Hi Ethan, the main difference between water and oil quenching steels is depth of penetration. The plain carbon steels require rapid cooling to increase depth of hardness. Water cools faster than oil (oil doesn't transfer heat as well) so it packs more of a punch and helps to get a part hardened through. Very large and thick parts of plain carbon steel will never be completely hardened (the outsides will harden but not the center) even when quenching in water. On the other hand, cooling a thin part with large surfaces (such as a knife) is much easier and that is probably why you are getting good results even with oil. This is good news, since quenching in oil will reduce part deformation caused by an uneven submersion in the quenching bath. Some knife makers will also play with heating and quenching to obtain very hard cutting edges and a very tough knife body. You may want to try this: If you heat the cutting edge portion (about half way up from the edge) of your blade with oxy acetylene torch ( this must be done rapidly because you don't want the whole blade to reach its critical quenching temperature) and then quench rapidly, you will get a blade that is both hard wearing (keeps an edge) and resistant to shock ( tough). I hope that this helps, be safe with the quenching in oil, it is best for safety (not burning you garage down) do perform this operation outside. Shops that do heat treatment professionally will have a dedicated fireproof area for this type of operation. Thanks for watching my videos and for taking the time to write, Marc.

Thank you for the reply and for the safety instructions. Indeed, I will continue to do heat treatment operations outdoors, away from the house! One follow up question: what type of steel would you recommend for the hobby knife-maker who wants to do his own heat treatment rather than sending the knife out to a pro shop?

What an eloquent comment

A lie brother

I produce the videos for fun and I thank you for overlooking the technical problems since I am in no way a professional video producer. It's all about helping and feeling useful and giving back and Yes! Receiving!!! Because praise from a grateful viewer (such as you and your comment) relay makes my day. Thanks Edgar, Marc

Marc, someone told me that (the most efficient cutting angle,) or maybe it was (the sharpest angle) was 45°. In your opinion what is the best angles for Knives, that would allow least drag on mateirial, yet be suitable for hard work, like wood work, camp tasks, even game dressing... Maybe the general wood chisel angle would be a good place to start...any ideas?

I was a teacher for 24 years so I am used to speaking in public (more in French than in English however). The videos are not scripted but I do have a good idea of what I want to say, I just haven't chosen specific words, that happens live. I do however do a lot of editing with "VEGAS MOVIE STUDIO", in fact I spend a lot more time editing a video than I spend recording it. Some videos (such as the latest one on threading) existed only in French and are translated at home with a blue screen and voice over. I have great fun doing all of this and I am very happy that people such as yourself enjoy what I do. Thanks for watching, Marc L'Ecuyer THATLAZYMACHINIST.COM

+THATLAZYMACHINIST You speak English very well sir. I'm slightly amused at the sort of, slow, "industry standardized education" style of the videos I have to say (not meaning that in a derogatory way of any sort).. It only took seeing a couple of your videos and the wealth of videos on your channel and I am an instant subscriber.. I agree with Jim: you do a fantastic job with these and I thank you so much for your content and your contribution to KZfaq!

Hi! Grey cast iron is machinable but will not produce chips. The material removed is more like powder or sand in shape. Malleable cast iron will produce chips but they tend to be segmented and not continuous. White cast iron very hard and can only be machined with technique that would be used on hardened tool steel, such as grinding ...). Thanks for a great question, I hope that this answer helps and thank you for watching my videos and for taking the time to write. Marc

+Simon Gomes You got my attention! Could you translate? Thanks for watching, Marc