Decided after ten years to finally build a forge

[gastlyTree]

So I've been meaning to build a forge for a long time. Around ten years. I finally decided to just do it. I'm trying not to spend too much money, but I have an advantage of having a lot of junk to work with. Total I've spent so far is around $10 on a couple 1/8th pipe fittings I didn't have. Those could probably be optimized, but I went with what I could find at local stores on a Saturday.

So what I've got so far is the preliminary forge blower, and the skeleton of the main forge body. The blower is made from a 1" ID x 10" piece of pipe that I found in the junk pile. I flared the ends to make a venturi. This was done with an oxy/propane torch and an old clapped out anvil horn. Then I cut some holes in the back flare, with a plasma cutter, to accommodate some 1/8th" fittings for the propane. A small hole was drilled into a coupler and pointed down the pipe. I'm not sure at the moment if the coupler is blocking too much airflow, But all I had access to the time was 2" nipples so a coupler was necessary. But anyway, these fittings are connected to and old oxy/acetylene torch hose and regulator I had laying around, and plumbed to a propane tank. I plan to solder the fittings in place so they don't move, but only after I'm happy with it.

 The main forge body I built out of an old air tank that has been condemned. It's not suitable as a pressure vessel anymore. I shortened it and am going to use the end cap as a door that swings up. I have an opening cut out so a hole of about 4 1/2" x 2" is open when the door is shut. I'm going to be lining it with refectory wool, and then covering with KAST-O-LITE 30 LI G PLUS, and then coating with a ceramic refectory coating. The entrance will have a firebrick at the base. 

I'd love to hear some feedback and suggested improvements.
 

 

[JHCC]

I'm not qualified to critique your burner, but your forge looks good so far. When you say "ceramic refectory coating", do you mean a kiln wash? Kast-O-Lite is already a refractory coating. 

Otherwise, Welcome to IFI!!

[Mikey98118]

The burner looks too short, and its exit flare (flame retention nozzle) shape is all wrong; it will never work. The flame is heavily reducing. Read through the Burners 101 thread.

[Frosty]

Welcome aboard G. T. glad to have you.

First off, that isn't a bad burner for not knowing what you're doing. It's not a good burner though, there are a number of serious problems that aren't going to be correctable. I'm not being harsh there is just too much wrong to try and fix. 

As Mike said the flare at the nozzle end isn't working, if anything it's disrupting the flow. As you can see, the flame is on one side of the burner this is in part because of the nozzle flare but more because your jet is misaligned. The jet is the hole the propane is introduced to the mixing tube. 

Yes, the copper pipe and coupler are obstructing the intake flow and to add to the problem causes turbulence further inhibiting combustion air induction. 

Your plans for the forge sound good with the exception of including a fire brick on the floor. Unless you are planning on using a Morgan Ceramics K-26 insulating fire brick it won't work very well. A hard firebrick is a huge heat sink, requiring extra fuel and time to heat to forging temperature and because it has about the same insulating properties as an equal thickness of limestone, it conducts more heat through and out of your forge.

If you'll do some reading in the Burners 101 section of Iforge you'll get a handle on what works for a Naturally Aspirated (NA) burner and the Forges 101 section has thousands of posts and discussions about building forges. There are lots of proven designs including the development periods where someone told us what they wanted to build and we mercilessly punched holes in the ideas. Finally ending up with some darned good forges. 

Frosty The Lucky.

 

[gastlyTree]

Thanks for the tips. Yes the burner was cobbled together in a day. It was mostly just to get hands on with it. I find it easier to grasp these new concepts if I've done some experimenting of my own to see how stuff doesn't work. I didn't let it on in the post and video, but I had a hunch that the whole thing wasn't gonna work.

After some preliminary reading in Burners 101, I think I'm gonna build a Frosty T burner.

And Frosty, The fire brick I ordered is listed as an insulating fire brick, but gives no more details than that. I can always skip the brick if it's not going to work. I just thought it would be a good reference point for adding the insulation.

Thanks again for the replies. I'll be updating once I make some more progress.

[Mikey98118]

I should have noted that the work you did was well formed, and I have no doubt that you only need to pick a working design, such as the "T" burner, to do just fine.

[Frosty]

Trial and error is an honorable pursuit. How do you think I came up with the T adaptation of jet ejectors for a forge burner? My first functional T burner was #3 and worked because I made it super adjustable. 

Like I said that's a good first attempt for not knowing how NA burner really works. You did well, your next one will be screaming HOT. Honest, I'll be around if you need help. 

