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heat treating steel

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PeterT

Ultra Member
Premium Member
This isn't urgent, but just putting feelers out for down the road a few months. At some point I'm going to have to harden some smallish parts on my model engine, like the rockers, cam ring, maybe pushrod ends, the odd self-made profile cutter... For the most part I envision machining them from oil hardening tool steel & then hardened to some typical spec, hopefully with minimal distortion. Some of the bits will have a bit of machining time invested, so would prefer not to bugger them up myself using my back yard torch & douse method.

I've noticed some model engineers or knife making hobbyists invested in mini heat treat ovens like Paragon or comparable brands. http://www.paragonweb.com/Heat_Treating_Furnaces.cfm
The small ones run ~1000 - 1500$ (I haven't looked for used ones yet). I've also read about related 'details'; stainless foil pouches, nitrogen blanket to prevent scale, types/temp of oil, heat soak time...

So I'm thinking a smarter approach is to buddy up with someone (ideally): hobbyist + local + has this equipment + has the knowledge + for part time $$ or swap some service? Anybody know of a potential connection? Ideally maybe I can get my parts done & simultaneously learn some things to apply to a purchase one day.
 
Jwest7788

Jwest7788

Joshua West
Administrator
Well I don't have a direct connection, but I recently purchase a pottery kiln with several metal related uses in mind.

I'm still working out the kinks in using it, but heat treatment is a to do to cover off of the list at some point.

Keep me in mind down the road, no promises but i hope to have some of thelearnings you are working on too at some point.
 
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PeterT

Ultra Member
Premium Member
Thanks for the nice offer, I'm all for learning. I never thought of a kiln actually. (If this drifts off the intent of Classified post, I'm happy to re-create in more appropriate section). But just while we are chatting I think these are some typical O1 heat treating temps. Is this in the range of your kiln & basically what you were targeting using it for? (all deg F): 1250-1350 pre-heat + 1450-1500 austenite + 150 quench (that's the unrelated oil bath obviously) + 350-400 temper (yields 63/62 Rockwell). http://www.simplytoolsteel.com/O-1-tool-steel-data-sheet.html

Maybe one day we could gather together some sacrificial test projects to experiment & economize on your electricity bill. Bring on the shop-made center punches, dagger blades, can openers! I've heard some folks just use an oven for tempering for small parts, so maybe even kiln isn't required?
 
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Tom O

Ultra Member
Well on Madmodder's site there has been a few built arduino style control for ramping, temp range ect. even the code is posted. I also have my Dad's kiln downstairs in the laundry room but a heat treat oven is in the plan though.
 
Jwest7788

Jwest7788

Joshua West
Administrator
PeterT said:
Is this in the range of your kiln & basically what you were targeting using it for?
Click to expand...

Yep, electric kilns should be able to reach at least 2200F, which is considered "mid-range" for firing pottery. (The most common range is "low-fire" at around 1600F)

PeterT said:
Maybe one day we could gather together some sacrificial test projects to experiment & economize on your electricity bill. Bring on the shop-made center punches, dagger blades, can openers! I've heard some folks just use an oven for tempering for small parts, so maybe even kiln isn't required?
Click to expand...

While I'm not worried about the cost of firing (assuming 100% usage for 10 hours, it's $3.25 at Enmax's posted rate today) I would be happy to plan a day. @Janger and I are already planning on casting something or other at some point.


Tom O said:
Well on Madmodder's site there has been a few built arduino style control for ramping, temp range ect. even the code is posted. I also have my Dad's kiln downstairs in the laundry room but a heat treat oven is in the plan though.
Click to expand...
I do have to get temp control sorted out before moving to actually using the kiln, appreciate this heads up!

Other things to cross off the list before use:
Ensure I won't burn garage down. --> Check heat from hot air rising to roof won't be too hot
Full safety gear
Temp control / monitoring
 
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Tom O

Ultra Member
I wouldn't worry about the electric bill too much it cycles on / off so when it reaches your temp setting it just maintains it, cooling down takes a while and the heat when opened is not a problem either. For safety I just use a face shield welding gloves and a princess auto welding apron/chap the gloves I will pick up soon will have the better insulation reflective foil for higher heats. I also use a old leather coat but if you are just wearing a shirt make sure it is cotton the synthetic can melt and fuse with your skin!
 
