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Jean Henri Chandler




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PostPosted: Thu 04 Jan, 2007 9:27 am    Post subject: Fixing an old sword         Reply with quote

I have this old sword which I purchased from a friend in the Czech republic a few years ago. It was made by Vladimir Cervenca and was quite well put together, but it's a fantasy configuration and therefore pretty much useless for my purposes as I'm really only interested in historical weapons. Due to the balance (the BP was about 18" down the blade) and weight (at least 4 lbs, maybe 5 lbs) and lack of an edge it really wasn't usable as either a training weapon for my WMA group or for test-cutting.

Nevertheless I held on to it because I really like Cervencas work (I saw a couple of his historical replicas when I was in Prague a couple of years ago and they were superb) and I knew the steel was good. I thought one day I could maybe do something to 'fix' it. The thing got a good 3 week soaking in Katrina last year and ended up coated in rust, but I still held on it to it, somewhat to the annoyance of my long suffering girlfriend.

Well I recently finally bought a metal grinder, and I went to work on this thing. First I ground off these kind of wings or lugs which were flaring out from the Ricasso about 2" on each side. Then I took about 3" off of the tip, and started putting a basic edge on the blade. This all brought the weight down some and the balance point moved back to about 12" from the quillons.

Then I started grinding on the blade trying to add a bit more distal taper. I doubt I did this very well as my skills with the grinder (first time I've ever used one on metal) are primitive to say the least, and it's probably quite uneven.

But I did grind off enough more material to move the BP to about 10" and knock off another ounce or two of weight. The sword is still to heavy to really swing around let alone go through a flourysh but it has a little spark of life in it that it never had before.

I have a couple of questions before I go any further with this.

I suspect I have probably messed up the temper with all this grinding. I know in a couple of small spots I could see the metal changing color in funny ways which gave me that distinct impression. Can I add some temper back to it with a little cold hammering perhaps? Pardon me if this is a stupid question I only remember from peening out a shield boss one time that I had apparently hammer-hardened it in the process which was making it harder and harder to work with (I wasn't annealing it as I worked) and I couldn't figure it out at the time. The concept of hammer-hardening was explained to me afterword.

So is there any way to harden it short of sticking it back in a forge and reheating it? Could I heat it up with say, a small burner and work on it?

Also, is there any reccomended way to do the distal taper a bit more accurately other than just eyeballing it and guestimating with the grinder?

Finally what is the best way to polish off or less aggressively grind away the grinder marks when I finally have it at the weight and balance I want (hopefully around 3.5 lbs and a BP around 6-7") and how should I do the final sharpening on it?

Any other advice would be appreciated.

Jean

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Addison C. de Lisle




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PostPosted: Thu 04 Jan, 2007 9:40 am    Post subject:         Reply with quote

Cold hammering doesn't temper the metal in the same way that heating it does, I don't believe. I have some experience with wirework in jewelry, and the more you hammer the wire the harder it gets (to a point), but I don't believe this alone is enough. You might be able to do something with a torch, but you might end up retempering part of it but messing up the area around it unless you use some sort of covering (like clay for example), but I'm still not sure that I would do this. When I tempered my knife I heated it to red, quenched it in oil, the put in into a toaster oven ( Happy ) until it turned straw yellow, let it cool, and repeated two more times. Then I submerged the sharpened bit in water while I took the spine of the steel through all the colors until it turned blue-black. The toaster oven bit was to relax the brittleness a bit (I believe) caused by the torch tempering. I suspect you may have to do something similar to your piece or there may be minor stresses in the steel which could be a problem later on. I think that the best way would be to remove the temper on the whole thing by heating it up to cherry red again, and start over. Of course, this would be difficult and time consuming due to the size of the blade, and the fact that you'd need to rehilt the whole thing.

For distal taper, you could go over each face on one side a certain number of times, then flip it over to the other side and grind the same number of times again.

As for removing grind marks, you could use sand paper if you have a lot of patience. A buffing wheel would also work if you have access to one.

For sharpening, if the blade converges at a good angle to the edge, then by cleaning it up if should be sharpened somewhat, and you can do the rest with a whetstone I think.

I've only made one knife before though, so all of this may be completely off Wink Laughing Out Loud

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Jean Henri Chandler




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PostPosted: Thu 04 Jan, 2007 12:22 pm    Post subject:         Reply with quote

Addison C. de Lisle wrote:
Cold hammering doesn't temper the metal in the same way that heating it does, I don't believe. I have some experience with wirework in jewelry, and the more you hammer the wire the harder it gets (to a point), but I don't believe this alone is enough. You might be able to do something with a torch, but you might end up retempering part of it but messing up the area around it unless you use some sort of covering (like clay for example), but I'm still not sure that I would do this. When I tempered my knife I heated it to red, quenched it in oil, the put in into a toaster oven ( Happy ) until it turned straw yellow, let it cool, and repeated two more times. Then I submerged the sharpened bit in water while I took the spine of the steel through all the colors until it turned blue-black. The toaster oven bit was to relax the brittleness a bit (I believe) caused by the torch tempering. I suspect you may have to do something similar to your piece or there may be minor stresses in the steel which could be a problem later on. I think that the best way would be to remove the temper on the whole thing by heating it up to cherry red again, and start over. Of course, this would be difficult and time consuming due to the size of the blade, and the fact that you'd need to rehilt the whole thing.

