Something about the Op's knife looks awful familiar but I'll not get the hump!
K
K
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Great chance to finally make that knife
- Thread starter zambezi
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reloader54
Well-Known Member
the regulator is directly responsible for maintaining the correct pressure, if an appliance is designed to run on propane at the higher pressure, then using a butane reg will reduce the gas flow resulting in a lesser flame and reduction in heating ability.
if this isn't the case then why would a propane cylinder be the answer?
The fitting on the bottle is different, you cant use a standard regulator on a butane bottle as far as I'm aware.
As the forge was setup with a propane bottle when he got it from his son, the regulator and burner are already there, I assume he cut the regulator off the hose and attached a BBQ reg, so he could use the butane bottle.
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reloader54
Well-Known Member
Not quite. Not only is my nephew's propane cylinder empty, I now see that the hose that came with it has no regulator.
I take the point that the relatively low pressure butane tank+regulator is unlikely to work even if I restrict the forge mouth. I will look into best alternate gas solution. Why I fancy the Surefire2+MAPP PRO option is that it will find applications away from the forge when I am not knife making. A dedicated propane solution would only serve the forge. Logical?
Makes sense, I can't argue with that logic!
I got to thinking about that one: obviously a Surefire type gun has a highly focussed flame which might cause heat-treating hot spots. [I was eyeing MAPP PRO torches up for the forge because they could later be pressed into service as the heat source for my annealing project which is currently...ahem...on a back burner]
Highly focussed MAPP PRO torches do not lend themselves to an even heating of the blade without some wizardry. The chap from Gough Custom did a great piece on DIY knife making including the forge. He advocates offering a propane torch up to the chamber at an angle to create a swirling heat effect:
Here's what I did. Just managed to get it hot enough.
that looks interesting, how do you get the blade out without it cooling? or setting yourself on fire? 
that looks interesting, how do you get the blade out without it cooling? or setting yourself on fire?
You should see the cave entrance on the other side!
I cannot see how I could modify my nephew's forge to take the Surefire torch so...I called FloGas today. It could not have been easier. In 3-4 days I will have a replacement 19kg propane cylinder and 0.5-4 bar regulator. While I wait for delivery, I will tackle some other tasks that have been on the to-do list for a bit.
It's D2 steel - I just took it out with pliers and let it air harden. Then tempered it in the Aga a couple of times.that looks interesting, how do you get the blade out without it cooling? or setting yourself on fire?
Interesting progress with your knife.
With a view to future use I would recommend a Sievert hand torch and acquire nozzles as you need them. I don’t use regulators. Both the Sievert torch and all the burners I have made up for my propane forges just use a Sievert hose-failure valve at the cylinder and the needle valve on the torch (or on the acetylene splitter controls for the self-built burners) to control the gas throughput…one side of the splitter goes to the burner(s) and the other to a lighting wand. The larger Sievert nozzle in the photo has been used for all sorts, including furnace burner and the smallest one is my cartridge case annealing nozzle.
My take on furnace and burner design has always been relatively simplistic. Focussing on the principle of containing heat in the chamber, and the burner producing a tangential swirl rather than worrying about the burner/mixer efficiency.
My burner design uses fan air pressure, gas jet into air turbulence and a simple restrictor nozzle to mix gas and air. I reckon the maximum gas and air volume one can burn within an enclosed chamber will release pretty much the same kW of heat whatever the delivery system…
The Sievert torch should be plenty for you. My first furnace was a simple quadrant cut from a 45 gallon oil drum with 25mm x 75mm ceramic fibre strips stacked around to form an arch. A fire brick (old storage heater) floor and back wall with a hole in the top middle with the big sievert nozzle pointing in and hitting the the arched ceramic fibre and woofling around…it was enough kW to give me 600m length heats of 2” square aluminium that I was forging for the Radley window grilles and lettering…
The main thing I would suggest to improve your nephew’s forge is to block off and contain the dragon’s breath which is such a waste of heat…you will need to play with how much of a flue gap is required in order not to get back pressure with a naturally aspirated torch or burner. But make sure any flue venting is at floor level and that the blade is preferably raised on a shelf (and out of direct contact with the flame). Just an “eyelid” to seal off the top of the forge chamber opening with an access vent / slot at floor level for exhaust and blade removal, will hugely improve the efficiency.
The eyelid could be made from anything, even wood would probably last long enough to get the chamber/blade up to temperature, but a ceramic kiln shelf or sheet of non galvanised steel would obviously be better…stick a galvanised sheet in vinegar overnight to get rid of the zinc...don’t add zinc fume fever to the hazards!
Alan
Oops! just noticed your update abut the propane cylinder...the eyelid bit above is still relevant though...and the Sievert torches are still excellent quality!
With a view to future use I would recommend a Sievert hand torch and acquire nozzles as you need them. I don’t use regulators. Both the Sievert torch and all the burners I have made up for my propane forges just use a Sievert hose-failure valve at the cylinder and the needle valve on the torch (or on the acetylene splitter controls for the self-built burners) to control the gas throughput…one side of the splitter goes to the burner(s) and the other to a lighting wand. The larger Sievert nozzle in the photo has been used for all sorts, including furnace burner and the smallest one is my cartridge case annealing nozzle.