An Insulating Fire Brick (IFB) won't degrade the forge's performance. Don't be surprised if it crumbles after a couple uses though. Common IFB is rarely rated more than 2,000f and can't take the rapid thermal cycling a propane burner subjects forge liners to. The Morgan Ceramics, K-26 IFB is rated to 2600f and is reasonably resistant to borax based welding fluxes. Here in the States K-26 seems to be replacing old type IFBs, you have to special order the old ones at the place I buy refractories.

Another good way to make a flat floor in a cylindrical forge is to lay a layer of Ceramic Blanket Refractory (CBR) along the length of the forge floor. Feather the edges so the transition from flat floor to curved wall is smooth. Rigidize it in place and plaster it with KastOlite 30, maybe a LITTLE thicker but mine has stood up well with a 1/2" floor and some of my friends are pretty rough.  

Coating it all with a good kiln wash is icing on the cake.

Frosty The Lucky.

[gastlyTree]

So I picked up some of the piping for the new burner. I've got a friend with a lathe so it should make the work that much easier. I found male 3/4" to male 1" Schedule 80 pipe that looks like it might make a decent flare. It's much more gentle that you're typical cast iron 3/4" to 1" coupler, and it would be easy to modify on a lathe. I'm gonna do some experimenting with it once I get the T built.

Would grinding down the threads in the openings of the T be beneficial at all?

[Mikey98118]

The consensus of opinion is no.

[gastlyTree]

So I got my friend to do some lathing for me and built the T

 

[Mikey98118]

Well, that should work out fine.

[gastlyTree]

This is a little late. 
I had built the burner and in testing I was disappointed with my results. I went trough a few mig tips trying to tune it and tried some different ends. Then I left it on the back burner for a while, and then winter has has me not going into the shop all that much. But today I finally decided to throw the materials I had together and see how it works.
Now I had heard that the burner doesn't work optimally unless it's in a forge, and I should have taken that to heart back in august. So I threw together the insulation I had on hand and tested it, and what do you know it worked. Now I know the forge is ugly as sin, inefficient, and will degrade quickly. But for testing purposes and not spending more money and waiting for things to arrive, I'm  quite pleased.

I did a few quick tests and then decided to try something  big in it. It's about 1"1/2 drive shaft from a combine, so it's got good carbon content. Took a little time to heat up, but it was within reason.

 

 

[Mikey98118]

What I see of the burner flame looks encouraging. If you want to feel less discouraged about your gas forge, finishing it would help a bunch!

I started out playing with oxy-fuel torches in my garage;Although their flames were quite hot, they wwere slow to heat up work pieces. So, I bought some fire bricks, and started experimenting with tunnel shapes, to try and improve heat retention. Were you are with your forge build isn't very different from that. When I built my first gas forge, there was no comparison between its fast heating of work pieces and a brick tunnel.

In other words, you don't need a hotter flame; you need to do a better job of retaining that heat.

[Frosty]

Heating large stock isn't so much about the absolute temp of the flame as it is BTUs per second input into the forge chamber. 

You're burner is sputtering largely because the output end is inside the chamber and pre-igniting the fuel air mix. The flow is fast enough to prevent a full back fire but still, it's not optimum to have the flame burning IN the burner nozzle.

Ditto Mike on finishing the forge, you won't burn as much fuel to achieve the temps nor will you be heating the shop as much.  Pull the output end farther out of the forge, I mount mine so it's barely through the forge shell, maybe 1/4" into the Kaowool outer liner. This also lets you form a smooth nozzle taper from the ceramic wool refractory and hard refractory for a better burn.

Nice burner, well done. It's almost there. Maybe close enough.

Frosty The Lucky.

[gastlyTree]

It's been way too long but I finally mostly finished the forge.

Two layers of 1" kaowool, a castable refractory layer, and then layer of ceramic refractory coating. The whole thing is sitting on a 1" kiln shelf with a layer of kaowool underneath for cushion and insulation.

In the video the flame sputters a couple times but afterwards I took a 10th of a inch off the mig tip and it was running smooth. It also seemed to me that it was burning a lot hotter as well.

Thanks for all the help.

 

Also my brother in the background helped quite a bit. He was inspired to make his own forge (he's making the body in the video). He's making a smaller one that he wants to run with a 1/2" Frosty T burner. For those times when you don't need a big forge.

 

[Irondragon Forge ClayWorks]

Looking pretty good and hot, should work for ya.

