My new forge - Taking suggestions, thoughts and observations...

[twodogzz]

I'm pretty pleased with my first forge build.

It's a 20# propane tank, Wayne Coe inspired design and materials (thanks, Wayne), David Hammer style burner from e-bay with my modifications. More detail on the design and materials below. 

I would welcome any suggestions, comments, and solutions to the issues listed.

 

I haven't tried to get it up to forge welding temperature yet but it heated a piece of 1" x 1/4" flat bar up to a bright orange  with a wet sheen. Not a lot of scale. It seems to be happiest in the 15-20 psi range which, correct me if I'm wrong, is a bit high for general forge work? Stable operation at 7 psi, but not enough heat at that setting to get up past dull orange. at 15 psi it took about 6 minutes to heat a cold horseshoe to orange.

Here's some random video before I get to details and issues:

 

There are a couple of issues that could use improvement if possible to correct at this stage.

1. First issue (or not an issue) is that the hot spot is off center, half hitting the floor, half hitting the wall. Should I try to correct this somehow? The burner tube is centered well. The mounting of the burner tube can be adjusted, could I aim it a bit toward the middle, even if it's a bit askew in the hole? Should I file a bit of the refractory at the opening to flare it out a bit?
2. The top and bottom disconnect so the chamber can be enlarged, propped with fire brick etc.  There's a bit of gap  where the walls meet the floor. I don't think this is a big problem, but should I stuff some ceramic wool in there for efficiency or safety? There was no excess heat on the exterior when it was at full heat.
3. Not a big deal, I don't think, but the opening for the flare as you will see in the pictures is glowing at the edge. Should I scoot the burner down until that glow disappears or is it fine/desireable? It's recessed 1" at the moment.
4. I think the flame looks to be tuned pretty good. Anybody disagree?
5. I know there's no concrete answer, but what is the optimal pressure range for operating a forge of this design?

Here are the specifics of the build:

• 0-30 psi regulator, shut off valve, needle valve, pressure gauge
• 3/4" David Hammer style burner, .035 mig tip
• ~350 cu. in.
• 2x 1" ceramic blanket
• Kast-o-lite 3000 castable refractory
• Metrikote IR reflective
• barbecue heat paint for suburban camouflage (that's just a grill, officer. Honest...)

Some more pictures:

 

 

 

[Frosty]

The burner flame is aimed into the corner of the floor and wall. This isn't nearly as good as it should be, it needs to be aimed at the closer side of the floor so it will cause a strong vortex in the chamber. A vortex will even the temperature in the forge considerably. As it stands the hot spot is half way up the far wall, your last pic shows the piece centered on the floor almost completely OUT of the hot spot.

Not a bad job, just needs a little tweaking.

Frosty The Lucky.

[twodogzz]

I think I have enough adjusting room to skew the burner in the mount to get about 3/4 of the hot spot onto the floor. I may have to flare out the inside of the hole in the refractory a bit to get the clearance for the flare, though. If I'm understanding you right, in relation to the permanent position of the welded mount, the tube should be vertical or close to it, right? 

Or wrong?

As it sits, the hole through the refractory does not give a lot of clearance. If by tweaking" you mean cutting, re-welding, grinding out refractory and re-packing in new refractory to get more of a vertical... hoo boy... that's some serious tweaking. 

Thanks for the input.

[Frosty]

No, you don't really want the burner perpendicular to the floor if you want even heat in the forge. The more tangential the flame impacts the refractory the more even the temperature and the longer the refractory will last.

I'm thinking the easiest way to realign the burner would be to shift the floor to the point the flame hits the close edge and crosses at a shallower angle. Yeah, I know that would mean pulling the liner out of the forge and moving it over say 4" and reattaching it.

Or, pull the liner and flip the forge over so the burner is aligned across the top tangential to the liner.

