Newbie knife maker questions

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Wally76

Member
I recently purchased a knife oven and some foil to wrap my knife (1095 steel) in to heat treat it. My question is in regards to removing the knife from the envelope before quenching. Is it that big of a deal to keep the wrap on and quench to help with cleanup? Does the wrap trap air and cause irregularities in the metal?

Also, if the purpose is to cool the metal 1000 degrees in the first 1-2 seconds, then why would I need to heat my oil (canola) up to 120 degrees? By not heating the oil up does this increase the chances of fracturing?


My only experience is making knives out of lawnmower blades then heating with a propane torch till nonmagnetic. Ovens and foil wraps are new to me.


Thanks!!
 
Heat treat foil is used mostly for stainless steels. Oil/water hardening steels don't need foil. Your concern about getting the steel out of the envelope is the issue. 1095 needs to drop quickly! The envelope will prevent that from happening. My understanding of the reason for heating the oil is to prevent a vapor barrier from forming between the steel and the oil, thus reducing the heat transfer to the oil. It sounds counter-productive to heat the oil, but it isn't.
 
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A lot of us use an anti-scale coating on carbon steels, like 1095, but like Jess said, no foil. Brownells sell a couple. You may also discover that 1095 is a shallow hardening steel and it confused me a little when I first started using it. I kept getting hardness lines, sort of like a hamon, here and there in different thicknesses across the blade. Depending on your finishing techniques, you may notice what I'm talking about. But, just jump in and go for it, 120 deg canola works just fine.
 
here is a paper on using vegetable oil to quench. they do a good job comparing to commercial quench oils and also have cooling curves for the vegetable oils. the ding on veg oil has never been effectiveness, but has been bath life. without added stabilizers and whatnot, veg oils will start to go rancid and breakdown after several weeks. the plus side is cost and availability, you should be able to find a gallon of canola, corn, or soybean oil at your local food store for less than $10.
http://ojs.sv-jme.eu/index.php/sv-jme/article/view/88_DOI_not_assigned/76
here is a link to Houghton Heat Treat you can find cooling curves of their oils to compare http://www.houghtonheattreat.com/products/product-2
 
Thank you all for the information! It gets a little overwhelming when trying to figure out the best way to go about this when reading the multiple opinions on the internet.
 
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wally76:
for first couple blades I would use a more forgiving steel than 1095. 1084 and 80CrV2 do not require as fast a quench as 1095 and will work just fine in canola oil.
 
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