Hammering at Altitude

[DickyPitts]

Howdy all.

 

I finally had time to light a fire at my new house in Bailey Co, I'm at about 8500 feet, and the views up here are amazing. I have some observations about hammering at altitude. Criticisms are welcome. I'm thrilled to be back in the game.

 

Got started on a couple of curtain rod hangers, and I'm trying to get a nice wide scroll at the end and then do some simple bends and a hook to hold the rod, I'll get some pic's up after I refill my propane tank and finish them.

 

Maybe it's just that I haven't had any forge time since late last summer, but heats don't seem to last as long up here. Counter intuitive because with lower pressure it seems that the metal would cool slower, less contact incidents with air molecules because of the lower pressure seems to say that the heat would last a little longer, but I found that I only got a little over 30 seconds of hammer time before the steel cooled from yellow to a dull red. I'm working half inch square mild steel. Anvil was cool, maybe that had a lot to do with it.

 

I'd forgotten how much time I spend waiting for the iron to heat up. Even with two irons in the fire I had plenty of time to rest between working pieces, which is a strange necessity up here where the air is thin. I'll get acclimated eventually, but at the moment I get winded walking to the mailbox. I've only been here three weeks.

 

Also, fuel seems to burn faster. I burned up a standard 30lb grill tank in an hour and a half at 9 psi in a 2 burner homemade naturally aspirated gas forge. Time for some forge tuning. Hopefully I'll be able to get my kaowool up from Alabama around thanksgiving. No reason to buy more when I've got most of a roll already. 

 

It's quite possible that it's just been too long since I swung a hammer, and my memory isn't perfect. 

 

Any other alpine smith's want to comment? What are your experiences?

 

 

Dicky Pitts.

[DickyPitts]

Ok, so I started the fire back up, and noticed that one of my burners wasn't going... oops. I loosened up the jet manifold hold downs, and moved the manifold around while the fire was burning, looking for a sweet spot. Found it, and the forge got a lot hotter. easily welding heat. Weld didn't take, but that's probably because the steel wasn't clean enough. wire brush though I might, there was still a layer of scale on the inside of the weld when I opened it back up for a look. I guess I need some borax. The fire does not seem to be scaling the metal though. That's good. All in all a great day. Got to heat up some metal and beat on it, and that's always a good day.

[John McPherson]

IIRC, Robb Gunter invented the original recuperative heat forge design because of the ineffeciencies of propane,especially at high altitude.Sandia labs being about 5400 feet above sea level where he was working at the time.YMMV

[Chinobi]

The altitude brings with it thinner air, so your forge has less oxygen to combust with, reducing the efficiency of your burners.  this is likely why you are noticing an increase in fuel consumption as you will need to tune your burners to a different mixture than you would at sea level.

 

hope you acclimate quickly and easily! i know i wouldnt function well at 8000 feet :)

[DSW]

Interesting thoughts. I'd have thought with thinner air, you'd need to lean out the mix to accommodate the reduced oxygen, thus cutting fuel consumption, though you would have a decreased heat as a result. I'd have also expected the reduced atmospheric pressure to have played havoc with the regulator, possibly causing the pressure settings to need to be adjusted to compensate for the lower pressure on the exit side of the diaphram.

[Chinobi]

im getting a little beyond my direct experience here unfortunately so i dunno how much i can really add to the discussion.  iv just heard anecdotal evidence of how gas forges react to different altitudes.  i saw pic's of Jay Kidwell's propane forge in operation at the school in los angeles (normally Jay and said forge operate at altitude, i cant remember how many thousands but i think it was in the 3-5 range) and it was a flamethrower, the sides were glowing on the outside of the shell despite a couple inches of i forget what kind of insulation/refractory.

 

the naturally aspirated venturi burners are usually constructed with a specific range of flow velocity in operation (from the how to's and spec's iv read on here and the net at large) in order to keep the primary flame contained in a specific zone of the nozzle geometry.  id think reducing the pressure (and subsequent velocity) feeding into the burner would cause a lot of additional problems with combustion.

 

but, i think id better retire to my armchair before i start getting too theoretical and wait for somebody who actually forges at something higher than low triple digits to weigh in :)

[Frosty]

Dick: Post a pic or two of the flame from the door, I'll let you know if and how it needs tuning. Thinner air means a rich burn if you don't tune it. No scale build up in the chamber means it's a little rich which is good.

 

You remember my old pipe forge and how much dragon's breath it had? Remember how it'd reduce scale on steel we put in it? That was burning WAY rich and went through quite a bit more propane than necessary for the work. If yours looks anything like that you need to lean it up a little, pulling the jet farther from the throat will lean it by increasing induction.

 

How's the new house?

 

Frosty The Lucky.

[DickyPitts]

Thanks for the responses all. I'll probably be going with a solid fuel forge soon, since i love the ability to localize heat. As it is, i'm going to continue playing with the gas forge until i can weld in it. Mostly because I can't give up on a project. (gets expensive some times) I'll get some pic's up later after it gets dark hopefully I'll be able to get some useable information. Moving the jets out from the throat doesn't seem like the best idea since it's a commercial setup, the nozzles, jets, and manifolds were tuned to each other. I moved the jets and manifold transverse across the plane of the nozzles to center the jets, and my efficiency went up a lot. I've also been playing with the pressure regulator. I've got a good orange heat with as low as five lbs, and I've gotten well above welding heat with 10 Lbs. I do think i'm scaling in the forge. I've examined some finished pieces and they're just coated with layers of scale. I'm brushing nearly every other heat to try to keep my pieces looking nice. The weld I tried only stuck along one side, and when I pulled it apart, there was a good bit of scale in between.