I wouldn't really rip the liner out and change it now. Liners are wear items the burner WILL burn it out eventually and the way it's aligned now, sooner than best. That will give you plenty of time to see how it works as is and when you reline it do so a little less permanently so you can shift it after you see how it works.

Frosty The Lucky.

[twodogzz]

I'm not able to post a response. I messaged it to you.

[WayneCoeArtistBlacksmith]

You may want to go back and look at the pictures of my forge on the Forge Supplies page at www.WayneCoeArtistBlacksmith.com.  The burner is angled across the top of the forge so that the flame enters at the top where the refractory curves around.  This sets the flame up to swirl around in the forge.

As it is is ok and I would not go changing anything now.  Plan making corrections as needed.

At 350 cu in you should be able to get to forge welding temps, depending on your elevation above sea level.  That is high gas pressure, you should be able to reach forge welding temps at about 10 PSI and general forging at about 5.

 If you had made the joint between the two portions smoother by screeding across from front to back while the casting was still soft you would not have the gap issue.  As your flame is aimed at that joint you may get some flame exiting there but it is no more safety or efficiency issue than the flame coming out the doors.

Over all a pretty good build.

[DSW]

Wayne/Frosty a question: Many of the gas forges of this style I've seen have a smaller opening or some sort of "door" to close down a large opening. Would  decreasing the height of that opening with bricks help with temps or do you need the large opening to get the flow right to keep your air/fuel mixture correct. Seems to me that large tall opening would be a big heat waster open full time.

[ThomasPowers]

Why do you need such a tall fire chamber?  The items you show working don't require it and excess space is excess heat loss.  I would definitely close off the upper section of the door to save on gas!

[twodogzz]

 

6 hours ago, WayneCoeArtistBlacksmith.c said:

You may want to go back and look at the pictures of my forge on the Forge Supplies page at www.WayneCoeArtistBlacksmith.com.  The burner is angled across the top of the forge so that the flame enters at the top where the refractory curves around.  This sets the flame up to swirl around in the forge.

As it is is ok and I would not go changing anything now.  Plan making corrections as needed.

At 350 cu in you should be able to get to forge welding temps, depending on your elevation above sea level.  That is high gas pressure, you should be able to reach forge welding temps at about 10 PSI and general forging at about 5.

 If you had made the joint between the two portions smoother by screeding across from front to back while the casting was still soft you would not have the gap issue.  As your flame is aimed at that joint you may get some flame exiting there but it is no more safety or efficiency issue than the flame coming out the doors.

Over all a pretty good build.

Thank you, Wayne. I debated with myself whether to orient the burner as you do on the forge pictured on your site. Most of this build was from your instructions, however I also took design cues from David Hammer's Super C design, and perhaps wrongly, I chose to mount it like he does for that design. If you look at his Super C, the burner orientation is more or less identical to mine. I understand there could be differences I'm not aware of, though. I chose to do it this way  based on that, and because of the simplicity of the fabrication. That was my thought process, anyway.

Won't be an issue with the next build which will be a ribbon burner.

As for the gap, I went back over it twice while the mortar was still soft, but apparently didn't do such a good job of it. 

 

34 minutes ago, ThomasPowers said:

Why do you need such a tall fire chamber?  The items you show working don't require it and excess space is excess heat loss.  I would definitely close off the upper section of the door to save on gas!

The items I show working are things I had handy to heat and beat in a test firing. I'll be using fire brick to close up the opening when it goes to work for real.

I appreciate everybody's input.

 

[twodogzz]

Did some tweaks today, repositioning the burner tube to skew slightly, filed out a bit more of the opening for the flare (it was a little bit narrower than I think it should be). Added fire brick to serve as doors, cut about a 1/4" thick piece from fire brick to serve as a bit of a riser for stock. It performed well in the 7-10 psi range. Heat is spreading out more now. Much more dragon breath than yesterday.

The downside is scale through the roof. Lots of adjustments on the choke and never did get it dialed in. 

