Source for modern hollow and round molding plane irons?

[Steve Voigt]

Kees,

It's not overheating. If anything, it's the opposite. The visual evidence of carbon pooling that you see in Larry's video happens at a lower temp than the loss of magnetism, which is what most people rely on to determine the correct temp. Larry's point, as I understand it, is that by watching for the carbon pooling instead of using a magnet or looking for color (definitely the worst way), you'll avoid overheating.

FWIW, the video makes it look a whole lot easier than it usually is in practice, though that depends on your method of heat treating. It takes some practice to see the carbon pooling when bits of scale are flaking off and ash is swirling around and you're nervous about the 1400° temp in front of your nose. I think most people will find it much easier to use a magnet, at least at first. And the risk of overheating or grain growth with the magnet method is very low.

I agree that decarb is really not an issue for most people. But for anyone who's concerned, Borax works very well as an anti-scale compound. It needs to be sprinkled on at the right temp, after the steel is no longer blue but before it starts to show any red. And it (the Borax) is tougher to remove than more expensive commercial anti-scale compounds. But it definitely works. I wouldn't bother in most situations, but i might use it for something like a float, where you don't want to have to remove a lot of material post HT.

[Patrick Chase]

I agree that decarb is really not an issue for most people. But for anyone who's concerned, Borax works very well as an anti-scale compound. It needs to be sprinkled on at the right temp, after the steel is no longer blue but before it starts to show any red. And it (the Borax) is tougher to remove than more expensive commercial anti-scale compounds. But it definitely works. I wouldn't bother in most situations, but i might use it for something like a float, where you don't want to have to remove a lot of material post HT.

I didn't know about Borax - thanks!

Out of curiosity how much material do you have to remove post-HT if you don't coat? My dim recollection from metallurgy courses (almost 3 decades ago) is something like 10-20 mils. Is that about right?

EDIT: It just occurred to me (I'm pretty slow in the morning) that Williams is actually *relying* on surface decarb to determine temperature.

EDIT 2: Dug out the text and looked - the 20 mil number is for a steel that requires ~1 hr soak at HT temp. O1 requires a much shorter soak, so I imagine decarb depth would be less, and now understand what you're saying. Thanks!

[Steve Voigt]

I didn't know about Borax - thanks!

Out of curiosity how much material do you have to remove post-HT if you don't coat? My dim recollection from metallurgy courses (almost 3 decades ago) is something like 10-20 mils. Is that about right?

EDIT: It just occurred to me (I'm pretty slow in the morning) that Williams is actually *relying* on surface decarb to determine temperature.

EDIT 2: Dug out the text and looked - the 20 mil number is for a steel that requires ~1 hr soak at HT temp. O1 requires a much shorter soak, so I imagine decarb depth would be less, and now understand what you're saying. Thanks!

Well, you figured it out, but just a little more…for standard industrial practice, .010-.020 is a good range. That's about what LV leaves to grind off, IIRC. But that is probably as much for grinding away the distortion from HT as it is for removing decarb. And, although no one is soaking plane irons for an hour, most places typically soak O1, probably 10-15 minutes for a plane iron, which does cause more decarb than an immediate quench.

On the other hand, if you're just a guy making molding plane irons in the driveway, you can get away with much less, probably more like .003. It's not possible to soak without a decent furnace, so that's why you see Larry quenching immediately in the video. An O1 iron done that way will probably not have as much edge retention, but as Kees mentioned it really doesn't matter for a molding plane.

The biggest issue for anyone heat treating at home is going to be technique. It's just like cutting dovetails; it takes some practice to get good, consistent results (but cutting dovetails is much much harder!)

[Jeff Keith]

For anyone interested in a great forum on all things blade related, I recommend Knife Dogs - http://knifedogs.com/forum.php And here's an excellent primer on heat treating - http://knifedogs.com/showthread.php?...ating-Tool-Box

This is another one of those hobby rabbit holes that can quickly suck you in. The forum owner, Tracy Mickley, is a great guy and from my home town.

[Patrick Chase]

Well, you figured it out, but just a little more…for standard industrial practice, .010-.020 is a good range. That's about what LV leaves to grind off, IIRC. But that is probably as much for grinding away the distortion from HT as it is for removing decarb. And, although no one is soaking plane irons for an hour, most places typically soak O1, probably 10-15 minutes for a plane iron, which does cause more decarb than an immediate quench.

On the other hand, if you're just a guy making molding plane irons in the driveway, you can get away with much less, probably more like .003. It's not possible to soak without a decent furnace, so that's why you see Larry quenching immediately in the video. An O1 iron done that way will probably not have as much edge retention, but as Kees mentioned it really doesn't matter for a molding plane.

