Grade 8 bolt hardness

[bigjake]

I've been reading a lot of posts from way back and there were a few posts by some folks that didnt think gr.8- 7/8"/14 bolts would not work for swaging dies. I did 2 separate tests: one on a section of threaded gr. 8 rod I ordered from McMaster Carr, and a random 3" bolt. I used an acetylene cutting torch to heat them brite red, and oil quenched them both. In both cases they became hard enough that I had to work pretty hard to cut them with a good mill file. I tested them beforehand with the file and they filed easily. Im going to do some more testing. I want to see how brittle they my be. They my not require tempering. I think It would be safe to use for the easy dies to make. I ordered a few of those blank dies from Pacific Tool and gauge to TRY and make a quality point form die

[bigjake]

The reason I use pre-threaded material/bolts is; Im not able to thread on my little 8" South Bend jr. It was built in 1932. Its not worn too bad for its age. Its very similar to the popular 9" bench lathe that SB made for yrs

I'm going to dunk the blazing hot 7/8" 14 bolt into water instead of oil to see how hard it gets.

[Scrounge]

The reason I use pre-threaded material/bolts is; Im not able to thread on my little 8" South Bend jr. It was built in 1932. Its not worn too bad for its age. Its very similar to the popular 9" bench lathe that SB made for yrs

I'm going to dunk the blazing hot 7/8" 14 bolt into water instead of oil to see how hard it gets.

You're probably going to get stress cracks all through it. What, exactly, are you looking for? Steel is tempered to get a certain hardness for various purposes. You've got to use the right alloy for what you want to do if you want it to work a long time. If you only need it once, you can play a little looser, but most people don't intend to use a die one time. Really hard steel can cut soft steel, but it tends to be really brittle. "Glass hard" is one phrase used in some of the old books on tempering steel. I've done some of that, playing about. A file will just skid right off, but drop the tool and it can shatter just like glass. And the fragments are sharp! Here's a list of some tool steels that are used to make dies, and the types of dies they're used for. https://alloytoolsteel.com/products/A-2/A-2.html Again, that's just one manufacturer.

Here's a list of free downloadable books from around the turn of the previous century that might be of help:https://archive.org/search.php?query...pering%20steel I've got a bunch of books on metalworking from archive.org.

And if you need surface hardness on a tough core, you can use a case-hardening compound to do that. Kasenit was the gold standard for a long time, but it's hard to find now. Cherry Red is more easily available. You can use bits of bone and leather, even. Some of the books tell you exactly how to do that.

Here's more from Scribd.com: https://www.scribd.com/search?conten...eel&language=1 Gotta be a member, and after a 30-day trial it's about $10 a month. Lots of good info there for metalworking, gunsmithing, reloading, and a whole bunch of other stuff.

Bill

[DougGuy]

You have to have a hardenable steel to do what you want to do. Many grades of steel cannot be hardened effectively. B7 studs are a good example, they are already at their intended strength when you get them.

[john.k]

The cheap Chinese Gr 8 bolts are the hardest IMHO,just a plain carbon steel .....softest HT bolts Ive seen would be Caterpillar ,no doubt high grade alloy steel........The cheap bolts need to be softened to work ,then simply rehardened by heating and dunking in oil or water .......oil tends to be more effective for a beginner ,simply because if water forms steam around the piece ,hardening is retarded.........Do NOT do the oil dunk inside ,dont use an old sump oil that is milky ,it will boil over everywhere and catch fire.