About an hour in it started sputtering and whistling, so I shut it down. The tank wasn't frozen up and is still about half full. Could the flare be getting hot enough to ignite the mixture in the burner tube?

[WayneCoeArtistBlacksmith]

By blocking the back door, and maybe even restricting the front you can control the amount of oxygen in contact with the metal.  Scale is formed by the presence of oxygen in contact with red hot steel.  Restrict the oxygen in the forge and you can get a complete burn with little or no oxygen in contact with the steel, thus less scale.  It will increase the dragon's breath.  An air curtain can help reduce the heat in front of the forge.

Let me know if I can help.

 

[twodogzz]

Thanks, Wayne. The back door was blocked yesterday and was partially open today, so that makes sense. I'll close it back up tomorrow and see.

[Frosty]

You are making WAY too many changes at once. Change one thing at a time and note what happens. Yes NOTES, take notes! Another mistake is trying to build a device from two sets of plans. Pick ONE, either Wayne's or Dave's. For example, a silly exaggerated example to make the point sure but the point is the same. Would you rebuild an engine using both Chevy and Ford manuals?

The openings in your forge are WAY too large. Even if the burners are running rich the high velocity gasses flowing past the openings will induce outside air into the chamber. Close off the openings as much as practical to maintain a positive pressure in the chamber.

Forget what I said about re-orienting your burner in the chamber. Once closed up it'll get plenty hot enough, make burner orientation experiments in a later forge. This one only needs a little tuning not a rebuild.

I do have one point on which I differ with Wayne. My experience has been that there are too many variables to be able to say what PSI range someone's forge should run under. Barometric pressure is a biggy whether elevation, weather pattern, wind pattern, etc. driven it's probably one of the biggest variables out there. Believe it or not my ears pop if I drive the 1/2 mile across Lucille cr. valley north of me or over the ridge 1/4 mile south of me and it takes several inches of mercury difference to make my ears pop. Humidity is another major factor though not nearly as great.

Then there are individual burner build variations that affect it's operation. My recommendation is to use the gauge to note what pressure makes your burner perform in what way. NOTES!

Notes are really important when a guy is learning how to work a new machine and yes these burners are machines, engines in fact. Once you've built a few, learned to tune them and understand what's actually making them work keeping notes isn't so important but for now. Take notes.

Frosty The Lucky.

 

[twodogzz]

5 hours ago, Frosty said:

You are making WAY too many changes at once. Change one thing at a time and note what happens. Yes NOTES, take notes! Another mistake is trying to build a device from two sets of plans. Pick ONE, either Wayne's or Dave's. For example, a silly exaggerated example to make the point sure but the point is the same. Would you rebuild an engine using both Chevy and Ford manuals?

The openings in your forge are WAY too large. Even if the burners are running rich the high velocity gasses flowing past the openings will induce outside air into the chamber. Close off the openings as much as practical to maintain a positive pressure in the chamber.

Forget what I said about re-orienting your burner in the chamber. Once closed up it'll get plenty hot enough, make burner orientation experiments in a later forge. This one only needs a little tuning not a rebuild.

I do have one point on which I differ with Wayne. My experience has been that there are too many variables to be able to say what PSI range someone's forge should run under. Barometric pressure is a biggy whether elevation, weather pattern, wind pattern, etc. driven it's probably one of the biggest variables out there. Believe it or not my ears pop if I drive the 1/2 mile across Lucille cr. valley north of me or over the ridge 1/4 mile south of me and it takes several inches of mercury difference to make my ears pop. Humidity is another major factor though not nearly as great.

Then there are individual burner build variations that affect it's operation. My recommendation is to use the gauge to note what pressure makes your burner perform in what way. NOTES!

Notes are really important when a guy is learning how to work a new machine and yes these burners are machines, engines in fact. Once you've built a few, learned to tune them and understand what's actually making them work keeping notes isn't so important but for now. Take notes.

