Stacy E. Apelt - Bladesmith
ilmarinen - MODERATOR
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Knifemaker / Craftsman / Service Provider
- Joined
- Aug 20, 2004
- Messages
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The grain looks nice and fine on that 1095 blade ( from what I can tell from a photo).
Lucy custom was talking about my PID controlled forge system. That will set the temp of the forge accurately, and regulate it. If you want a full size forge to run at a per-set temperature, there is no better way that I know of.
When I take a reading in the forge that is not PID controlled. I shut off the gas flow and wait a few seconds for the TC to get a true reading. This is in a full size forge with 2" of kaowool and a satanite and ITC-100 coating. The forge has run for 15-20 minutes to allow all the refractory to get heat soaked and the chamber to come up to the temperature I want. The TC is mounted in a ceramic sheath along the side of the forge wall. It gets heated along with the wall. The reading when the flame is on is just a tad higher than when it is off. What I want to know is how hot the whole chamber is, not how hot my flame is. The TC seems to equalize in five to ten seconds. The well soaked chamber, nor the hot blade laying on it, does not cool down appreciably in those seconds. I usually skooch the blade over against the wall under the TC while taking these readings to keep the blade at the chamber temp. This also allows any hot spots ( like the tip) to come down and even out the blade temp.
I have never used a 2BF, but doubt they will soak nearly as well as the forge in the above scenario. A TC in a 2BF will help a bit, but will mostly be reading the flame. You would have to shut off the gas and allow the TC to come to the chamber temp, which would take 5-10 seconds. In a 2BF, the whole thing would probably start to cool down in those seconds, but I don't know how much. If the TC is in a sheath, the sheath is being heated somewhat like the blade is, and the reading would likely be somewhat more accurate.....again, I don't know how much more.
The problems with a 2BF are:
1) The size of the chamber is quite limited.
2) The refractory type is insulator only. It has no real volume of refractory layer to become a thermal mass to even out the chamber temp. This means the 2BF will be hottest by far where the flame is and much cooler where the flame isn't. I know some are built better than others, but they all are having to deal with this problem.
3) Heat source - A 2BF usually runs with an overly hot small flame source, usually designed for plumbing and other tasks than heating a forge. The flame is not intended to create a neutral chamber atmosphere ( since it isn't intended to create any atmosphere in a semi-closed chamber at all). A proper forge burner, preferably blown, would provide a much better heat source, but would be too big for a 2BF. Zaph seems to have a compromise with his small venturi burners, but the problem is still with the chamber size still being small.
With these and other limitations, as well as all the work that seems to go into building them, in most of the home made 2BF and their cousins I have seen I believe the person would have been much happier making a simple tubular forge. The shell can be almost any metal tube about 5-6" wide by 10-12" long. Line that with 1" kaowool and 1/4" of satanite. Use those fire bricks to make a cradle stand for the forge, to block off the back when not needed for long blades, and to act as barn doors for closing the front of partially when trying to do HT. All the materials needed would cost very little more than a 2BF costs...probably $30 max. A visit to another makers shop may find the tubing needed in the scrap bin and the kaowool and other supplies/materials as surplus left over from another forge build. A few pipe fittings and an hour in the shop will come up with a workable venturi burner. A $30 LP gas regulator and hose will finish out the forge. I can't imaging spending more than $100 on building a nice forge, and half that with some good scrounging skills.
Lucy custom was talking about my PID controlled forge system. That will set the temp of the forge accurately, and regulate it. If you want a full size forge to run at a per-set temperature, there is no better way that I know of.
When I take a reading in the forge that is not PID controlled. I shut off the gas flow and wait a few seconds for the TC to get a true reading. This is in a full size forge with 2" of kaowool and a satanite and ITC-100 coating. The forge has run for 15-20 minutes to allow all the refractory to get heat soaked and the chamber to come up to the temperature I want. The TC is mounted in a ceramic sheath along the side of the forge wall. It gets heated along with the wall. The reading when the flame is on is just a tad higher than when it is off. What I want to know is how hot the whole chamber is, not how hot my flame is. The TC seems to equalize in five to ten seconds. The well soaked chamber, nor the hot blade laying on it, does not cool down appreciably in those seconds. I usually skooch the blade over against the wall under the TC while taking these readings to keep the blade at the chamber temp. This also allows any hot spots ( like the tip) to come down and even out the blade temp.
I have never used a 2BF, but doubt they will soak nearly as well as the forge in the above scenario. A TC in a 2BF will help a bit, but will mostly be reading the flame. You would have to shut off the gas and allow the TC to come to the chamber temp, which would take 5-10 seconds. In a 2BF, the whole thing would probably start to cool down in those seconds, but I don't know how much. If the TC is in a sheath, the sheath is being heated somewhat like the blade is, and the reading would likely be somewhat more accurate.....again, I don't know how much more.
The problems with a 2BF are:
1) The size of the chamber is quite limited.
2) The refractory type is insulator only. It has no real volume of refractory layer to become a thermal mass to even out the chamber temp. This means the 2BF will be hottest by far where the flame is and much cooler where the flame isn't. I know some are built better than others, but they all are having to deal with this problem.
3) Heat source - A 2BF usually runs with an overly hot small flame source, usually designed for plumbing and other tasks than heating a forge. The flame is not intended to create a neutral chamber atmosphere ( since it isn't intended to create any atmosphere in a semi-closed chamber at all). A proper forge burner, preferably blown, would provide a much better heat source, but would be too big for a 2BF. Zaph seems to have a compromise with his small venturi burners, but the problem is still with the chamber size still being small.
With these and other limitations, as well as all the work that seems to go into building them, in most of the home made 2BF and their cousins I have seen I believe the person would have been much happier making a simple tubular forge. The shell can be almost any metal tube about 5-6" wide by 10-12" long. Line that with 1" kaowool and 1/4" of satanite. Use those fire bricks to make a cradle stand for the forge, to block off the back when not needed for long blades, and to act as barn doors for closing the front of partially when trying to do HT. All the materials needed would cost very little more than a 2BF costs...probably $30 max. A visit to another makers shop may find the tubing needed in the scrap bin and the kaowool and other supplies/materials as surplus left over from another forge build. A few pipe fittings and an hour in the shop will come up with a workable venturi burner. A $30 LP gas regulator and hose will finish out the forge. I can't imaging spending more than $100 on building a nice forge, and half that with some good scrounging skills.
Thanks for your input.