Building my first forge - general questions and feedback

[Torque_576]

Hey everyone, this is my first post. I’m towards the end of building my first forge. It is of my own design and was constructed out of one 3/16” steel sheet. I acquired about 8 Clipper bricks from a local soda kiln. These are extremely hard - difficult to even cut with a diamond wheel. Additionally, I picked up about 10, what the seller believed to be K23 bricks. They’re very soft and can be shaped quite easily. I opted to make a box and inlay the Clipper bricks inside for the floor of the forge. Then I made the top a two burner and lined it with 2” of Kaowool. I welded tabs on the sides of both pieces so that I can easily remove the top for repairs in the future. I tried to design something with a lot of forethought so that it would last me as long as possible.

https://flic.kr/p/2m6QTXP

https://flic.kr/p/2m6QTSU

After doing more research, I’ve read that often times the hard bricks are better heat absorbers than they are heat reflectors. So my plan is to coat the entirety of the floor and the inside of the top portion with ITC-100 and try and prevent that heat absorption. I didn’t want to swap out the bottom with the K23 bricks because they’re so soft that I’m concerned that they would just wear away with use and sticking and dragging metal in and out of the forge. Luckily, I can still do that later on if I find that the Clipper bricks aren’t doing the job - hence the removable lid.

https://flic.kr/p/2m6UJxX

https://flic.kr/p/2m6QTSP

https://flic.kr/p/2m6UJxG

https://flic.kr/p/2m6RVzw

Currently, I’m at the Satanite stage of the process. I put some between the bricks for the floor and now I’m working on the lid - as seen below. I’ve done my first layer really thin after reading some other posts. And then yesterday I did the next thicker layer. I took the torch to it this morning after nearly 24 hours and the refractory begins to turn brown - almost as if it is burning. Is this normal? It makes me hesitant to hook up the burners and do a low quick burn. Should I wait until I’ve built up all of the layers and then do the firing of the burners or do it for each layer even if it begins to turn brown? I see a slight bit of cracking in the corners, which I need to repair. But I’m not sure if that should occur before or after the firing in case that crack grows.

https://flic.kr/p/2m6RVGR
https://flic.kr/p/2m6UJvh

Thoughts on the design? I have the floor hanging out on each side the width of one brick so that I can turn a brick on end to close off the forge when needed. But I can also remove it for working on longer projects. I also added all-thread handles on both sides for tool rests and for anything I want to add on in the future.

Thank you in advance for your input, answers, and advice. Cheers.

Seth

 

[Ron Raducanu]

I probably can't offer any useful advice, but I'd love to see some pictures, if you have any.

 

[Torque_576]

I probably can't offer any useful advice, but I'd love to see some pictures, if you have any.

I'm working on setting up Flickr now, as I believe that's the only way I'm going to be able to do this.

 

[Torque_576]

I probably can't offer any useful advice, but I'd love to see some pictures, if you have any.

Is that better? I attempted to upload photos.

 

[Natlek]

Currently, I’m at the Satanite stage of the process. I put some between the bricks for the floor and now I’m working on the lid - as seen below. I’ve done my first layer really thin after reading some other posts. And then yesterday I did the next thicker layer. I took the torch to it this morning after nearly 24 hours and the refractory begins to turn brown - almost as if it is burning. Is this normal? It makes me hesitant to hook up the burners and do a low quick burn. Should I wait until I’ve built up all of the layers and then do the firing of the burners or do it for each layer even if it begins to turn brown? I see a slight bit of cracking in the corners, which I need to repair. But I’m not sure if that should occur before or after the firing in case that crack grows.

I don t know about Satanite but some bricks do just that ,get brown and then with more temp. white.As far as i know that was organic part of glue burning.....

 

[Torque_576]

Anyone?

 

[Stacy E. Apelt - Bladesmith]

I did not reply because I wasn't sure you would like my answer. What you are building looks great, but the design has some flaws. It would have been better to make your post before you started, not when were half way done.
First - The hard bricks will need a layer of insulation under them. It can be an inch or two of kaowool, or a layer of the soft firebricks. You will have to make another base section with soft bricks or refractory wool to insolate the heat from the hard bricks. Without this insulation layer the heat from the hard bricks would radiate down under the forge and make the shell red hot.
Second - While the straight down burners are a popular style, a round or even hexagonal camber with angled burners is fare better.
Third - 3/16" steel is way overkill for a forge shell. While that isn't a bad thing in itself, when it gets hot it will stay hot for a long, so be cautious around the forge for a long time after use.

Firing/curing a forge is a slow process. Fire on low for a five seconds and let it sit for ten minutes. Fire for 10 seconds and repeat. Keep doubling the firing time and let it cool for ten minutes until you are firing for 30 minutes. Let it cool completely and then fire on high for 30 minutes. The bricks and refractory will change colors.

NOTE:
The hard brick floor will be a great heat sink to hold heat for more even HT, but it will take a good 30 minutes to fully soak before working in the forge.

 

[Torque_576]

I did not reply because I wasn't sure you would like my answer. What you are building looks great, but the design has some flaws. It would have been better to make your post before you started, not when were half way done.
First - The hard bricks will need a layer of insulation under them. It can be an inch or two of kaowool, or a layer of the soft firebricks. You will have to make another base section with soft bricks or refractory wool to insolate the heat from the hard bricks. Without this insulation layer the heat from the hard bricks would radiate down under the forge and make the shell red hot.
Second - While the straight down burners are a popular style, a round or even hexagonal camber with angled burners is fare better.
Third - 3/16" steel is way overkill for a forge shell. While that isn't a bad thing in itself, when it gets hot it will stay hot for a long, so be cautious around the forge for a long time after use.

