Forges 101

[Another FrankenBurner]

I have built and used forges with both sizes of cylinders you are talking about.  If you are doing 2 inches of blanket with 1/2 inch of kast o lite, remember you are subtracting 5 inches from the diameter of the shell.  The smaller helium cylinder finishes at about 4 inch diameter by 12 inch length.  The larger propane cylinder finishes about 7 inch diameter by 12 inch.  While this doesn't sound like a significant difference, the volume of the latter is three times the former.  Definitely different burner requirements.  

As a decent in between, the propane cylinder with extra blanket on top and bottom, gives an approximate oval.  This drops your forge volume while having wider floor space.  I am a convert to the oval forge.  

As to the rounding hammer project, if you are going down the Alec Steele 3.5# line, I would not attempt that in the helium cylinder forge.  If you haven't tried a rounding hammer yet, I recommend trying one first.  If you are new to the hobby, I also don't recommend starting with a 3.5 pounder.  Heavier fatigues muscles quickly.  Tired muscles cause bad form, miss hits, bad habits.  After all that, some like bigger hammers.  Brent Bailey swings 7lb cross pein.

In the beginning, I bought a 4lb sledge from harbor freight and ground it into a rounding hammer.  It's heavy.  I later bought a 2.5lb drilling hammer and converted it.  The head is closer to square than a sledge so it gives good corners for differing radiused sides for tilted fullering.  I changed the handle as I prefer a longer handle.  I have several now in different weights.  I even have a "good" one and I generally go back to the 2.5lb drilling hammer cheapo.  

[Fishgod]

On 4/3/2020 at 7:16 PM, Another FrankenBurner said:

I have built and used forges with both sizes of cylinders you are talking about.  If you are doing 2 inches of blanket with 1/2 inch of kast o lite, remember you are subtracting 5 inches from the diameter of the shell.  The smaller helium cylinder finishes at about 4 inch diameter by 12 inch length.  The larger propane cylinder finishes about 7 inch diameter by 12 inch.  While this doesn't sound like a significant difference, the volume of the latter is three times the former. 

FrankenBurner,

Thanks for the input.  I think I will go with the propane cylinder and pick up a second burner.  This way I have a good balance of size and use. 

I get you on the the larger hammer.  I would like to make a few different sizes.  first off though are a heck of a lot of punches, chisels, and fullers. I picked up 6ft of 1045.  I was also sent a large USPS priority box of sucker rod from a really nice gentleman off of one of the the facebook groups I'm in.  

I m planning on making a few hammers later in the year after I get a bunch more practice.  One nice thing is my 20 year old son is home since Covid-19 closed his college and he is now doing on-line classes from home.  With that said,  I will have a striker that's strong and ambitious :).  

[Another FrankenBurner]

Alright, now that you have it figured out, I'll play devil's advocate to complicate things. The helium tank forge is a great forge.  Especially for people new to the hobby.  Mainly because of fuel consumption.  Making nails, s hooks and leaves in a propane cylinder forge is like getting groceries with a big rig.  Especially in the beginning when everything takes several heats to learn to move the metal.

When I throw my little metal into the vast cavern of a large forge, I see the fuel being wasted.  My first forge was a monster, like everyone else's.  You know, so I could make any project I could ever imagine.  One forge for everything.  I very quickly realized that it was more cost effective to build a second smaller forge than to run the big one to make small things.  I have since made an even smaller forge.  I use the smallest forge which will accommodate the work.

The only problem I have with the helium jug forge is the very small floor space.  Making a larger split cross in one is challenging.  This is why I have converted to the oval forge.  Still round so the flames spiral.  Smaller volume for less fuel requirement but with the wider floor of a bigger round forge.

Some of my favorite forge work is striker cooperation with my father or brother.  

[Mikey98118]

Down the road, he will still use the small forge most of the time, and a larger forge only when necessary.

[Frosty]

The burner you got from Larry is a 3/4" isn't it? The forge you're proposing will be under 150 cu/in if you put a flat floor in it. I'll be a real fight just keeping the burner lit without expecting good performance from it. It'll make a fine forge but wants a 1/2" or two 3/8" burners. It's an excellent size forge and better than starting out with a crazy too LARGE one like I did. Well, that was #3 or 4, #1 was too large but it was mostly WAY over gunned at 350 cu/in and a 1" burner. I have a bunch of old forge "models" collecting dust in odd corners of the shop. 

As Mike has said many times. I'll paraphrase, forge and burner are NOT two different things, they are components of a whole, a machine and need to be matched to function properly.

