Gas forge choice

[Aaron Gouge]

Hey all,

    So I’ve been using an Atlas mini forge since 2018. I’m contemplating upgrading to something bigger that will allow me to do larger pieces. I’d like to make more tomahawks, hatchets and axes. 
     I really love the Atlas mini Forge. It’s held up well and their customer service has been excellent. I have contemplated going with their Graham forge. I think the chamber on that one is 5 x 13. 
     Would those of you with more experienced  consider that an adequate size? Thoughts on other gas forges? 
     Thanks

Aaron 
 

[Alan Longmire]

The few times I've made a hawk in a gas forge it was with a chamber measuring around 7" diameter by 12" long, with a blown burner on one and a blown ribbon burner on the other.  I found I much prefer solid fuel for hawks because of the ability to get spot heats, but that's just what I'm used to.  I suspect a five" chamber will work, but it sounds a little small for axe work.  Have you considered building your own rather than buying?

[Geoff Keyes]

I have a forge that I built for doing long billets of damascus.  I have a press, so taking an 18" long heat is doable.  100 cfm fan driven (a version of the system in this post) common rail twin orifice.  All of that sounds impressive, but it's just a second burner inlet using a single pipe for the gas.  The forge chamber is a piece of 1/4" wall tube, 24 inches long by 12".  2 wraps of wool makes that an 8" chamber.  I used a thick coat of mizzou over the inner layer of wool.  It does not have a door in the far end (due to space considerations) so there is a fair bit of dragons breath.  I plugged the end of the tube with 4 inches of wool.  The 2 burner outlets are spaced about a quarter of the way from each end.  It's a bit of gas hog (big chamber) but it will heat a  billet 5"x 5"x 1.5" without too much trouble.

It needs a reline and I'm considering splitting the case lengthwise and adding 4" of width, making and oval chamber, better suited to axes, but still good for damascus.

Geoff

[Aaron Gouge]

7 hours ago, Alan Longmire said:

The few times I've made a hawk in a gas forge it was with a chamber measuring around 7" diameter by 12" long, with a blown burner on one and a blown ribbon burner on the other.  I found I much prefer solid fuel for hawks because of the ability to get spot heats, but that's just what I'm used to.  I suspect a five" chamber will work, but it sounds a little small for axe work.  Have you considered building your own rather than buying?

    Hey Alan, I have considered building my own. I know there’s a lot of information out there on building your own. Yet the time planning, sourcing materials and building all take from my limited forge time. So I am undecided…hence why I wanted to hear all your alls thoughts on the size of the Graham Forge. 

[Aaron Gouge]

5 hours ago, Geoff Keyes said:

I have a forge that I built for doing long billets of damascus.  I have a press, so taking an 18" long heat is doable.  100 cfm fan driven (a version of the system in this post) common rail twin orifice.  All of that sounds impressive, but it's just a second burner inlet using a single pipe for the gas.  The forge chamber is a piece of 1/4" wall tube, 24 inches long by 12".  2 wraps of wool makes that an 8" chamber.  I used a thick coat of mizzou over the inner layer of wool.  It does not have a door in the far end (due to space considerations) so there is a fair bit of dragons breath.  I plugged the end of the tube with 4 inches of wool.  The 2 burner outlets are spaced about a quarter of the way from each end.  It's a bit of gas hog (big chamber) but it will heat a  billet 5"x 5"x 1.5" without too much trouble.

It needs a reline and I'm considering splitting the case lengthwise and adding 4" of width, making and oval chamber, better suited to axes, but still good for damascus.

Geoff

  It sounds like you you are getting thier!! 

[Matt Walker]

3 hours ago, Aaron Gouge said:

I wanted to hear all your alls thoughts on the size of the Graham Forge. 

Thumbs up. I like that it's blown, cast refractory and flame entering at somewhat of a tangent. Alan is correct, it can be built for less money but for a plug and play production forge it is way ahead of most and has what I would build into one. 

[Doug Webster]

I'm considering their blown burner.  Forge looks great too.  Let us know your experience if you purchase one.   I think you'll be happy with the 5" × 13".

[Aaron Gouge]

 So I talked to Charles today,  the owner of Atlas Forge. He recommended the single burner Firestirm forge that they make. It has a 6 inch chamber by 13 inches long. 

