Gas forge shape reconfiguation

[Joel OF]

Hi folks, I've finally got round to giving some proper thought to the ugrade / shape reconfiguration of my gas forge which will utilize the burners I salvage from my existing forge and I'd really appreciate it if some folks could advise whether my ideas seem ok.

I have attached some images of my existing small farrier forge, which really isn't working for me in terms of shape. The burners on this forge are 1,1/2" or 38mm in new money.

I have also attached basic line drawings showing the internal working area dimensions of my existing forge (shaded in with diagonal lines) and the size I plan to reconfigure it to. The little vertical red lines are where my burners are currently placed and where I intend to move them to. Hopefully it's clear that what I want to do is make the forge wider, shallower in depth and taller in height.

Incase you can't read my writing, the internal working area dimensions of my exisiting forge are:  Width 10,1/2"  Depth 8,1/2"  Height 3,1/8"  Cubic inches = 278
The internal working area I think will work better for me is:  Width 13,1/2"  Depth 4,1/2"  Height 4,1/2  Cubic inches = 278

On my forge as it is the burners are spaced 2" apart. Do you think where I intend on moving the burners to looks about right? I have drawn them 4,1/2" apart.

Although I haven't designed the doors yet I intend to have vertically opening doors on all 4 faces. The idea behind this is so that I can turn the forge through 90 degrees to either give me quite a long heat on a small number of bars going in the 4,1/2" x 4,1/2" doors, or a relatively short heat on lots of bars going in the 13,1/2" x 4,1/2" doors. I'm not a bladesmith.

Having spoken to a refactory supplier I would be insulating the walls and roof with an inner layer of 3" thick soft refactory fire brick rated for 2550F (1400C), followed by an outer 2" thick layer of ceramic fire blanket. I will try and design the doors so they also have this brick + wool insulation in them. From memory the supplier's advice was to have a 1" thick 42% alumina dense fire bricks on the floor rated for 2730F (1500C), followed by the soft fire brick and wool underneath. By comparrison the insulation on my existing forge seems pretty rubbish.

Gas forges confuse me quite a bit, I really don't understand the terminology much but I'd love it the wiser ones could cast their eye over these plans and give me a thumbs up / thumbs down in language I can get my head around. Thanks in advance.

[Mikey98118]

The new forge shape is a big improvement; ditto for the new burner position. However, you can buy Thermal Ceramics K26 insulating bricks from eBay, and I recommend you look into them thoroughly before wasting your money on out of date tech.

[Joel OF]

18 minutes ago, Mikey98118 said:

The new forge shape is a big improvement; ditto for the new burner position. However, you can buy Thermal Ceramics K26 insulating bricks from eBay, and I recommend you look into them thoroughly before wasting your money on out of date tech.

Thanks for the quick reply. I looked up the bricks you mentioned but they seem to only be available in the US and I'm in the UK.

Unfortunately I'm very green when it comes to gas forges and wouldn't have the first clue as to what's new or old tech. The only comment I could make on the insulating fire brick I have been guided towards by a supplier is they called it a Grade 26. I'm aiming to keep things simple as you may have already noticed my intended dimensions for the new forge shape is based on cutting 9" long soft fire bricks in half.

One thing's for sure, on this forge at least I don't want to go down any route of casting insulation. I thought I'd just knock that on the head before anyone suggests it 

[Mikey98118]

How ironic; Thermal Ceramics are one of the Morgan companies; you may find the product is just misplaced from view...

Were to find stuff is always a struggle, even in the US market; you guys at the other end of the pond need to stick together; especially about sharing sources. If I was in your shoes, I would look to the bladesmith groups for information first, and then inquire through Morgan. I believe they make these bricks in India, so you should be able to find them in England

[Frosty]

Not to be picky but those are 1/2" burners NOT 1 1/2". The burner size and output are determined by the narrowest part of the burner, the throat. Most modern burners are made with plumbing pipe so it works out to the same as the whole tube.

Note the full length taper on the mixing tube. This feature is what allows these burners to put out as many or more BTUs/ minute than much larger pipe burners.

You might have to contact the company to find out what name they're marketed under in the UK. I think companies do that to make book keeping easier which helps avoid taxes . . . legally of course. 

Frosty The Lucky.

[Joel OF]

7 hours ago, Frosty said:

Not to be picky but those are 1/2" burners NOT 1 1/2". The burner size and output are determined by the narrowest part of the burner, the throat. Most modern burners are made with plumbing pipe so it works out to the same as the whole tube.

Cheers for the tech info. I'm taking it as a positive that it's the only thing you picked up on.

[Frosty]

They're good forges even though I can never remember the name. Metalmangler has one just like yours with a liner in worse shape and it works fine. 

I'm ignoring the rest, I can't believe you posted a picture displaying that kind of . . . art? work. Have you NO shame man?! 

Better? 

Frosty The Lucky.

[Joel OF]

18 minutes ago, Frosty said:

They're good forges even though I can never remember the name. Metalmangler has one just like yours with a liner in worse shape and it works fine. 

I'm ignoring the rest, I can't believe you posted a picture displaying that kind of . . . art? work. Have you NO shame man?! 

Better? 

Frosty The Lucky.