Larry's burner will work just fine in a 20lb. propane tank forge, especially if you put a flat floor in it. It's a pretty standard forge for a LOT of people. Shortening the length with refractory and a flat floor will get you in the 300 cu/in range, lift the floor another 1/2" and it's in easy peasy welding range under a 3/4" burner. 

Frosty The Lucky.

 

 

[Fishgod]

Thanks all,  I'm going to go with the propane tank.  I will pour a levelish floor in it after the 2 inch of Insowool.  I might have to pick up 2 more feet of insulation.  I will look at anding an additional layer to the ceiling.  if the volume is over 300ish SQ inches.  What is a good source for the kiln shelves?

[Frosty]

Rather than pouring a flat floor use a strip of Insulwool, feathering the edges so it's flat to the contact point with the sides.  Making a wider floor is generally  better use of materials than lowering the roof, it makes more usable floor while reducing the height the same amount. 

Frosty The Lucky.

[Mikey98118]

Lego blocks

Frosty and I have discussed box forge advantages back and forth for a few years, and one of their best aspects is that their size and shapes can be reconfigured, if they are employed as what he likes to call brick pile forges; that is to say, with minimal, or even no, steel bracing.

Going further, they can also be used, like Lego blocks, to reconfigure burner placement, for maximum efficiency. The novice can then, insure (or disprove) a presumption of what will work efficienatly in a forge, before building a permanent shape with sheet metal. Thus, the cart remains behind the horse, instead of in a ditch.

[Fishgod]

35 minutes ago, Frosty said:

Rather than pouring a flat floor use a strip of Insulwool, feathering the edges so it's flat to the contact point with the sides.  Making a wider floor is generally  better use of materials than lowering the roof, it makes more usable floor while reducing the height the same amount. 

Frosty The Lucky.

Got it Frosty,  I will go with that.

[Frosty]

If we weren't stuck at home you could drive down and I'd show you fun with a brick pile. I model forges and burner placement with IFBs, it saves me time and money getting things right. The club held a forge and burner build workshop a couple years ago and the gang turned out some nice, steel framed brick forges. 

"Distribution International" in Anchorage sells Kaowool, Morgan ceramics K-26 Insulating Fire Brick (IFB) and Kastolite 30 li. in stock and are happy to order special stuff if you want. They even give the club a discount. 

Frosty The Lucky.

[Fishgod]

Frosty

That's good to know.  I want to pick up a few bricks to have around.  

Glenn reached out to me and we had a great phone conversation. We talked for about a half hour.   I have a couple feet more of insulation headed my way.  Excited to start the build.

[Frosty]

Glenn's great for long phone calls, he's a good guy.

Frosty The Lucky.

[pnut]

2 hours ago, Frosty said:

he's a good guy

I'll second that. Had numerous convos myself with him and always learn something and get a couple chuckles to boot. 

Pnut

[Mikey98118]

Aiming burners update

Progress in any feild changes the goal posts. For the last few years, we could easily predict probable best positions in a given forge design,. However, the batch of new burners, with differing flame characteristics are making that harder; this applies to box forges, more than other designs. So, box forges will benefit most from experimental positioning, during construction; still another reason to employ the latest firebricks as their refractory.

 

[Cris J]

Hey guys

I started working on a larger shell design as was suggested by Frosty a few days ago. I was doing some more reading as well and came across a section where Mikey mentions making things variable, and another section at the beginning of this thread by Mikey stating that starting with a smaller forge build would be a good idea (I agree). 

i wanted to run one aspect of design your guys’ way. I have a long, old air tank about 30”. My idea was to cut off 5” of that and use that length of shell EVENTUALLY. 
 

To start with a small design as Mikey had suggested, my idea is to use only 12.5” as my small starter forge. This should only require one burner per the volume I got. Then EVENTUALLY reattaching the other half when I have more experience to do the blade smithing I want. 

Does the concept of putting each half together later on make any feasible sense to your guys’ boundless experience?

[Mikey98118]

Yes, some people do just that kind of thing. Some people build a mini-forge from a one gallon paint can (bought new from a hardware store). Coffey-can furnaces and forges have been around for many years. Some people carve out two bricks to make a mini-forge. Half a car muffler makes a fine mini-forge. The choices are endless.

[Another FrankenBurner]

My oval mini forge quickly became the go to forge for anything that will fit.  I like the gas mileage.

I once built a single fire brick forge.  I believe it was a 1.25" bore about 4 inches long.  I fired it with a map gas torch.  It worked well for a while but the k23 fire brick eventually turned to rubble.  I have now abandoned the use of k23 and k26 fire bricks.

[Frosty]

Chris: I probably didn't say it very well. When I suggested larger diameter I wasn't suggesting a larger forge but a more proportional one. a forge 3" in diameter and 6" long is a excellent proportion but 3" x 16" is very hard to heat evenly and worse will heat a lot more length than you can realistically work per heat and damage the steel.

