Thread: Chipping Norris Blade

that's not just a crack issue of tempering, it is a crack in the blade most likely.

What does it feel like when you're honing it? Does it seem hard? if it seems really hard compared to a very plain blade, I would temper it in an oven at 375F twice and see if it improves. that'd be about 190C.

if there is a question about the temperature stability of the oven, I would preheat a pan of sand or something similar, measure the temperature of it after two hours in the oven and then adjust from there. You don't want to overtemper.

Originally Posted by D.W.

that's not just a crack issue of tempering, it is a crack in the blade most likely.

What does it feel like when you're honing it? Does it seem hard? if it seems really hard compared to a very plain blade, I would temper it in an oven at 375F twice and see if it improves. that'd be about 190C.

if there is a question about the temperature stability of the oven, I would preheat a pan of sand or something similar, measure the temperature of it after two hours in the oven and then adjust from there. You don't want to overtemper.

Thanks David,

Slow to grind.. No defects visible.

Temper for 1 or 2 Hours each run ?
Cool in oven ?

Cheers M

1 hour should be fine for each temper. Really a single temper should do the job as long as the iron gets to 375F and stays there even for half an hour. the tempering schedules usually refer to a tempering time of "one hour per inch of thickness" or something like that.

there shouldn't be much in the iron at this point that would require a double temper - I wasn't thinking hard enough - usually in an iron that was quenched fairly recently, there's a little bit of retained austenite converted to martensite (which is what you want a tool to be made of) in the first temper, and the second tempers it. Even in that case, the plain steels like that iron will be made from probably also don't have a real need for a second tempering.

The typical range of good tempering behavior in a very plain steel (which that will be) is about 375-425. at 350 or a little below, an iron can still have poor behavior due to lack of toughness even though it will seem like "it gets really sharp".

Is there any way you can get a picture of the break out area close up with a phone and enlarge it? it should look like white with no texture at all. I doubt they enlarged the grain on any of those old irons, but losing track of one in tempering could've occurred. So, too, could've rehardening and then losing track of tempering.

Surely that blade wasn't like that when it left the factory, which begs the question of what happened to it in the meantime to cause it to be so brittle? The blade in my (late model) A5 was on the soft side, if anything - it didn't mind pine & soft cabinet woods, but lost its shine pretty quickly on anything like spotted gum. I wonder if someone found the blade too soft for their liking, hardened it, & didn't temper it sufficiently (or at all)? In any case, I don't think a mild oven tempering can do any harm, my understanding is that you are not likely to over-soften at the temperatures you're talking about unless you forget it & leave it cooking overnight (don't laugh - I could easily do that! ), so nothing to lose by giving it a go.

You can't use it like it is, so I hope for your sake you can get it workable - I'd hate to think what a replacement blade would cost you, supposing you could find one, especially if it's the 2 1/8" size. You could use a blade meant for Bailey types, but they are a good deal thinner than Norris's blades, so you would lose the fine mouth gap. Making your own is possibly the best course if you can't get the current blade to cooperate??

Cheers,

Originally Posted by IanW

Surely that blade wasn't like that when it left the factory, which begs the question of what happened to it in the meantime to cause it to be so brittle? The blade in my (late model) A5 was on the soft side, if anything - it didn't mind pine & soft cabinet woods, but lost its shine pretty quickly on anything like spotted gum. I wonder if someone found the blade too soft for their liking, hardened it, & didn't temper it sufficiently (or at all)? In any case, I don't think a mild oven tempering can do any harm, my understanding is that you are not likely to over-soften at the temperatures you're talking about unless you forget it & leave it cooking overnight (don't laugh - I could easily do that! ), so nothing to lose by giving it a go.

You can't use it like it is, so I hope for your sake you can get it workable - I'd hate to think what a replacement blade would cost you, supposing you could find one, especially if it's the 2 1/8" size. You could use a blade meant for Bailey types, but they are a good deal thinner than Norris's blades, so you would lose the fine mouth gap. Making your own is possibly the best course if you can't get the current blade to cooperate??