Ha! No I meant I'm taking it as a positive you didn't pick up on any of the shape reconfiguration details. E.g burner positions.

i.e if my only obvious mistake is how I described the size of the burners, all else must be in good order.

[Frosty]

Oh, the drawing. Not sure what all the red marks are. I assume they're proposed burner positions but we speak different blueprintese. 

I'd go for the wider position in your drawings. The ratio in the forge you have now is pretty close to optimum spacing.

Frosty The Lucky.

[George Geist]

6 hours ago, Frosty said:

They're good forges even though I can never remember the name.

Valley Hot Box.

Is one of the better ones.

George

[Frosty]

That's the one, thanks George. 

Frosty The Lucky.

[Everything Mac]

Looks good to me. When you say you want to have doors on all 4 sides though, how are you going to support the roof? Or are you having it open on 3 sides with a solid back?

Grade 26 bricks are what I've been using. - Well that's not strictly true. I've been using ceramic blanket and a dense castable refactory in my little forge but the mk2 version I'm building will be using the grade 26 bricks. I believe the 26 are better at insulating than the higher grade 28's.

You can't go far wrong with either a dense brick or castable floor backed by some insulating material. I've gone for a 2" block with an inch of blanket under it, which should be ok. 3" insulation brick walls / roof.

I'd be very interested to see what door design you come up with.

All the best
Andy

[Joel OF]

Thanks for the tips @Everything Mac

You've clearly thought a bit further ahead than me in terms of construction seeing as you're questioning the roof! T.B.H I don't know yet, I haven't drawn it up. I suspect something along the lines of channel section at the corners (2 pieces per corner, 1 facing width ways and 1 facing depth ways) to allow verically raising/lowering doors to open/shut via a very KISS engineering pulley system.

I thought I'd tackle that once my dimensions have been approved...which they seem to be by all!

[Everything Mac]

My only worry with that is that you would have a weak spot in your insulation at the corners.

I wondered if a beefed up "C" frame design with a hinged door on the back say 9" wide. Then you'd have 3 open sides and would still be able to fit long sections of wider material in.

I'm not sure I if you're on instagram Joel but "Jorgenhaal" recently built a very nice gas forge with big arches for the door pulley system. Not exactly KISS but looked cracking.

All the best
Andy

[Joel OF]

Hmm, now thinking about the shape I want I wonder if using insulating board cut to shape rather than bricks is my best bet.

My current forge has 40mm (1,1/2") thick insulating board for the walls and roof. Any idea how insulating board compares to insulating bricks? I'd still back it up with 2" of wool.

[Everything Mac]

Not too sure off the top of my head. The only board I've come across is only rated to 1260*C. Board also has the same issue as blanket in that the fibers are carcinogenic when dislodged (when being cut for example) - Bricks are the way forward for me.

Saying that board certainly makes life easier for your roof. And as long as you wear your PPE when building the forge you should be fine.

Andy

[Everything Mac]

*Nope I'm talking rubbish - you can get 1400*C board but it's twice the price and castreekilns are out of stock.
Andy

[Joel OF]

Ho hum, I think the combination of wanting the 4 door shape that can't be achieved with bricks (nothing to support the central bricks) and the high cost of insulating board means I will have to at least cast the roof afterall. I think I'd use half an insulating brick at each corner to prop the roof up.

I might rope a friend in to help me with the casting, I've never done anything like that before and he's a bit more clued up on that sort of thing...so I can blame him if it all goes wrong 

[Everything Mac]

Ok Joel, it's really not too hard at all. You mix it with water and treat it like mixing concrete. It has a tendancy to clump though and you get dry bits, so get in there with a mixing attachment or a bent bit of 1/4" round in a drill.
You get a good working time but I couldn't say how long exactly. half an hour maybe? It seems to start getting hard after a couple of hours. I always leave it a couple of days to dry thoroughly before doing anything with it but that's been purely because I'm busy rather than anything else.

There's three types: dense, insulating / light weight and medium weight.
As I understand it all, Dense makes a good heat sink / is toughest so makes a good floor. Insulating, is obviously insulating like ceramic blanket or boards, good for your roof. Medium weight is a mix of the two.

I'd try and get the fine grade if I were you. I've been using the coarse stuff and it is quite course. Maybe vibrating it or something would help but I've no way of doing that.

I'm also told you should mix in stainless steel needles which can be bought by the kilo at castreekilns. I've literally just ordered some which is why I mention it. They're supposed to help bind it together and add strength.
-Just thinking, if you can add stainless steel needles, I'm sure you could add something like a stainless steel cage to the mould. Think something like the rebar cages you see on construction sites. You could cast the entire shape for your roof with the right design. Welded up from threaded stainless you could bolt your roof on. Just a thought.

All the best
Andy

[Joel OF]

Thanks @Everything Mac that's brill, cheers. I'll post pics when I get crackin'

[Everything Mac]

Cool. Best of luck with it. 

 

Reading back my last post I didn't word it very well. I meant to say that you could cast the flat portion of the roof as well as the upright or "post" section on one side so that it's all one piece. With a bit of stainless bar in the posts it could then be bolted to the floor portion. Hope that makes sense. 

Those stainless needles arrived by the way - they're a lot bigger than I was expecting, maybe 30mm long and 1mm diameter. They look more like shavings from some machining than anything else. 

All the best 

Andy