# Frankengrinder needed a friend



## epicfail48 (Mar 27, 2014)

So i present to you the bride of frankengrinder, the heat treatment oven:









Fair warning, this is a fairly image heavy post, and gimme a break, i cant come up with a clever name for everything. First off, i want to say that this is a prototype, a proof of concept to see if i could build a furnace capable of reaching the temperatures needed to heat treat some of the more exotic steels. M2 HSS, for example, requires a prolonged soak period of 2200 degrees Fahrenheit to develop full hardness, so i needed something that could get that hot.

Im almost there. The body of the unit is soft firebrick, with 3 elements pulling a combined 19 amps of power and using that energy to heat an area roughly 14x9x3.5, plenty big enough for any knife i care to grind. Temperature is controlled through a fancy little PID temperature controller that can hold the temperature within a few degrees of where i want to set it, from 0 all the way to 2300 degrees, where the firebrick would start to melt. Or it would, if the temperature controller worked and actually shut power off when it was supposed to.

Anyway, full pictures of the setup below, but electricians and anybody concerned with safety, look away now!









Yes, that is a crap-ton of exposed wiring, yes i have the relay dangling in front of a fan for heat dissipation, no, none of the electrical connections are shielded as well as they should be, and no, i am neither stupid nor suicidal. You did read the part where i said this was a prototype, right?

Anyway, the proof is in the pudding as to how well it works, and this sucker gets really hot fairly fast. 1800 degrees in about an hour, if you believe the temperature controller: 









It also has the lovely effect of looking like a miniature portal to hell at heat:

















Plenty hot enough to bring a knife blank up to its critical temperature, ready for quenching:









Side note, anybody wanna guess how hard it was to get that picture? If you guessed somewhere between "very" and "sweet jesus christ thats hot where the bloody hell did i put my camera oh my god do i still have hair on my arm", you would be correct

And finally, a warning for anybody who wants to build their own; pay attention to wire sizing. Now, wiring everything up i made sure to over-engineer everything. 12 gauge cord going from the outlet to a pigtail, 14 gauge solid powering the controller and 10 gauge stranded feeding power to the elements. What i neglected to consider, however, was the outlet i had it plugged into. Originally, I was testing the oven by using an extension cord, and i was rather puzzled as to why it took 3 hours to get up to 1400 degrees, when it by all means it should get to 1500 in 30 minutes. The answer? Voltage drop. Measured under load, the normally 124v supply from my house outlets was dropped down to 108 volts at the oven. Doesnt sound like much, but it was a nearly 300 watt decrease in the raw power to the coils, not to mention lowering the temperature the heating coils were running at and lowering the max temperature i could reach. Lesson learned, avoid extension cables!

Now all i have to do is get a new controller so i can actually stay at a set temperature, and get some steel, and ill be ready to make that knife ive been planning in my head for the last month, complete with a full build thread showing everything start to finish!


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## Road rider (Jan 29, 2012)

Insane but very cool


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## Toolman50 (Mar 22, 2015)

Looks dangerous. I'd be afraid I'd catch the house on fire. 
Stay with woodworking. You don't have to heat wood to 2000 degrees.


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## epicfail48 (Mar 27, 2014)

Toolman50 said:


> Looks dangerous. I'd be afraid I'd catch the house on fire.
> Stay with woodworking. You don't have to heat wood to 2000 degrees.


Yeah, but steel is so much more fun!


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## Woodychips (Oct 3, 2015)

Holy crap! You do this indoors?!!!!


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## was2ndlast (Apr 11, 2014)

You're nuts....but funny. I like your style.


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## mikeswoods (May 18, 2009)

More pictures!

I've played with heat treating and tempering for awl blades and marking knife blades---all torch work.

I like the controlled heating that your oven allows---


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## epicfail48 (Mar 27, 2014)

Woodychips said:


> Holy crap! You do this indoors?!!!!


Its a lot safer than the pictures make it look. There's no toxic gas output or anything, the only issue is the heat output, but eben the the firebrick insulates so well that after 3 hours the outside is only barely hot.


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## epicfail48 (Mar 27, 2014)

mikeswoods said:


> More pictures!
> 
> I've played with heat treating and tempering for awl blades and marking knife blades---all torch work.
> 
> I like the controlled heating that your oven allows---


All in due time my friend, all in due time. I've got the seller I bought the temperature controller from shipping out a replacement, once that gets here I'll get everything wired in a slightly less risky fashion. After that, well, then I start doing build threads


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## k9scooter (Mar 5, 2014)

That's pretty cool! You live on the edge my friend..... I don't think the wife would allow that in my house... she knows me too well!