Cheers,

Ian

Many things you inferred there are correct. Yes it 2 1/8 inch Norris bladed would be pain to replace. The blade was soft. The edges buckled when I tried to use it. Unusable. I assume the blade was edge treated and used until it couldn't be, as the plane showed plenty of use.

There is a large heat treatment operation just a hope skip and a jump across the road - at work. Asked the treatment cost to treat the blade-$65 or so + gst. Could have tried it myself but needed a decent heat source knock up a forge, some sort of tong oil then disposal of said oil - and a possibility of burns and other disasters with crude setups. For a one off project decided it wasn't worth the effort and let them heat treat blade.
They test the Rockwell was well 28 proir , 58 post. Nothing alarming there. It sharpened and preformed fine for a few projects, until I noticed a small notch, yesterday.

Cannot vouch for the tempering process that was apllied. The blades in the oven now. Will double temper and try again.. and see if a useable blade results..

PS- the oven has timer, some crazy Swiss one, that tells you off , if you don't programme her correctly.. Many beeps.

Cheers M

at 58 hardness, the blade should've rolled instead of chipping like that unless the grain is very large. If that blade is laminated, it is a water hardening steel, and I think a lot of folks can't handle them now because even oil hardening steel is a bridge too far for some operations (dimensional stability).

but maybe they have dealt with water hardening steels before. If you were in the states, I'd have shrunk the grain on it and rehardened it for you for free.

Thankful the offer David. Yes, likely tad far to send a plane blade, a mere 17,653 km's.
As for the Rockwell, the sampling location is likely random. The edge never rolled after re treating.. Seemed to be keen.

However The blade may not have liked been shocked, twice... May be full of microfractures.
Been tempered, twice. Will regrind tomorrow, then we see...

Originally Posted by MartinCH

Thankful the offer David. Yes, likely tad far to send a plane blade, a mere 17,653 km's.
As for the Rockwell, the sampling location is likely random. The edge never rolled after re treating.. Seemed to be keen.

However The blade may not have liked been shocked, twice... May be full of microfractures.
Been tempered, twice. Will regrind tomorrow, then we see...

Is it laminated? If so, they can be quenched in brine, and really even in water, but quenching in water instead of brine is violent and asking for cracks.

I didn't read this, I learned it. Brine is by physical properties a "slower" quench than water, but due to the way vapor jackets form when you put something hot in liquid, the salt allows the brine vapor jacket to collapse uniformly, and the quench is actually faster and far more uniform. More uniform in cooling is good.

I'll spare everyone the details of what can cause problems in terms of cracking even in brine, but it's most likely what these blades were designed to be quenched in if they are 125 years old. Oil if they are more like 75-90- just guessing, but what speed of oil is needed also stands out.

I do my own heat treating because I don't really trust the shops that are very focused on computerized process to get what I'm trying to do - or didn't at the start. It's not uncommon for blades that are oil or water quenched to come back cracked. Adjustment (hammering) for straightness is sometimes required and if it's done roughshod, a whole batch can have cracks that show up only in grinding and finishing later.

In the case of your blade, the easiest way to see if there is cracking is to flatten an area of the blade to a polish.

https://ofhandmaking.com/wp-content/...02/image-1.png

You can see on this picture that the crack with the arrows is pretty easy to see, but the one further to the left is a little less easy, and this is magnified pretty significantly, so that definitely makes it easier to see. In some cases, you can only see the cracks after a break or when steel is flexed.

There could be many other things that would allow a sizable chunk to come out of an edge and be no further threat, but I don't know how likely they are in a company that would've had the skill and experience to make blades for norris. Cracks occur in my chisels as shown above in brine usually if I push the limits forging too hot or too cold and then heat treat, and the steel shown cracked is a little more tricky (it's ball bearing steel) than most of the stuff used in older blades.

