Prevent spaces between tang and handle material?

E

Ethan_Hardy

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Sep 10, 2011
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I finished my second knife a couple days ago and I noticed that when I sanded the handle material down to be flush with the sides of the tang there are what looks like air spaces or pockets of epoxy between the flat of the tang and the flat of the handle material. What is this caused by? Not clamping hard enough while the epoxy is drying? Are my flats not perfectly flat enough causing pockets of additional epoxy to build up?

I will post pictures tonight.
 
That is something you must check during a dry fit. Odds are the tang or scales or both are not ground flat, most likely the scales is you ground since they are softer. A liner may be more forgiving than your scales.
As always post the best pics you can.
 
This application for a liner isn't the answer. That would just be masking the issue and not solving it. There is no solution for something that isn't flat except to make it flat. Your tang and your handle scale both need to be flat. As was mentioned, check the fit dry before glue up. Put the pieces together and hold them up to the light. If a sliver of light gets through, you have more work to do. Mills, surface grinders and disc sanders work very well for getting things flat but new makers may not have all the toys. So sanding parts against a thick sheet of glass, granite counter top or surface plate can work well. Check the surface by holding a steel ruler on edge across the surface and check for gaps. If there are none, lay your sandpaper down either with some liquid to form a little stiction or with some repositionable spray adhesive. Then carefully sand the parts flat, paying close attention to where you are adding pressure.
 
Mating surfaces were not flat.

A granite surface plate or a piece of glass with a sheet of 120grit or 220 grit sandpaper spray glued to it will help get them flat flat flat before glue up.

So get them close however you had been doing, then bring them to the flat surface and move the piece in a figure 8 motion. Check for gaps before glue up.

Get them thiiiiiiiin lines.
 
Another ’trick’ to follow progress is apply bluing or marker pen to a surface. Then sand a few strokes will reveal low spots.
 
Also, I put a slight hollow grind down the center of the tang area that will be covered by the scales. I leave a 1/8" or more flat perimeter for The scales to seat on. This not only assures that the edges sit flat to the tang, but also makes a glue reservoir to assure a good bond. It everything is dead flat on the tang and scales, the glue can be almost completely squeezed out in clamping and leave a weak glue-starved joint.
 
Thank you Stacy, for a beginner like me, who doesn't have the ability to hollow grind a tang (Craftsman 2x42) I have also read that drilling a variety of small "pock marks" on the inside of scales can create glue reservoirs to prevent glue starvation. Am I correct in this?
 
What I do is basically a combination of what others have said. Once I have the tang dead flat, I drill holes through the tang for epoxy to pass through. I then hollow grind the center of the tang using a 50 grit belt, and also drill shallow holes in the back of my scales. When I use a liner, I make sure to drill those scale holes deeper than the liner thickness. My thought it’s that this gives mean an epoxy well between each scale and the tang, as well as direct epoxy bond from the scale, through the liner, through the tang, through the other liner, and all the way to the other scale. I did a long term test like this by leaving a glue up in the door pocket of my old truck outside for two years. The sample saw everything from temps below -40C to well over 60c in the summer with the windows up sitting in the sun. Both scales stayed attached
 
I drill holes through the flattened tang with matching shallow holes in the handle material. Then, I undercut the holes in the handle scales with a small carbide burr to create a mechanical lock between the epoxy and the handle scale. This, along with the handle pins, flat well-fitting parts, roughed up mating surfaces and thorough cleaning of parts before glue-up result in a pretty solid handle.
 
Rancho5 said:
Thank you Stacy, for a beginner like me, who doesn't have the ability to hollow grind a tang (Craftsman 2x42) I have also read that drilling a variety of small "pock marks" on the inside of scales can create glue reservoirs to prevent glue starvation. Am I correct in this?
Click to expand...

Think outside the box...I have used my angle grinder with grinding and cutoff discs, and a Dremel with a small cutoff wheel to make grooves and a hollow tang.

I have also used the Dremel to grind a hollow in the scale to achieve the same result. I suppose you could use a file, or even a pocket knife to whittle out a hollow in the tang.

~billyO
 
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Mini hijack. Do yall use just any granite plate or an actual "granite surface plate" the latter being pretty expensive
 
valknut said:
Mini hijack. Do yall use just any granite plate or an actual "granite surface plate" the latter being pretty expensive
Click to expand...


in usa amazon

Granite Surface Plate 9" x 12" x 2", A Grade
Price: $38.99 + $19.11 shipping

plus any number of suppliers for the chinese 12x18 still fifty ish$

you can get some great glass scraps out of the dumpster from a glass shop
12mm thick or so-even better if you ask them
pretty flat
 
12345678910 said:
in usa amazon

Granite Surface Plate 9" x 12" x 2", A Grade
Price: $38.99 + $19.11 shipping

plus any number of suppliers for the chinese 12x18 still fifty ish$

you can get some great glass scraps out of the dumpster from a glass shop
12mm thick or so-even better if you ask them
pretty flat
Click to expand...
Thanks count. Wonder if g10 or mircata would preform
 
valknut said:
Mini hijack. Do yall use just any granite plate or an actual "granite surface plate" the latter being pretty expensive
Click to expand...

If $50 is costly, I get pretty good results using a scrap piece of granite from a counter top making place. They usually have a pile of scraps free for the taking and I've gotten pieces about 1 1/2 inches thick and 18" square (with about 2" of one corner broken off). I've got a few pieces of various sizes.
 
One thing that's happened to me isn't so much lack of flatness, but tiny bevels at the top of the spine along the tang, (sometimes the bottom too) that also ends up showing a glue line. Caused of course by not approaching and leaving the belt squarely. These can be ground out even if the scales are already attached but it's trickier. Close qc inspections with lenses has been a big part of my process but this is easy to miss if not aware.
 
12345678910 said:
in usa amazon

Granite Surface Plate 9" x 12" x 2", A Grade
Price: $38.99 + $19.11 shipping

plus any number of suppliers for the chinese 12x18 still fifty ish$

you can get some great glass scraps out of the dumpster from a glass shop
12mm thick or so-even better if you ask them
pretty flat
Click to expand...

You can also just buy a granite tile at the hardware store. If you get one that is highly polished it’ll be pretty flat.

I think the one I bought was 5 or 10 bucks...
 
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