Induction heater coils for the Blacksmith 

Go for it. You'll find it adequate for all types of small work.

Cool but not yet practical. But in a similar vein, Evan Blackstone (who has a great overview video: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-GU6n488i2mI.html) has 3d printed bending forms. At the extreme, you could even melt the plastic out much like I burn wood forms out of mine.

A one or two loop coil on the outside should work. You can use tubing as small as 3/16", which would minimize the required space. Heating from the inside is problematic.

@@ejoftheanvil Thank you , that saved me from trying inside heating.

I do find the flex lead useful. It is awkward attaching it to the induction machine and then attaching a coil. But, it's less annoying than dragging out my oxy-acetylene so I don't regret having it.

Plate is trickier. Anything too large to fit in a loop of some shape will heat less efficiently. And with only about 2" of coil length, you can hit that size quickly. You're pretty much stuck with a flat coil. I do need to talk about how a flat coil works (the ones shaped like a stove top burner). That's definitely on my todo list.

@@ejoftheanvil I know quite a few armourers who would be very interested in watching such a video :)

I have one, but it doesn't seem to give very useful results. A better meter might help, but the tricky part is that the inductance changes enormously when metal is inserted into the coil for heating (and it changes further as the metal heats, esp after the austenite phase transition). I'd at least need to measure it with various types of stock inserted and that's complicated by the fact that forging will be changing the metal each heat...

That's a safety feature of the hotplate, not a limit of the technology. I can heat anything that conducts. I have soldered copper (as you saw). I've also used the induction heater to forge brass, copper and aluminum.

@@ejoftheanvil Thank you for the clarification!

Yes, see this video: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-KDkcZ3UpDvI.html . It's not quite that long, but it could be and still be viable.

The documentation says "no". I suspect it's possible. Steel melts at a high temperature which would require special consideration.

he has! ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-xEdp4ULeK_4.html

See my reply on "Induction Blacksmithing: replace your torch with a flexible induction wand". As for maximum length, maybe 4 feet, but shorter is better for performance. Mine are 32 inches.

You could do a 2 loop coil that big. Depending on what you heat, you *might* be able to do 3 loops.

@@ejoftheanvil thank you

I think that would be hard. Further, a hot plate is usually 1800W instead of 7500W. So, even if it worked it wouldn't be very effective.

Definitely a good option. 5/16" will flare enough to use with 8mm flare nuts. My personal preference for 1/4" is that I can get it "anywhere". 5/16" is not something I can pick up at my local hardware store. (Tho it's much easier to get than 8mm.)

@@ejoftheanvil, thanks for the quick feedback! I have multiple 8mm flare fittings, and my local hardware store actually had 5/16 copper pipe!

Hi, again! I have been banging my head against the wall trying to make an oblong coil to do wider stuff. Any tips, or better yet, do you make and sell coils, lol?

@@ejoftheanvil, Hi, again! I have been banging my head against the wall trying to make an oblong coil to do wider stuff. Any tips, or better yet, do you make and sell coils, lol?

@@MinionsSmithy Let me know a bit more about the issues you're experiencing. It's probably easier if you contact me directly as the comments here are not great for details. Look for my contact info on the Saltfork Craftsmen web site.

Up to 70 amps

@@ejoftheanvil I apologize for the confusion, I should have been more specific. I was specifically asking if the load from the outlet ever exceeded 20A

@@H-D52 That's the 70 amps, which is why a 110V configuration is generally impractical. You can get 70A, but only by wiring directly to the supply with absurdly thick wires.

@@ejoftheanvil I went back and watched your 110v vs 220v video and it makes more sense now. Is there anyway you could do a comparison video of the 110v hookup with standard 20A circuit heating metal vs 220v?

@@H-D52 I may do that at some point. I'd need to wire up another cable to do that with mine. For now, I'll just describe the issues. Basically, full power is 7.5kW (the 15kW figure is a lie that I note in my video). 20A 110V gives you 2.2kW. So, 220V is 3.5x more power. The first issue is that the induction heater doesn't limit itself to 20A. You'd have to fiddle with the power output setting to find the point where you don't trip your 20A circuit breaker. It'd be somewhere about 30%. The second issue (and essence of your question) is heating time. It will take 3.5x longer to heat things. Consider 3/4" rod. That takes up to 60s from cold with my optimal coil for that size. So, 3 1/2 minutes. But, it'd be worse than that because the metal is losing heat. I'd guess it'd take over 5 minutes. (And would give you a bit over 30s of hammering time.) Worse, 3/4" is big enough that it might *never* get up to a good heat because heat loss is faster as it gets hotter and at some temperate you lose heat as fast as you add it. My guess: 1/2" could get to a welding heat, 3/4" to a good forging heat, and 1" only a low forging heat.

Good ideas! I have also considered salt or sugar as internal support for bending tubing, but never tried. Sand would work as well, but could be a pain to remove unlike salt or sugar which would dissolve in water.

@@ejoftheanvil I'll have to try the salt, that is a good idea. If that works it will be great to not have to plan ahead. Thanks again.

I have greatly enjoyed your videos. Your comments on matching the coil to the work is right on the money. The problem is that while using flare nut connections for coils is fine for semi-permanent coil connection, it is a very poor choice for coils that must be frequently changed. Having worked with induction coils in the past, the first thing I did was to make very simple quick connections for my coils. Coils can then be changed without any tools in less than one minute, removing the tendency to live with a poorly matched coil. The quick connect removes all the issues that you frequently mention about metric flare nuts and tubing sizes as well as wear on the fittings. I would send you some photos, but this forum provides no method. On a separate topic, coil shorting from work contact can be eliminated by coating a regular fiberglass cloth sleeve with kiln wash made of finely divided Zirconium Silicate (Zircopax Plus) plus colloidal silica solution mixed to a creamy consistency. Unlike bare fiberglass sleeving, the coated sleeve is totally impervious to contact with work heated above forge weld Temperatures. At the end of the day when the hand gets shaky the liner is very beneficial. The sleeve is only about 0.01" thick allowing full use of the coil interior. Because of the extremely high infrared reflectivity of zirconium silicate, heat loss from the work piece is significantly reduced. An extended sleeve past the coils allows for work to be heated over a significantly longer length without thermal radiation cooling Keep on videoing

@@jimmyjohnson7241 You can find my contact info at www.saltforkcraftsmen.org/Contactus.shtm . I'd love to see pictures of your quick-connect setup. Perhaps I can feature them in a follow-up video?

Yes. The coil I forgot to show is a single long and narrow loop that I made for heat treating the cutting edge of a draw knife.

Yes. I have a 40A breaker. I used to have a 30A breaker, but the unit can draw enough to trip in in rare circumstances. It's 7.5 kW. Some 220 v units actually say 15 kW, but they're not. They are 15 kVA (maybe), but that's just a technicality that makes for a more impressive spec and doesn't really mean anything.

I'm not really set up to do that.

400by400mm heater koyal