My take on furnace and burner design has always been relatively simplistic. Focussing on the principle of containing heat in the chamber, and the burner producing a tangential swirl rather than worrying about the burner/mixer efficiency.
My burner design uses fan air pressure, gas jet into air turbulence and a simple restrictor nozzle to mix gas and air. I reckon the maximum gas and air volume one can burn within an enclosed chamber will release pretty much the same kW of heat whatever the delivery system…
The Sievert torch should be plenty for you. My first furnace was a simple quadrant cut from a 45 gallon oil drum with 25mm x 75mm ceramic fibre strips stacked around to form an arch. A fire brick (old storage heater) floor and back wall with a hole in the top middle with the big sievert nozzle pointing in and hitting the the arched ceramic fibre and woofling around…it was enough kW to give me 600m length heats of 2” square aluminium that I was forging for the Radley window grilles and lettering…
The main thing I would suggest to improve your nephew’s forge is to block off and contain the dragon’s breath which is such a waste of heat…you will need to play with how much of a flue gap is required in order not to get back pressure with a naturally aspirated torch or burner. But make sure any flue venting is at floor level and that the blade is preferably raised on a shelf (and out of direct contact with the flame). Just an “eyelid” to seal off the top of the forge chamber opening with an access vent / slot at floor level for exhaust and blade removal, will hugely improve the efficiency.
The eyelid could be made from anything, even wood would probably last long enough to get the chamber/blade up to temperature, but a ceramic kiln shelf or sheet of non galvanised steel would obviously be better…stick a galvanised sheet in vinegar overnight to get rid of the zinc...don’t add zinc fume fever to the hazards!
Alan
Oops! just noticed your update abut the propane cylinder...the eyelid bit above is still relevant though...and the Sievert torches are still excellent quality!
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Propane cylinder and high pressure regulator finally arrived today 
Hoorah! And the forge is now a monster inferno that gets knife to temp tout de suite. 
Knife taken beyond magnetic loss by 2 mins. Still looked same cherry red and then quenched in rye oil. The sizzle and surface spall looked encouraging
File skates on heat treated surface, bites into original bar stock and un-hardened heel of knife
Steel wool 
removed most of the surface clag...
Hoorah! And the forge is now a monster inferno that gets knife to temp tout de suite. Knife taken beyond magnetic loss by 2 mins. Still looked same cherry red and then quenched in rye oil. The sizzle and surface spall looked encouraging
File skates on heat treated surface, bites into original bar stock and un-hardened heel of knife
Steel wool removed most of the surface clag......back to the 4000 stones to polish faces 
a bit. I am not looking for a concourse finish.
Once I had achieved a fair polish, I took stock and to my chagrin discovered that the blade had warped a tad. Eish. If I had spotted that, final cooling past quench would have been in a vice with appropriate straighteners applied. Now? metal is probably too hard to bend safely.
Per the image, the blade section looks straight and the handle looks straight. It would appear to have bent about its mid section at the narrowest point where the forefinger inlet is cut
It is no show stopper, just irritating. I think I will sleep on it and decide a.m. whether I maybe give it a gentle squeeze to see how it reacts. The other option is to make it a taper tang and pretend I always intended to do that
. That would also serve to align the spine, heel and tip.
a bit. I am not looking for a concourse finish.Once I had achieved a fair polish, I took stock and to my chagrin discovered that the blade had warped a tad. Eish. If I had spotted that, final cooling past quench would have been in a vice with appropriate straighteners applied. Now? metal is probably too hard to bend safely.
Per the image, the blade section looks straight and the handle looks straight. It would appear to have bent about its mid section at the narrowest point where the forefinger inlet is cut
It is no show stopper, just irritating. I think I will sleep on it and decide a.m. whether I maybe give it a gentle squeeze to see how it reacts. The other option is to make it a taper tang and pretend I always intended to do that
. That would also serve to align the spine, heel and tip.Bavarianbrit
Well-Known Member
Here is a new take on sharpening blades, all in german but the video makes it very clear how it works, using neo magnets to hold the blade while running a diamond stone along the edge.
Glad to hear you got there in the end with your heat treat, I would guess/suggest you did not plunge the blade into the oil straight, and one side started cooling before the other.
Your bend is no where near as bad as one of my early attempts, just chalk it up to a learning experience, you will be far more disappointed if you try to straighten it and it snaps, trust me, I still have some of my regrets floating around on my work bench.
Now just get it tempered down, put a handle on it and enjoy it, and start thinking about the next!!
Your bend is no where near as bad as one of my early attempts, just chalk it up to a learning experience, you will be far more disappointed if you try to straighten it and it snaps, trust me, I still have some of my regrets floating around on my work bench.
Now just get it tempered down, put a handle on it and enjoy it, and start thinking about the next!!
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