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## Burb (Nov 30, 2012)

Chris, this is really "cool"!!!! But in an insane kinda way!! I'm looking forward to see this come to fruition. 

Let me know if you need another fire extinguisher. I may have an extra...


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## epicfail48 (Mar 27, 2014)

Burb said:


> Let me know if you need another fire extinguisher. I may have an extra...


...crap, that would be a pretty good thing to have around, wouldn't it?


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## WesTex (Jan 5, 2014)

Only if you need to use it! 😏


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## epicfail48 (Mar 27, 2014)

*She lives!*

Got the new temperature controller in yesterday, so i got everything all hooked up and tested. Works like a charm now, been holding within 10 degrees of 700 for a little over an hour now, so shell do for my heat treatment and tempering needs nicely:









Ive got some more parts coming in, a heatsink for the relay and a few fans, and once those get here ill start building a proper enclosure for all the electronics. Really need that heatsink actually, that SSR get really bloody hot! 

After i get the electronics worked out i still need to get all the firebrick actually cemented together, and then build a slightly better enclosure for the oven proper. Ive already got the raw materials for a frame, in the form of 3 treadmill skeletons with some lovely thick-walled steel rectangular tubing, and my plan at this point is to cut the rectangle diagonally into steel angle, then weld that up into a nice frame to fit all the bricks in. Maybe skin it with some steel sheet. The only problem with that plan is that i dont own a welder. Or know how to weld for that matter. Ah well, problems for a different day i suppose. Still, i really need a better frame for this thing so i can build a door for it!


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## Burb (Nov 30, 2012)

This project is going to be an Epic Success!!! I was describing your idea to the guy making knifes at Silver Dollar City in Branson a few weeks ago and he was saying you've got a future in knife making!! He said you really sounded like you had the right spirit and could be the future. So, looks like you could get a summer job there if you want it LOL...



epicfail48 said:


> The only problem with that plan is that i dont own a welder. Or know how to weld for that matter. Ah well, problems for a different day i suppose. Still, i really need a better frame for this thing so i can build a door for it!


I could have helped you more a couple weeks ago but that welder & plasma cutter sold in less than 24-hours from me posting it for sale.


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## epicfail48 (Mar 27, 2014)

Burb said:


> So, looks like you could get a summer job there if you want it LOL...


...you have no idea just how awesome that would be


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## Burb (Nov 30, 2012)

epicfail48 said:


> ...you have no idea just how awesome that would be


Don't be afraid to set your sights high. I'd encourage you to focus on learning just as you are. There's no reason why you couldn't work there in the next few years.


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## hwebb99 (Nov 27, 2012)

Not knowing how to weld is no excuse for not making ugly welds like these. Not having a welder is a bigger setback. The only way to learn to weld is to get out in the shop and melt some metal.


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## epicfail48 (Mar 27, 2014)

hwebb99 said:


> Not knowing how to weld is no excuse for not making ugly welds like these. Not having a welder is a bigger setback. The only way to learn to weld is to get out in the shop and melt some metal.


Call me cocky, but i have no doubt that after a few practice swipes (okay, a lot more than a few) i could manage to lay a decent bead with a welder. The main issue for me is, well, i dont have a welder, and buying one is a little out of my price range, what with the 2-300ish for a welder and the 80 for the helmet and the 20 for the gloves and the 30 for the apron...

This stuff adds up quick!

Side note, i have no issues melting metal, the problem is doing so in a controlled way...


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## epicfail48 (Mar 27, 2014)

So yet another small update, i finally, err, liberated a clamp-on ammeter from work so i could check out just how much power im drawing. The results were... puzzling. With 3 coils, each at 20 ohms resistance, wired in parallel, i should be getting a resistance of the coils all together of roughly 6.7. Checking them with a multimeter, the total coil resistance was actually 7.something, so close enough. Now, using ohms law, the voltage over the resistance should give me the current, so 120/7= roughly 18 amps of power draw. Thats the way the math should work out, and the fact that this bloody oven keeps tripping a 20 amp circuid braker with nothing else but a fan out it would support that. Heres the weird part though, the meter only read 15 amps. 

So yeah, screw it, i broke math. No idea how the merry devil that one worked out, but im going to assume that the meter i grabbed was a little faulty and go to bed...


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## hwebb99 (Nov 27, 2012)

epicfail48 said:


> Call me cocky, but i have no doubt that after a few practice swipes (okay, a lot more than a few) i could manage to lay a decent bead with a welder. The main issue for me is, well, i dont have a welder, and buying one is a little out of my price range, what with the 2-300ish for a welder and the 80 for the helmet and the 20 for the gloves and the 30 for the apron... This stuff adds up quick! Side note, i have no issues melting metal, the problem is doing so in a controlled way...


