First time Gas forge build - in process

[rls1160]

PI have been building a new gas forge over the last several weeks. It included building a small 4" x 6" ribbon burner and casted refractory forge shell and forge burner base.

It is a bottom fed burner table with a casted D-shape forge shell. The forge is not complete.

Today I was able to fire it up just to test the burner and fuel supply.

Next items to complete:

1: Coat the interior of the forge with Pilstix.

2: Add a layer of 1" ceramic board insulation to the casted forge shell.

3: Fabrication of a sheet metal shell enclosing the ceramic insulation.

4: Fabricate doors.

I am attaching some pics and a video of the burner running.

The forge internal dimensions are 12"w x 9-3/4"h x 15-1/2"d

- Casted shell thickness approximately 2"

-Casting material: HWI Versaflow 60 plus

- Reflective coating Pilstix - to come.

 

Forge burner table  base is a three layer base consisting of:

2300 degree IFB 2-1/2" x 22" x 25"

1" ceramic board insulation

1/2" of casted refractory Versaflow 60 plus which is Flux resistant and has a 3000 degree heat limit.

 

Air supply lines are 1-1/2" black iron pipe

air/gas mixer is a 1-1/2" iron tee with a 1/8" iron pipe gas feed. Currently there is no gas jet installed in gas/air mixer.  I have brass plugs that can be drilled to create a specific gas jet size.

Propane metering valve and two stage gas welding regulator and 1-1/2" gate valve for air regulation.

Blower is an old Hye Sung coal forge blower that I had from my old coal forge. It says it has a static pressure of 40 ounces. 

The burner is a 4" x 6" casted ribbon burner that Was welded from 12 GA sheet metal and then casted with 26 holes roughly 7/32" in diameter.

 

 

 

The current state of the forge build, some of it temporary like the support rack for the blower and the PVC air/fuel line below forge.  That was rigged up just for burner test.

Here are a few things I came across while building.

Originally I base planningbto have the blower mounted at floor level and feed Air/Fuel straight up into burner.  Like this

But it occured to me that this layout could potentially be a safety factor. Propane being heavier than air could in the case of a leak collect at the floor level and come in contact with the blower motor which is not explosion proof.

Secondly it seemed counter intuitive to try to feed a heavier than air gas from below.  The conventional thought on ribbon burners is that they run at low gas feed pressures. Another reason to come up with a top down fuel/air set-up.

So I reconfigured it so the sequence of fuel air system are as follows.

Blower set 12" above forge, will have heat protection shield if needed.

Next  is air gate valve followed by gas mixer followed by 54 inches of piping run from outflow of air mixer to burner face. Pipe run includes 3 - 90 degree elbows.

A union fitting sits between air mixer  and burner for easy disconnect of air/fuel feed.

Now for some thoughts on the burner testing which was not scientific in any manner. Nor did include any testing or measuring.

Just some observations:

I get a fairly neutral blue flame but it seems a bit on the cold side (low heat output).

If I push too much air the flames start to jump off burner face.

I can add both fuel and air and maintain decent flames that are still married to the burner face.

If I push the air and fuel to high I get the following. 

 

I am thinking one or more of the following are could be issues.

The air/fuel supply is too small (maybe should be 2"). Although I did calculate the total burner port area and matched that to the air/fuel pipe area. They are very close to equal.

The unjetted gas feed port in the mixer is preventing proper mixture ratios, fine gas control, or leading to poor mixing.

Lastly the blower does not have sufficient static pressure.

Forge heating:

I don't have proper doors installed nor do I have the Pilstix coating applied and tye outer shell insulation completed. It's too early to say if the forge will heat properly.

I may have built it with more thermal mass than what is ideal. I did not want to deal with friable ceramic insulation,  desired a flux resistant interior and wanted to reduce heat transfer from forge to shop.

Not sure if a met my goals we will see.

CHEERS!

 

 

[Irondragon Forge ClayWorks]

46 minutes ago, rls1160 said:

gas welding regulator

Is the regulator rated for all fuel or propane? If it's from an Acetylene/Oxygen torch set the propane will eat up the seals in no time. Other than that, I say you have done a bang up job making a forge to envy.

PS: couldn't help but notice what I think is an antique Ford Model A in the background of one of the pictures. From what I could see it looks like new. Speaking of pictures you might want to edit the post and reduce the size of them so they load faster and don't take so much band width.

[Latticino]

If the flame is lifting off the burner face you have plenty of air and gas and shouldn't need more for that burner.  If you can ever get the forge to heat up the flame speed will increase and you may be able to turn the burner up further (yes I am aware that is a kind of catch 22, but with doors you may be lucky).  I am not familiar with the castable you used, but it looks like a high alumina refractory castable rather than a high alumina insulating castable.  The former can be quite heavy and makes a great flame face, but the thermal mass will take some time to heat up and may cost you in fuel bills if you don't have an adequate overall thermal resistance in the walls.  As I've stated many times, I like a 2" layer of 2600 degree ceramic blanket with a 3/4" castable insulating refractory for the forge walls, roof and floor. Check the listed k value for the refractory material you got and compare it to refractory blanket (lower numbers are better and the heat transfer quantity is directly related to the temperature difference between the inside and outside of your forge and that value).

