Making Plane Irons for wood planes?

[Alan Schwabacher]

The chip breaker is fairly effective at making a thin blade behave almost as well as a thicker one. It essentially allows two thin blades to pretend they are one thick one by pressing down near the edge to hold it steadier, without epoxy. That seems to be the major role of a chip breaker: allowing cheaper blades to behave better. But if you are making your own, they might as well be thick.

[george wilson]

We got the blacksmith's shop to make most of our plane irons. They were,however,in the habit of using 1070 carbon steel for the welded on bits. It was better to weld with than the more premium 1095.The Cooper's shop had a hard row to hoe. They always used white oak for barrels,and had no heat in their shop. They came and asked me if I could help them out with a longer lasting blade for their long cooper's planes. their blades were 4" wide.(we had already made some long cooper's planes for them. Their old planes suffered quite a bit from white oak being shoved over the same spot year after year.)

I made them some A2 steel blades. They held up MUCH better,and we hand forged them. They were undetectable from more authentic bitted blades.

A2 will get a soft skin if gotten hot and exposed to air,so I had to work out a way to forge a tapered blade without ruining the steel. We just heated the top end of the blade and hammered it into a taper. The last 2 1/2" was not gotten to any glowing heat. Then,we wrapped the blades in stainless steel foil with a little piece of brown paper inside to burn off the oxygen in the envelope. Put in too much,and the envelope would burst,ruining the A2. You had to be careful. We put the wrapped up blades into our electric furnace to get the optimum temperature. Steels have optimum hardening temperatures,and you lose some durability if you are more than 25 degrees off.

We'd heat the blades up and remove them. We had a 400 degree oven waiting to draw the temper as soon as the blade got just cool enough that you could pick it up. This is another important step. Let it get fully cool,and the life of the blade suffers. About 130 degrees F is when you should temper the iron.

The blades worked very well. I never signed them,only stamping a 1/16" A-2 on the side of the blades to remind them what steel the blade was made of. I didn't want flack from the blacksmith's shop as the irons weren't made of authentic metal!!

I had also warned them that they'd have to come to the toolmaker's shop to grind them on our blue zirconia belts. Sandstone wheels weren't going to do much to them!!!

I knew these irons weren't made of authentic steel,but those poor guys had to work that tough wood all day in the cold or heat,and I wanted to make their lives a little easier. The irons were hand forged,with round tops. No one could tell they weren't bitted unless they could remove the iron and have a very close look,for they were left black,except down at the cutting edge.

When we started to think about planes,my director told me that he didn't have a problem if we made the blades all 1 piece anyway. That was surprising,since everything else was niggled over for hours!

[Jonathan McCullough]

@ Sam: I got a Buck Brothers Made in China special 2" plane iron to put on a jack plane for horking off big chunks of wood. It most reminds me of a chrome-vanadium iron I have from an old Sargent. It's not bad actually, and for that purpose it's great. But as to whether the steel is suspect, you've got to consider whether that just about any international player can make O-1, and the fact that just about anyone does. As far as I'm concerned, all steel is suspect, and anyone anywhere can flub it. Ooops, did some old 1950's SS brightwork get into that batch? Oh well, we'll still sell it as O-1. Consider also that more and more steel in anything you buy is coming from China.

Although I might disagree if it were my livelihood, $40 seems a lot to pay for any plane iron. I haven't tried epoxy with two plane irons yet, but if I make a little woodie, I'll probably give the diy "lamination" a try.

[Sam Takeuchi]

I actually have more faith in the steel industry than that. After all, that's what they make, and that's why they have so many variety of steels as well as grades of steel. If they are so sloppy as to sell botched batch that are out of order specification, they have much bigger and serious problems than complaints from blade manufacturers. I'm not saying that they are all honest and reliable, but manufacturers and companies that sell quality blades do spend a lot of time and money to find firm that can supply quality of steel that meet their requirement as a part of whole manufacturing process. And it shows in the end product.

As far as stock blade from the past century goes, they weren't that great, even the early to mid 20th century laminated type. Those blades were produced in the cheapest manner acceptable at that time. They work ok on softwood, but couldn't hold edge for reasonable amount of time on hardwood. I wouldn't hold them up as standard of bench mark for anything, though. I say this, because something like material removal with jack plane is actually heavy work. You can ignore dull blade or tear out at this time, but if you have to remove 3/8" (or even 1/4" for that matter), it should be done in the most efficient and least tiring manner. Trying to get that much with a blade that wouldn't hold edge reasonable well is extremely tiring, especially on hardwood.

