As anyone made a long tempering oven?

[Aerindel]

Usually, I temper things in my kitchen oven.

However, I'm working on a crossbow prod now, and need to temper something both hotter...600º, and longer, than will fit in my oven.

Thinking it shouldn't be that hard to rig up an electric oven with a 600º capacity and say, 4' long or so....but wondering if anyone has just done it so I don't have to invent it first.

 

[Magus]

I made a quenching vat out of stainless tubing for BIG knives. My "oven" was a rosebud.
will this help?

 

[Magus]

 

[SoulSeeker]

I would say take 1-2 gas oven elements end to end and make one. Want it longer? Go 3. It may go through more propane but will get the job done.

 

[Magus]

The last big blade I tempered was over wood coals in a pit using a leaf blower.

 

[Aerindel]

I would say take 1-2 gas oven elements end to end and make one. Want it longer? Go 3. It may go through more propane but will get the job done.

I don't know how I would control gas burners well enough for tempering.

 

[SoulSeeker]

I don't know how I would control gas burners well enough for tempering.

There used to be available from Trader Joe's a high pressure regulator for propane to 60lbs. If you angle the burners and make a 1 to 3 manifold out of brass fittings you can control all 3 with the 1 regulator and 1 flow valve. I have a setup for my backyard foundry.

 

[Aerindel]

There used to be available from Trader Joe's a high pressure regulator for propane to 60lbs. If you angle the burners and make a 1 to 3 manifold out of brass fittings you can control all 3 with the 1 regulator and 1 flow valve. I have a setup for my backyard foundry.

Regulating the propane isn't the problem, its that I would need a thermostat for gas control, I'm sure they exist but no idea how to source or use one. This oven needs to be accurate within about 20º between 400º and 700º. I don' think I could manually set a regulator to maintain that temp. Even on the lowest possible setting I think the burners would have to turn off and on, so I would also need pilot lights for re-ignition.

I think electric is just going to be a lot easier for this.

My plan is to cut off the top a old hot water heater, insulate the inside, regular fiberglass should be fine for such low temps, place a electric range burner in the bottom, with a 240v thermostat set up 'somewhere' inside the tank.

With a relatively low volume, and basically no thermal mass outside of the part to be tempered, it shouldn't take that much of a burner to heat the space to the desired temp, then its just a matter of letting the part heat soak long enough to be sure its up to temp, and then turning the the thing off.

 

[Peanut]

Electric ovens are made to cycle on and off... GE says theirs have a temp cycle of plus or minus 30 degrees..

You'll find it much easier controlling gas heat for a stable temp than electric.

Check tool & die shops or machine shops. All their tempering ovens are gas. You might be able to hire them to do it for you. No idea what it might cost, doesn't hurt to ask though.

--------------------------------------

https://products.geappliances.com/appliance/gea-support-search-content?contentId=18068

Understanding Expected Oven Temperature Fluctuation
The Oven temperature fluctuation varies by model and each individual Oven can be different.

The temperature range can vary by + 30 degrees and – 30 degrees Fahrenheit as the oven cycles on and off for a total temperature fluctuation of 60 degrees.

This fluctuation is common for our Ovens. Some may fluctuate a little more, some a little less.

The temperature swing can vary by how and where you are measuring the temperature in the Oven.

The temperature swing can also be influenced by the room temperature or number of door openings.

 

[Canon29]

Haven't done such- my metal projects never exceeded the capacity of the ol oven. Im usually tempering @450.

A crossbow prod at 600 eh? And one that's closer to 4 feet long? Makin a monster eh?

Plan sounds pretty good. How long does the piece need to temper before cutting off the heat and air cooling? You might be able to get away with regulating it manually if you can control the heat, might be worth experimenting with ila little before buying a thermostat.

 

[Tirediron]

If I was doing this, I would use a couple of pieces of steel pipe, with screened wood ash for insulation. that way there is some thermal mass for temperature stability. maybe even a stand off third pipe inside and use indirect heating. I concept looks good in my head, don't know if it can out clear

 

[montanabill]

just for info I made a oven for curing powder coat at 400. I used the parts of a electric range and built the frame from square tubing and sheet metal insulated on the outside with fiberglass insulation...used the stove oven controller for heat regulation, didn't even cut any wires and had both oven elements and the four stove top burners all arrayed on the bottom of the oven..It was big enough to do a motorcycle frame.

 

[Aerindel]

just for info I made a oven for curing powder coat at 400. I used the parts of a electric range and built the frame from square tubing and sheet metal insulated on the outside with fiberglass insulation...used the stove oven controller for heat regulation, didn't even cut any wires and had both oven elements and the four stove top burners all arrayed on the bottom of the oven..It was big enough to do a motorcycle frame.