That is a pretty large forge, what is the internal volume?

[rls1160]

Latticino the internal forge dimensions are 12"w x 9-3/4"h x15.5"d.  However it has a sloped roof (D shape) so I calculate something less than 1800 cu.in. or about 1 cubic foot.

That burner was fashioned off a pine ridge burner that was spec'd for around a 1.5 cu.ft. cavity.

I can tell you the thermal conductivity rating on tye refractory I used is higher than kastolite, I realize it's going to be on the higher end of thermal mass scale.

 

The supplier was local and unfortunately I had the material before I discovered other materials with lower thermal conductivity numbers.

Thank you for tyhe insights.

 

 

 

 

[rls1160]

Irondragon,

Thank you for the nice compliment.

As for the regulator, it's a regulator from my propane gas cutting and heating rig. I had purchased that regulator long ago from my welding supplier when I switched from oxy-acetylene to propane to run my large rosebud torch and then converted cutting equipment to propane.  A Cheaper and safer gas  for cutting and heating.

I will double check the model and specs to make sure it's good to go for propane.

That you for the heads up on that one.

Rick

 

 

 

 

Irondragon I will look into how to reduce image size, sorry about that.

[rls1160]

Update November 15th

Well my HWI Versaflow 60 casted forge cavity has too much thermal mass and the product has a thermal conductivity rating of 7.9 so basically it socks the heat away from the forge preventing it from reaching proper heat.

Today I crafted a makeshift brick pile forge for testing. I used 2300 degree IFB bricks without any IR coating. 

The results were amazing!  

I have not been able to find Kast-O-Lite locally there is a refractory supply house that can order it.  What I am considering based on my tests today is to split the 2300 IFB bricks I have in half to make   1-1/4" x 4-1/2" x 9" bricks and mortar them inside the casted forge as a lining then coat with Pilistix.

Is this a reasonable way to address the issue I am having. Or do I simply abandon the concept of a casted monolithic forge cavity in favor of an IFB brick pile forge until I can secure a proper insulating castable?

 

 

[Goods]

Can you get bubble alumina? (Not sure if that’s the right term) If so you may be able the mix that in with the versaflow to improve the insulating capabilities. (Just and idea, not sure if it’s a good one.)

Keep it fun,

David

[Frosty]

What I recommend to folks starting out with propane is to make a brick pile forge first. They can be enlarged or ensmalled to suit, you can test burner placement and orientation for the one time price of the bricks. Buy good ones though, Morgan appears to have started making K28 in quantity making their k-26 a bit obsolete. 

That way you don't invest a lot of time, effort and money building something that might not work well or at all until you know what you need and want. 

You put in a huge amount of work and money on a beautiful job but without the necessary knowledge made a few mistakes that are going to be hard to recover. 

Lots of guys will gladly help if you wish to make what you've built work but personally I think you'd be farther ahead to read forges 101 for a while and start over. If you decide to make this one work I'll help as I can. I'm not married to my opinions.

Frosty The Lucky.

[Irondragon Forge ClayWorks]

2 hours ago, Goods said:

bubble alumina? (Not sure if that’s the right term)

That is the right term(name). We were having trouble with our forge lined with Satanite coming up to temp. or reaching welding temp.

I ordered bubble alumina from Hightemptools and applied it according to directions and that solved the problem for us. The forge comes up to welding heat rapidly and the bubble alumina is holding up just fine.

I even poured a floor with what was left over.

[rls1160]

Frosty Thank you for the input. I went through a ton of pages in both the 101 forge, 101 burners and ribbon burner pages.

Yes I invested time effort and money into a casted D-shape forge using the refractory I used for the burner. I learned alot through the process and by the mistakes made. 

My local refractory supplier can get Kast-O-Lite 30 LI in 1-2 weeks. So my plan is to use the IFB bricks to figure out sizing. 

The forge I casted is 15" deep x 12" wide by 9-3/4" to center roof. It is D-shaped and has interior cavity volume of 1,515 cu.in. a bit less than 1 cu.ft.

I got to that size by based on what I typically forge.  A 4" x 6" pine ridge ribbon burner had a forge capacity of 1 to 1.5 cu.ft. 

I didn't feel it was appropriate to use the the general approximate 350 cu.in. per burner as a guide as referred to I'm many of the iForge posts throughout the burner and forge sections. 

It's very difficult to determine the btu output on a multiport burner so It felt a bit like trial and error to find thebsweet spot.

So rather than continue to waste others time on the forum I decide to move forward with the information and productvI had on hand. 

I knew the refractory I used was borderline on the based on what I had leaned via iForge pages. 