 

Think I should move this to the gas forge section? pictures to follow.

 

Jerry, I love the house. It's coming together and I've finally got time to do some forge work. (more than have time, I now have a honey do list of things to make)

[DickyPitts]

Ok, Lots of pictures:

 

First the forge stuff:

 

These are pic's of the forge up and running. I know the color looks high yellow, but I blame that on my phone's camera color balance. The hottest it got up to in an hour of running was a medium to high orange. I may be able to improve that with a second layer of kaowool, (mine's in alabama, not here in colorado where I can get at it easy) and a layer of ITC100. 

 

Maybe you guys can suggest something else from the photo's.

 

Another failed forge weld pic, You can see separated scale right in the joint:

 

Next up, my shop at the moment:

 

My most recent project (still warm to the touch at time of posting)

 

And a pic from my front porch for Jerry and Deb Frost:

 

Thank you for your responses.

 

Dick

[Frosty]

I can't see much of the flame but it looks like it's running a bit lean if anything. Can you choke it?

 

When I do a faggot weld like that, I match the join halves and open it enough to clean it really well, I thin file is so much better than a brush. Then I flux it lightly and close it cold. then I bring it to heat ad weld. Get it clean and close enough and it'll begin exchanging electrons without heat, add heat and it's a done deal. Personally I've never had what I'd call good luck fluxing at orange after wire brushing.

 

If scaling is a serious problem you can flux the work to forge. It'll help prevent scale forming but it's going to be messy, molten borax is going to spray at every blow. It's really only for situations where scale is causing serious problems.

 

Great view you have from your porch, I'll make sure Deb sees it. I'd say your current set up is nicer than the one we worked in here, I didn't even have a post vise.

 

Frosty The Lucky.

[DickyPitts]

Memories Jerry, I remember digging that 200+ lb Trenton out of the snow and ice. I thought it looked bigger than I was but we muscled that thing up on a stump and had at it. I remember you wouldn't let me swing a hammer at the Kohlswa until i'd managed not to bang on the face of the trenton for a while. I remember nearly gassing ourselves out of the tent when we didn't have quite enough ventilation. You had a post vice, two actually, but they were on the bottom of the materials pile. I believe we did get one of them set up eventually. 

 

check my definitions real quick:

 

Lean= too much air, not enough fuel

Rich= Too much fuel, not enough air.

 

If i've got a lean condition, I could choke the burners, or increase inlet pressure. I'm hoping to tune the thing to run well without a choke, depending on gas pressure. unfortunately the grill tank i'm using keeps freezing up and causing my pressure to drop like a rock. Maybe a choke is the only way, but the best way I can think of to do that would be to build a box around the inlets and put a flap on the box. I did have it choked with duct tape, which worked...sort of.

 

This thread is kind of bouncing all over the place, does anyone else out there play around at high altitude? I believe the guys from DragonForge LTD. started out in a studio in Bailey.

[Frosty]

Yeah I still protect the Soderfors like I did then, it's the first and best anvil I've ever owned. I still make sure new guys have enough hammer control to not hit the anvil instead of the work. The Trenton, while a good working hardness on the face isn't near as hard as the Soderfors, a new sharp file will barely mark it so I'm concerned about a dangerously large chip could come off the near edge and open a femoral artery. I'm good at 1st. aid but really hate practicing it.

I remember mounting the vise now. I think we put it on a birch round nailed to a piece of plywood?

 

Yes: lean= not enough fuel. Rich= too much fuel.

 

The flame looks pretty close, try a little tin foil till you get the openings the right size, then worry about something  more permanent.

 

Even running a 100lb tank it wants to freeze up, at demos, etc. I run off a 40lb and it's freezing in less than an hour so I put it in the slack tub. The water, even as ice has a much higher specific heat than propane so keeps it from freezing and maintains pressure and volume until the bottle is almost completely empty.

 

Jer

[ThomasPowers]

How about a blown forge?  When I was using a friends set up around 7000' here in NM he was running a blown propane large forge at welding heat  I know because my 36" of 2.5" sq stock was sitting in the forge and another person slid a chunk of 3/4" round stock against my piece and we had to hammer it off---no flux, no force just two pieces sliding together!

[anvil]

Craig May is -up the road/ down the road/ across the road. Look him up. Good smith and good people. Also check out the "Rocky mtn Smiths". Good people too. Oh, and welcome to Colorado, land of " Rocky mtn high". I'm north of the land of enchantment (N.M), Mancos, Co. don't ask where its at--- even the people of Mancos don't know where Mancos is. Lol

[ThomasPowers]

On many aspirated forges turning up the gas does not rich out the burn; it stays pretty much the same way it was at lower pressures.

 

Chokes are needed.  My current burner I use a stainless hose clamp and move it to where it's needed.

[mccumber]

I'm north of the land of enchantment (N.M), Mancos, Co. don't ask where its at--- even the people of Mancos don't know where Mancos is. Lol

 

 

Lol what does it say when I knew exactly where you're at? Used to go that direction a lot when I was younger. Was born in Alamosa and had family in Durango and further west :)

[anvil]

Dang, now we'r both in trouble! I've spent most of my time wsst of Colorado Springs. Came to the 4-corners area 4 years ago. Been getting coal at Hesperus and decided on Mancos to reroot. Love it here.