Drum forge don fogg

[HSC ///]

Can someone explain to me exactly what this is? Why the large drum size? How does it work? What are the advantages?

thanks

 

[Stacy E. Apelt - Bladesmith]

Big drum vertical forge
BIG burner
Lots of insulation
Large port for large billets.

Drum forge WIP | BladeForums.com

 

[Natlek]

Can someone explain to me exactly what this is? Why the large drum size? How does it work? What are the advantages?

thanks

As far as I know that drum size forge is not build/used for forging steel .They are used to heat treat long blades like swords .......
Advantage ? Well if you don't have a long one electric heat treat oven , drums works

 

[HSC ///]

As far as I know that drum size forge is not build/used for forging steel .They are used to heat treat long blades like swords .......
Advantage ? Well if you don't have a long one electric heat treat oven , drums works

Thx that makes more sense to me now. How do they control the temperature stability?

 

[Stacy E. Apelt - Bladesmith]

I stand corrected. Don's drum forge was a vertical sword HT forge. He had a shorter side port vertical forge for damascus.

 

[timgunn1962]

Big drum vertical forge
BIG burner
Lots of insulation
Large port for large billets.

Drum forge WIP | BladeForums.com

I think the forge that the OP is referring to will be the horizontal-drum Heat-Treat forge, rather than the vertical welding forge.

I have come across a couple of these, one apparently built by Don Fogg himself, the other with the addition of PID temperature control. Personally, I feel the non-PID version is more elegant, though it takes a little more time and attention to get it set to the desired temperature.

The basic design is a horizontal 45(imperial)gallon/55(US)gallon/205litre drum, insulated with a single layer of 1” kaowool blanket. The 2” bung hole is at the bottom of one end and a fairly small hole, perhaps 8 square inches in area from memory (though I could be wrong) is cut at the top of the other end for workpiece access and exhaust. As I remember things, the blanket was retained by stainless steel wire loops and there were longer hanging loops to support the workpiece in the forge just below the top of the drum. A thermocouple was used close to the midpoint of the workpiece.

The burner was pretty small. I am fairly sure the Don-Fogg-built one used a 1/2” burner. This points into the 2” bung-hole and excess air is drawn in along with the flame. Adjusting the burner adjusts the ratio of flame to excess air and therefore adjusts temperature.

I think the large volume and relatively thin insulation probably contribute to the very even heating. The original purpose was for Heat-Treating swords, but it works for knives just as well. Increasing the exhaust/work port size to accept significantly larger sections looks like it would adversely affect the evenness of the temperature distribution and pretty much any other change also seems likely to be detrimental (more insulation, bigger burner, smaller volume).

The PID version used 2 burners: a very small pilot burner and a bigger main burner that cycled on and off with a PID-controlled solenoid valve.

The manual version would hold temperature to within a couple of degC at the thermocouple and with a variation along the length at workpiece level of less than 5 degC, when I had a poke about with a long thermocouple.

The PID version showed a little more variation at the thermocouple, perhaps 5 degC, but was a set-and-come-back-in-20 minutes job, where the manual version needed small adjustments over the 20 minutes to get it to target temperature.

I have looked online for pictures of such a setup and I think the only one I found was of one at Batsons forge.

The advantage is that it is cheap, easy and very effective. The main disadvantage is that a drum that size takes up quite a lot of space and is not very portable.

There are a couple of ways to get similarly-even and -controlled temperature in a smaller package.

A friend has built a version using a 25-litre drum and he used a perforated-plate horizontal baffle above the burner to achieve even heating (I think the inverse-square law probably means the large volume and longer distance between burner and workpiece plays a part in the even heat distribution of the full-size version, which does just fine without the baffle) It works pretty well and uses the same tweak-the-burner temperature control as the Don-Fogg version. I think he uses a "Bullfinch" brand torch.

We discussed electric HT ovens a while back. He makes kitchen knives using Carbon steels, including stainless-clad SanMai and pattern-welded steel, and it seemed likely that going electric would just give greater scale/decarb. He has stuck with the little drum forge.

I took a slightly different approach and used a commercially-available Venturi mixer (a 1/2" Amal Atmospheric Injector) with a stepped burner nozzle into a minimal-clearance hole in one end of the drum. My drum is a 20"-ish length of 10" thin-wall steel tubing, lined with one layer of 1" blanket and with the ends made from disks of 1" board and press-fitted.

To get it to work well (with even temperature distribution), I found I needed the burner at the top and the exhaust/workpiece port at the bottom.

On the other versions, excess air is used to bring down the temperature to that needed for HT. On mine, excess Propane is used to bring down the temperature.

A theoretical advantage to this is that the burner is run very fuel-rich (reducing) scaling is minimized (at least compared to an electric HT oven). I suspect it runs so rich that it also helps to reduce decarb, but I've not done any rigorous testing to confirm or refute this.

My version *MUST* be used outdoors because the Carbon Monoxide levels produced would swiftly result in death if used indoors: with the partially-burned exhaust gases leaving the exhaust port at a relatively low temperature, there is no further combustion outside the forge (Dragons Breath) to convert the Carbon Monoxide to Carbon Dioxide. I suspect the CO level in the exhaust is in the percentage range. Wikipedia says that only 1.28% CO will cause "Unconsciousness after 2–3 breaths. Death in less than three minutes."