The biggest issue for anyone heat treating at home is going to be technique. It's just like cutting dovetails; it takes some practice to get good, consistent results (but cutting dovetails is much much harder!)

Thanks for the detailed (and patient) explanation. Much appreciated!

So you're saying that a vacuum furnace is the Leigh jig of heat treating? :-)

[Allan Speers]

Out of curiosity how did he prevent decarburization? (loss of carbon near the surface during heat treatment)

Did he use an anti-scale coat of some sort? If so do you know what it was?

The pros use molten salt baths, vacuum or inert-gas furnaces, etc but clearly if he did it in your backyard he didn't have access to any of that.

Patrick, this is the second time you've posted about decarbonization. I've read about it, but all reports are that it's a very minor problem when working a small piece of 01. There are lots of "how to" guides on HT and annealing, and none that I have read say this is anything to be concerned with, as long as you follow all the correct steps. (Don't overheat, etc.)

If you know otherwise, I'd definitely like to know the details.

[Patrick Chase]

For anyone interested in a great forum on all things blade related, I recommend Knife Dogs - http://knifedogs.com/forum.php And here's an excellent primer on heat treating - http://knifedogs.com/showthread.php?...ating-Tool-Box

This is another one of those hobby rabbit holes that can quickly suck you in. The forum owner, Tracy Mickley, is a great guy and from my home town.

Ron Hock's sharpening book also has a pretty decent short treatment of the basics, though not at the level of detail that I was asking Steve for or that I had to hit the texts to find.

[Patrick Chase]

Patrick, this is the second time you've posted about decarbonization. I've read about it, but all reports are that it's a very minor problem when working a small piece of 01. There are lots of "how to" guides on HT an annealing, and none that I have read say this is anything to be concerned with, as long as you follow all the correct steps. (Don't overheat, etc.)

If you know otherwise, I'd definitely like to know the details.

I think the key word here is "ask", as in I asked because I didn't know.

I knew that decarb and scaling are big enough concerns that professionals in industry (and at larger tool manufacturers like LV and Hock) typically use vacuum/inert-gas furnaces, salt baths, or anti-scale coatings. I asked the question because I wanted to know how people making plane irons in their driveways/yards deal with the issue, though I incorrectly assumed that the answer involved some sort of coating (the "driveway/yard" bit rules out the other "pro" solutions). The answer (per Steve) turns out to be that they compromise a bit on dwell time at critical temp to reduce depth of decarb (thereby leaving some hardness on the table as Steve pointed out), and then grind away the fairly shallow decarb that remains.

EDIT: Steve, the more I think about it the more I recognize that that your answer was both simply/clearly worded and very information-dense. Thanks again!

EDIT 2: Decarb is definitely not something that's caused by or specific to "overheat" or any other process flaw. In order to have hardening you must have carbon mobility, and that mobility enables decarb. IMO the big takeaway from Steve's post is that for stuff like molding plane irons it makes sense to bias the process in one direction (potentially incomplete hardening due to short dwell at critical temp, but shallow decarb) rather than the other (complete hardening by staying at critical temp for longer, but deeper decarb).

[Kees Heiden]

When the temp is higher, everything happens a lot quicker, decarb included. That's why I don't really understand what happens during forging. Long time at very high temperature. Sounds as if you will end up with construction steel. But somehow that doesn't happen. The scaling effect plays a role probably. Scale is iron oxide. It acts a bit like a buffer to the atmosphere. And if iron disapears just as quickly as the carbon, you might end up with tool steel again.

[Patrick Chase]

When the temp is higher, everything happens a lot quicker, decarb included. That's why I don't really understand what happens during forging. Long time at very high temperature. Sounds as if you will end up with construction steel. But somehow that doesn't happen. The scaling effect plays a role probably. Scale is iron oxide. It acts a bit like a buffer to the atmosphere. And if iron disapears just as quickly as the carbon, you might end up with tool steel again.

As Steve confirmed, the depth of significant decarburization is on the order of half a millimeter even for fairly long dwell times. IIRC (and as you suggest) that happens because the decarbed material acts as a passivation layer. For a lot of applications having to remove that much material after forging and presumably annealing but before heat treatment isn't an issue. Removing it *after* HT is a pain though.

[Kees Heiden]

When you look at the Seaton chest chisels, they are incredibly thin down to 2mm at the working end. The cast steel ones are not laminated because they still had trouble welding cast steel back then, so they are solid cast steel. I don't know if they ground half a mm from the face, that would have taken them a very long time, but they did grind and polish them.

