Jump to content
I Forge Iron

Planning First Propane Gas Forge Build


MDDstudios

Recommended Posts

My old wood forge that I have been using for the past four years is no longer keeping up with what I want to do, and needs to be fixed up, so I figured I might as well move on to a propane forge, and based upon everything I have read in this section, I figured that I should build my own. My parents always told me that if I was going to do something I should do it right. I have spent the last few weeks reading the posts in this section, and on Larry Zoeller’s forge site, dealing with building your own gas forge, and while I have the gist of it, I still have some questions, and appreciate any feedback on my design. Therefore, this post is just to make sure I have everything down, and to double check the information I already have.

The purpose of this forge is to be a sort of multi-purpose forge. I have made several projecst from bottle openers to hose holders, and even a few knives. It was actually the current knife I am forging that made me realize I needed to upgrade my forge. I do eventually want to get into some larger projects, such as axes, larger candleholders, and damascus. I expect to eventually be doing some traveling with this forge setup so while I tried to design the forge to be compact, I also tried to keep it robust to handle travel.

            I figured the forge would be oval shape. The inner dimensions would be 12”L by 9”W by 5”H, equaling 540 cubic inches (CI). I was considering a 4”H or even 6”H, but thought that would be too small and too big, but as most of my projects are flat, I might go ahead a do a 4”H ceiling. The outer dimension I believe should be about 12”L by 7-8”H by 12”W, but this can be changed depending on any advice I get from this post.

            For the body I am considering using a cold-rolled piece of sheet metal 1/8” thick, and riveting it together. For the ceramic blanket/Kaowool I was thinking 2 seperate 1” blankets or even three 1” blankets. After that, ITC-100 or something similar in a ½”-1” thick layer. With the floor covered in high alumina kiln shelves, or duraboard. With insulating hard firebricks for doors covered with the high alumina kiln shelves, or dura board to reflect the heat better.

            I am estimating that this build will take 2 burners at ¾”, set in at an angle towards the floor to circulate the heat better. While I have downloaded Frosty’s “T” Burner, I am considering just buying a couple of burners from Larry Zoeller, because I am not sure if I am completely comfortable with creating my own burners, yet. As for a regulator, PSI gauge, and hose, I have plenty of propane stores in the area, so I should be able to find what I need simple enough. I think a 0-30 PSI gauge should be big enough.

            I know that TSC sells 100 gallon tanks of propane, is this a good size, or should I consider a different size? If this is a good size, do I need a specific kind or regulator?

            Do you think I will be able to achieve welding temperature, for damascus, with this setup?

            Do you believe I will be able to efficiently block off half of this forge and use only one burner, for smaller projects?

            How thick of stock do you believe a forge this size could heat to forging temperature?

Link to comment
Share on other sites

I only have a couple suggestions. First 1/8" is WAY too heavy for the shell, you aren't heating projects more than say 150 lbs. are you? I use 14 ga. and it's overkill, 16 ga. should be plenty robust for the size you propose.

NO Itc.-100 it's  way too expensive and there are better products for significantly less, they just don't contain zirconium. Plistex of Matrikote fire HARD so they'll take significant mechanical abuse without damage. ITC-100 doesn't fire hard and will rub off too soon to be practical kiln wash, it's formulated as a release agent so molten crud doesn't stick to the inside of furnaces and kilns. Make sense?

As a general size and shape like what you're thinking and a pair of Larry's 3/4" burners are a comfortable too much, well within easy turn down range. They'll serve you well. 

Your heat baffle closures are good just make them stable, you WILL be bumping the forge around working in it and you don't want HOT kiln shelf or bricks falling. They tend to spoil the party. Not having enough porch or baffle slides is a major design flaw in my NARB forge. I'm embarrassed to show pics

12" is a little longer than I've found useful, heating more than you can work under the hammer does BAD things to steel. It decarbs and grows crystals (grain growth) unnecessarily. A pass through back door allows even heating of long projects and you have to move them anyway, the inside of forges are rarely the same temperature full length. Yes? Even my NARB forge has zones that are hotter than others.

A 100 gal.:o tank is a LONG way from portable unless you were to buy one trailer mounted and earn a CDL endorsement to transport it. A 100 lb. (approx 25gl) tank doesn't require a CDL endorsement and is about the most normal folk think of as portable. They're large enough it isn't going to slush up  running a pair of 3/4 burners full out for 8 hrs. 

