I reckon all budding knife makers, and also the ones who’ve been doing it a while, need to listen to this guy - he really knows his stuff, and can explain it very well too. A great series of videos!
aint just knife makers, pdr guys dont unerstand stress either whn pulling dents, but there is a proper way...it involves understang stress, same with welding, you dont understand stess in metal? your work will be awfully warped.
I appreciate finally seeing good metallurgical information about knifemaking. I am a metallurgist for a large captive heat treat department. The onlything I dissagree about is the movement in the quench oil. I agree that the stirrin is counter productive, but having good even flow around the entire piece of steel can reduce distortion caused during the quench. Quench flow helps to break up the layer of gas that forms on the hot steel at the begining of the quench. The goal is getting the same cooling around the entire part to prevent uneven residual stresses. Quench oil choice is also a factor. Using an oil with the corect speed for the material. Keeping the quench oil at the correct temperature can be a factore. Oil designed to be used at 150F will not have the correct viscocity to give a good even quench at room temperature. The temperature of the steel as it goes into the quench is a factor as it can change the amount of retained austenite in your steel. Grinding after heat treatment can also change your residual stresses in the steel. if you go from compressive to tensile stress on one side of the steel when grinding that will warp the blade. We see it in caurburized steel rings. A ring perfectly flat and round after quench can distort during grinding of the OD if you distort the residual stresses.
Hi Robert that is a fantastic reply and thanks for the compliment too! Funny enough, the next set of videos coming are about quenching oils, how speed affects your quality and many other important things to know for a knife maker! Hope to see you in our other videos! Cheers!
Ah! Robert - you speak music to my ears - a man that understands distortion. I don't think you can fully understand how it hides in crooks and crannies waiting to jump out and bite yer arse when you least expect it 🤣🤣🤣🤣
I worked in the heat treat department in several factories, small and large. I agree with Robert on the formation of gas around oil quenched parts, or worse, steam pockets on water or brine quenched parts. This can also result in soft spots. Rather than agitate the part, agitate the quench media. As for retained austenite, not letting it cool down enough before tempering or too severe a quench, particularly with air hardening steels, are also causes. If there is enough retained austenite, the parts may "Rockwell soft" after hardening and mislead one into thinking it was a poor quench. They can then increase in hardness after tempering. (This "secondary hardening" is normal for D2 and most HSS). One indication of too much retained austenite is the part shrinks after the hardening operation instead of showing the approximate 4% volume growth associated with the transformation to the martensite structure during hardening. One way to get rid of the retained austenite is to give it a cryogenic treatment, but be sure to give it a second tempering to eliminate having brittle,untempered martensite in the part. As for carburized parts, one of their advantages is the residual compressive stress in the case (which increases the fatigue life in parts such as bearings). This is the result of the difference in the transformation temperatures between the low carbon core and the high carbon case. On non-uniform cross-sections, the ratio of case-to-core has an effect on the change of shape of the part during heat treatment. As for distortion, one job used thin, 9" long pieces of CRS (distorts just by machining it) that were carbonitrided in a cyanide pot and quenched in water. To solve the problem of distortion, they were first heated to 1540F for an hour while laying flat and allowed to air cool. This solved the problem. As for knives, whether its W1, O1, A2, A6 etc., you may want to try annealling (furnace cooling them) them in a straightening fixture after all the primary ops are completed, and then heat treating them. To prevent any de-carb, use an atmosphere controlled or vacuum furnace, or wrap them in stainless foil.
Great videos! It's a joy to witness Graham's years of expertise showcased with the excellent and tastefully modern editing skills demonstrated here. Cheers on the great work all around!
Great videos vince,when I have an issue with distortion,I ring Graham and his advice is great. Has helped me loads listening to him ramble on 🤣😉 total top guy 👍 Regards Davy
Thanks for the feedback- really appreciate you taking time to comment! And super thanks for sharing with your subscribers too! Hope to speak with you again in the near future!
Cheers Peter and nice to see you again! We have a video too on different knife edges (and how to keep them sharp) and also another one that might interest you is one of the UK makers, Sharman Knives, who is a part time knife maker, showing off a digital-camo pattern-welded (Damascus) knife! See you again buddy!
another fantastic video! I make a lot of kitchen knives, and with blades that thin you get really good at managing and correcting warp. Stainless is especially challenging because you can’t simply thermal cycle it to stress relieve it as easily as non-stainless steel due to the nature of stainless being air hardening. Another factor is cryo. A lot of perfectly straight blades want to warp during the cryo cycle. As Graham says, those invisible stresses seem to rear their ugly head at the most inopportune times after you thought the coast was clear.
Hey dude nice to see you back! Kitchen knives seem to be more problematic than thicker ones for warping / distortion but you are right, practice makes perfect! Thanks again for watching and I hope you are enjoying the content we put out! - Vinz
1st, great video. 2nd, just want to add my 2cents. i have found that doing a horizontal quench with the tip pointing magnetic north has greatly reduced bends and warps during heat treating as well as in the temper..
A veritable goldmine of useful information! Graham and the video ;) I understand the theory but can't do the practice, which is why I send my blades to a professional to heat treat properly nowadays.