Frosty The Lucky.

 

I know it sounds like a lot of changes, but it really wasn't. All the initial tweaks took about 10 minutes. 5 minutes after that I was beating hot metal. That's what you said in your first response, no? "A few tweaks"?

I haven't and don't plan to rebuild this one. I've tweaked it. I might need to tweak it a little more, I'm mostly happy with it save for getting the scale issue figured out. The openings are a size I desire and can be closed down easily with $2 worth of fire brick. I did it today. I'm not building forges to "experiment". I'm building forges to forge stuff. For better or worse, what it is, is what it will be, as will the next.

I get your point about not using different designs, but search around and show me any two homebrew forges that are identical. I see a lot of really fine work from people using the sketchiest of equipment. They're one step ahead of me: They've done really fine work.

And remember... Every NASCAR race Dale Earnhardt ever won in a Chevrolet was riding a Ford 9" rear end. 

 

Cheers

[Frosty]

If you were at Earnhardt Racing's level, making forge burners we'd be asking you questions.

Not being snippy, I misunderstood what you were doing and asking. Sounds like you have a pretty good handle on things.

Frosty The Lucky.

[twodogzz]

I'm at Earnhardt's level... at something. I'll let you know when I figure out what it is.

I think I did pretty good. It seems to be heating up metal, and I learned some stuff.

So here's a simple enough question from a noob: In general, does performance suffer as the fuel tank empties? It feels like it's at about half-full. Maybe a bit less. Something caused the sputtering and ignition in the mixing chamber about an hour in yesterday. Need to figure that out.

Today is a cold day with plumbers ripping up both bathrooms, so all I get to do today is sit and speculate.

[ThomasPowers]

Yes the draw rate supportable on a propane tank is dependent on size and ambient temp.  Using a regulator does help; but a small tank under cold conditions can't vaporize enough propane to keep up.  Common method is to place the tank in a washtub of warm water to create a "warmer ambient" for it.

[twodogzz]

Thanks, Thomas. It didn't "freeze up" with frost on it like I have seen discussed here. It was about 50 degrees yesterday and the tank didn't feel much colder than that. We'll see, when I fire it up next time.

 

[ThomasPowers]

check for debris in the burner orifice?

[twodogzz]

None found.

[jcornell]

I consistently found when I was using one 20# tank that after about an hour of forging, my burner started getting less hot.  The problem was mostly solved when I bought a manifold and ganged two 20# tanks together.  Sometimes there would be visible frost on the tanks, some times not.

40# and 100# tanks are dandy, but hard to schlep in the back of my sedan.

Edited February 5, 2016 by jcornell
clarity

[twodogzz]

2 minutes ago, jcornell said:

I consistently found when I was using one 20# tank that after about an hour of forging, my burner started getting less hot.  The problem was mostly solved when I bought a manifold and ganged two 20# tanks together.  Sometimes there would be visible frost on the tanks, some times not.

40# and 100# tanks are dandy, but hard to schlep in the back of my sedan.

I'm certain that one of those solutions is in my immediate future.

[Mikey98118]

Twodogzz,

I really enjoyed your forge build video on YouTube, and hope the outcome doesn't discourage you. I won't add anymore advice than you've already recieved about the forge, other than to encourage you to keep tweaking. If you want to use so much less gas that your tanks don't freeze up, build a different burner. The  Frosty "T" burner is as easy a build as you'll ever run across, and isn't a gas hog.

[Forging Carver]

What I would do is use this one, make some cash with it, and then make another one with the cash you made if your not happy with it. That is what I plan to do with my little freon forge I am building. You learn from the first build and get better on the next.

[Mikey98118]

I think two five gallon cylinders should have at least one-third more surface area than one ten gallon tank; another good reason for ganging two or more five gallon tanks together. "Schlepping small propane cylinders  tied upright in a partially open  (but properly secured in position) trunk is legal; schlepping them in the back seat isn't.