Jwest7788

Jwest7788

Joshua West
Administrator
Tom O said:
I wouldn't worry about the electric bill too much it cycles on / off so when it reaches your temp setting it just maintains it, cooling down takes a while and the heat when opened is not a problem either. For safety I just use a face shield welding gloves and a princess auto welding apron/chap the gloves I will pick up soon will have the better insulation reflective foil for higher heats. I also use a old leather coat but if you are just wearing a shirt make sure it is cotton the synthetic can melt and fuse with your skin!
Click to expand...
Appreciate that, yeah I knew the electricity would be cheap, wasn't sure about the potential causes of concern for the hear inside the kiln.
Thanks! You've given me renewed confidence.
 
Mphenley

Mphenley

Member
Moderator
Premium Member
Does your kiln have a really low range, around 400F? Or do you not really have a reliable control in place? Depending on the interior size, I would think it might be usable to cure powdercoat paint as well...
 
Jwest7788

Jwest7788

Joshua West
Administrator
Mphenley said:
Does your kiln have a really low range, around 400F? Or do you not really have a reliable control in place? Depending on the interior size, I would think it might be usable to cure powdercoat paint as well...
Click to expand...
It has two temperature control knobs, so I can set the rough temp. (Without a pyrometer, I can set only in ~percentages of maximum, with an unknown maximum) haha

So yeah, need a pyrometer or some other way or reading high temp reliably.

Once I have a pyrometer or similar setup, then yes, it will be able to manage anywhere from lookwarm to hot hot hot.
 
Johnwa

Johnwa

Ultra Member
Jwest7788 said:
It has two temperature control knobs, so I can set the rough temp. (Without a pyrometer, I can set only in ~percentages of maximum, with an unknown maximum) haha

So yeah, need a pyrometer or some other way or reading high temp reliably.

Once I have a pyrometer or similar setup, then yes, it will be able to manage anywhere from lookwarm to hot hot hot.
Click to expand...
There is a temperature control on aliexpress

http://www.aliexpress.com/item/Dual...th-thermocouple-K-Relay-Output/638549196.html

It needs to be coupled to a relay

http://www.aliexpress.com/item/2014...te-Relay-Controller-3-32V-DC/32226842249.html

The relay needs a heat sink
http://www.aliexpress.com/item/New-...-Type-Heat-Dissipation-Newest/1695690418.html

The Ssr only turns off one leg of the supply. They also tend to leak a bit of current as a result the heating coils are alway energized so you should have a safety interlock that turns off both legs of the 240v supply when you open the kiln. Your kiln may have this. The alternative is to make sure you power off the kiln before you open it.
 
Johnwa

Johnwa

Ultra Member
Jwest7788 said:
Hey Johnwa, This is perfect, Thank you!

What happens if you open the lid when the coils are energized?
Click to expand...

Nothing as long as you're just taking a look. The problem arises when you reach in to take something out. It's too easy to make contact with the coils so better safe than sorry.
 
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Tom O

Ultra Member
I just ordered one of them it should be good for casting I saw a site a while back how to make a immersion temp control by putting the sensor in a graphite tube I'll see if I can find it.
 
Johnwa

Johnwa

Ultra Member
I've been doing a bit more research on the Aliexpress REX C100. I contacted one of the sellers and asked if they had one good to 1300C. He did respond but I think we have a language barrier. I think he said all of them were good to 1300C.?? I sent him another email pointing out the 0-400C range.

I also found this on YouTube
Apparently you can access a hidden menu and choose higher set points.
I happen to have one of these gathering dust on a shelf so I will give it a try.
 
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Tom O

Ultra Member
That will be interesting to check out when mine gets here I bought the1300 celsius one I wonder if it is maxed out or able to ge higher.
 
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