Argon for heattreat

In a provious post, Ray Rogers was talking about using argon with your heattreat oven. Does anyone have this type of setup and if so what type of valves, fittings, flow rates are required. (Pics of setup appreciated)

Thanks in advance,

Bob Sigmon

Geno has this setup, maybe he will shed some light on it for you.

I have that setup. You can see a little of it in my shop tour at www.rayrogers.com/wauconda.htm

My oven is a Paragon and it has a factory setup for using argon. All they did was drill a hole in the back of the oven and screw a flange on the back with a piece of threaded pipe welded to it. They built in an argon regulator but you could buy your own (just like an acetylene regulator). Experiment with the feed rate but it doesn't take much witha continual feed....

Thanks, Ray.

Could you let us know how well it work for keeping down the scale? It obviously works or you'd be railing on it, but I would just like to hear you thoughts.

Thanks again,

Bob Sigmon

Bob,

I don't really have anything to compare it to. This is the only heat treat setup I have ever had and I've never been in any other knife maker's shop. I will say that before I had this rig I sent my blade to Paul Bos and he uses nuetral atmosphere ovens. After heat treating my blades look just like his. There is some scale or discoloration but nothing that isn't easily removed, and very light to no pitting depending on the steel...

Thanks, Ray.

If I may another couple of questions.........


1 Do you do anything specific in the way of ventilation when using the argon?

2 Does your argon manifold have a brand name on it? I would kinda like to look around and see what's available.

Thank you for all your information.

Bob Sigmon

You should do something for ventilation, but it doesn't require much. I used to have the heat treat setup in a shack outside my main shop so that solved that problem. Now it's in the main shop so I usually leave the door open and stay outside myself as much as possible. You only use the argon for the heat treat phase (not for tempering) so you're usually not talking about a lot of time anyway. The feed rate is so low that very little gas is released into the air anyway. You may make more blades than I do but it takes me about 6 months to use up a moderate sized (170 cu ft?) bottle of argon.

The 'manifold' is handmade. It's nothing but a few square inches of plate steel with holes drilled in each corner and a piece of pipe welded at 90 degrees to the center of the plate where there is another hole. What you attach to that depends on how fancy you can be. Paragon got pretty fancy with some kind of regulator/valve assembly that they could tie in to the electronics of their oven's control board. This way, the gas only feeds when the heating element has power going to it. That's real nice and saves some gas but it isn't necessary. An ordinary argon regulator, which you can get at any welding shop, will regulate the flow of the gas out through any gas line that you can attach to the regulator. The other end of the gas line goes to tha home made adapter which is mounted over a hole drilled all the way through the back, fire brick and all. Set the regulator for a very, very small feed rate and experiment until it looks good to you...

That's what I needed to know. I have basic ventilation in my shop and I'll just beef that up if I do the argon thing.

Thanks for the heads up on the regulator, etc. I stop by the local gas supplier, luckily about 3 block from the store that I work at.

BTW, I am brand new to knifemaking, so I have no idea how many knives I be producing. At first I sure the number will be low. I'm just trying to take my time setting up. I'm a real big fan of trying to do it right the first time. Saves Money in the long run.

Thanks for all you input.

Bob Sigmon

Ok, now I have a question.For years doing Mig welding we have used Argon/CO2 mixes, with CO2 being colder and the higher concentrate of Argon being hotter and cleaner.How does this effect the heat settings of the oven using a hotter atmoshpere? If it does not produce hotter temps then would any other inert gas result in the same effect? Dave

I'm not a welder so I may be way off base here but as I understand it neither argon nor CO2 support combustion. The idea in the oven is to displace oxygen, get it out of there. Since argon doesn't burn nor support combustion as oxygen does (that's why the say neutral atmosphere) it neith adds nor subtracts from the heat in the oven. Now, if the fact of the gas coming in and expanding should cause some cooling effect - and remember we're talking about a very low feed rate - then the electronics in the oven compensate for that automatically by turning up the heat. Basically, I think this must be a non-issue since the oven's documantation doesn't mention it.

My guess (guess, I said) on the Argon/CO2 mix is that the heavy CO2 helps keep the gas in place while MIG welding and would probably do the same in the oven although that's not needed because the door is closed and therefore does the same thing!

I use argon, but in the envelope, not the oven.
The oven takes too much,(constant flow of 10-15 CFH)
I just fill the envelopes that hold the blades and seal them shut.

Argon is 10 times heavier than air. Better to check out the ventilation for pet height. Pets that are closer to the ground will be affected more by the heavy gasses.
The CO2 mixture is to get a weld to lay down better.Not much application here in an oven. Some welding gasses mix three or more gasses in one bottle, no need for fancy mixtrures here. Anything that displaces oxygen will work.

The way I fill envelopes is to fold the envelope, put the blade inside, fill up envelope with argon and seal. I hold a lighter over the hole where the air comes out, when the flame goes out, the envelope is full. When the gas snuffs out the flame, just fold the top flap over twice.

Unless you are attempting to use argon at a large rate in a small confined space I would not be overly concerned about ventilation. Welders use argon all the time and the only time that it gets to be a concern is in the confined spaces. I have used it for thirty years. Argon will displace oxygen from the bottom to the top in a container as it is heavier than air. The amount of argon you would use in an oven is negligble.

Gene,

I just checked with Evenheat. They feel that their elements would not work well with an argon atmosphere.

Could you explain your system of delivery that you use for the argon/envelope method?

Thanks,

Bob Sigmon

Thanks Gene, I was curious as if any inert gas would work.When welding with CO2 the welds are much colder and the welder must be set at a higher amperage to weld. Using higher conentrations of argon allow the amperage to come down and result in a better cleaner weld.But I see the way you are using it the concentration does not affect the temperature around the knife.Verrrrrrrrrrrrry interesting.Dave.

Actually Bob, Paragon (my oven) says their elements don't work well with argon either, yet they still built it. I don't know about your oven but mine has an plain, coiled wire element that is about 4 or 5 feet long when you buy a new one. The documentation says that the argon atmosphere prevents the element from oxidizing and it needs to oxidize some to protect the wire and allow a long life. Bottom line according to Paragon: argon = shorter element life. Now, since you only use the argon for heat treat and not for tempering (a much more time consuming process) the elements seem to get plenty of time to oxidize. Anyway, mine last about 2 years and if that's a shorter life I can live with it. I'll do most anything to avoid messing with that foil...