BTW, 0.5 mm of scale on an object under forging is pretty normal. So that would explain something. The decarbed layer is mostly lost as scale. The rest is technique, moving quickly and precisely.

[Mike Allen1010]

I haven't seen that edition on the stands yet. Did the article have a source for materials? That used to be standard practice for build it articles with harder to find hardware.

jtk

Hi Jim, the article says you can buy 01 tool steel in short lengths at McMaster Carr and Online metals.

Thanks all for the advice and suggestions – much appreciated! I sincerely appreciate all the expert insight about: decarb, scaling, carbon pooling, MAPP torches, vacuum/inert-gas furnaces, salt baths, or anti-scale coatings.This gives me exactly the same feeling I had in freshman organic chemistry "oh crap, everyone here is waaaaay smarter than me and I have no business getting within 10 feet of this stuff".

That said, I have complete faith in Steve and my fellow Neaanders who suggest I bite the bullet, quit being a sissy and buy the LN plane irons, MAPP torch, fire bricks etc. and get on with the grinding, heat treating etc. Even though this will be my first metallurgy experience and I'm certainly in way over my head, I'm going to give it a shot. What can go wrong? Err.... there in lies the problem, seems like a lot could go wrong! I may not end up with usable plane irons, but at least if I don't burn the house down I can say I gave it a shot.

Thanks for the encouragement to try something new. I will let you know how I make out. Maybe after giving this a try, I won't feel like trying to tune up old, vintage planes is so bad. Wish me luck!

All the best, Mike

[Patrick Chase]

Hi Jim, the article says you can buy 01 tool steel in short lengths at McMaster Carr and Online metals.

Thanks all for the advice and suggestions – much appreciated! I sincerely appreciate all the expert insight about: decarb, scaling, carbon pooling, MAPP torches, vacuum/inert-gas furnaces, salt baths, or anti-scale coatings.This gives me exactly the same feeling I had in freshman organic chemistry "oh crap, everyone here is waaaaay smarter than me and I have no business getting within 10 feet of this stuff".

That said, I have complete faith in Steve and my fellow Neaanders who suggest I bite the bullet, quit being a sissy and buy the LN plane irons, MAPP torch, fire bricks etc. and get on with the grinding, heat treating etc. Even though this will be my first metallurgy experience and I'm certainly in way over my head, I'm going to give it a shot. What can go wrong? Err.... there in lies the problem, seems like a lot could go wrong! I may not end up with usable plane irons, but at least if I don't burn the house down I can say I gave it a shot.

Thanks for the encouragement to try something new. I will let you know how I make out. Maybe after giving this a try, I won't feel like trying to tune up old, vintage planes is so bad. Wish me luck!

All the best, Mike

Believe it or not you can get annealed O1 from Amazon. I ordered this a while back and the stock I received was Starrett p/n 56976 (precision-ground O1), which was a pleasant surprise (that bar usually goes for $40+).

[Mike Allen1010]

[QUOTE=Patrick Chase;2544797]Believe it or not you can get annealed O1 from Amazon. I ordered this a while back and the stock I received was Starrett p/n 56976 (precision-ground O1), which was a pleasant surprise (that bar usually goes for $40+).[/QUOTE]

Thanks Patrick for the information. For some perspective on my level of ignorance I have no idea what this "annealed" is of which you speak (seriously, no idea). I just punched in my order for the LN moulding plane irons - about $100 bucks for 6 irons - to make a pair of #4, 6 and 8 H&R's.I understand I'll have to do some kind of voodoo "heat treating" before the irons are usable.

I just finished making the wooden plane bodies using the closest pieces I could find to quarter sawn in whatever I had on hand [Cherry, Maple and Paduck (sic)]. Given my level of ignorance and anxiety about this project, I am clearly hearing my Dad's voice in my head; "Buy the very best tools you can afford and you'll never be disappointed. Go for the less expensive/lower quality alternative and you'll regret it. The most expensive tool is the one you have to replace because you screwed up the first time around". My Dad was a tough SOB (he flew > 50 missions over Hanoi in a F-105 In the late 1960s and early 70s), but dammit, the older I get, the more I realize he didn't say sh** if he didn't know exactly what he was talking about.

Between the need to "heat treat" the plane irons and making plane bodies that fit them exactly and hold the irons in the tight tolerances needed to build effective molding planes, I'm thinking I should have just written the check to Matt Bickford and gotten on the waiting list.I enjoy woodworking – toolmaking not so much. I kind of think I screwed up here. I'm committed now. We'll see how it goes.

Mike

[Steve Voigt]

Mike, relax, you will be fine. If you haven't looked at this already, it will tell you most of what you need to know:
https://hocktools.wordpress.com/2011...of-tool-steel/