Hello Rob! Could not agree with you more - Graham is full of useful information and I need to dig out more of what he has - hopefully he’ll be kind enough to share some more hahahaha
Just found this channel.. subscribed 😁 all the best from the north west of England Lincoln 🤙👍 btw definitely ordering some Damascus from Clarke knives.. beautiful 🤯
Hi Harwood Blades! Happy to see another UK maker watching the channel! If you want to get added to our map, please feel free to check it out here: ukbladeshow.com/makers-near-me
@Graham Clarke You showed your stainless blades are clamped after they are quenched. I try the same with thick aluminium quench plates. But when you remove it from the press for cryo treatment, won't it still warp due to not all structure changed to martensit? I wonder whether the quench plates should at best be kept on for (1st) cryo treatment...
I have a vice with long pieces of rectangular steel tube and thin wood mounted on the jaws. The vice is mounted on its side so it's in the same orientation as that guy's press. Other than that it's propane forge/oven and oil.
Luckily of the 100+ knives I made so far I only lost two due to too much distorison. I am stock remover not a knife smith. What do I do to mitigate this issue. - Stainless steels like Niolox or the Crucible CPM steels I send to a heat treater that I trust and who knows what he does. - I rather leave the blade thick before heat treatment. For example thin kitchen knives with a blade thickness of about 2 mm, I don‘t pregrind the bevel. I leave it thick. Do I need to grind a bit longer? Yes, but with the right belt not much of an issue. - Most carbon steel knives/tool steel knives I heat treat myself. Proper stress relieve and normalization is a must. I do it for all baldes even with steels sold as annealed and normalized. - Slight bends/distorions I fix after tempering. I don‘t overbend at tempering, never had any luck with it. Maybe due to practice. I have a set of small ball peen hammers 5 to 9 mm ball diameter. I put the blade on an anvil and lightly hammer the concave side of the bend. I mean really light, not a lot of hand force, just use the hammers weight. I frequently check with a straight edge. I learned this trick during my apprenticeship as a tool and die maker (1976-1979). In the molds we had very thin parts in the cavities and those always came out bend from hardening. Before we further ground and worked on those parts had to be straightend. Of course you see the littele dimples and need enough steel to grind those out. On blades that I pergrind I leave an edge between 0,5 -0,8 mm that was always enough to get the dimpels out. Btw. i made those small ball peen hammers myself during the apprenticeship, still have them.
Hi Roland and thanks for your fantastic and comprehensive input! I think point 1 is best thing to follow if you want it done. It’s the same reason I would send my car to a mechanic to give me peace of mind it’s done properly. Thanks again for taking time to comment!
if you quench in oil you can pull your blade out when it's warm, and bend it into shape while the martensite forms. Otherwise, you can just use a straightening hammer, wich is very safe on a tempered blade. I've never broken a blade with this kind of hammer
Nice video Grahan. I heard knives with thickness around 1 mm are a pain to make because they bend so much. Is 1.8 - 2 mm knives manageable or are they significantly harder to make than 3 mm?
Comment on the question. Well I prefer to let the piece cool ever so slowly from working temp after any working of the metal. No quench just a bucket of hot smothering ashes.
Oh how I know those conversations with customers about distortion. Best had before the work is started generally. Distortion is horribly complicated when you get down to the details. There are dozens of interdependent factors and only a few of them the heat treater has any influence over. Go to a reputable contract heat treater and listen to them!
I reverse bend with folded steel foil, an old piece of 1084 and a c-clamp. I've gotten pretty good at that, but it's a pain in the ass. I also peen. But none of this is ever done before the first temper. I also stress relieve steels like AEB-L and Magnacut, both of which are warpy.
After normalizing, if it is bent, reheat above critical, and straighten the knife. Re-normalize the blade to see if there is still warping. Repeat until the blade stays straight, then harden and temper.
It's funny that it came up in this video because I heat treated some knives for someone recently. All 14C28N he said. Brilliant said I, into the oven and plate quench every one of them. All came out straight as you'd like. Except one of them wasn't hard. At all. It was a different thickness to the others, so I checked with him if it might be something else. Oh! It might be 1095. Well, that would explain that... Normalised and HT as 1095, Bob's your uncle. Can I also say I love it when people give me blanks to HT with either no or very little bevel grinding on them. Like Graham says, I will do my best to give you back a straight knife but sometimes it might not happen. People do expect miracles for less than a tenner per knife!
Hello mate nice to see you again and yes, heat treatment can be tricky for people and expect the world from it from experts but hopefully these videos might help increase the knowledge that people have so they can set their expectations correctly 🥳
my 1st knife bent on me, but it's totally functional. only made a few so far, but after forging, I put the knife blank in a section of square tubing and heat them both to non magnetic. then put them together in a bucket of ash to cool slowly. not sure if it's necessary or not but it seems the extra mass of hot metal from the steel tube let's the knife blank cool slowly enough to fully anneal (or normalize?). they come out of the ashes straight then I can quench and temper without much distortion. I didn't invent this, just copied it from someone else.
@@UKBladeshow HAHAHA, sounds like it does it's job then. It reminds me of the factory I work at where the wave solder machine literally has a picture of a hand getting it's fingers torn off by the chain.
Question: Should knife and blade smith use steel wire and bars rather than plates? What forms of flux reduce delamination the most? Does filling the canaster with Argon gas help with canaster Damascus?