I do demos with a 40lb. tank and two NARBs don't slush it up in a 5-6 hr. session but you want it FULL to start. You'll be drawing propane fast enough you want to keep your tanks as full as reasonably possible. When my 100lb. tank falls much below 1/2 it starts frosting up on the outside and that's the precursor to the propane slushing up and losing delivery pressure and volume.

I think you have a decent plan, we'll help get it tweaked into a SWEET forge. ;)

Frosty The Lucky.

Link to comment
Share on other sites

First....listen to Frosty.  He has much experience.  Like he says, the basics of your plan are great.  Here's my thoughts.  

2 hours ago, MDDstudios said:

For the body I am considering using a cold-rolled piece of sheet metal 1/8” thick

 

1 hour ago, Frosty said:

I use 14 ga. and it's overkill, 16 ga. should be plenty robust for the size you propose.

FYI: I generally us 18-20 gauge and use a little 1/8" flat stock around the rims and where the burner attaches if necessary.  But I have used hardware cloth (wire screen) with 1/8" flat stock to make a frame for some burnout kilns.  The shell only holds things in place, it doesn't get super hot (3-400 degrees F), it just doesn't take a lot of abuse.

 

2 hours ago, MDDstudios said:

I know that TSC sells 100 gallon tanks of propane, is this a good size,

Too large...basically fine if you don't want to move it but a pain to fill.  I just bought another pair of tanks from amazon: "FlameKing YSN-301 Propane Tank-30 Pound Refillable Steel Cylinder with Type 1 Overflow Protection Device Valve-DOT and TC Compliant, 30 lb, White" for $45 each.  Fantastic deal!  One is fine, but I use two connected together.  The larger surface area prevents the tanks from freezing up when I am forge welding.  

2 hours ago, MDDstudios said:

The inner dimensions would be 12”L by 9”W by 5”H

That's fine.  But like Frosty says, you don't need the depth since you will only be working on 5" or so at a time.  If you were making knives like I do, then a longer forge allows you to heat treat a longer blade.  If you are doing twists over a long length a longer forge would be useful.  The con is that a longer forge uses up a lot more propane, but you can always turn off one burner and plug up the tube with some ceramic wool.

DanR

Link to comment
Share on other sites

I disagree with Zoeller burners--in your case. For your forge design and size, you want a single bottom mounted ribbon burner. "T" burners and fan-blown burner bodies have both worked out well with ribbon burners. These burners have turned out to be simple enough for most newbies to build well  on their first try; or you can buy a commercial unit.

Forget about ceramic fiber board; it is a way over priced material since Morgan K26 insulating hard firebricks came on the market. Also the brick should last better in a mobile forge. Plistex also makes a good choice with as a hot-face for the brick in a mobile forge.

High alumina kiln shelves are still one of the better choices as forge floors, but are too much of a heat sink to use on walls. You would be better off using 1/2" thick hot-face layers of Kast-O-lite 30.

Link to comment
Share on other sites

2 hours ago, Frosty said:

 Make sense?

Yes, that does make sense. Thank you.

2 hours ago, Frosty said:

 Your heat baffle closures are good just make them stable

I plan to use a couple pieces of [ channel steel to create a sliding rail system to move the bricks easily, and to keep them secure.

3 hours ago, Frosty said:

12" is a little longer than I've found useful

What do you find to be a good size? 6" or 8" long? If I cut the forge down to that size, I should be able to make do with a single burner, correct.

3 hours ago, Frosty said:

A 100 gal.:o tank

1 hour ago, D.Rotblatt said:

Too large...

I meant a 100 pound tank. My fault.

1 hour ago, D.Rotblatt said:

 If you were making knives like I do,

I do make knives. That is part of reason why I am planning on building a new forge. However, you are right. I want to use this forge for other projects as well, and a longer forge would eat up my propane. What would you recommend for a length size? 6" or 8", maybe? Could I still use a forge that long to heat treat knives, and possibly something longer?

