Single Burner Forge Recommendations?

[intrex]

Hey Everyone, 

I have a coal burning rivet forge and a clam shell (with hinged walls) 2 burner gas forge.  I am not sure how many hours I get out of a 40lb tank but it can't be more than 8 hours at the most.  After filling up my 40lb tank and a regular 20lb tanks I was thinking that I would use propane much more often if my forge was more efficient.   Over the last few years the majority of the forging that I do is on regular shaped stock 1" or under in thickness stock.  For the vast majority of what I do a small single burner forge would be fine and I have the 2 burner if I need it.  I am looking at getting something like this http://www.ebay.com/itm/Atlas-Mini-Forge-propane-knifemaking-forge-w-30K-BTU-burner-and-regulator-/112007645631?_trksid=p2352135.m2548.l4275 size to be my new primary propane forge.  

Do you all have any recommendations for mini forges of this size?  If possible I would want one that I could easily replace the fire brick in.  I also don't want something with wool in it that is going to require a lot of maintenance.  I am decent with a Mig and could build one myself but am inclined to buy one at the 100-200 price range.  

Thanks for any suggestions,  

[Latticino]

IMHO forge efficiency is related to several variables:  interior volume, insulation quality and door design.  The first is a function of the size of work you want to do.  The second is an interesting variable as better insulating quality (lower thermal conductivity) is often indirectly related to material density, but some material density is helpful if you are going to be working up to a significant thickness (as the mass of cold metal will significantly cool the forge interior every time you put it in).  It becomes a trade off on whether you go with light weight high temperature insulating blanket material, medium weight insulating fire brick, or relatively heavy weight insulating castable material (not castable refractory, castable insulation).  In my experience it is a good idea to combine these materials and use the appropriate ones for appropriate parts of the forge.  I have found that insulating fire bricks don't hold up for me (my gas forge made with 2300 deg. F insulating bricks only lasted (4) firings).  The surface doesn't do well with direct flame impingement, and they don't handle thermal shock well either.  Perhaps on a smaller scale they would do better, or maybe the Atlas forge uses better bricks.  I don't have the data handy right now, but if I recall correctly insulating brick doesn't have as low a thermal conductivity per inch thickness as blanket, though likely slightly better than most high temperature insulating castable.

As far as door design, it doesn't look like the Atlas forge has any at all.  Needless to say, door design can vary quite a bit if you have a NA or blown burner.  The former doesn't use electricity, so you don't have energy loss there, but the latter can have a much smaller door opening, so you lose less heat.

An idler circuit, or some kind of forge temperature control, will also save you gas, if that is your key criteria.  Personally I think the time you use doing the forging is the most expensive commodity you spend, so I would say an efficient forge is one that allows you to work most effectively.

If you get one of the Atlas forges I'd be interested in hearing your experience with it.

[Mikey98118]

I wouldn't want to hear it. The sound of moaning and weeping isn't sweet to my ears. I can't see much of the forge's construction details, except the the burner will create one heck of a hot spot, but the burner is JUNK!!! I doubt that the rest of the forge is built any better. If you want good fuel economy  with heavy stock, I would suggest you back track every thread on ribbon burners for the last few months; add some sweat equity with your money, and never need to look back.

[Frosty]

Did you say that mini forge is actually lined with fire brick? The burner is crap, just another example of being able to MAKE anything "work".

Why not ceramic blanket? It'll last far longer than fire brick and is a much more efficient insulator. Even the expensive soft fire brick is only good for 2,400f on a good day, most is only 2,200f and has a pretty short lifespan in a decent forge. I get MAYBE 3 firings before the soft brick starts to crumble.

Check out Teenylittlemetal guy's 2 brick forge for a MUCH better design. Easy fast and works a treat. Scale it up to a 3 or 4 brick forge and heating 1" bar is easy. But that's IF you gotta have a fire brick forge. The real surprise to me about his design is how well the up-draft burner works, it fires straight up on one side of the forge. Junk doesn't fall in and it heats far better than the same burner in a more conventional alignment. If all you're doing is heating straight bar I'd at least give this one a shot.