The forge bottom feed burner table is great, I really like the flexibility it provides for what is used as the forge cavity. 

So what to do now? 

I can purchase Kast-O-Lite 30 LI and recast.

If I recast is my cavity size workable? What thickness should the casting be, my current one was 2" thick. I have 1" thick Ceramic board that could be used as an other wrap insulator to the castable.  

Or I can use the 2300 IFB I have to test sizes.

Once I figure that out, purchase 2600 or 3000 IFB bricks and just settle on a brick pile forge. 

The internal cavity size of the IFB brick pile test forge is 14 1/4" deep x 9-1/4" wide x 9-1/4" high that equates to 1240 cu.in.

I was able to get to a low forging heat but not forge welding heat. I did not expect to hit welding temps with a make shift set-up like it is.

I am not a knife maker so I need something that will accommodate a bit larger form into the forge. 

[Frosty]

I haven't searched enough to find the info I need to equate Pine Ridge ribbon burners and NA propane burners. Gun (blown) burners don't follow the same rules of thumb for burner size vs forge volume and multiple orifice guns follow a different scale yet. 

Even so, "one, well tuned 3/4" NA burner will bring 300-350 cu/in" is the meter I use when building NA propane forges and it's just a rule of thumb, not calculated with the appropriate gas, combustion, etc. properties. 

I'd disregard that in your case.

I do have experience comparing my best effort T burners with bargain basement commercial linear burners and the T is sort of a not too far off second. Guns don't have the same things to overcome so you can get a lot closer with a home built gun burner. Still there is a LOT of precision internal design in a Pine Ridge burner and I'll be impressed indeed if you get as close as 50%. Very impressed. 

My initial T burner shop forge was WAY too large at around 1,450cu/in and powered with four 3/4" T burners and it will hit welding temp everywhere. I just never light more than two at a time if I need to heat something long. I've lit all four for hammer ins so up to 6 guys could work without tripping over each other but that's about it. If I use that one I typically close it to a single burner. I'm not a bladesmith and don't do little stuff either. . . Not always anyway.

All I can really say from experience is that is a HUGE forge, my professional blacksmith friends all run forges under 40 cu/in and often do landscape scale jobs, Gates, fences, arbors, planter hangers, etc.

The NARB forge is about 450 cu/in and opens along one side though I screwed up the build and didn't leave room for a porch so it's hard to close up enough to get serious heat in the whole chamber but I can heat some pretty large pieces in it.

Sorry for the ramble I get carried away. The current cast refractory liner is too thick and too poor an insulator; a major heat sink. Just because heat conducts through a material slowly doesn't mean it's insulating a commensurate amount, the thermal mass takes a lot of energy to heat and the entire thickness absorbs decreasing levels. A lot of thermal mass is a good thing if you have a high turn around through the forge, lots of cold steel going in and hot coming out. The thermal mass holds heat to transfer through IR radiation. But if you don't do a high volume you still have to heat the liner. 

I do more relaxed smithing so my forges are thickly insulated with a relatively thin hard refractory flame face to withstand direct flame contact and mechanical abuse from steel going in and out. 

Were I building a forge with the general dimensions of yours I'd probably build a 3 layer liner like I did with mine. Unless I needed the thermal mass for the above reasons in which case I'd adjust the thickness of the inner liner to provide what I thought I needed. Then when I learned the truth of the thing I'd adjust again till I got close enough to live with until it was time to reline the forge. 

Can you live with fuel consumption and less than expected temperature as it stands now or can you live with the reduced volume involved in installing IFBs?  It will lose 4 1/2" of width and 2 1/4" height an 2 1/4" length if you leave bare IFBs. 14-1/2" of kiln wash will toughen it up against mechanical abrasion, bangs and gouges and up the re-radiated IR. Good things. 

I'd leave the floor as is with maybe double the thickness of kiln wash. I'm a fan of floor mounted (up draft?) burners, a good friend of mine has a couple one a ribbon burner and they are good performers. He hasn't complained abut crud falling into them in the several years he's been running them.

Were I in your situation I'd make the decision based on the volume. You CAN get the desired heat/fuel consumption performance in exchange for the loss in volume with what you have now. If I could live with it I'd use it till it needed relining. Don't forget to factor in the cost of organ K-28 IFBs to make the temporary liner. 

Of course if you have enough of the current castable refractory left you COULD rip this liner out, leaving the floor and make an insulating outer liner with K-28 IFBs and apply a thin layer of the current refractory and a final kiln wash. Think about this one and do a little addition. How many more IFBs will it take to make an insulating outer liner as opposed to the IFB flame face inner liner we're talking about, 10+/-? Don't forget it'll maintain the as cast volume.

Whatever you line it with a liner is a wear item, it WILL wear out eventually though some modern refractories will outlast me for sure. By time the liner you decide on now wears out you'll have dropped enough dollar bills in the forge cookie jar and know enough of what you want/need to build a super forge. 

Hmmmm?

Frosty The Lucky.