[timgunn]

Just looking at the Atlas website, the burner(s) on the Firestorms are very similar to the burner on the Atlas Mini. If you find the Atlas Mini has all the capability you want/need except for the size, the Firestorm is probably a good choice.

 

Note that the Atlas Mini and Firestorm burners do not have chokes (they are Naturally Aspirated burners) and run a fixed air:fuel ratio. This means you have no means of adjusting the flame temperature. Your only adjustment is how much mixture you feed: gas pressure adjustment.

 

In case you don't know, the gas flow varies as the square root of the pressure, not linearly with pressure. I often see comments along the lines of "I was running at 20 PSI and now I can run at 10 PSI, using half the gas". In fact, having the pressure will reduce the gas flow by just under 30% (to 70.7%; One divided by the square root of Two is 0.707). To halve the gas flow, you'd need one-quarter the pressure: 5 PSI.

 

Having a choke on a Naturally Aspirated burner allows the operator to alter the air:fuel ratio, changing the flame temperature and the composition of the forge atmosphere. Having independent adjustments for Fuel and air on a blown burner does the same thing. 

 

The Graham burner is a blown burner and looks like a much more versatile piece of kit for bladesmithing to me.

 

I don't think I know many bladesmiths who would choose a fixed-air:fuel-ratio burner over one with variable air:fuel ratio after using a variable one. 

 

It is worth noting that burners can be changed later, if/when the forge needs to do something it cannot do with the original burner, so long as the new burner will fit in the old burner port. I think I'd be checking whether the Graham burner will fit the Firestorm. 

[Aaron Gouge]

14 minutes ago, timgunn said:

Just looking at the Atlas website, the burner(s) on the Firestorms are very similar to the burner on the Atlas Mini. If you find the Atlas Mini has all the capability you want/need except for the size, the Firestorm is probably a good choice.

 

Note that the Atlas Mini and Firestorm burners do not have chokes (they are Naturally Aspirated burners) and run a fixed air:fuel ratio. This means you have no means of adjusting the flame temperature. Your only adjustment is how much mixture you feed: gas pressure adjustment.

 

In case you don't know, the gas flow varies as the square root of the pressure, not linearly with pressure. I often see comments along the lines of "I was running at 20 PSI and now I can run at 10 PSI, using half the gas". In fact, having the pressure will reduce the gas flow by just under 30% (to 70.7%; One divided by the square root of Two is 0.707). To halve the gas flow, you'd need one-quarter the pressure: 5 PSI.

 

Having a choke on a Naturally Aspirated burner allows the operator to alter the air:fuel ratio, changing the flame temperature and the composition of the forge atmosphere. Having independent adjustments for Fuel and air on a blown burner does the same thing. 

 

The Graham burner is a blown burner and looks like a much more versatile piece of kit for bladesmithing to me.

 

I don't think I know many bladesmiths who would choose a fixed-air:fuel-ratio burner over one with variable air:fuel ratio after using a variable one. 

 

It is worth noting that burners can be changed later, if/when the forge needs to do something it cannot do with the original burner, so long as the new burner will fit in the old burner port. I think I'd be checking whether the Graham burner will fit the Firestorm. 

Hey Timgunn, 

     Thank you for your in-depth reply! So part of my conversation today with Charles is that the firestorm does come with a choke on the burner. He just recently updated/changed the burner system on the firestorm. He’s not updated his website as of yet.

    He said about 3-4 months ago he would’ve advised the Graham over the firestorm for that very reason. But with the new burner he felt like the firestorm is the better option.
    

[timgunn]

Sounds like Charles has it covered then.

 

If you do go for the Firestorm, please will you post some pics and your impression of its performance? 

[Aaron Gouge]

Will keep you all posted if I go that way in a month or two. There are some other shop items on the list before the forge. 
     Aaron 

[Bob Ouellette]

If you haven't gotten or built a new forge yet, I'm building one that will have a  variable chamber size. My intention is to be able to do ironwork as well as blade work. Essentially, you change the chamber size by sliding fire bricks into and around the forge and have the option of running a second burner. I'm casting the second of 2 ribbon burners as soon as I find some dopamine in mixing the refractory. Then it's just lining and plumbing from there.

 

It's scalable to whatever width/length you want or need and allows for odd shaped pieces as well. I'd be willing to build one for you if you're interested.

 

Edited February 7 by Bob Ouellette