There’s been a video recently on forge welding. You’re more likely to get a answer putting your question on that one. I’ll try answering as best I can - I’m a ferrous metallurgist but not a blade maker (alas). And the following only holds for carbon steels. I don’t know fluxes well enough to answer. Sorry. However, the reason to use a flux is to remove scale and get a nice clean surface. If you can avoid scale forming you can ditch the flux. If you can get rid of the air in the canister before heating then you would prevent scale forming and ruining your welds. Argon sounds like it’ll do the trick (though be careful and ventilate the area - Argon can kill) The main thing that will prevent a solid forge weld is scale and general crud on the surface. I’ve unfortunately never had the chance to try but I would image that plate would be easier to use since there’s a whole lots less surface to generate defects compared with wire. I’ve seen some very pretty blades made with wire/bearings/bolts etc so if the art of the craft is what interests you then don’t let that stop you from using wire.
Wow that is very sweet of you man thanks for that comment! Graham is an absolute legend and I am extremely thankful that I’ve been able to share this video for the knife making community!
Oh yes, This man is a treasure. But if you want, there are also some other nice clips on metal structure topic which are awesome: 1. Old BBC document from 1973 "Properties and grain structure": ruclips.net/video/uG35D_euM-0/видео.html&ab_channel=moodlemech 2. Real Engineering with Alec Steele about heat treatment: ruclips.net/video/6jQ4y0LK1kY/видео.html&ab_channel=RealEngineering 3. Steve Mould with a little ball bearings model on atomic structure: ruclips.net/video/xuL2yT-B2TM/видео.html&ab_channel=SteveMould I love the topic and I hope this helps too :)
I temper anything under an 1/8 inch clamped to a flat 1/2 inch steel plate. It's more prominent in stainless but if I counter bend on very thin it has taken the new bend. Let the plate and work cool down natural at room temp before unclamping. On high carbons especially at thicker material I'll use three bits of round stock and a vice with a torch and clean the edge so you make sure to keep your temp below straw. I have also used a hammer and anvil right after quench while it's still to hot to touch. Good luck figuring it out y'all!
Awesome video. So glad RUclips suggested one of your videos a few days ago. Warping is so frustrating. I lost 6 knives about a year ago and then built a plate quench vise. Straight blades but I noticed that it isn't quite hard enough. Graham, what is best HC steel if plate quenching? Been using 1080 type steel.
You'll really struggle to get max hardness with a plate quench on a many carbon steels and plain carbon such as 1080 in particular. Their required quench rate down to below about 350-400 Celsius is just too fast for plate quenching - I use a fast or accelerated industrial quench oil for these materials. Choose steels with some Chrome content such as 80CrV2, 52100 or A2 ( in ascending Cr Content) for much better plate quenching results.
Great stuff! Particularly interested in tempering to straighten comments... I've had mixed results but I've been tempering at 400° instead of 450°... Does it degrade steel quality of you temper more than 2-2 hour cycles? I've got one rt now that's been cycles twice at 400 ° clamped a bit past the bow but the bow just came rt back... Should I clamp straight at 450 ° or clamp beyond straight the other way?
@@stevesyncox9893 ty... I usually torch the spine as well... This blade however has a hamon and I've discovered thru error that torching the spine on hamons kind of ruins the hamon for etching so I'm trying to avoid that... I'm gonna try tempering with a jig at a higher temp and see what happens...
@@Bar_D_Forge thanks for the question Kevin! Very good question indeed and I must say, we only touched a little bit about tempering but maybe we can discuss that in-depth if that is of interest?
@@Bar_D_Forge cheers man - I promise we have more good stuff coming shortly but don’t forget to watch the content we’ve put out in the last 12 months - everything from knife makers showing their process to knife maintenance tips etc!
Weird question about clamp quenching. Has anyone ever used materials like copper, silver, or tungsten for that? Obviously copper and silver because they have greater thermal conductivity and greater thermal mass than aluminum. But if I remember correctly pure tungsten has better thermal conductivity than 7075 aluminum? Which is like the least conductive aluminum, but maybe the mass makes up for it? If no one has done silver and copper, is it because they're too expensive or too soft? If it's one or both of those would tungsten solve that? Does this ultimately not matter because no one is insane enough to build big ass plates of tungsten for small batch heat treatment and in production you would just design the process to not need something so intensive?
There was a cable-tv show years ago, I think it was on the History channel and called 'Iron & Fire'? - In one of their episodes, - he explained that quenching with the blade facing magnetic north, reduces the possibility of warping. Is this a myth, or a credible hypothesis? Also, on another note about quenching - Instead of 'swishing' the blade (in any direction) during the quench, why not have your quench tank plumbed to a reservoir with a small electric pump that keeps the oil circulating to quickly move super-heated oil away from the blade? Drawing the oil straight down while re-introducing cooler oil through the top would (in theory?) 'draw' heat down the length of the blade (from tang-to-tip) and perhaps assist aligning its crystalline structure. I don't know - it's just a thought.
Haven't heard the one about magnetic north for a few years 🤣🤣🤣🤣🤣🤣 One of the bigger myths in my opinion. Industrially, oil would be circulated in the tank to prevent the build up of hot areas and pass it through a cooler but properly formulated quench oil has additives in it to aid even quenching at the required rate (fast or med oil for example). I don't (and don't advocate) move a blade once its immersed in the oil. Just hold it still and let the oil do the work.