Yeah, unfortunately, normal ovens don't go up to 600º

 

[Aerindel]

Haven't done such- my metal projects never exceeded the capacity of the ol oven. Im usually tempering @450.

A crossbow prod at 600 eh? And one that's closer to 4 feet long? Makin a monster eh?

Plan sounds pretty good. How long does the piece need to temper before cutting off the heat and air cooling? You might be able to get away with regulating it manually if you can control the heat, might be worth experimenting with ila little before buying a thermostat.

Yep. 450 is my usual for blades, but for making springs you need to go a bit hotter.

Yes, I hoping for a monster. The first experimental prod has a goal of 500lbs. I have the metal for a second, that should be around 1000.

The prods are only going to be about 30" but I figure I may as well make this large enough to handle bigger blades, my quench tank is 48" so I will make the oven sized to take that.

How long, and indeed, the temperature, is unknown. Its very frustrating. You would think in 2025 this would be easy information to find, but AI has completely destroyed search engines and I have had no luck finding real data on heat treating for springs....all the AI's think they know better than me and think I am trying to make blades, from springs, rather than springs, from metal that is often used for blades.

 

[LadyLocust]

Usually, I temper things in my kitchen oven.

However, I'm working on a crossbow prod now, and need to temper something both hotter...600º, and longer, than will fit in my oven.

Thinking it shouldn't be that hard to rig up an electric oven with a 600º capacity and say, 4' long or so....but wondering if anyone has just done it so I don't have to invent it first.

Hubby uses a torch (oxy-acetylene) and watches his colors

 

[Aerindel]

Hubby uses a torch (oxy-acetylene) and watches his colors

I've done that before. Its worked well for blades, but the last time I tried that on a spring, it broke when I tried to span it.

 

[LadyLocust]

I've done that before. Its worked well for blades, but the last time I tried that on a spring, it broke when I tried to span it.

Hubby said that method requires a tremendous amount of attention.

 

[Aerindel]

Hubby said that method requires a tremendous amount of attention.

He is not wrong.

Its okay for blades because you are trying to get a differential temper anyway, a lot harder for a large spring where you are after maximum uniformity.

 

[Neb]

The answers of temp and time depend on the type of steel used and desired properties.

Form Gemini...

Tempering spring steel involves a balance between hardness and toughness, and the ideal temperature and time depend significantly on the specific type of steel and the desired properties of the spring. Here's a breakdown of the key factors:
General Principles:
* Purpose of Tempering:
* Tempering reduces the brittleness of hardened steel, increasing its toughness and ductility.
* It involves heating the steel to a specific temperature below its critical point, holding it there for a period, and then cooling it.
* Temperature and Toughness:
* Lower tempering temperatures result in higher hardness but lower toughness.
* Higher tempering temperatures result in lower hardness but maximum toughness.
* Time:
* Holding the steel at the tempering temperature for a sufficient time allows the structural changes to occur evenly throughout the material.
Specific Considerations:
* Steel Type:
* Different spring steels (e.g., 5160, 9260, 1095) have different tempering requirements.
* For example, high carbon steels will have different tempering requirements than alloy steels.
* Desired Properties:
* A spring that needs to be very flexible will require a higher tempering temperature than a spring that needs to be very hard.
* General Tempering Ranges:
* Generally, tempering temperatures for spring steel range from approximately 300°F to 1000°F (150°C to 540°C).
* Holding times typically range from 1 to 2 hours.
* Stress relief of pre made springs can be done at lower temperatures, such as 375F for one hour.
Practical Tips:
* Always consult specific heat-treating charts for the particular type of spring steel you are working with.
* Accurate temperature control is crucial for consistent results.
* Multiple tempering cycles can improve the uniformity of the tempering process.
In summary:
There is no one size fits all answer. It is very important to know what type of steel you are working with. Then to consult heat treating charts for that specific steel.


Ben

 

[Aerindel]

The answers of temp and time depend on the type of steel used and desired properties.

Form Gemini...