Link to comment
Share on other sites

16 minutes ago, Mikey98118 said:

you want a single bottom mounted ribbon burner. "T" burners and fan-blown burner bodies have both worked out well with ribbon burners

From what I have read about ribbon burners, the reason I have not seriously considered one is because they need a blower, and I am lacking electrical power where I forge. From what I understand though, you are writing that I could build one that uses air, and does not need a blower, correct. If that is true, about how big of a ribbon burner is needed per cubic inch? Also, why bottom mounted?

Link to comment
Share on other sites

Wrong, multiple outlet burner, a ribbon is only one of many shapes of multiple outlet burners, Do NOT need blowers. Most home built gun (blown) ribbons have serious issues being over blown. The design flaw seems to have become a legacy error. It's how EVERYBODY does it. <sigh> Commercial multiple outlet burners do NOT shoot flame several feet out the openings of the furnaces in which they're used, they have very soft HOT flames, either naturally aspirated or gun.

Take a look at the "NARB lives," thread. I describe why I decided to make a Naturally Aspirated Ribbon Burner. (NARB) The steps and experiments I took, the results. and why I do NOT put a difusser plate as described in the plenum. The legacy flaw in John Emerling's design. 

Frosty The Lucky.

 

Link to comment
Share on other sites

Frosty us right. Over the last year NARBs have outclassed fan-blown ribbon burners; I only mentioned them because you mentioned purchasing a burner, and fan-blown are, at present, the only commercial ribbon burner choice I'm aware of; that will change pretty soon.

Link to comment
Share on other sites

IIRC some of the commercial multiple outlet burner makers are: AGF, ERB (Ensign Ribbon Burners), Prine Ridge I think? 

Check out glass blowing sites and suppliers.

The commercial burners look like they have thin blue carpet for the flame. 

Frosty The Lucky.

Link to comment
Share on other sites

3 hours ago, MDDstudios said:

What would you recommend for a length size? 6" or 8", maybe?

My regular small forge is one brick long inside (the bottom is an insulating fire brick with a coating of zircon/colloidal silica slurry for strength and flux resistance).  I believe that is 9".  The forge, with a single burner pointed down, has a nice 4-5"  hot spot in the center. Good for control of heating.  About 250 cubic inches total inside, it will forge weld.  You can heat treat a 9" blade with it.  I have since replaced it with an 8 x 2.5" NARB.  Now there is an even heat over 7+" and for the whole width of the brick.  My NARB is modified by using smaller holes for the nozzles. I talk about it in Frosty's thread. A couple of pics of the forge are about halfway down the page here:

3 hours ago, MDDstudios said:

I could build one that uses air, and does not need a blower, correct. If that is true,

 

Frosty figured out how to do it.  Read his thread starting here, pioneering work Frosty!  Again!

The downside of the ribbon burner is that it takes longer to build and is a bit harder build.   Not too hard, just more skill sets.  A basic 'T' burner is easy as can be to make and works well.  I would start with that, and if you want you can build another forge or modify yours to accept a ribbon burner.  Step at a time, see what you really need by building easy and thus faster and trying it out.  You'll have your own ideas as to what type of forge you want. 

Just to confuse you, if you want really multi-purpose forge, make a brick pile forge.  Make a couple of 'T' burners.  Buy a box of K26 IFB (insulating fire bricks).  Make a table maybe 3 bricks wide and two long (13.5" x 18") covered with firebricks.  Make two or three assemblies with a brick and burner mounted on the top center of one of the 4.5 x 9" faces.  Now, put bricks where you want for the walls, put the bricks with burner mounted on them across the top of the walls, a couple of bricks for the front and back doors, hook up a propane line, and off you go!  You can change the size as you want, add an extra burner, whatever!  Very little work, you'll use all the parts later when/if you want to build something else.  Very little time investment.  You can see the size that you use most.  You can make it longer for heat treating that sword you really want to make.....  I'm not saying your original idea is not good, it's fine.  Just thinking that  these little forges are not really good for odd shaped items.  Even guards for swords that I work on get problematic in a small forge.

DanR

Link to comment
Share on other sites

Arghh, I see I was wrong when I recommended "NARB lives" to a fellow who was asking about ribbon burner build details. <sigh> Ah, head slapping time that was earlier in THIS thread. Dan linked the thread I was talking about.

It's hard to beat a brick pile forge for figuring out what size ad shape forge you'll like best and you can change them as needed. I have a case of IFB next to my set up for testing new burners and placement.

