Info Favorites Register Log in Discussion Forums

Forum index Memberlist Usergroups Spotlight Topics Search
Forum Index > Off-topic Talk > How much does it take to ruin a temper? Reply to topic
This is a standard topic  
Author Message
Borger Kruge

Location: Norway
Joined: 13 Sep 2003

Posts: 20

PostPosted: Tue 17 Feb, 2004 1:04 am    Post subject: How much does it take to ruin a temper?         Reply with quote


I own a blunt Lutel bastard that I've been thinking about sharpening to an "appleseed" edge, but I haven't decided yet. The purpose of this would be to be able to test cut with this sword, which is longer and heavier than my other medieval and early renaissance swords. It so happens that I have access to a professional metal workshop with belt sanders and everything, but one question has started to bug me:

By grinding and sanding down the blunt edge to a sharp one, would I easily generate enough heat to damage the temper of the sword? The blade is made of a Chrome Vanadium steel hardened to approx. 50 rockwell. How would I be sure that the metal never exceeds the "heat limit", and approx. how many degrees would that be?

I'm also aware that the original tempering probably made the surface of the blade harder than the core. Do you think that the process of grinding down the edge could bring me to a softer portion of the blade, bringing the edge hardness down to an "unpractical" level?

The blade has a blunt measuring an "edge" that is 1,5mm wide. Grinding this to a sharp edge would probably alter the characteristics of the sword, but I'm not so worried about this, since Lutels blades never were too historically correct anyway.

I appreciate any input, thanks,

View user's profile Send private message
Peter Johnsson
Industry Professional

Location: Storvreta, Sweden
Joined: 27 Aug 2003
Reading list: 1 book

Spotlight topics: 3
Posts: 1,757

PostPosted: Tue 17 Feb, 2004 3:48 am    Post subject:         Reply with quote

Start grinding with a course belt, some 60 grit or so. Do not wear gloves.
When the blade becomes uncofortable to hold, it is time to dip it in water. Keep a tube of water close at hand, that is long enought to quench the whole blade.

Work slowly and carefully. Work all sides equally much. Keep turning the blade after e few strokes on each side of the edge. Do not apply much force and use a new sharp belt. You will see that this is a quick way of keeping your nails short....Be careful.

Start with establishing a 45 degree edge bevel down to almost sharp. Dip the blade in water every fourth run or so to be sure. The thin edge will overheat before the rest of the blade gets warm enough for you to notice.

When you have establised the 45 degree edge you can begin grinding away dead meet up towards the spine, Concentrate on establishing a good cross section that is symmetrical and free from dips. Most swords benefit from a domed edge bevel. It should stil be farily thin behind the vey sharpness. ust how thin you can make it depends on the heat treat of the steel and what targets you want to cut.
Move with even deliberate strokes. Change direction ever so often so that you go across at an angle from your previous strokes. This helps establishing a surface with less dips and wawes. You will have to grind away material along an area some 15-20 mm from the edge to turn a blunt sword into a sharp one. Be careful when you grind the tip . This overheats quickly and it is easy to grind it too thin. Save it for the last touches with a new sharp fine belt.
A sharp edge on your sword will change handling quite a bit. Point of balance will not shift very much but you will feel a great change in the feel of the weapon. If the pommel was large to begin with this might become a problem if the pivot point shifts beyond the tip of the blade. If so you might want to grind the pommel down a bit.

When cross section is established evenly al over the sword you can turn to a new fine belt, some 320 grit or so. Start with the areas closer to the spine of the sword and work towards the edges. That way you will minimize risk of overheating the edge.
The heat needed to damage the temper is above 250 degrees. This will show as a brown-purplish color. Remember that the fine edge will reach that temperature in very short order if you keep still or use too much force or a dull belt. Cool often in water.
Yes, the blade will stain from water, but you will have to polish by hand afterawards anyways.

You should now have a blade that is almost cutting sharp. If you can find 600 grit belts repeat the process, removing all rough marks.
Be very careful!
You do not want the sword to snag in the belt and swing free on any of your bodyparts. Always think what will happen *when* you slip, not *if* you slip.
Now it is time for hand polish. Count on spending some 5-10 hours hand sanding if you want a nice finish. Use wooden blocks and emery paper. I use vegetable oil as lubricant. I usually go again from rough to fine, but this is up to you. Finish with 600 or 800 grit and oil,
Now the edge will have reached cutting sharpness, so be very careful: mind your fingers! (a sharp sword will always claim at least one bleeding cut, regradless, but it is good to avoid having to be stitched answering questions about how you got that cut.)
The last sharpness is established with stones and a leather strop.

An edge established this way will not have a visible secondary bevel. All will be blended smoothly. You can establish the very last sharpness with the stone at a slightly blunter angle.
As the sword is 50 HRC it will have to be blunter than a harder sword. I would recommend a main bevel of some 25 degrees total and final stoning of some 50 degrees.

Sharpening a blade that is mounted is tricky especially when you need to work close to the hilt.
I would leave the last 10 cm or so less than sharp.

A blunt training sword is not ideal to turn into a sharp weapon, but you can still have fun with it and learn some in the process.

Have fun and good luck!
View user's profile Send private message Visit poster's website
Russ Ellis
Industry Professional

Joined: 20 Aug 2003
Reading list: 42 books

Posts: 2,607

PostPosted: Tue 17 Feb, 2004 5:38 am    Post subject:         Reply with quote

I don't have anything to add to Peter's instructions except for a reiteration of his warning. BE CAREFUL. I don't know how much metal working experience that you have, but if you have any you know how dangerous it can be. Sharpening a blade is especially dangerous because you are TRYING to create something dangerous. Peter is right, one slip and that sharp or semi-sharp piece of metal will be going in some direction you least expect. On another forum I read an account of some guy that was suing Burr King (maker of a particular belt grinder) because he was grinding a knife, the knife got loose and the grinder basically shot it through his foot. Now the suit was ridiculous, but the injury was all to real. This sort of thing can happen. If you have never done this sort of thing before I would suggest buying a cheap fixed blade knife or two and practicing on that first.
TRITONWORKS Custom Scabbards
View user's profile Send private message
Borger Kruge

Location: Norway
Joined: 13 Sep 2003

Posts: 20

PostPosted: Wed 18 Feb, 2004 12:32 am    Post subject:         Reply with quote

Mr Johnsson, Sir! That has got to be the most qualified answer I could possibly get, thank you! I will save your instructions for later use, to be sure I don't loose them.

And I will be careful. I hate cutting myself, which I have actually found is a good feature Big Grin because it makes me completely fanatic about safety.

Thanks again,

View user's profile Send private message

Display posts from previous:   
Forum Index > Off-topic Talk > How much does it take to ruin a temper?
Page 1 of 1 Reply to topic
All times are GMT - 8 Hours

View previous topic :: View next topic
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum

All contents © Copyright 2003-2018 — All rights reserved
Discussion forums powered by phpBB © The phpBB Group
Switch to the Basic Low-bandwidth Version of the forum