For distal taper, you could go over each face on one side a certain number of times, then flip it over to the other side and grind the same number of times again.

As for removing grind marks, you could use sand paper if you have a lot of patience. A buffing wheel would also work if you have access to one.

For sharpening, if the blade converges at a good angle to the edge, then by cleaning it up if should be sharpened somewhat, and you can do the rest with a whetstone I think.

I've only made one knife before though, so all of this may be completely off Wink Laughing Out Loud


Thanks

Is there any way to tell if I've messed up the heat-treat or should I just assume so under the circumstances?

All I was thinking of doing with this thing when I've finished with it is probably some forms and some light test-cutting. I wonder if that would be safe...

J

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Matthew Parkinson
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PostPosted: Thu 04 Jan, 2007 1:55 pm    Post subject:         Reply with quote

first the finish on the blade.
what kind of grinder did you use, is it a angle grinder? if so then you can use sanding disks on it to smooth the finish a bit, they are available up to 120 grit at most of the box stores. if not then a file then sand paper/stones is most likely the way to go. (I would foll up the sanding disk with paper/stones also, unless you used a belt grinder(what most if not all pros use to finish knives and swords, unless doing trtraditionalifinishingin that cas it is just a matter of ststeppingp through tttherits ununtilhe finish is as fine as you want it.

As to the temper,
if you heated the steel enough to show colors (straw blue or purples) you have affected the temper. all is not lost however .
so long as the heat did not get to the edge cutting ability will not be affected and over all strength shouldn't be affected to much, you could re temper the blade a bit softer by heating it with a torch (I wouldn't go past blue and a straw or brown would be better.)but the right way to fix the temper would be to re heattreat it, that is to re finish the blade heat the whole thing up to critical (most steels that is around 1450-1550 F) and quench in oil(hardening the blade) then temper back down with a torch to a straw color or just into the blues or with an oven for two hours at around 375-425. it is harder to pin down what temper to give it with out knowing what alloy the steel is.
you can help keep the temper by cooling the blade in water as you grind it closer to final shape/polish. (make a pass with a the grinder cool the blade repeat etc.)

good luck hope this helps
MP

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Bruno Giordan





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PostPosted: Fri 05 Jan, 2007 4:23 am    Post subject:         Reply with quote

\"So is there any way to harden it short of sticking it back in a forge and reheating it? Could I heat it up with say, a small burner and work on it? \"

these would just be the last nails in the coffin of your temper.

Forget cold hammering too.


You have to anneal it properly in a forge, then you have to rework it by grinding.

When you are finished grinding, you can give it back to the tempering shop.

Obviously you must have disassembeld the sword prior to taking any action.


The road you have taken brings nowhere.

You have slightly decarburzed the blade so far (colors), just don\'t do anything worst like cold hammering.

Simply polish it with different grit sandpaper passes, from coarser to finer, and leave it as it is if you can\'t do disassembling and re-tempering..

Without dissassembling, grinding to correct shape, annealing and re-tempering you won\'t get a correct blade.
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Jean Thibodeau




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PostPosted: Fri 05 Jan, 2007 1:33 pm    Post subject:         Reply with quote

Jean Henri Chandler wrote:
Is there any way to tell if I've messed up the heat-treat or should I just assume so under the circumstances?
J


Well you could take a sharp file and see if it grabs or slides if you gently try it on the edge. ( Gently because you don't really want to take away some material from the edge unless it's already fairly dull.

A very hard 60 r.c. blade should feel almost glass like if you put a file to it i.e.very little if any bite.

With the usual 52 r.c. for most sword blades a file will bite and cut with some pressure and the softer the edge the easier will the file bite.

With your sword you could see if the file bites uniformally or if there are softer areas: This won't give you an absolute idea of the hardness but at least a relative comparison about the presence or absence of soft areas.

If you didn't really overheat the blade " much " there might only be very minor loss of hardness.

One thing that it might be too late for as advice would have been to constantly cool the blade by dunking it in a water tank or using a very wet old rag and wetting the blade often: If the water steams off quickly it is too hot and should be wetted until it doesn't steam off.

If the sword was clamped in a vice and the grinder hand held use the wet rag and if the sword was held in hand then dunk in a tank.

Oh, and polishing with finer sanding media or buffing can heat up the blade very fast.

Anyway I have only done this when reworking smaller thing like knife blades but the thing is to not do multiple grinding passes without cooling the blade and if one hold the blade with naked hands one can feel when it is getting too hot.

As well near the point when working close to the thinner section near the edge the thinner stock will overheat much faster and this is where ruining the heat treat is most easy to do.

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