Induction Work Coils for Brass Cartridge Annealers - Part 1: Design

[@Tin_Bender]

This is the best practical explanation I've seen of coil sizing. It's stated in the video to size the coil close to the workpiece for maximum efficiency. This is true, but I will add, if the builder wants to use a more affordable 600W Mean Well power supply, increasing the diameter will be necessary to lower the amperage to specs. This series of videos has convinced me to start a scratch-built, Raspberry Pi Pico controlled version of this annealer with a better GUI.

[@frenchcreekvalley]

I think you have done a really good job here. My only comment is that I suggest the you keep the frequency BELOW about 110 kHz to minimize stress on the Mosfets. With lower frequencies, they (the Mosfets) spend less time in "Linear Mode" and act more like a simple on-off switch that a variable resistor.

[@TechDregs]

I think my actual frequency on my system ended up being around 75khz. It's surprising how a little manufacturing error changes the coil inductance. Just a little more gap between the windings, just a little spring back so the inner diameter isn't as tight as planned.... I ended up with quite a bit lower frequency than my target. Still works great, fortunately.

[@frenchcreekvalley]

@@TechDregs Yes. I think you got your center to center coil distance calculation a little too short since you didn't account for the insulation (4.7 vs 5 mm isn't very much) I usually figure that my calcs will get me within about 25% or closer to the actual measured frequency.

[@NirNova98]

Hey good evening, I made a 3,500 W induction heater (220v17a / 48v~50a), and I need help, because I’m not that’s good with coils 😅 I made an induction heater just for fun , melting copper tables, and I want to move on from a tiny cup to a bigger one, but I don’t want the resistance to drop down due to more material that I will put inside the coil (also, I want the diameter of the coil to be bigger). So the issue is I don’t know what amount of turns and the size it should be. If you can help I will very appreciate it 🙏🏼

[@TechDregs]

Well, the video contains anything I can tell you. It depends on how your resonant system works... presuming you're using something similar to mine, you have to see what the capacitance is, and then use the formulas to determine what inductance your coil needs to have to hit the frequency you want to heat your material. Then, you have to design your coil to hit that inductance. I would figure out what internal diameter I want and whether you are ok winding a dual layer coil. Then start seeing how many turns you'd need using the websites I linked. If you need a lot of turns, you're probably going to want to dual layer the coil so it doesn't get too long (unless long is ok).

[@ChrisBriedenhann]

Just checking, did you change out the 470nf caps for 330nf caps

[@TechDregs]

You mean from the original Schematix version? Yes, but mainly because that's the value that I could easily find for higher frequency rated capacitors. I used capacitors meant for induction cookers.

[@ChrisBriedenhann]

Thanks, great info on all your vids

[@mastermoarman]

have you ever considered doing a 2.1666 turn 3 layer coil?

[@AquaTech225]

What’s the fiber sleeves used called

[@TechDregs]

Fiberglass sleeve. :-)

[@ericwh86]

how did you choose the frequency you are targeting?

[@TechDregs]

Cartridge walls are roughly 0.3-0.5mm thick. That penetration depth in Brass occurs around 70-200khz (depends on temp). See pg 63: www.routledgehandbooks.com/pdf/doi/10.1201/9781315117485-3. For thicker iron pieces, you want lower frequencies. Most systems keep the frequency above 20khz to avoid creating audible noise, although your pets may still be bothered by it. :-)

[@umbra3324]

@@TechDregswhat book are you referencing? Link only takes me to the home page

[@TechDregs]

Yeah looks like they took it down. Handbook of Induction Heating (ISBN 9781315117485). You use to be able to view the PDF.

[@umbra3324]

@ thank you so much. I just found your channel. I love your vibe. Keep up the great work

[@rx0-7]

Bro what if we provide the glass fibre coating (sleave )for the coil to prevent by getting heated from the bullet shell?

[@TechDregs]

The fiber sleeve is mostly just to make sure that nothing shorts the coil. It won't prevent the coil from getting pretty hot during use.

[@fixedgear37]

the sleeve does nothing for heat, water cooling is there for a reason

[@DLN-ix6vf]

There are a bunch of you guys on KZbin promoting DIY induction coil annealers. Why don't you manufacture one, get it Govt. approved and market it at a good price. Then we don't have to buy one made in New Zealand, if you can get one. Maybe all of you DIY guys get together and build one.

[@TechDregs]

I've thought about it. The main reason is that it's not worth leaving my current job.

[@DLN-ix6vf]

@@TechDregs no guts no glory.

[@evgenitv2679]

studio.kzbin.info/door/TA7XGTBn0Hw5m7jUWtSV_gvideos/upload?filter=%5B%5D&sort=%7B%22columnType%22%3A%22date%22%2C%22sortOrder%22%3A%22DESCENDING%22%7D

[@stepannovotny4291]

jeez, by the time you've inserted your work-piece into the coil, the inductance will change completely so just wing it and adjust your turns based upon actual outcome.