How about hitting Wayne Coe's site, ordering just enough Kast-O-Lite 30 castable high alumina bubble refractory to make the hard liner, a pint of one of the IR "reflective" kiln washes he offers and just build a forge to suit? The experienced and professional skuttlebutt here is saying Kast-O-Lite 30 far exceeds the heat and abuse both mechanical and chemical modern blacksmiths can administer. Then just wrap it with some kaowool and a shell. All the shell does is contain the liner material and support the work, black steel stove pipe will hold a couple hundred lbs. over 1'+ without batting an eye.

Build or buy a GOOD burner and the hardware.

Why waste $270 on that definitive example of "50% donkey" manure?

Frosty The Lucky.

 

[intrex]

Hey Guys, 

Thanks for the feedback and suggestions.  I only wish Frosty had some passion about burners and forges :).  It looks like the two brick forge with a purchased burner is the way to go to get my mini forge setup and running quickly.  

[Mikey98118]

Well, that brings us down to what burner to buy. Chili Forge makes the best burner, period, and costs less than the next best. Next comes the Hybrid burner family; I personally don't like Price, but his burners are almost as good as a Chili burner, and comes in more sizes. Size choices are very important to you in a mini forge.

That was the "A" list; short, wasn't it? The "B" list comes from Devil Forge; an eBay supplier; they are low priced for what they are (as long as you don't also buy one of their useless foreign regulators),  and they perform adequately.

Every other naturally aspirated burner I've seen for sale so far is JUNK. Of course, you could save a lot of money and make a simple to construct and perfectly adequate "T" burner,unless money burns a hole in your pocket...

[Mikey98118]

OOPS! I forgot Larry Zoeller's "Z" burner; this is a very nice running burner for a very low price, and almost makes the "A" list for performance.

[Latticino]

Personally for a very functional mini forge I used a standard 1 gallon paint can and lined it with 2" of high temperature ceramic blanket, rigidizer and a final inner layer of high temperature refractory cement (applied in several very thin layers).  I then cobbled together a 1/2" Frosty T and it appears to work pretty well.  Haven't got enough miles on it to be able to talk about longevity or ultimate temperature, as it is just prototyped at this point (need to finalize a stand, doors and burner support), but the whole thing must have run me under $30 as I had the scraps of wool, a regulator and hose laying around from another project.  So far I think I have about 2 hrs. worth of assembly time in, so not sure if you could make a 2-brick faster (but if you do be sure to buy extra bricks).

[Frosty]

Heh, heh, heh, yeah I'm trying to learn to care about forges and burners a little. Mike is starting to rub off on me so there may be hope.

Do you have or have access to a drill press and moderate shop skills? A T burner is easy to make and works pretty well. It's not a Ferrari it's more of a trusty old pickup truck design. (I always feel so presumptious calling it a "design". The ratios for tweaking jet, tube length, etc. to different sizes is in the Illustrated T burner plans as found here on Ifi somewhere.

Now I'm off to take a cold shower.

Frosty The Lucky.

[intrex]

Hey Frosty

I do have a drill press and decent shop skills.  What I don't have is a lot of is free time.  After rebuilding a few pole vices, belt sanders, anvil stands, drill press, torches, coal forge, and making more tooling than I can keep track of I am starting to see the value in purchasing some things for the shop.  It seems like I have spent more time making things to make things than actually making things if that makes sense.  

We will see how much shop time I can get in this weekend and if I can get around to messing with these designs.

Thanks for all of the guidance 

[Frosty]

Take a look at the Illustrated plans, the technique I lined out takes less than an hour to get it to the tuning stage. When I had my lathe wired I was turning them out in under 15 minutes. It REALLY is a simple easy burner.

Frosty The Lucky.