blocks for all I know. His handle on the Australian board is Apricotripper. I figured if he liked apricots he must be an OK fellow.

Not sure if he did any heat treatment or not. I think he mostly used his grinder.

He even got me inspired when he made a skewed blade for a Stanley #55.

Makes me feel like looking at the Australian forum to see if he is still posting there. Yep, just looked, he is still posting at woodworkingforum in Australia.

Any way, some of his blade making is here and is likely not buried under as many new posts.

Here is one post found by doing a quick SMC/Google search of his name:

http://www.sawmillcreek.org/showthread.php?t=41979

jim

[Larry Frank]

Just a quick note on using old files. It is difficult if not imposible to know what type of steel was used for a file. Given the different types of steel, there is no real way of knowing if treating it at such a low temperature will make a difference. The only way of knowing is to try it. Given the amount of work that you are going to put into the steel, it might be better to buy a plane blank or a high carbon blank of know steel grade. That way you can heat treat it to get the properties that you want.

[James Scheffler]

Originally Posted by Larry Frank

Just a quick note on using old files. It is difficult if not imposible to know what type of steel was used for a file. Given the different types of steel, there is no real way of knowing if treating it at such a low temperature will make a difference. The only way of knowing is to try it. Given the amount of work that you are going to put into the steel, it might be better to buy a plane blank or a high carbon blank of know steel grade. That way you can heat treat it to get the properties that you want.

The 428F temperature is probably a compromise based on the range of steels used in the past. I was hoping one of our resident metal experts would weigh in.

I'm leaning toward trying it anyway. But like most of my projects, it needs to get in line. I'm currently working on a smooth plane using a LV A2 blade, so I'll have something to compare a "recycled" blade to. Actually, success or failure with the smooth plane will probably determine whether I go forward with the file project. I'm guessing they will be addictive!

Jim

[James Scheffler]

Originally Posted by Michael Faurot

If that works to anneal it, I'd like to hear back on your results. I've done it by heating the metal up with torches and then just letting it cool slowly to room temperature.

-snip-

If you are able to successfully anneal that file into something you can cut and shape, you'll have to harden and temper it again when you're done.

The way I understand it, the file has already been hardened and then tempered back to RC68-ish. I believe it can be tempered again down to a lower hardness without going back through the hardening step first. Of course, I've never actually done it....

Jim

[Michael Faurot]

Originally Posted by James Scheffler

The way I understand it, the file has already been hardened and then tempered back to RC68-ish. I believe it can be tempered again down to a lower hardness without going back through the hardening step first. Of course, I've never actually done it....

Hardening and quenching are fairly easy. At least that's been my experience with O1. Just heat it up till it's cherry red, then quench it in used motor oil. With a typical plane blade, this takes about 5 minutes or less.

Tempering is what takes time. At least with a toaster oven it does. Waiting for the metal to turn a wheat color seems to take anywhere from 1-2 hours.

[george wilson]

Old files have a very high carbon content. Do not be so certain that new ones would be better. Some cheap files are just case hardened,and soft inside.Some rasps are made that way.

You need to grind the teeth entirely away,and actually go below the remains of the gullets of the teeth you've ground off. The cyanide hardened teeth gullets go below the surface,and can make harder spots in your finished cutting edge,and cause uneven dulling of the edge. Don't worry about the cyanide. You won't kill yourself. It's in the metal.

As much carbon as files have,it would probably not get them too soft even if you heated them to a spring blue color. If the file is left too hard,the cutting edge will chip on a microscopic level,and the blade will appear to get dull because the edge broke off,though you can't see it.

[James Scheffler]

Originally Posted by george wilson

You need to grind the teeth entirely away,and actually go below the remains of the gullets of the teeth you've ground off. The cyanide hardened teeth gullets go below the surface,and can make harder spots in your finished cutting edge,and cause uneven dulling of the edge.

This is really good to know! I would have just ground away the bare minimum to get to a flat surface.

Thanks,
Jim