I've heard that when normalizing, you don't have to let it sit till room temperature. Is that true? Might that be the reason I'm getting warps? Great series btw!!!
No doesn't need to get to room temp. The yardstick I used to work to for industrial work was below 400 Celsius for more than 20-30 mins. Regards Graham Clarke
Hahaha! Swearing doesn’t seem to be of much help fixing the bend but yeah, I hear lots of people using the 3-pin method - does it work all the time doing that or have you had failures on this method if you don’t mind me asking mate?
I use the same method with mine that come out with a bend. Depending on the bend I have used one pin and 2 small c-clamps, 2 pins and 1 c-clamp, and a few months ago I used 2 pins and 3 c-clamps. Success rate is pretty good and some steels respond better than others. Have had a couple over the years though that just wouldn't come out. I took one back to the forge, relieve the stresses (or at least I though I did), lightly tap the blade flat again, and went through the quench again. The blade was straight as an arrow but put a recurve bow in the edge. Weirdest thing I had seen. Of course that one was scraped but man did it freak me out.
@@UKBladeshow it works more than you think but I have had it where I've over bent it the other way and it snapped or just had it where it not worked at all
What I don't get is why he didn't suggest the #1 solution to end up with a straight part after heat treating, normalizing before cutting. This is a common practice in machining parts that have to be heat treated after. Let the raw material warp all over while there's still enough material there to machine/grind it back true.
In practice that would be the way, yet many industrial tips and tricks seem to not make it into the knife making world. Then again when you get an already ground or forged knife for Q+T it is probably already way too late, unless you convince them to pay for a stress relieve or normalization too.
@@dragoscoco2173 Oh totally. Definitely something you have to think about before grinding. Sure it costs, but it's better than throwing away a 1/2 day or more work.
Depends on the steel. Anneal. Normalize. If the steel is one that can benefit from thermal cycling. Then thermal cycling. However doesn't mean repeat the same normalizing procedure, when done properly the first one has a specific temp heated to and cooling rate and the next cycle has a different cooling rate and temp. From there quench. If going into water thin thin wash of clay. Very thing wash that's even. Oil meh. Depending on steal and other machining processes. Anneal in the middle of working.
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How is the most knowable dude about knife and metal working, a metallurgist, only getting >200 views. i love this dude. From the 🇺🇸 with♥
Hi 👋 thanks for taking time to comment! See you again in our other Graham videos!
Because this is how the world works unfortunately lol
I reckon all budding knife makers, and also the ones who’ve been doing it a while, need to listen to this guy - he really knows his stuff, and can explain it very well too. A great series of videos!
Cheers Andrew - I appreciate the lovely feedback! We have a handful more Graham videos coming so hope to see you on them too mate!
- Vinz
Thanks Andrew - much appreciated comment.
aint just knife makers, pdr guys dont unerstand stress either whn pulling dents, but there is a proper way...it involves understang stress, same with welding, you dont understand stess in metal? your work will be awfully warped.
This is the best series explaining this topic I've seen. Dude is a gold mine of knowledge.
Cheers kaxitaksi! Lovely to hear your thoughts and feedback! Hope to see you again soon!
Stress cannot be created or destroyed, only transferred between the steel and the person trying to make something useful out of it.
Cheers namn
The 4th Law of Thermodynamics. We have a future Nobel laureate.
Only just stumbled across this channel. Incredible video production quality, criminally under viewed. 10/10 would recommend.
Wow - such a lovely feedback! Thank you very much!
- Vinz
Welding (especially stainless) has tought me plenty about distortion and heat the necessary pre-heating or post-heating. Very well presented.
Thanks for the feedback! Glad you enjoyed the content! Hope to see you in our other videos too!
Took me 6 years to get straight thin blades every time. And hes right. Great video.
Thanks for dropping by to comment!
I appreciate finally seeing good metallurgical information about knifemaking. I am a metallurgist for a large captive heat treat department. The onlything I dissagree about is the movement in the quench oil. I agree that the stirrin is counter productive, but having good even flow around the entire piece of steel can reduce distortion caused during the quench. Quench flow helps to break up the layer of gas that forms on the hot steel at the begining of the quench. The goal is getting the same cooling around the entire part to prevent uneven residual stresses. Quench oil choice is also a factor. Using an oil with the corect speed for the material. Keeping the quench oil at the correct temperature can be a factore. Oil designed to be used at 150F will not have the correct viscocity to give a good even quench at room temperature. The temperature of the steel as it goes into the quench is a factor as it can change the amount of retained austenite in your steel. Grinding after heat treatment can also change your residual stresses in the steel. if you go from compressive to tensile stress on one side of the steel when grinding that will warp the blade. We see it in caurburized steel rings. A ring perfectly flat and round after quench can distort during grinding of the OD if you distort the residual stresses.
Hi Robert that is a fantastic reply and thanks for the compliment too!
Funny enough, the next set of videos coming are about quenching oils, how speed affects your quality and many other important things to know for a knife maker!
Hope to see you in our other videos! Cheers!
