Perfectly flat tang?

Fletch Helical

Fletch Helical

Joined
Sep 29, 2009
Messages
1,614
From what I remember Stacy telling me when he helped me with my first knife was to not do a lot of sanding on the where the scales will sit because it can cause it to not be flat. I'm working on getting a knife ready for HT and I laid it down flat on my surface plate. Then I took a flash light and held it along the edge of the plate and looked at it from the other side to see if there is any light shining through. Basically towards the ricasso and butt areas it's contacting the plate.... on both sides with some light shining between the 2 points. So when it flip the knife over I have basically identical contact points on the plate. I'm not sure if this is normal because when I did my knife with Stacy I sanded the bejeezus out of everything anyway, and I didn't have a surface plate either at the time.

What I'm wondering is: Will that gap in the center work itself out after I put the corbys on or will I likely see gaps? I really didn't touch the tang much in terms of sanding to begin with, with the exception of getting that bit of scale, or whatever it's called off the piece of steel. It's a piece of 1084 I got a while back from Kelly.

It just seems odd that I may have sanded a near identical low spot on both sides of the knife while sanding the whole length of the tang.
 
When your sanding its almost impossible to stay perfectly flat, so what you are doing is taking a little off each side creating a hump in the middle. What I do to get rid of this problem is hollow grind down the middle of the tang making flats along each side. I seem to get a really good fit with this method. I learned this from an SR Johnson video.
 
But my instance is actually the opposite of a hump in the middle. I can see daylight through the middle of the tang. The handle area is only contacting near the ricasso and butt.
 
I think this is about the same problem I'm having. I can't offer much help other then to tell you to not try to "force the fit". It could potentially stress the handle material which could make it fail later on.

Make sure to use a push stick at all times, I'm not sure if this'll help any but it does help even out the pressure. Best thing to do though, would be to use a good disc grinder or make sure the stock is precision ground.
 
Ooooh! I'm sorry, I misread your post. I must agree with the previous post, it sounds like a disc would even out the high and low spots.
 
It sounds to me like you are tilting the blade down and working on the edge of your plate instead of working on the flat. It's hard to say without seeing exactly what you are doing though. If the gap is small (.005 or less) and there is corby screw or other tensioning fastener in the middle of the grip the gap will probably disappear when you tighten the scales down.
 
Mike Quesenberry said:
When your sanding its almost impossible to stay perfectly flat, so what you are doing is taking a little off each side creating a hump in the middle. What I do to get rid of this problem is hollow grind down the middle of the tang making flats along each side. I seem to get a really good fit with this method. I learned this from an SR Johnson video.
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I'm going to try this on my next blade. I've tried to taper a few tangs and I can never get a good fit to my scales, even on my flat platen. I was considering dying my epoxy to make the small gaps less noticeable but if hollow grinding works I'd be happier with that method :thumbup:

BladefulArt said:
I think this is about the same problem I'm having. I can't offer much help other then to tell you to not try to "force the fit". It could potentially stress the handle material which could make it fail later on.
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did that already :mad: clamped on my scales and when I took them off...crack...ruined.
 
Definately hollow out the tang a bit.... At that point, you can flatten it with paper on glass or marble... if you want to get really OCD.

Hollowing out also makes for a better epoxy bond.


Rick
 
How do I go about hollowing out the tang? I don't have a wheel to do hollow grinds.... Can I just whack it with the angle grinder a bit?
 
Matt,
The low spot in the center is far less of a problem than low ends. If it is minor ,let it be, it will disappear when the Corby bolts are tightened. You can sand the tang flat on a surface plate if it is more than a small bow.

To hollow the center of the tang ( the part under the scales), use anything that will grind the metal. A Dremel tool with a carbide disk or ball burr works fine. A 3" disk on a angle grinder ( go gentle!!), or the contact wheel of a small belt grinder will do it ,too.

The surface does not need to be pretty or even, just relieved so the wood sits a tad above the center of the tang. This makes a reservoir that fills with epoxy,and avoids glue starved joints. If you remember the first knife you did, I relieved the tang up to about 1/4" from the edges.
 
Fletch Helical said:
How do I go about hollowing out the tang? I don't have a wheel to do hollow grinds.... Can I just whack it with the angle grinder a bit?
Click to expand...

sounds risky lol, but it might work. you could try a half round file or just buy a small cylindrical or round stone bit for your hand drill (or even a dremmel). though a wheel sounds much easier.
 
bladsmth said:
Matt,
The low spot in the center is far less of a problem than low ends. If it is minor ,let it be, it will disappear when the Corby bolts are tightened. You can sand the tang flat on a surface plate if it is more than a small bow.

To hollow the center of the tang ( the part under the scales), use anything that will grind the metal. A Dremel tool with a carbide disk or ball burr works fine. A 3" disk on a angle grinder ( go gentle!!), or the contact wheel of a small belt grinder will do it ,too.

The surface does not need to be pretty or even, just relieved so the wood sits a tad above the center of the tang. This makes a reservoir that fills with epoxy,and avoids glue starved joints. If you remember the first knife you did, I relieved the tang up to about 1/4" from the edges.
Click to expand...


Yeah I remember it, I also remember sanding the tang almost even with the areas you ground out :p. I mean it seems like it's a very minor gap..... What's strange is I took a blank I'm profiling now, and I haven't even touched the sides of the blank with any sandpaper. I can still see light from the flashlight coming through on that one too.

When you look at it without a light it both of them look like they're sitting flat on the plate. But when I slide a light along the edge of the plate and look even with the other side of the plate I can see the light poking through a very small gap.
 
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