 My welding skills have improved greatly with only a small amount of practice. Mig welding is almost fool proof, but stick welding is a lot harder. Who needs gloves and an apron? If you go with a mig welder you forgot about needing a gas cylinder.


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## shoot summ (Feb 21, 2014)

hwebb99 said:


> My welding skills have improved greatly with only a small amount of practice. MIG welding is almost fool proof, but stick welding is a lot harder. Who needs gloves and an apron? If you go with a MIG welder you forgot about needing a gas cylinder.


You can use flux core in many of the smaller migs with decent results. I did for some time. Adding gas changes it completely, makes for better welds, and much cleaner. 

I've got a Lincoln 135, got it in the clearance rack at HD for about $200, had a ton of stuff with it as well, like they just cleaned out the excess welding aisle.

I keep looking at a bigger Miller unit, but can't justify the $1K spend on something I'm not exhausting the limits of today.

A good auto darkening helmet is mandatory for a beginner, many of the sub $100 units meet the ANSI standard and are quite usable.

Gloves to me, are necessary as I'm always positioning a support hand near the action, and don't like to get burned. HF has gloves cheap.

An apron isn't required, but covering up in old clothes is suggested. Sparks go places you don't want them, and exposed skin will eventually get "sun burned".

Clamps and magnets help also, as well as a good surface to weld on. HF has all of these covered at a decent price as well. Their welding table is actually pretty decent.

The biggest thing to remember welding is proper heat penetration of the object(s) being welded, I've fixed a number of welds for friends that just globbed the weld on the surface with no heat penetration, the parts separated under load.

A nice attribute of the smaller 110V welders with flux core is the ability to take it places to weld. I built the mounts, and welded these gates in place with my little Lincoln.


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## hwebb99 (Nov 27, 2012)

I also wear gloves because I like to touch hot parts without getting burned. I also wear them stick welding because the splatter is more severe than a mig and burns you. A 110 volt welder works ok for minimal use. You will just have to properly bevel all the pieces and clean them really good. You will also have to keep your welding secession short or you will trip the duty cycle of the welder. For high strength applications you should bevel and clean your parts even with a good welder, but I get by fine welding rusty crap. If you have a wood stove those gloves serve double duty of putting wood in the stove without getting burned.


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## shoot summ (Feb 21, 2014)

hwebb99 said:


> I also wear gloves because I like to touch hot parts without getting burned. I also wear them stick welding because the splatter is more severe than a mig and burns you. A 110 volt welder works ok for minimal use. You will just have to properly bevel all the pieces and clean them really good. You will also have to keep your welding secession short or you will trip the duty cycle of the welder. For high strength applications you should bevel and clean your parts even with a good welder, but I get by fine welding rusty crap. If you have a wood stove those gloves serve double duty of putting wood in the stove without getting burned.


I've done a lot of welding with my little 110V Lincoln, and have yet to trip the duty cycle. I know what you are saying, but so far, for me, it hasn't been an issue. I calculated the total length of welds in the wood rack I built(pic below) to be 16', did it all in one evening, my duty cycle was beyond tripped...


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## Maylar (Sep 3, 2013)

Nice project with the oven. I looked into that a while back when I thought I'd try my hand at knife making, but discovered that I didn't want to become a metallurgist :blink: So I buy the blades from someone else and just make handles.

As for welding, I took a night class at the local tech school and learned what I needed to know. It's a handy skill to have sometimes.


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## epicfail48 (Mar 27, 2014)

Maylar said:


> Nice project with the oven. I looked into that a while back when I thought I'd try my hand at knife making, but discovered that I didn't want to become a metallurgist :blink: So I buy the blades from someone else and just make handles.
> 
> As for welding, I took a night class at the local tech school and learned what I needed to know. It's a handy skill to have sometimes.


I've noticed that the steel is one of those things that gets massively overcomplicated when people talk about it, but in real life is dead simple once you get your hands on it. Sure, there are some complicated steels, but most of the common knife steels are "heat to temperature x, cool in cooling medium, heat again to temperature y".


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## epicfail48 (Mar 27, 2014)

*Another update!*

So the heatsink and fans i ordered finally came in, so i was finally able to work out the electronics box:









Nothing fancy, just 1/4 mdf, butt jointed, glued and brad nailed. An inside view:









Perhaps a little large, but i wanted to make sure id have room for sufficient airflow, as well as room to work around all the wiring. I also wanted to leave a little extra space for a second SSR, in case i ever decide to convert the oven to 220v. Nothing fancy on the inside either, just a bunch of pretty simple wiring, and a 12vdc power supply to run the 2 120mm fans, the kind one would normally use in a computer. 

Finally, its a little less of a fire hazard! Not much, mind you, but a little...


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