Ah! Robert - you speak music to my ears - a man that understands distortion. I don't think you can fully understand how it hides in crooks and crannies waiting to jump out and bite yer arse when you least expect it 🤣🤣🤣🤣
I worked in the heat treat department in several factories, small and large. I agree with Robert on the formation of gas around oil quenched parts, or worse, steam pockets on water or brine quenched parts. This can also result in soft spots. Rather than agitate the part, agitate the quench media. As for retained austenite, not letting it cool down enough before tempering or too severe a quench, particularly with air hardening steels, are also causes. If there is enough retained austenite, the parts may "Rockwell soft" after hardening and mislead one into thinking it was a poor quench. They can then increase in hardness after tempering. (This "secondary hardening" is normal for D2 and most HSS). One indication of too much retained austenite is the part shrinks after the hardening operation instead of showing the approximate 4% volume growth associated with the transformation to the martensite structure during hardening. One way to get rid of the retained austenite is to give it a cryogenic treatment, but be sure to give it a second tempering to eliminate having brittle,untempered martensite in the part. As for carburized parts, one of their advantages is the residual compressive stress in the case (which increases the fatigue life in parts such as bearings). This is the result of the difference in the transformation temperatures between the low carbon core and the high carbon case. On non-uniform cross-sections, the ratio of case-to-core has an effect on the change of shape of the part during heat treatment. As for distortion, one job used thin, 9" long pieces of CRS (distorts just by machining it) that were carbonitrided in a cyanide pot and quenched in water. To solve the problem of distortion, they were first heated to 1540F for an hour while laying flat and allowed to air cool. This solved the problem. As for knives, whether its W1, O1, A2, A6 etc., you may want to try annealling (furnace cooling them) them in a straightening fixture after all the primary ops are completed, and then heat treating them. To prevent any de-carb, use an atmosphere controlled or vacuum furnace, or wrap them in stainless foil.
Here is a genuine expert with practical experience who can also explain what is going on. Thanks again.
Hi Stephen thanks for the feedback! Happy to hear you are enjoying the channel!
Great videos! It's a joy to witness Graham's years of expertise showcased with the excellent and tastefully modern editing skills demonstrated here. Cheers on the great work all around!
Thanks Khaki! Your appreciation is warmly welcomed and glad to see you enjoyed the vid! Hope to see you in our other videos!
Great videos vince,when I have an issue with distortion,I ring Graham and his advice is great. Has helped me loads listening to him ramble on 🤣😉 total top guy 👍
Regards
Davy
Cheers Davy! Graham will probably never admit it but he’s an extremely helpful chap. Thanks bud!
Learn to do your own treatment is the takeaway.
Good video.
Cheers Dave!
Absolutely love the warning sticker !!!
The warning label is very concise in my opinion.
Brilliant video, will share this with my subscribers for sure. Thanks for sharing 🙂
Thanks for the feedback- really appreciate you taking time to comment! And super thanks for sharing with your subscribers too! Hope to speak with you again in the near future!
I love the knowledge I get from this channel, but my favorite part was the danger sign on the press.
Hahaha yeah - that is also knowledge haha! Cheers mot D!
Best safety message ever bar none on the brake pot. Capable of being applied to every tool or hazardous procedure
Cheers for the comment John and I hope you enjoyed the video!
@@UKBladeshow really enjoying these thanks. Just come across them and subscribed straight away.
Thank you for an excellent and understandable explanation of a complex topic!
Thanks for dropping by to comment Charles! Glad you enjoyed the vid!
This guy is wicked smart!! Love his straight-to-it No BULL-$HIT attitude!!!
Graham is a fantastic source of information for knife makers and we are all lucky to have him in our community. Thanks for watching!
I just found this channel and I love the content. Thank you so much. Please keep up the great work. New subscriber.
Hi Wes! Lovely to have you onboard mate! Thanks for watching and hope to see you in our other vids!
Thanks Graham.
Hi Matty! I hope you enjoyed the video!
Another great video. As a hobby knife maker I am getting a lot out of these videos, keep ‘em coming please
Cheers Peter and nice to see you again! We have a video too on different knife edges (and how to keep them sharp) and also another one that might interest you is one of the UK makers, Sharman Knives, who is a part time knife maker, showing off a digital-camo pattern-welded (Damascus) knife!
See you again buddy!
another fantastic video! I make a lot of kitchen knives, and with blades that thin you get really good at managing and correcting warp. Stainless is especially challenging because you can’t simply thermal cycle it to stress relieve it as easily as non-stainless steel due to the nature of stainless being air hardening. Another factor is cryo. A lot of perfectly straight blades want to warp during the cryo cycle. As Graham says, those invisible stresses seem to rear their ugly head at the most inopportune times after you thought the coast was clear.
Hey dude nice to see you back! Kitchen knives seem to be more problematic than thicker ones for warping / distortion but you are right, practice makes perfect!
Thanks again for watching and I hope you are enjoying the content we put out!
- Vinz
@@UKBladeshow The thinner the material the more difficult to keep flat - try keeping kitchen foil flat 🤣🤣🤣🤣🤣🤣
1st, great video.
2nd, just want to add my 2cents. i have found that doing a horizontal quench with the tip pointing magnetic north has greatly reduced bends and warps during heat treating as well as in the temper..
Hi Scott thanks for the comment and appreciation!