The only clever bit of my setup is the Amal injector, which provides extremely fine adjustment of the mixture and thereby the temperature, and for which I can claim no credit. It will hold to within plus/minus 1 degC at the thermocouple and to within 5 degC variation along the 15" working length. Working temperature is adjustable between 760 degC (1400 degF) and around 1050 degC (1920 degF).

 

[HSC ///]

I think the forge that the OP is referring to will be the horizontal-drum Heat-Treat forge, rather than the vertical welding forge.

I have come across a couple of these, one apparently built by Don Fogg himself, the other with the addition of PID temperature control. Personally, I feel the non-PID version is more elegant, though it takes a little more time and attention to get it set to the desired temperature.

The basic design is a horizontal 45(imperial)gallon/55(US)gallon/205litre drum, insulated with a single layer of 1” kaowool blanket. The 2” bung hole is at the bottom of one end and a fairly small hole, perhaps 8 square inches in area from memory (though I could be wrong) is cut at the top of the other end for workpiece access and exhaust. As I remember things, the blanket was retained by stainless steel wire loops and there were longer hanging loops to support the workpiece in the forge just below the top of the drum. A thermocouple was used close to the midpoint of the workpiece.

The burner was pretty small. I am fairly sure the Don-Fogg-built one used a 1/2” burner. This points into the 2” bung-hole and excess air is drawn in along with the flame. Adjusting the burner adjusts the ratio of flame to excess air and therefore adjusts temperature.

I think the large volume and relatively thin insulation probably contribute to the very even heating. The original purpose was for Heat-Treating swords, but it works for knives just as well. Increasing the exhaust/work port size to accept significantly larger sections looks like it would adversely affect the evenness of the temperature distribution and pretty much any other change also seems likely to be detrimental (more insulation, bigger burner, smaller volume).

The PID version used 2 burners: a very small pilot burner and a bigger main burner that cycled on and off with a PID-controlled solenoid valve.

The manual version would hold temperature to within a couple of degC at the thermocouple and with a variation along the length at workpiece level of less than 5 degC, when I had a poke about with a long thermocouple.

The PID version showed a little more variation at the thermocouple, perhaps 5 degC, but was a set-and-come-back-in-20 minutes job, where the manual version needed small adjustments over the 20 minutes to get it to target temperature.

I have looked online for pictures of such a setup and I think the only one I found was of one at Batsons forge.

The advantage is that it is cheap, easy and very effective. The main disadvantage is that a drum that size takes up quite a lot of space and is not very portable.

There are a couple of ways to get similarly-even and -controlled temperature in a smaller package.

A friend has built a version using a 25-litre drum and he used a perforated-plate horizontal baffle above the burner to achieve even heating (I think the inverse-square law probably means the large volume and longer distance between burner and workpiece plays a part in the even heat distribution of the full-size version, which does just fine without the baffle) It works pretty well and uses the same tweak-the-burner temperature control as the Don-Fogg version. I think he uses a "Bullfinch" brand torch.

We discussed electric HT ovens a while back. He makes kitchen knives using Carbon steels, including stainless-clad SanMai and pattern-welded steel, and it seemed likely that going electric would just give greater scale/decarb. He has stuck with the little drum forge.

I took a slightly different approach and used a commercially-available Venturi mixer (a 1/2" Amal Atmospheric Injector) with a stepped burner nozzle into a minimal-clearance hole in one end of the drum. My drum is a 20"-ish length of 10" thin-wall steel tubing, lined with one layer of 1" blanket and with the ends made from disks of 1" board and press-fitted.

To get it to work well (with even temperature distribution), I found I needed the burner at the top and the exhaust/workpiece port at the bottom.

On the other versions, excess air is used to bring down the temperature to that needed for HT. On mine, excess Propane is used to bring down the temperature.

A theoretical advantage to this is that the burner is run very fuel-rich (reducing) scaling is minimized (at least compared to an electric HT oven). I suspect it runs so rich that it also helps to reduce decarb, but I've not done any rigorous testing to confirm or refute this.

My version *MUST* be used outdoors because the Carbon Monoxide levels produced would swiftly result in death if used indoors: with the partially-burned exhaust gases leaving the exhaust port at a relatively low temperature, there is no further combustion outside the forge (Dragons Breath) to convert the Carbon Monoxide to Carbon Dioxide. I suspect the CO level in the exhaust is in the percentage range. Wikipedia says that only 1.28% CO will cause "Unconsciousness after 2–3 breaths. Death in less than three minutes."

The only clever bit of my setup is the Amal injector, which provides extremely fine adjustment of the mixture and thereby the temperature, and for which I can claim no credit. It will hold to within plus/minus 1 degC at the thermocouple and to within 5 degC variation along the 15" working length. Working temperature is adjustable between 760 degC (1400 degF) and around 1050 degC (1920 degF).

Thank you for this detailed response
Much appreciated

Harbeer