Frosty The Lucky. 

Link to comment
Share on other sites

18 minutes ago, MDDstudios said:

Apparently I need to take long look at ribbon burners, and modify my design more.

Respectfully, here's something to think about.  It's fun to play and design, we all do it and love it.  Don't let it get in the way of playing/working/moving forward. As long as your old wood forge is still up and running go for it!  If not, make something easy and quick to keep you working and tinker in the off time!  I've been known to be guilty of over designing, and over the years I've found that designs made without experience tend to go awry...they generally work, but are not what I really needed or time and money spent on unnecessary features or..... 

Dan R

Link to comment
Share on other sites

Well said Dan. We do, we all LOVE to tinker and reinvent wheels or we wouldn't be blacksmiths. As driving part of that trait is our imaginations. We're dreamers and can dream up some wonderful sounding corners to paint ourselves into.

A too large forge is almost a right of passage, everybody seems to have at least one collecting dust somewhere. I lucked out when I built my REALLY crazy silly too large forge, I built in enough flexibility about 1/4 of it is a usable size, occasionally almost 1/2. For the most part though it takes up floor space better used for a table, tool stand, pedestal tool or just room to walk.

Once I build a forge I like well enough I'll dismantle the  crazy large shop forge, maybe preserve the split brick floor and expanded metal shelf on the spreaders as useful. 

I'm not happy with my latest forge even though I LOVE the burners. While I have building Kaowool and cast refractory lined forges down to a practiced routine, Morgan K 26 IFB and how much cheaper they are than the old lower temp IFB has me thinking hard about building with IFB instead. 

It won't matter what you build, you WILL analyze the results and be designing the next generation as it heats up the first time. No joke, we all do it.

Frosty The Lucky.

 

Link to comment
Share on other sites

Mikey98118, mentioned putting a ribbon style burner on the bottom of the forge floor. My concern with that is keeping the forge portable. However, someone, not on this site, asked if would it be possible to run the pipe that goes between the burner head and the propane "T" joint (following Frosty's design), underneath the forge, if the forge had a flat bottom, such as a "D" shaped forge on legs. My concern with this is the radiant heat from the forge and the effect it would have on the piping.

Link to comment
Share on other sites

3 hours ago, MDDstudios said:

if would it be possible to run the pipe that goes between the burner head and the propane "T" joint (following Frosty's design), underneath the forge, if the forge had a flat bottom, such as a "D" shaped forge on legs. My concern with this is the radiant heat from the forge and the effect it would have on the piping. 

My NARB is floor mounted (pointing up of course) in my "D" shaped forge, and I run the mixing tube under the forge to the opposite side of where the burner is mounted.  It barely protrudes past the outer edge of the floor frame, and I haven't detected any problems with radiant heat as a result.  My forge floor is comprised of a half inch+ layer of Kastolite 30 with 2 inches of fiber blanket (Superwool) below that, and the mixing tube is about 1 inch below the bottom of the floor.  I think that the cooler fuel/air mix moving through the tube is enough to offset whatever heat bleeds through the bottom of the forge floor.  When my forge is up to full temperature the outer shell, including the bottom of the floor, is too hot to comfortably rest my hand on it for more than a few seconds, but still cool enough that I do not get burned immediately when I touch it.

Link to comment
Share on other sites

On 6/10/2019 at 12:22 PM, MDDstudios said:

My concern with that is keeping the forge portable.

It's easy to make the burner removable for portability.  On mine I make the nozzle extra long so it sticks out of the forge.  A simple single thumb screw holds the burner tube in place.  I put a hose clamp on the burner tube as a stop so it goes in the same amount each time.

Also, another thought on my part.  You might consider making a list of what you want from your forge in order of priority.  Some things don't play well together.  For example, as a forge becomes portable it becomes less multifunctional. It's difficult to make it very adjustable if you are making it portable.  If you want to HT long knives, it will need several burners and it is also less portable and should have a wide even flame (ribbon burners are great for this), but if you like a localized heat it will not do this well.  If you want a forge for forge welding, it will be more difficult to make it run it at low temperatures and you may want a vertical forge.  Trade offs.  We'll keep feeding you ideas, and all of them will sound good, but may not fit together.

All good ideas up there!  I'll look forward to see what you end up making!  

Dan R

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...