A veritable goldmine of useful information! Graham and the video ;) I understand the theory but can't do the practice, which is why I send my blades to a professional to heat treat properly nowadays.
Hello Rob! Could not agree with you more - Graham is full of useful information and I need to dig out more of what he has - hopefully he’ll be kind enough to share some more hahahaha
Have you tried input internally stresses to straighten the steel blade? Peening one side will input compressive stress on that surface.
Just found this channel.. subscribed 😁 all the best from the north west of England Lincoln 🤙👍 btw definitely ordering some Damascus from Clarke knives.. beautiful 🤯
Hi Harwood Blades! Happy to see another UK maker watching the channel! If you want to get added to our map, please feel free to check it out here: ukbladeshow.com/makers-near-me
Does it make sense for a knife maker to anneal their supposedly annealed yet already worked by unrolling stock before doing any forging?
@Graham Clarke You showed your stainless blades are clamped after they are quenched. I try the same with thick aluminium quench plates. But when you remove it from the press for cryo treatment, won't it still warp due to not all structure changed to martensit? I wonder whether the quench plates should at best be kept on for (1st) cryo treatment...
Another amazing video.
Cheers Rob and thanks for watching! I hope the video is also informative and entertaining at the same time? What do you think can we improve on?
I have a vice with long pieces of rectangular steel tube and thin wood mounted on the jaws. The vice is mounted on its side so it's in the same orientation as that guy's press. Other than that it's propane forge/oven and oil.
I wonder if you could do CPM aluminum bronze and if so if work hardening would make the edge even better and how close that would be to the low 50s
Hey this is a really educational about heatreatig an metallurgy 👍
Can you recommend some books on the subject ??
Luckily of the 100+ knives I made so far I only lost two due to too much distorison. I am stock remover not a knife smith. What do I do to mitigate this issue.
- Stainless steels like Niolox or the Crucible CPM steels I send to a heat treater that I trust and who knows what he does.
- I rather leave the blade thick before heat treatment. For example thin kitchen knives with a blade thickness of about 2 mm, I don‘t pregrind the bevel. I leave it thick. Do I need to grind a bit longer? Yes, but with the right belt not much of an issue.
- Most carbon steel knives/tool steel knives I heat treat myself. Proper stress relieve and normalization is a must. I do it for all baldes even with steels sold as annealed and normalized.
- Slight bends/distorions I fix after tempering. I don‘t overbend at tempering, never had any luck with it. Maybe due to practice. I have a set of small ball peen hammers 5 to 9 mm ball diameter. I put the blade on an anvil and lightly hammer the concave side of the bend. I mean really light, not a lot of hand force, just use the hammers weight. I frequently check with a straight edge. I learned this trick during my apprenticeship as a tool and die maker (1976-1979). In the molds we had very thin parts in the cavities and those always came out bend from hardening. Before we further ground and worked on those parts had to be straightend. Of course you see the littele dimples and need enough steel to grind those out. On blades that I pergrind I leave an edge between 0,5 -0,8 mm that was always enough to get the dimpels out. Btw. i made those small ball peen hammers myself during the apprenticeship, still have them.
Hi Roland and thanks for your fantastic and comprehensive input!
I think point 1 is best thing to follow if you want it done. It’s the same reason I would send my car to a mechanic to give me peace of mind it’s done properly.
Thanks again for taking time to comment!
Gold
This guy is why I read comments
if you quench in oil you can pull your blade out when it's warm, and bend it into shape while the martensite forms. Otherwise, you can just use a straightening hammer, wich is very safe on a tempered blade. I've never broken a blade with this kind of hammer
Great video!!!!
Cheers 2 Walter!
How do I mitigate distortions? I comply with the needed Normalising Cycles and limit the most common types of stress raisers before hardening.
Nice video Grahan. I heard knives with thickness around 1 mm are a pain to make because they bend so much.
Is 1.8 - 2 mm knives manageable or are they significantly harder to make than 3 mm?
Comment on the question. Well I prefer to let the piece cool ever so slowly from working temp after any working of the metal. No quench just a bucket of hot smothering ashes.
Oh how I know those conversations with customers about distortion. Best had before the work is started generally.
Distortion is horribly complicated when you get down to the details. There are dozens of interdependent factors and only a few of them the heat treater has any influence over.
Go to a reputable contract heat treater and listen to them!
I reverse bend with folded steel foil, an old piece of 1084 and a c-clamp. I've gotten pretty good at that, but it's a pain in the ass. I also peen. But none of this is ever done before the first temper. I also stress relieve steels like AEB-L and Magnacut, both of which are warpy.
After normalizing, if it is bent, reheat above critical, and straighten the knife. Re-normalize the blade to see if there is still warping. Repeat until the blade stays straight, then harden and temper.
Brilliant!
Thanks 😊
It's funny that it came up in this video because I heat treated some knives for someone recently. All 14C28N he said. Brilliant said I, into the oven and plate quench every one of them. All came out straight as you'd like. Except one of them wasn't hard. At all. It was a different thickness to the others, so I checked with him if it might be something else. Oh! It might be 1095. Well, that would explain that...
Normalised and HT as 1095, Bob's your uncle. Can I also say I love it when people give me blanks to HT with either no or very little bevel grinding on them. Like Graham says, I will do my best to give you back a straight knife but sometimes it might not happen. People do expect miracles for less than a tenner per knife!
