Amateur Rockstar Hopeful

[tmoore4748]

Hi everyone! Not much to tell about myself in this quick one, other than I'm super excited to get questions answered, as well as posting a few of my favorite shop projects I've completed. I'm an aircraft, motor vehicle, and marine mechanic, as well as welder, fabricator, carpenter, blacksmith, and all-around easily bored dude, so I keep up with as much as I can. No task too large, nothing too small!

[Jon]

Hi tmoore4748 - welcome to HomemadeTools.net

You'll fit in well here with those interests

What are you thinking of building next? Anything we can help with?

[tmoore4748]

I've got several huge ones, all mostly to do with shop organization. I'll be moving from NC to Washington (yes, the state) in March, so stuff has got to get mobile. My table saw cart is gonna get rebuilt from wood into metal; a wood bandsaw that needs extra pulleys for cutting metal and a mobile base for it; a new mobile base and dust filtration for my blasting cabinet; and a full teardown and rebuild of a Logan 1961 Model 1875 lathe, and all the extra toys you can think of to go along with that. Also rebuilding my Forge, building a 2x72 belt grinder (so I can finish my craftsmanship quickly), and tons of other similar stuff that's too long to list here. Like I said, I get bored really quick.

[Jon]

Sounds like fun. Keep us posted with pics.

[tmoore4748]

Here's a random one for the list of projects this weekend, the forge: I'm finishing my forge build, and plan on hardening/carbonizing a few tools once complete. I've used stainless foil before, but I'm all out. I do have stainless tape, the kind used for sealing ducting, that's pretty high quality 3M stuff; is that a suitable substitute, or will the adhesive mess with the hardening process in some unknown, strange way? I'm thinking it'll work just as well, as long as the edges are folded properly, as it'll just burn off if it's adhesive out, not touching the part, but I just don't know.

[turnings]

Here's a random one for the list of projects this weekend, the forge: I'm finishing my forge build, and plan on hardening/carbonizing a few tools once complete. I've used stainless foil before, but I'm all out. I do have stainless tape, the kind used for sealing ducting, that's pretty high quality 3M stuff; is that a suitable substitute, or will the adhesive mess with the hardening process in some unknown, strange way? I'm thinking it'll work just as well, as long as the edges are folded properly, as it'll just burn off if it's adhesive out, not touching the part, but I just don't know.

I am imagining that you are relying on the nickle/iron alloy of the stainless steel to over-lay an hardening surface to your tools. Normally impurities in the heating source will alter the final composition of the face hardening alloy deposition. Using oxy. gas as a heat source requires a neutral flame so an indication of the type of forge to be used, viz coal, charcoal, natural gas/air or electric arc is important as is the aging process of the forge construction, excess moisture will alter the hydrgen/oxygen calorific value of the fuel stream.
At best I would use an adhesive solvent to cleanse impurities, and try to ascertain the type of S.S.being used.

Turnings

[Geoff Keyes]

First of all, where in Washington are you headed? There is a pretty active blacksmithing community here, I can help you get in touch.

Second, I believe the word you are looking for is "carburizing" .

This manufacturing process can be characterized by the following key points: It is applied to low-carbon workpieces; workpieces are in contact with a high-carbon gas, liquid or solid; it produces a hard workpiece surface; workpiece cores largely retain their toughness and ductility; and it produces case hardness depths of up to 0.25 inches (6.4 mm). In some cases it serves as a remedy for undesired decarburization that happened earlier in a manufacturing process.

https://en.wikipedia.org/wiki/Carburizing

This is also called "case hardening". What material are you trying to harden? The stainless foil only protects the material from O2, which can be a problem trying to case harden steel (well strictly iron or mild steel, anything with less than .4 C). You are not going to migrate anything from the foil.

Traditionally, you prepped a piece of iron to case harden by packing it in a sealed environment with some kind of carbon rich medium, ground bone and cow dung we commonly used. This was then heated to about 1500 F for long periods, days often. My relevant text is packed, but if memory serves you get penetration of something on the order of 1/10th of MM per hour of carbon migration in 1 inch square stock. Once the material is carbon saturated, you then harden as normal.

It's true that you want a reducing flame for the HT process (O2 will leach your carbon back out of the steel quite fast) but steel when sealed up doesn't care how it's heated.

Today, when this is done they use big induction coils in a sealed chamber of CO2. No matter what, it takes hours at temp to get results.

Geoff

[tmoore4748]

Geoff, headed out to the base near Spokane. I've heard lots of good stuff about the base, so I'm hopeful. And thanks for the term correction (truly not being sarcastic, I'm just on my phone, so my brain is a little off). I'm familiar with the process, as I've hardened 1018 a bunch of times in the past for home made bits (I'm often too cheap to get tool steel, and have ready access from the local shop of off cuts), but, I had to learn it trial and error until my father gave me his old handbook, a 26th edition (he's an engineer). I apprenticed for a smithy in Germany for a few years, so I was able to get the basics, but as a machinist, I needed a better understanding, so I started experimenting.

[tmoore4748]

The alloy is 314 SS, made by 3M, for use in industrial heating and cooling, as well as aircraft. The adhesive on it is very strong, so you end up having to cut it off it adhered to something you didn't want, and if it somehow adheres to itself, both sides adhesive, it's not coming apart. No fun to work with unless you have gloves on, for sure, 'cause it'll cut up your hands in a heartbeat like shim stock. The Forge is mostly propane burn with forced air to charge, and for low carbon stuff it's just anthracite and forced air to get to hammering temps. I don't bother with annealing and heat treating in the Forge, it's all oven controlled based on the temp charts in the machinists handbook (just got my 30th edition!). For carbon requirements I mostly stick to ground up Kingsford, but I've been looking at higher quality alternatives, because I'm looking into making some shop tools, which will need more than case hardening for the tasks I'm looking at

[Geoff Keyes]

Most of the smiths I know are wet (West) side, but I do have some contacts on the dryside, including a good one for small amounts of tool steels.

The thing to remember is that bladesmiths have been HT carbon steels for 2K years, without tools more sophisticated than a magnet and their eyes. A pyrometer can be had for less than $50, so that is a good investment. Most of the information in the machinery handbook is good, but it's aimed at more industrial processes, the data is based on 1 inch cross sections. A .250 or less section often behaves quite differently. As an instance, L6, (an old formulation for industrial bandsaws) is a pretty standard oil quench steel, if you go by the handbook. In thin sections, it can be treated as an air quench steel. I did a test run of some hard duty tactical hatchets in L6. Air quenched I got 65Rc (+/- 1) on air quenched coupons and the axes. I tempered them to 55Rc and I can chop up concrete building blocks without damage to the edge. All of that was done in an electric HT oven. I have also gotten similar results using a gas forge.

It's difficult and expensive to get good coal out here in the West. If you are burning BBQ briquettes you might as well be burning wood scraps. You can buy lump charcoal at the big box stores if you must. Propane is really the way to go, though, depending on your design, it can be trouble running a forge low enough to HT, gas forges run well in the 1800 F to 2300 F ranges.

In my experience, the folks who use HT foil (BTW my steel supplier can get you rolls of it) are mostly guys working in the high carbon stainless steels, and even then, it's not needed, it just makes clean up quicker.

Geoff