While $40 for a blade seems expensive, remember, the blade is the heart of a hand plane. Entire plane is actually built around this piece of steel. And $40 seems like a lot, but for that price, you can make several blades by buying quality steel, cut, grind, heat, temper and flatten. Yes, a lot of steel is produced in China, and I'm sure there are a lot of crappy quality steels are available, but if you were serious about quality of steel, you wouldn't pick the cheapest steel of unknown origin, would you? Even if quality and specification is as good as or better than what you seek, but don't want one out of China, you can find suppliers who sell steels made locally, Sheffield, Sweden or elsewhere. Also if you want to go extreme, there are level of quality control within steel production with paperwork for every single step of the way going all the way back to the mine. Though, don't expect that sort of quality control in plane iron production, though. All in all, what I mean is quality steel isn't made with bunch of buckets on the floor (even though I have seen documentary about China's backyard steel production...literally with buckets). Blades sold by manufacturers and companies today, who knows? Maybe they were made in China, but I guarantee you, reputable manufactures and companies do pay attention to quality and grades of steel before they produce and sell.

[george wilson]

Many machinists on another forum have complained about the messed up tool and mild steel they have bought from their suppliers. It's getting to the point where most of the steel is coming from China,I guess. Machinists have ruined expensive milling cutters from running into half melted ball bearings( VERY hard),and various other junk they find in the steel.

Quality control is very sloppy in China. That includes the pieces of soccer balls some of you have found in Chinese plywood,and other stuff,like it delaminating,or not staying flat,having big voids,etc.

[Ron Petley]

I bought a bar of 3/8ths 01 steel, no cap iron, cut it to length with a hack saw. length would be long enough to stick up above your wedge so you can get at it once it is installed in your plane. Width would be a little less than the inside widt of the plane you are going to build. Cut ir square it makes it easier later.
I flat ground one end to 27degrees leaving about 2mm thickness at the point. If the point is to thin it overheats in my home heat treating.
Once heat treated I ground the point to 25 degrees, and flattened the back and sharpened like any other plane blade.
Thats about it heat to non magnetic, hold for 5 min, quench in oil, I have olve oil at 135F I did a interuped quench, quench and remove when it is just hot enough to somke the oil, about 400F.
Heat treat in a oven at 400F in a sand filled container for 2 hours.
Grind and sharpen and you are good to go. Not much metal working mostly quench and heat treating.
Hers is a post with my set up in it.
http://www.sawmillcreek.org/showthre...ghlight=Petley

http://www.sawmillcreek.org/showthread.php?t=96540

Cheers Ron.

[george wilson]

I just plain quench till the blade is cool enough to have passed through the "hardening gate" as it is called. Interrupted quenches may not fully harden any steel. If you have a toaster oven,it should be pre heated to 400 degrees(I put a high temperature thermometer's long shaft into mine ( can't trust the toaster's thermometer).

As soon as your iron is quenched,and you can barely manage to hold it(about 130 degrees),place it at once into the toaster oven after hurriedly wiping off the oil.

This is THE BEST WAY to get the most durability from your blade. If you have no toaster oven,and let the metal fully cool before tempering,you won't kill the quality of the blade,but it is better to do as I have written,to get the absolute most out of it.

[Ron Petley]

I am not sure what the process’ and purposes are for other smith interrupted techniques, but here is what the concept is from a metallurgical point of view and why I would do it.
Austenite is FCC (face centered cubic) which is a most efficient atomic stacking arrangement. All the other transformation products that occur on cooling are BCC (body centered cubic)or body centered in nature like the BCT(body centered tetragonal) of martenensite, which takes much more space for the same amount of atoms. So while we do get simple thermal contraction as metal is cooled it is fairly small compared to the massive expansion you get when you have a BCC transformation. This all seems academic, but some folks may not realize this. I recently read an article that stated that steel contracts when martensite forms, this is so completely opposite of the facts that I was shocked the editors let it get by them, it is quite basic and fundamental that the martensite transformation is one of the most expansive.

So when you cool a blade and one part cools quicker than the other it will reach a body centered (hopefully martensite) transformation sooner. If this happens you could have expansion on one part of the blade while another is still contracting, it is obvious what the dangers of this may be, and since the part that has not yet transformed is still very plastic austenite, there is plenty of room for permanent shape change. If you interrupt the quench just before this transformation and allow the entire blade to equalize in temperature before continuing, it becomes very obvious how advantageous it can be to have the entire blade hardening evenly at the same time.

It is best done as near the transformation temperature as possible without beginning it. In oil I like to pull the blade out at the point where there is just a few wisps of vapor coming off the steel and the oil is able to coat the blade without burning off or flashing. Many oils have a vapor point that approximates 400F. so that can be helpful.
I think it is splitting hairs, whatever works for you is the best and sticking with it for repeatable results is what it is all about.
The basic method is sound and full quench is easier and has less room for error, so good point George.
Also getting the blade into the oven as soon as you can is also a important point I missed, thanks for pointing that out.
Cheers Ron.