How Not to Fix a Loose Bolster, and a Question About Ruining Blade Temper

J

Josh Feltman

Joined
Feb 12, 2001
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4,501
Well, the bolster on my chiruwa WWII blem was a bit loose, so I decided to try some superglue to tighten it. No luck. It let loose after the first few chops into big walnut stump I use for testing chopping. I then decided to try gently tapping it into a tighter fit with a hammer. Big mistake. It left little crescent-shaped dents in the brass, even through the rag I had wrapped around it. Oh well, the crescent is one of the symbols of Nepal, right?:rolleyes:

Anyway, I then heated the bolster with a candle for about 45 seconds or so to try to re-melt the laha, thinking this would eliminate the looseness in the bolster. It didn't work, but I am wondering if this is enough heat to damage the temper of the blade. Anyone know?

Well, finally the problem seems to have pretty much fixed itself when the horn handle slabs expanded a bit after I applied hooflex. Guess I should have tried that in the first place.

So, my two questions to the learned cantina members:
1) Is there a preferred method of fixing a loose bolster?

2) Is the heat of a candle flame on the bolster for a minute or so enough to damage the blade temper? Is there any way to tell if the temper has been affected?

Thanks,
--Josh
 
Live and learn Josh. Show me an expert and I'll show you a guy who's boogered up a lot of stuff learning how not to booger stuff up.;)

Sarge
 
Yeah, it was definitely a learning experience. Overall the knife looks really sharp. The dings in the brass aren't that bad, and I could probably sand them all the way out if I wanted, but I think it would remove too much brass. Next time I will definitely ask here before I start pounding though.
--Josh
 
The candle is not enuf heat to mess with blade temper. You;d need to generate over 1000 F to get into trouble.

As for the crescent markings, if too deep to remove thru buffing, jsut add a bunch more dings so it looks roughed up intentionally. Seen this done with brass and copper habakis (collars) Use hammer again, or drag a file across it for some linnear texture. thiis was done by Japanese smiths, so that the collar wound fit snugly into the saya (scabbard) throat.

Keith
 
Josh,
To melt Laha you have to boil the handle, but in your case this might be bad. You might have the scales fall off or crack due to them being boiled, but that is a BIG "might". The safest way to fix this is to use Epoxy. I like the 2-hour stuff just because it runs into places that the 5 min stuff wouldent get to.

If it is a itty bitty crack, use some kind of syringe to get it in there. You can also mix the epoxy with acetone to dilute it if your syringe has a tiny needle.
 
To effect the temper you need to exceed the temperature at which the blade was tempered, for simple steels this can be as low as 250 F, which you can easily exceed with direct flame. However, a khukuri is hardened in the upper part of the blade and there is a lot of steel between where you were applying the heat to the part that you would be concerned about softening, so like Bill said I doubt you have a problem. If you effected the temper you will see the steel discolor, it starts out straw colored and will turn black if you really burn it.

-Cliff
 
Well, I didn't see any color changes. Is the color change temporary, or does the steel retain the color after it cools? I think it should be ok--the brass bolster got really hot (too hot to touch with bare hands) but the steel next to it only got warm. Like I said, I probably only heated it for a minute or so, rotating the knife the whole time to get even heating.
--Josh
 
The color change doesn't go away, you will also note that the burnt steel will be *much* softer and prone to really large burr formation when you file it. If you could hold on to it, you didn't overheat it. You have to be a bit more careful with really thin blades, as they can overheat really quickly as there is no amount of steel to soak up the heat.

-Cliff
 
I don't think I would be banging a bunch more dents in the brass but, I would leave the ones you have as a reminder of what not to do. Like Yvsa says, It will just give the knife a bit of character and , you will remember them.

I have been told many times. The gent that claims to have not made any mistakes probably hasn't ever done anything. :)
 
Well, I managed to sand the dents out by probably about 50%. I'm just gonna leave the rest because they are a good reminder of my foolishness, but they also add a rugged look. I still had a minor (feel but not see) amount of play in the bolster, so I managed to drip some 2-ton epoxy down into the space between the bolster and the blade, and actually got better penetration than I did with superglue. I checked the knife this morning, and everything is locked up tight as can be. I did a bit of chopping and even whacked the blade flats into a piece of firewood a few times and everything held. I think my loose bolster is a thing of the past.
--Josh
 
Originally posted by Josh Feltman
Well, I'm just gonna leave the rest because they are a good reminder of my foolishness
Click to expand...

It's not foolishness. It's the price of knowledge.
 
As has been mentioned before the heat of the candle wouldnt damage temper. It doesnt take much to make pitch flow, but a candle isnt enough. About 30 secs with a propane torch would make it flow, and not damage the temper. Especially if heated on the spine. The heat would travel up the tang. However, since there is epoxy ready in there, I would not advise trying to make the pitch flow with heat. Heat and epoxy dont mix. The epoxy just burns.
 
kismet-- duly noted:D

Federico-- thanks for the advice, but I think the epoxy will hold. If it ever breaks and falls out, I'll try the propane torch, but even the candle had me worrying like a big sissy about damaging my khuk :rolleyes:
--Josh
 
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