I would love to have seen them laminating old irons. The base steel stock probably came from a rolling mill but they still had to laminate it. Once the blades were solid steel (like the later norris), they're probably all just rolled stock that's heat cut and heat treated.

Hi David

The blades not laminated. No sign cracking like you show.

Put the crack under magnification. The broken part has faceted crystal appearance. There are flat faces that sparkle back at me. Cheeky really. Tried looking for a similar photo of a steel fracture but could not find one similar.

I will see if I can a photo of sorts...

Regards


PS
One of the Chinese manufactures on Aliexpress makes laminated blades. I quite like them particularly as they $15 each. The steels apparently a HSS and I have chopped some up to make plough plane blades. Worked well.

David,

Photo of the larger chip.


IMG_6448.jpg

Cheers M

https://i.imgur.com/DHeDQxF.jpg (1/10th inch thick steel taken with a cell phone at about 5x magnification - so almost what it looks like to the naked eye - except in reality this just looks like white fine clay texture. Scaling the picture up to monitor size also increases the scale some)

It will look something like this. Scale is everything here. I snap samples like this when working up a heat treating regime for a steel, or even the same steel but from a new supplier or trying something out. It sounds dumb, but one may look like this - this is 52100, and another vendor's steel may look like this : https://i.imgur.com/LlNQxw7.jpg (40x optical in this case - the blotches are a concern because they suggest a lack of uniformity in the alloying elements - but they may not have any effect on performance. I'll get the stuff that looks uniform over this at the same price, though)

I don't blow up grain at this point - fortunately skill is past that, but I will enlarge it sometimes on purpose to see where it enlarges -usually it gives you confidence that you have more working room than you think to chase high hardness.

This would be an example of overheated steel with grain growth - it's file steel from my "early days" cutting my teeth. I could bring the grain size back quickly now, but at the time, i didn't know how to. Same steel now at double the magnification:
https://i.imgur.com/DXPKHs9.jpg (also 40x optical)

pretty much the case with your blade, if you can discern sandy crystals even when zooming in with a camera, there are problems. I've broken some old tools on purpose and if they are of a good name, there is never grain enlargement. When someone who is less skilled than me (ok, I'm just being goofy pretending to be a master heat treater, but I've perhaps hardened and tempered half a thousand things and worked up methods to chase hardness without growing grain) and is heat treating their fifth thing or something they're not familiar with, it's easy to grow grain.

The steel that will be in a norris iron that's uniform single steel should not give you much to look at. The last picture above is at 100x optical magnification - the only thing you should see even at that with a steel like norris (or sorby if they were making them for norris) is maybe a few carbides -which are the sparkly bits, and you'll sometimes see a little bit of carbon here or there - the black stuff. We don't want to see much of that.

*if* the blade has enlarged grain, then the chance that it will ever be stable is practically zero. It's possible to have tiny grain and still have a fragile blade, but the steel chosen in the old days generally was of a type where that didn't happen.

So, what clued me in to ask about all of this? The shape of the smaller break (not the large one) is unusual. It looks like the crack runs one way and then there's another transverse part. A lateral break due to something like a knot or even running into a nail could look round like the bigger break out and that's usual. The shape of the other one is less so.

I don't know if you ever see forged in fire there, but it's something I never saw until people pointed it out to me (the show). They always break knives there and show just horrid looking coarse steel - you should scarcely be able to ever see anything grain wise with the naked eye. grain size on a finer steel like a plain blade steel is going to be a few ten thousandths of an inch.

David,

Are there any further suggestions to improve this particular blade ,"*if* the blade has enlarged grain, then the chance that it will ever be stable is practically zero." does not at all sound promising..

Cheers M

Originally Posted by MartinCH

David,

Are there any further suggestions to improve this particular blade ,"*if* the blade has enlarged grain, then the chance that it will ever be stable is practically zero." does not at all sound promising..