Firing/curing a forge is a slow process. Fire on low for a five seconds and let it sit for ten minutes. Fire for 10 seconds and repeat. Keep doubling the firing time and let it cool for ten minutes until you are firing for 30 minutes. Let it cool completely and then fire on high for 30 minutes. The bricks and refractory will change colors.

NOTE:
The hard brick floor will be a great heat sink to hold heat for more even HT, but it will take a good 30 minutes to fully soak before working in the forge.

I appreciate the reply. I definitely want to hear the criticism. Honestly, I didn't join the forum until about this point in the build. Luckily, I still have time to make some tweaks to the base. Both the soft and hard bricks are 2.5" thick, so I have a fairly deep bottom to work with. Thoughts to cutting the soft bricks in half width-wise, then putting a layer of kaowool underneath that and a little layer of the Satanite and ITC-100 on top of that for the bottom? That would be pretty easy for me to do at this point. I understand the benefits of the hard brick with regards to the heat treat, but they are a huge pain in the butt to cut. Also, there's no chance that I want to make another base. It took forever, especially with my lack of time/welding skills available. The 3/16" steel was a material of opportunity as that's all I had laying around and thought I would make something diesel that would last forever.

At this point I have used only a torch to heat up the refractory. I but my second to last layer on today and will let that dry for quite a while before firing up the forge. I want to prevent as much cracking as possible. I'll keep everyone posted with the process. I appreciate your inputs!

 

[Torque_576]

I did not reply because I wasn't sure you would like my answer. What you are building looks great, but the design has some flaws. It would have been better to make your post before you started, not when were half way done.
First - The hard bricks will need a layer of insulation under them. It can be an inch or two of kaowool, or a layer of the soft firebricks. You will have to make another base section with soft bricks or refractory wool to insolate the heat from the hard bricks. Without this insulation layer the heat from the hard bricks would radiate down under the forge and make the shell red hot.
Second - While the straight down burners are a popular style, a round or even hexagonal camber with angled burners is fare better.
Third - 3/16" steel is way overkill for a forge shell. While that isn't a bad thing in itself, when it gets hot it will stay hot for a long, so be cautious around the forge for a long time after use.

Firing/curing a forge is a slow process. Fire on low for a five seconds and let it sit for ten minutes. Fire for 10 seconds and repeat. Keep doubling the firing time and let it cool for ten minutes until you are firing for 30 minutes. Let it cool completely and then fire on high for 30 minutes. The bricks and refractory will change colors.

NOTE:
The hard brick floor will be a great heat sink to hold heat for more even HT, but it will take a good 30 minutes to fully soak before working in the forge.

Additionally, there is always the option to purchase thinner hard bricks to use on top of the kaowool or soft brick. Just trying to use what I have before taking that route.

 

[Stacy E. Apelt - Bladesmith]

I would suggest using the soft firebricks as the bottom and put a 1/4" layer of satanite over them. Don't cut them in half.
As Torque suggested, you can purchase thin hard brick called kiln shelving as a floor if you want.
If you know a person or company that does tile/brick work they will have a diamond wet saw that will cut your hard bricks in a short time.

 

[Natlek]

I would suggest using the soft firebricks as the bottom and put a 1/4" layer of satanite over them. Don't cut them in half.
As Torque suggested, you can purchase thin hard brick called kiln shelving as a floor if you want.
If you know a person or company that does tile/brick work they will have a diamond wet saw that will cut your hard bricks in a short time.

In my muffle HT furnace which i buy from friend on floor is cast iron try .I try one piece for short time in my gas forge and it hold pretty good . Cast iron can handle temperature and rapid change of temperature ......Don t you think that can be used in gas forge over soft insulating bricks ? 5mm thick one will get heated fast and will hold that temperature which i think is good thing in forge ? Flux should not be problem i think ?

 

[Torque_576]

I would suggest using the soft firebricks as the bottom and put a 1/4" layer of satanite over them. Don't cut them in half.
As Torque suggested, you can purchase thin hard brick called kiln shelving as a floor if you want.
If you know a person or company that does tile/brick work they will have a diamond wet saw that will cut your hard bricks in a short time.

Here’s the only thing, I want to avoid remaking the bottom for the reasons listed above, which means I have about a 2.5” deep pan to work with. That’s why I was thinking I’d do 1” of kaowool, satanite, then the soft brick with satanite again on top of that for the floor. The only thing is at that point the brick will be too thick as they are 2.5” themselves, hence the idea of cutting them width wise and making them about 1.25” in width. Thanks for the replies.

 

[Stacy E. Apelt - Bladesmith]

Just put the 2.5" thick softy bricks in the 2.5" deep pan. Set the kiln shelf on top of them. You really don't need the satanite if the bricks fit snugly together.

 

[Torque_576]

Just put the 2.5" thick softy bricks in the 2.5" deep pan. Set the kiln shelf on top of them. You really don't need the satanite if the bricks fit snugly together.

Ok thanks, Stacy. I guess I was misunderstanding thinking you were saying there needed to be multiple layers on the bottom, but I suppose you were referencing the hard brick. They do fit snuggly together, which is good.

 

[Atlas Knife Company]

Unless you are dead set on using flux, just make the entire forge from the soft bricks. Tune your burners properly and you won't need flux. If you do need flux, which won't be very often, you can always use a stainless steel sheet/tray to catch the flux. You'll waste a lot less propane this way.

I understand you are likely copying the forges you see on TV, but those are blacksmith forges, and really inefficient for making knives. A swirling flame pattern, directed inward with a small rear opening will get much hotter and use less propane. The chamber will be more evenly heated, which is of great benefit for making blades.