Repairing a dented edge.
Dec 12, 2012 3:00:25 GMT
Post by Brendan Olszowy on Dec 12, 2012 3:00:25 GMT
I had an email from a client about fixing an edge which was hammered on something hard and folded down a little bit. The dent is about 3/8" long.
This is what I told him I'd do to repair it (thought it might help someone):
What you'd need:
A heat source (Fine torch, or gas stove).
Hard metal plate (Anvil, wieght plate, Flatbar, Angle held in vice etc)
Hammer
Sandpaper and cork block. 240 grit and 400 grit wet and dry
Mill File or Smooth file
Edge Honing stone
*What I would do if I had it here:
I'd first heat just that area of the blade lightly with say a gentle torch (could be a low stove burner) to a straw hue. Thats not very hot (about 400F). When heating, the gas fumes semprini the colour oxides forming in a timely fashion. So I'd hold it over the flame (Maybe an inch above it) and then pull it out every few seconds to give it another few seconds for heat oxides to form to monitor the colour.
You'll just want to heat say an inch radius around the edge, and try to focus the heat more toward the meat of the blade if at all possible, rather than directly at the edge. Just watch that edge very often (removing from the heat source) for the beginnnings of that straw colour. Once it start to colour she's hot, and will run up the colours real fast.
Getting the blade 'hot' (straw hue). See the hilt furniture of this sword: www.fableblades.com/Ring%20of%20Fire.html
It's ok if it goes a little purpley/blue toward the edge, but you don't want it going to light blue if you can help it. Actually purpley/blue is ideal (~500F) but you have to keep checking every couple of seconds, it as it will move super fast once the straw colour comes in.
Example of purple/ blue: www.fableblades.com/Glamdring.html
Then working very quickly, lay the blade edge flat down on an anvil with the fold pointed up and gently try to tap it back down into line, with a small hammer, feeling for resistance and brittleness in the metal. I temper the edge to be soft enough that they're not inclined to crack under such stress. But still hard enough to hold an edge. But repeated bending is obviously not ideal and could induce a crack. But it's not likely when at this heat. I fairly abuse the blades at this tempering heat when straightening them after quenching. They can give and reset when at this heat. The molecules are active and movable, but you can't forge at this heat.
Try to get the press down done within 20 to 30 seconds of leaving the flame, and 5-10 seconds of laying it on the anvil (can be any smooth, flat, hard steel surface). Still - pay attention to the feel of the metal. In this hot state it can be giving, but if it's very resistant don't force it. I would have pre torched the flat steel surface to reduce the heat sucking from the blade.
Now you won't get it pressed down like new, but it will put more meat back where it belongs and reduce overall impact.
If you need to reheat it and try some more, first sand off the oxide colour. A scrub with 400 will do it. You just want some shiney metal in there again so you can watch the colour come in again.
Once you have it back in line let it air cool before further refining it.
The next step it reshaping the edge.
For this I'd use drawfiling and sanding. If it's actually pretty neat already after the press down you may be
Drawfiling: I use a second cut Mill file. Youre more likely to have a smooth file laying around. Basically one holds the file perpendicular (90 degrees) to the edge and pushing the file away you shave the metal. Thats how I get all the surfaces of the blade so flat. And shape the edges in the first place.
Next using sand paper on a cork block you can smooth out any file marks. I'd work from 240 to 400 grit. Thats fine. The satin finish of that grade will make it easy to work retouches back into the overall finish. You'll be needing to get off that oxide colour while you're at it.
Finally hone the sharp edge back with your favourite stone. Hopefully a decent natural stone like arkansas stone, or even a super fine diamond stone. Not one of those crappy hardware store blue stones.
Thanks
Brendan
This is what I told him I'd do to repair it (thought it might help someone):
What you'd need:
A heat source (Fine torch, or gas stove).
Hard metal plate (Anvil, wieght plate, Flatbar, Angle held in vice etc)
Hammer
Sandpaper and cork block. 240 grit and 400 grit wet and dry
Mill File or Smooth file
Edge Honing stone
*What I would do if I had it here:
I'd first heat just that area of the blade lightly with say a gentle torch (could be a low stove burner) to a straw hue. Thats not very hot (about 400F). When heating, the gas fumes semprini the colour oxides forming in a timely fashion. So I'd hold it over the flame (Maybe an inch above it) and then pull it out every few seconds to give it another few seconds for heat oxides to form to monitor the colour.
You'll just want to heat say an inch radius around the edge, and try to focus the heat more toward the meat of the blade if at all possible, rather than directly at the edge. Just watch that edge very often (removing from the heat source) for the beginnnings of that straw colour. Once it start to colour she's hot, and will run up the colours real fast.
Getting the blade 'hot' (straw hue). See the hilt furniture of this sword: www.fableblades.com/Ring%20of%20Fire.html
It's ok if it goes a little purpley/blue toward the edge, but you don't want it going to light blue if you can help it. Actually purpley/blue is ideal (~500F) but you have to keep checking every couple of seconds, it as it will move super fast once the straw colour comes in.
Example of purple/ blue: www.fableblades.com/Glamdring.html
Then working very quickly, lay the blade edge flat down on an anvil with the fold pointed up and gently try to tap it back down into line, with a small hammer, feeling for resistance and brittleness in the metal. I temper the edge to be soft enough that they're not inclined to crack under such stress. But still hard enough to hold an edge. But repeated bending is obviously not ideal and could induce a crack. But it's not likely when at this heat. I fairly abuse the blades at this tempering heat when straightening them after quenching. They can give and reset when at this heat. The molecules are active and movable, but you can't forge at this heat.
Try to get the press down done within 20 to 30 seconds of leaving the flame, and 5-10 seconds of laying it on the anvil (can be any smooth, flat, hard steel surface). Still - pay attention to the feel of the metal. In this hot state it can be giving, but if it's very resistant don't force it. I would have pre torched the flat steel surface to reduce the heat sucking from the blade.
Now you won't get it pressed down like new, but it will put more meat back where it belongs and reduce overall impact.
If you need to reheat it and try some more, first sand off the oxide colour. A scrub with 400 will do it. You just want some shiney metal in there again so you can watch the colour come in again.
Once you have it back in line let it air cool before further refining it.
The next step it reshaping the edge.
For this I'd use drawfiling and sanding. If it's actually pretty neat already after the press down you may be
Drawfiling: I use a second cut Mill file. Youre more likely to have a smooth file laying around. Basically one holds the file perpendicular (90 degrees) to the edge and pushing the file away you shave the metal. Thats how I get all the surfaces of the blade so flat. And shape the edges in the first place.
Next using sand paper on a cork block you can smooth out any file marks. I'd work from 240 to 400 grit. Thats fine. The satin finish of that grade will make it easy to work retouches back into the overall finish. You'll be needing to get off that oxide colour while you're at it.
Finally hone the sharp edge back with your favourite stone. Hopefully a decent natural stone like arkansas stone, or even a super fine diamond stone. Not one of those crappy hardware store blue stones.
Thanks
Brendan