Cheers M

It's possible to shrink grain without too much effort on an enlarged grain steel. It's actually something I can do in about five minutes with an induction forge, you just basically reheat the steel to temperatures where grain boundaries are re-established and recreate what's there. it doesn't address cracking, though.

But let's go back to practical - if you temper it at 375 and it's still really brittle, put it aside and scout ebay for another similar sized parallel iron. Water hardening and oil hardening steel weren't necessarily designed for a hand and eye heat treater (water hardening steel was, but probably not oil hardening), but they can be done by a hand and eye heat treater accurately and manipulated by someone who knows what they're doing. I think there is no legitimate market for that, though, as far as blades go, and it's important with plane irons, for example, that the person heat treating them if doing it by hand is used to heat treating plane irons.

It is also the case that sometimes an iron is just bad from the start, but that has only been my experience with stuff like Thistle brand in the US or some ohio tool irons. The stock quality was probably poor and there's nothing you can do to reharden them and bring them back to a good state. I've had maybe 8 norris planes. The early ward irons (parallel) probably all went between 61 and 63 hardness and the later sorby irons, I never tested because those planes are gone, but they were marked Norris....those just by memory of feel, I'd say probably were in the 59-ish hardness range. Characteristics in use are pretty significantly different in an iron at 59 vs 62 if you are doing thin shaving work.

David, from my very limited experience (a grand total of 1!), the 59-ish you quoted for the later Norris irons sounds pretty right to me. The iron in my plane was usable, but it could definitely have done with a couple more notches up the scale, imo. That would have made it a far better blade, I think.

Martin, I know you don't want to get into making plane blades, but it's possibly the best, and likely to be the cheapest solution to your problem. A few years ago, I would have reacted to the suggestion much the same way as you did above - in fact I did consider making an iron for my Norris soon after acquiring it, but promptly rejected that idea as waaay too much faffing around & well beyond my capabilities! But when I got seriously into making planes, I soon found the limitations and expense of fitting them with commercial irons to be a nuisance, and it often entailed extensive grinding or other modification to fit the planes I wanted to make. I kept reading about other makers who nonchalantly described making their own blades & saying how good they were, so eventually, I decided to try. After a bit of a false start (see below), I am now getting very consistent results with 1084 using my very basic "coffee can" forge. The blades are more than adequate, I don't know what Rockwell hardness they are after the light temper I give them but I'd judge it to be comfortably north of 60. The most surprising thing was how well they perform, I did not expect it from what is a very basic steel, but they are as good as any of my comercial blades (better than some) & I have no complaints about their edge-holding, they handle she-oak & gidgee without fuss.

I think the 'secret' is not to be too ambitious; use a steel that's easy to harden, like O1 or 1084. The results I'm getting with simple 1084 exceed my expectations, and the best part is it's (almost) idiot-proof. The only serious problem I had was trying to quench in old sump-oil (it simply doesn't work!), and certainly not in water or brine (I cracked a blade right across that way! ). So I read the instructions (a novel experience for me!) and purchased an $8 bottle of Woolies cheapest canola oil which did the trick (works best if you warm it, especially on a cold day), and it's still doing the job, albeit a bit more odoriferously, after many more blades. If you don't get hardening on your first attempt, just heat & try again 'til you get it proper hard, then give it a light temper. Getting rid of spent oil should be no big deal, it's a biological product & while I wouldn't advise tipping it down the kitchen sink, it won't do much harm if you tip some in a corner of your backyard (& there are other options for used cooking oil in most municipalities).

It doesn't cost the earth to have a go and it adds another string to your bow - you are already seriously addicted to tool making & improving, so another little side-track is hardly going to make much difference. You can get enough 1084 from Artisan Supplies for ~$40 to make 4 or 5 blades, so even if you messed a couple up completely, it would cost less than a new blade (if any are available).


Cheers,
Ian