I probably did too  much explaining. My main point was to aim for a reasonably even proportion for better general utility.

Frosty The Lucky.

[Cris J]

Thanks Mikey at least I know the new design will work. 

And I’ll make sure to stay away from those bricks then FrankenBurner

Oh I see Frosty I may have just misread as well. I’ll keep it around to see if a smaller forge all together would be nice. Cut it down to 3” x 6” and such. 

Would the proportion 8.5” dia and 12.5” height work then, Or should I try to shoot for halves like in your example? In my skimming I haven’t come across anything having to do with proportion in relation to those two measurements.

[Another FrankenBurner]

I did not mean to imply all firebricks are bad.  I think the general consensus is the k23 bricks are not great but several members report good things about the Morgan Thermal Ceramic K26 bricks.  I destroy them with my forge, maybe because of how I thermally cycle them.  I have made a tougher alternative which takes the abuse so I can abandon firebricks as baffle walls.

Also, the heavier fire bricks, I never use them inside the forge but I have a whole pile of them for various tasks in the smithy.

I have a forge at 3.5 inch diameter by 12 inch length powered by a tamed 3/4 burner originally.  A Ron Reil Freon cylinder mini forge from back when.  The burner doesn't like it very much but it works.  It does the job.  It would probably make a nice knife makers forge.  It has a hot spot right in the middle and cools as you get nearer the front/rear.  In order to heat anything in the hot spot, it has to have six inches or better in the forge.  I would rather have your idea of 3 inch by 6 inch with a smaller burner.  

As to the diameter vs length, if we are talking about 1 central burner, I have notice that the closer the length matches the diameter, the happier the burner.  The openings are cooler than the center so the length a bit longer than exact is better.   I am into the oval/lozenge shape now but if I was trying to hit the magic 350 in³ with a cylinder forge, I would probably go with a 7 inch diameter by 9 inch length and see how that worked out.  Going to 6.5 inch diameter would drop to 300 in³ which would make forge welding heat easier to obtain.

[Cris J]

I wasn’t assuming they are all bad I’ve just seen a few times k23’s don’t take the cycling very well. 

Thank you for the tip on the proportions though FrankenBurner with the burner relation. I’m thinking I’ve got enough knowledge to know how to not blow anything up (my primary reason for reading so much before starting in on burners and all that anyway). 

Now I think I’ve got to hit the pavement with the tips you’ve all got here and reference back to Lou’s consolidated notes on the whole process, see what I can make work on my end. 

[Frosty]

There's confusion with the numbers for IFBs. One metric uses k## to mean a heat range while Morgan Thermal Ceramics k## ratings actually refer to the brick's maximum sustained working temperature rating. 

The last time I bought the old IFBs I used to use the guys I buy from were surprised they crumbled at all let alone in just a couple thermal cycles. THEN I told them how hot my forge gets and I found out the old  k23 IFBs were good to 1,800f. No wonder they fall apart! Try these instead, they're rated to 2,600f. 

This is why I make a point of SAYING, "Morgan k-26 when talking about IFBs and I suggest you not let the guys selling you fire brick convince you they're all the same because they have the same number designation. Morgan k23 IFBs are rated to 2,300f. max sustained temp.

Frosty The Lucky.

[Another FrankenBurner]

Frosty, I will refer to them the same way.  Unfortunately I have crumbled several of the authentic Morgan K26 bricks.  Even when handled with care.

Cris, you are not alone in the concern of blowing yourself up.  My advice, do not turn the gas on to the forge with the garage door closed, then go into the house to prepare and eat lunch, then back out to the garage where you ignore the smell and try to light the forge.  Avoid that kind of thing and it is like lighting a gas grill.  I'd give more mind to carbon monoxide than explosions.

[Frosty]

Morgan k-26 have a max temp rating of 2,800f but that's the upper edge of it's all out safety margin and begins to suffer. Much higher and I'm not surprised it begins to fail. I decided building Kaowool and KOL forges was much cheaper than ordering Morgan k-29 IFBs. Aie YI YI! $

MY NARBs don't push k-26 IFBs enough to hurt them. 

Frosty The Lucky.

[OzarksBackwoods]

Done a lot of reading but I haven't seen anything, so I'm not even sure it's an issue. Does rigidizer bond on both sides of the wool, or is that just an interface between wool and flame surface? Used a lot of forges over the years but never got into building my own til now. Just want to make sure I get it right. Bought my steel and made my t burner today, probably gonna make a standard burner for now and cast a ribbon later. Focused on forge for now...