Hello mate nice to see you again and yes, heat treatment can be tricky for people and expect the world from it from experts but hopefully these videos might help increase the knowledge that people have so they can set their expectations correctly 🥳
my 1st knife bent on me, but it's totally functional. only made a few so far, but after forging, I put the knife blank in a section of square tubing and heat them both to non magnetic. then put them together in a bucket of ash to cool slowly. not sure if it's necessary or not but it seems the extra mass of hot metal from the steel tube let's the knife blank cool slowly enough to fully anneal (or normalize?). they come out of the ashes straight then I can quench and temper without much distortion. I didn't invent this, just copied it from someone else.
At 5:21 that has to be the best warning label ever
I know! Stops everyone (including myself) from using equipment hahaha!
@@UKBladeshow HAHAHA, sounds like it does it's job then. It reminds me of the factory I work at where the wave solder machine literally has a picture of a hand getting it's fingers torn off by the chain.
Question: Should knife and blade smith use steel wire and bars rather than plates? What forms of flux reduce delamination the most? Does filling the canaster with Argon gas help with canaster Damascus?
There’s been a video recently on forge welding. You’re more likely to get a answer putting your question on that one. I’ll try answering as best I can - I’m a ferrous metallurgist but not a blade maker (alas). And the following only holds for carbon steels.
I don’t know fluxes well enough to answer. Sorry. However, the reason to use a flux is to remove scale and get a nice clean surface. If you can avoid scale forming you can ditch the flux.
If you can get rid of the air in the canister before heating then you would prevent scale forming and ruining your welds. Argon sounds like it’ll do the trick (though be careful and ventilate the area - Argon can kill)
The main thing that will prevent a solid forge weld is scale and general crud on the surface. I’ve unfortunately never had the chance to try but I would image that plate would be easier to use since there’s a whole lots less surface to generate defects compared with wire. I’ve seen some very pretty blades made with wire/bearings/bolts etc so if the art of the craft is what interests you then don’t let that stop you from using wire.
this is absolutely one of the best explained videos on that topic out here!
even better explained than the teacher that taught my class this stuff.
Wow that is very sweet of you man thanks for that comment! Graham is an absolute legend and I am extremely thankful that I’ve been able to share this video for the knife making community!
Oh yes, This man is a treasure. But if you want, there are also some other nice clips on metal structure topic which are awesome:
1. Old BBC document from 1973 "Properties and grain structure": ruclips.net/video/uG35D_euM-0/видео.html&ab_channel=moodlemech
2. Real Engineering with Alec Steele about heat treatment: ruclips.net/video/6jQ4y0LK1kY/видео.html&ab_channel=RealEngineering
3. Steve Mould with a little ball bearings model on atomic structure: ruclips.net/video/xuL2yT-B2TM/видео.html&ab_channel=SteveMould
I love the topic and I hope this helps too :)
Thanks mate and please pass your comments to my son David - apparently I usually "Waffle on like a Deranged Old White Hair" 🤣🤣🤣🤣🤣🤣
@@clarkeknives4159 haha😂 nah, it's knowledge that could make my life easier during the next year when I'm doing my master so every bit is welcome 😅
I temper anything under an 1/8 inch clamped to a flat 1/2 inch steel plate. It's more prominent in stainless but if I counter bend on very thin it has taken the new bend. Let the plate and work cool down natural at room temp before unclamping. On high carbons especially at thicker material I'll use three bits of round stock and a vice with a torch and clean the edge so you make sure to keep your temp below straw. I have also used a hammer and anvil right after quench while it's still to hot to touch. Good luck figuring it out y'all!
That’s nice of you to share your thoughts and method thanks Mike!
@@UKBladeshow if we don't keep sharing it's going to get lost. Appreciate your channel.
Awesome video. So glad RUclips suggested one of your videos a few days ago. Warping is so frustrating. I lost 6 knives about a year ago and then built a plate quench vise. Straight blades but I noticed that it isn't quite hard enough. Graham, what is best HC steel if plate quenching? Been using 1080 type steel.
Hi Jeffrey thanks for watching another UK Bladeshow video! I’ll be speaking with Graham again soon so I’ll ask your question! Thanks!
You'll really struggle to get max hardness with a plate quench on a many carbon steels and plain carbon such as 1080 in particular. Their required quench rate down to below about 350-400 Celsius is just too fast for plate quenching - I use a fast or accelerated industrial quench oil for these materials. Choose steels with some Chrome content such as 80CrV2, 52100 or A2 ( in ascending Cr Content) for much better plate quenching results.
@@clarkeknives4159 Thank you!
Great stuff! Particularly interested in tempering to straighten comments... I've had mixed results but I've been tempering at 400° instead of 450°... Does it degrade steel quality of you temper more than 2-2 hour cycles? I've got one rt now that's been cycles twice at 400 ° clamped a bit past the bow but the bow just came rt back... Should I clamp straight at 450 ° or clamp beyond straight the other way?
@@stevesyncox9893 ty... I usually torch the spine as well... This blade however has a hamon and I've discovered thru error that torching the spine on hamons kind of ruins the hamon for etching so I'm trying to avoid that... I'm gonna try tempering with a jig at a higher temp and see what happens...
