Building a Forge - Question

[amcardon]

*Changed the title to accurately reflect what I'll be using this for*

Hey guys. A friend of mine is finishing up his Masters in engineering and has to do a project. We were going through ideas that could be fun and as soon as a heat treating oven was mentioned we saw no further need for discussion So, going off the tutorial from british blades and making a few slight alterations we have all the bricks cut and most of the body/frame ready to go. So, to my question. When I picked up the firebrick I asked the guy about inswool and he said that that they had quite a bit of "scrap" that I could have and he gave me probably 15-20 sq ft of 1" inswool. So, this is a whole new ballgame for me and I was wondering if adding a layer of inswool between the brick and the frame would make any difference? I have never used a forge like this or used inswool or ever used firebrick so I don't know exactly how they insulate. Does the brick insulate so well that the outside of the brick doesn't even get hot? Would inswool do anything for insulation/efficiency or just act as a spacer with no thermodynamic effect?

Here's a shot of what the back of the forge will look like:

I was also wondering about the element. Do I need to buy a wrapped kanthal element? I have heard of people wrapping their own and I have access to a lathe and other equipment so I can wrap the wire myself very easily if its easier this way...

 

[Bill Burke]

I would put the inswool between the brick and the forge/oven body. All the brick only ovens that I have been around get quite hot on the outside. nice looking oven son far

 

[chris609]

Pre made elements are not that expensive check here for some as well as other supplies. http://www.duralite.com/kiln-furnace-studio.htm

 

[amcardon]

K - so with the inswool I know that the air pockets play a major role in its insulating properties but how will it function if crushed? I'm wondering about the bottom of the forge - if we line it with inswool it will be crushed by the weight of the bricks so it will greatly decrease it's density and thermodynamic properties. So, is it worth lining the bottom or is it a waste of time? I have enough room to either do a single layer on the top and bottom or 2 layers on top, which would be most efficient?

Chris - thanks for your link, I sent them an email. I think we have all the other parts ready to go: heat controller, SSRs, thermocouples, etc...

BTW - speaking of parts, the heat controller we are using has inputs for 2 thermocouples to equalize the 2 readings, where is the best placement for the 2 thermocouples?

 

[amcardon]

Ok, I have another question... (big surprise)

This HT oven should be pretty darn accurate with the equipment we will be using. There are 3 driving forces for us building the oven:
1) My buddy needs a project to complete his masters in mech. engineering and this fits the bill (and he's able to get the controller, SSRs, TCs for free ;-)
2) I am trying to make metal look/act like a knife and a HT oven will hopefully allow me to do the whole process start to finish
3) We are designing a knife for a Men's group at our church and will be making a run of about 20 knives and are trying to keep costs at a minimum and sending out for HT will greatly offset costs

So, now to my question. We are trying to decide what steel to use for the knives. Since I will be doing the HT is the HT process for 1095 gonna be out of my newb league? Should I go with 1080/1084? I really like the 1095 knives that I have (don't have any 1080/1084) and would like to do 1095 but a lot of people have made comments that it isn't the most newb friendly (or is that in reference to people trying to HT with a torch?) so I don't know which to go with. Doubt it makes any difference, but the blades will all be cut out with an EDM that my buddy has free access to.

So yeah, loaded question, but should we be okay using 1095? If "no," then what would you recommend?

Thanks guys.

 

[Bill Burke]

the only problem with 1095 is the very short amount of time that you have to go from the oven to the quench to get full hardness. Less than a second. and it requires a very fast oil or water/brine quench medium.

On the other hand 1080/1084 gives a little more time to get past the nose and it is more through hardeningdue to the manganese in it so will harden well in any reasonable quench.