I can't control the wind, all I can do is adjust my sails. ~ Semper Paratus

[Frosty]

I can't tell much about the flames from  the video, the first one is mostly swinging around. I don't hear any sputtering that matters. I'd have to guess. If there is any it's probably from exhaust being drawn in instead of clean air. That would be the result of the burner being directly above the doorways. If you rotate the burner intakes 90* it might take care of it. BUT that's just a guess, I can't tell from the video.

How about a few still pics. Videos are mostly distracting without providing anything useful. How about one straight in to show the flame in a cold forge and one from the side to show the "dragon's breath" to let us see how much unburned fuel is in the flame exiting the forge?

What I CAN see looks a little rich but it's hard to tell, the freshly laid refractory and kiln wash will burn orange or yellow oxidizing the calcite binders rather than burning rich. I can not tell.

I don't usually watch videos because they don't tell me much of use. Worse, they burn a lot of bandwith for . . . ?

Frosty The Lucky.

[Mikey98118]

Well, one thing even a video can show, is that the forge interior is quite hot. There isn't likely to be any major problems going on with the burner, with such a good result. What Frosty wants is a flame photo, so that we can see if there is any fine tuning left to do, but you're safely in the ballpark

BTW, know that you will actually be using that forge, I hope you are no longer using an Acetylene pressure regulator, and definitely not an acetylene fuel hose. I have listened to torch repair experts disagree on the possible dangers of using a MODERN acetylene regulator with LPG, but they both agreed on not using an acetylene fuel hose with LPG. Hose fires are soooo depressing.

[gastlyTree]

I had never heard that about the hoses, but noted. The plan was to buy a propane regulator and hose anyway. I don't know if the regulartor I used counts as modern, it's about 40 years old.

Here's the pictures. Just lit in a cold forge. As for unburnt fuel leaving the forge I wasn't able to capture it in a photo even with the lights off, but there was a little bit wisping out.

Running at about 5 PSI and I've got the needle valve turned down a bit

[swedefiddle]

Good Morning,

When you fire up the Forge, you will have higher Propane pressure. As the refractory heats up, you can turn the Propane pressure down. What the number is, is irrelevant, no 2 gauges read the same. Take a couple Fire Bricks and make an adjustable door with an opening at the bottom. two half bricks, one on each outside edge with a full brick across the top. You have to have an opening, for the chimney effect. Make it adjustable.

You should connect to the Saskatchewan Branch of the Western Canadian Blacksmith Guild. I have their contact if you would like. There are quite a few around/in Saskatoon but the membership is spread out quite a bit. Like the wind, here, there, everywhere.

Neil

[Mikey98118]

Okay, yes, you can certainly improve on that flame. I will let Frosty talk you through that; it's his burner design.

But, I suspect that you have interference with the flame going on by the surrounding refractory.

[Frosty]

Thank you for humoring me gastlytree, those tell me everything I need to know. Your flame could lean up a LITTLE bit, we're talking sanding a couple thousandths at a time, little bit. It's close enough to use though and the forge is HOT. Your call. I agree with Mike your burner is miss aligned in the holder and is impinging on the refractory losing energy and form. Tweak it straight and it'll improve. That's from looking at the flame in the cold forge.

The pic across the opening says the burner is adjusted just fine, what little dragon's breath is insignificant. If steel is not forming scale in the forge I wouldn't mess with tuning it any more. If it stutters it's the exhaust from the openings mixing with the combustion air, rotating the burner 90* when you adjust the alignment should to it. EZ PZ. I don't see any oxidizing calcite orange flame either. SWEET.

Oh YEAH, 40 years is WAY TOO old to be a multi fuel regulator, maybe but not likely. Do NOT use it for acet or any other fuel gas when you remove it, consider it dead and dispose of it, even the gages diaphragms are damaged. Propane is a VERY chemically active gas it requires special rubbers, plastics, etc. or it will erode it. Same for the hoses. Sad but like Mike says fuel hose fires are an OH SO interesting way to end a day's work.

You have a winner of a forge, especially for a first build. 

Neil's recommendation for door closures is sound and the flat smooth porches front and rear are ideal. If you leave around 1" 25mm space between the bricks and the forge exhaust will be spread over a large area minimizing back pressure  on the burner while maximizing contact with the bricks. Coat them with your kiln wash and they become thermal baffles and WILL increase the effectiveness of the forge. The temp will only increase a little bit but the baffles will r-radiate more IR into the forge to do work for you and will be a heat shield so YOU don't get toasted like a marshmallow in front of it.

Well done. Frosty The Lucky.