@@stevesyncox9893 thanks Steve, sorry if we didn’t clarify it but yes, it’s Centigrade hahaha! Thanks for your input as well - really appreciate it!
@@Bar_D_Forge thanks for the question Kevin! Very good question indeed and I must say, we only touched a little bit about tempering but maybe we can discuss that in-depth if that is of interest?
@@UKBladeshow absolutely... I need to learn everything from you guys, absolutely fabulous content...
@@Bar_D_Forge cheers man - I promise we have more good stuff coming shortly but don’t forget to watch the content we’ve put out in the last 12 months - everything from knife makers showing their process to knife maintenance tips etc!
Weird question about clamp quenching.
Has anyone ever used materials like copper, silver, or tungsten for that?
Obviously copper and silver because they have greater thermal conductivity and greater thermal mass than aluminum. But if I remember correctly pure tungsten has better thermal conductivity than 7075 aluminum? Which is like the least conductive aluminum, but maybe the mass makes up for it?
If no one has done silver and copper, is it because they're too expensive or too soft?
If it's one or both of those would tungsten solve that?
Does this ultimately not matter because no one is insane enough to build big ass plates of tungsten for small batch heat treatment and in production you would just design the process to not need something so intensive?
There was a cable-tv show years ago, I think it was on the History channel and called 'Iron & Fire'? - In one of their episodes, - he explained that quenching with the blade facing magnetic north, reduces the possibility of warping. Is this a myth, or a credible hypothesis? Also, on another note about quenching - Instead of 'swishing' the blade (in any direction) during the quench, why not have your quench tank plumbed to a reservoir with a small electric pump that keeps the oil circulating to quickly move super-heated oil away from the blade? Drawing the oil straight down while re-introducing cooler oil through the top would (in theory?) 'draw' heat down the length of the blade (from tang-to-tip) and perhaps assist aligning its crystalline structure. I don't know - it's just a thought.
That sounds super interesting man! I’d definitely speak with Graham at some point soon to see whether this could work! Thanks for the input!
Haven't heard the one about magnetic north for a few years 🤣🤣🤣🤣🤣🤣 One of the bigger myths in my opinion.
Industrially, oil would be circulated in the tank to prevent the build up of hot areas and pass it through a cooler but properly formulated quench oil has additives in it to aid even quenching at the required rate (fast or med oil for example). I don't (and don't advocate) move a blade once its immersed in the oil. Just hold it still and let the oil do the work.
I've heard that when normalizing, you don't have to let it sit till room temperature. Is that true? Might that be the reason I'm getting warps? Great series btw!!!
Thanks for the comment! Funny enough, we have normalising as our next video coming soon! See you in our other videos!
No doesn't need to get to room temp. The yardstick I used to work to for industrial work was below 400 Celsius for more than 20-30 mins. Regards Graham Clarke
i have actually cracked thin and thick blades moving it the wrong way in the oil.
Respect The pro
Thanks again for the comments!
if my knife comes out with a bend, i usually swear abit and then temper it with a slight reverse bend via the 3 pin method
Hahaha! Swearing doesn’t seem to be of much help fixing the bend but yeah, I hear lots of people using the 3-pin method - does it work all the time doing that or have you had failures on this method if you don’t mind me asking mate?
I use the same method with mine that come out with a bend. Depending on the bend I have used one pin and 2 small c-clamps, 2 pins and 1 c-clamp, and a few months ago I used 2 pins and 3 c-clamps. Success rate is pretty good and some steels respond better than others. Have had a couple over the years though that just wouldn't come out. I took one back to the forge, relieve the stresses (or at least I though I did), lightly tap the blade flat again, and went through the quench again. The blade was straight as an arrow but put a recurve bow in the edge. Weirdest thing I had seen. Of course that one was scraped but man did it freak me out.
@@UKBladeshow it works more than you think but I have had it where I've over bent it the other way and it snapped or just had it where it not worked at all
@@shaungreen679 hahaha yeah that can happen too!
Imagining the modern salesman selling bent knives for cutting bananas. 🤔
🤪
What I don't get is why he didn't suggest the #1 solution to end up with a straight part after heat treating, normalizing before cutting. This is a common practice in machining parts that have to be heat treated after. Let the raw material warp all over while there's still enough material there to machine/grind it back true.
In practice that would be the way, yet many industrial tips and tricks seem to not make it into the knife making world. Then again when you get an already ground or forged knife for Q+T it is probably already way too late, unless you convince them to pay for a stress relieve or normalization too.
@@dragoscoco2173 Oh totally. Definitely something you have to think about before grinding. Sure it costs, but it's better than throwing away a 1/2 day or more work.
Depends on the steel. Anneal. Normalize.
If the steel is one that can benefit from thermal cycling. Then thermal cycling. However doesn't mean repeat the same normalizing procedure, when done properly the first one has a specific temp heated to and cooling rate and the next cycle has a different cooling rate and temp.
From there quench. If going into water thin thin wash of clay. Very thing wash that's even. Oil meh.
Depending on steal and other machining processes. Anneal in the middle of working.
Distorted or sheeps foot that needs a bit of a grind ?!?
Hahaha or both?! Nice to see you back Rob! Thanks for watching mate!
Dr:knife 😄
haha thanks Daniel!
This is a guy who is definitely tired of being bitched at by knife makers 😂