Tempering spring steel involves a balance between hardness and toughness, and the ideal temperature and time depend significantly on the specific type of steel and the desired properties of the spring. Here's a breakdown of the key factors:
General Principles:
* Purpose of Tempering:
* Tempering reduces the brittleness of hardened steel, increasing its toughness and ductility.
* It involves heating the steel to a specific temperature below its critical point, holding it there for a period, and then cooling it.
* Temperature and Toughness:
* Lower tempering temperatures result in higher hardness but lower toughness.
* Higher tempering temperatures result in lower hardness but maximum toughness.
* Time:
* Holding the steel at the tempering temperature for a sufficient time allows the structural changes to occur evenly throughout the material.
Specific Considerations:
* Steel Type:
* Different spring steels (e.g., 5160, 9260, 1095) have different tempering requirements.
* For example, high carbon steels will have different tempering requirements than alloy steels.
* Desired Properties:
* A spring that needs to be very flexible will require a higher tempering temperature than a spring that needs to be very hard.
* General Tempering Ranges:
* Generally, tempering temperatures for spring steel range from approximately 300°F to 1000°F (150°C to 540°C).
* Holding times typically range from 1 to 2 hours.
* Stress relief of pre made springs can be done at lower temperatures, such as 375F for one hour.
Practical Tips:
* Always consult specific heat-treating charts for the particular type of spring steel you are working with.
* Accurate temperature control is crucial for consistent results.
* Multiple tempering cycles can improve the uniformity of the tempering process.
In summary:
There is no one size fits all answer. It is very important to know what type of steel you are working with. Then to consult heat treating charts for that specific steel.


Ben

Yes, I am painfully aware how bad AI is on this subject. It actually impressive how many words It can use to say nothing. I really could have used it to write papers for me in Jr. high.

 

[Neb]

Yes, I am painfully aware how bad AI is on this subject. It actually impressive how many words It can use to say nothing. I really could have used it to write papers for me in Jr. high.

Exactly.

What type of steel are you working with?

Ben

 

[Aerindel]

Exactly.

What type of steel are you working with?

Ben

5160

 

[Neb]

5160

Gemini says...

Finding precise tempering charts can be tricky, as results can vary based on factors like:
* Specific 5160 composition: Even within 5160, slight variations exist.
* Heat treatment setup: Furnace accuracy, quench speed, etc., play a role.
* Desired hardness: The end application dictates the target hardness.
However, I can provide you with general guidelines and information gathered from reliable sources:
Key Tempering Considerations for 5160 Steel:
* 5160 is known for its toughness, making it popular for springs and blades. Tempering is crucial to balance hardness and toughness.
* Tempering involves heating the hardened steel to a specific temperature, holding it, and then cooling it. This reduces brittleness.
* Typical tempering temperatures for 5160 range from roughly 300°F (149°C) to 600°F (316°C), or higher, depending on the desired hardness.
* It is common practice to temper 5160 steel twice.
General Tempering Chart Information:
Here's a summary of tempering information compiled from the search results. Please note that these are guidelines, and testing is always recommended:
* Lower Tempering Temperatures (300°F - 400°F / 149°C - 204°C):
* Results in higher hardness, suitable for applications needing a sharp edge.
* May have slightly reduced toughness.
* Higher Tempering Temperatures (400°F - 600°F / 204°C - 316°C):
* Results in increased toughness, ideal for applications like springs or impact tools.
* Will have lower hardness.
* Information from New Jersey steel Baron indicates the following.
* 300°F / 149°C. 63 HRC.
* 350°F / 177°C. 62-61 HRC.
* 400°F / 204°C. 60-59 HRC.
* 450°F / 232°C. 57-58 HRC.
* 500°F / 260°C. 55-56 HRC.
* 550°F / 288°C. 53-54 HRC.
* 600°F / 316°C. 52-53 HRC.
Important Notes:
* Always perform tempering in a controlled environment.
* Double tempering is highly recommended for 5160.
* Consider the intended use of the steel when selecting a tempering temperature.
* Sites like knifesteelnerds.com provide very in depth information regarding the heat treating of various steels.
I hope this information is helpful.


Ben

 

[Aerindel]

Like last time, useless AI slop.

 

[Canon29]

Tempering with a torch is a no go. First off, the prods temper isn't just about adjusting hardness/toughness like you would a knife, it's primarily about flexibility. Which is quote a bit more difficult to get rigjt- especially at this scale. The issue with that is if you do it wrong, then crank 1000lbs of potential energy into it and it snaps its extremely dangerous to the person holding it or anyone nearby... so you're not speed tempering it with a torch for sure.

I'm guessing aerindel has plans for safety bindings, even after he gets his tempering oven squared away.

 

[Aerindel]

I'm guessing aerindel has plans for safety bindings, even after he gets his tempering oven squared away.

Indeed.

And wear armor designed to protect against being straight up SHOT with a 1000lb crossbow,

I'm too worried about safety....by the time I shoot it, it will have been drawn a bunch of times. Among other things I have to make a tillering jig just to string it.

But it's a $50 chunk of metal that took about four hours to forge. Breaking it would make me sad.