tool for tapering scale holes for peening pins...

V

Vulcanite

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Jan 16, 2009
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My terminology is off probably...

I came to an understanding of how you attach handle scales or bolsters to knives w/ like brass pin stock. You drill through, then like, flair the holes in the scales, put pin through that is just a little bit longer, put it on anvil w/ pin centered and peen w/ hammer. That should mush both sides and permanantly attach the scales to the tang. Then grind smooth.

I like the idea of doing this better than tapping & screwing b/c it is simpler and you can use smaller diameter pins on a smaller area where you need more than one fastener but there isn't room for more htan one counter-sunk screw.

What is that tool called that sort of reams out the holes in the scales a little near the surface so you can peen the pin stock? I need something that could do this to brass or aluminum bolsters too? Thx


Also, what if you want to attach the scale to the tang temporarily, so you can grind it while it is on the tang to shape, but then be able to take it off to maybe engrave it or something before permanently attaching it? Is there a way to do this?
 
A tapered reamer is what you need

some people super glue the bolsters in place as a temporary fix

Richard
 
The tool you are looking for is called a counter sink. The peening works better with tougher scale materials, there is some risk of over-peening the end, causing it to over-expand in the scale and split it open.
I use 2-3 small drops of super glue to temporarily attach the scales to the tang for drilling and shaping, then when I'm done I pop them lose with a light wooden mallet.
 
Yep counter sink. Lowes has them. Another good tip is to make use of your drill press table and set the depth using the table before you start actually drilling the material. That way you have the same size hole on both sides.
 
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You can also use a drill bit, 1/64-1/32 larger than your pin hole, and just go deep enough to give the hole a flare at the top, when doing this be careful that the bit doesn't grab the work piece and suck in deep. The tapered reamer is the way to go, but this cheap way works on a tight buget.
Dale
 
I simply use a pocket knife to countersink holes. It works on unhardened steel, brass, NS, stainless, etc.
If you want to temporarily pin scales, don't flair the holes and leave the pin head raised. You can file it off later.
 
The tip portion of a spade bit(flat ended drill bit used for woodworking) turned by hand, makes a nice taper for peining pins.
Darcy:)
 
Doesn't a counter sink make like a 90 degree angle, so that you can fasten bugel head type screws below or flush w/ the surface. Seems like you would want an acute angle on the...flair you cut so you can get deeper...peen action.

I'll use the super glue trik, or the trick of just peening the pins outside the scales, grinding the ends off and then flaring and counter sinking again later.

Will good paper micarta work well w/ peened brass or SS pins?
 
The best answer is a tapered reamer. It cuts a small taper in the pin hole. Different reamers for different size pins. This way after you peen the pin, you can grind down the pin and scale flush without getting the dreaded ring around the pin. These can be used for wood or softer metal. They can be turned by hand with no chance of it over cutting. You just run out of reamer. I bought mine at USAknifemakers. A little pricey, but will last a long time unless you try to cut hardened steel. They work great for putting pins in metal bolsters and having them not show after grinding flush.
Chip Kunkle
 
Vulcanite said:
That is a good trick, at least for non-metal scales. Thx
Click to expand...

Works even on 416 ss bolsters and of course softer metals like brass and nickelsilver. I put the spade bit in the drill press and run it powered on low RPM´s.

Brian
 
I found a small tapered cutter bit for a rotary tool like a Dremel. I just stick it in my drill press and it works pretty good to flare the holes for peening...
cutter.png
 
I'm not sure what they are called but you can get a tapered drill bit with a countersink on it for use with true wood screws. The true wood screw like boatbuilders use is tapered and these drill bits are made for that. Woodcrafters should have them or go online and look at places which specialize in woodworking tools. Be sure the bit is tapered - a lot of the cheaper countersinks use a straight bit
 
I think that there is a misunderstanding of what each tool does, and that scales and bolsters are not the same thing.

A tapered reamer makes a continuously tapered hole. You purchase one in an exact diameter range, or with a desired amount of taper, like .125"@ 7°, or .125" to .128" A 1/8" hole that has been tapered with a reamer is 1/8" at the bottom and continuously widens at the reamer angle to a wider diameter at the top. As the softer rivet material is hammered hard , it expands to fill the taper, and locks the two pieces of metal together solidly. This is the normal assemble technique for bolsters. The metal of the bolster is filed smooth and shaped as desired, with no loss of strength ,as the pin is locked in the tapered hole all the way down. Using a matching rivet material will make this assembly nearly invisible. Scales attached by this method may be split or damaged.

A countersink makes a chamfer at the end of a hole. You purchase one with a desired degree of angle, like 135°. A 1/8" hole that has been countersunk is 1/8" all the way until the top, where it flares at the angle of the countersink. The soft rivet material is gently peened and mushroomed to fill the tiny chamfer and make a head. The mushroomed metal can be rounded into a domed head, or filed flush. If filed flush, care must be taken to avoid removing too much metal and leaving no head. This is the common practice for riveting thin scales to a handle, and for pins in hidden tang handles. The handle has to be shaped to the final size before riveting the head.
A bolster attached with a countersink would likely come loose.

Where the confusion comes, is that a tapered reamer is often used to open up the holes in a wooden or ivory handle so the rivet/pin can be easily inserted without binding and risking splitting the material. However, the rivet is not usually peened to expand into the taper. The epoxy used in assembly fills the minute taper, and helps lock the pin in place. The pin should be spun in a drill with 120 grit paper against the side to put micro-rings on it. This method allows for the pins to be installed with epoxy during handle assembly, and then the entire handle is shaped after the epoxy cures. Done with the right size reamer, the ring of epoxy around the pin is almost microscopic. Many who use this technique dye the epoxy to match the handle material and the joint is invisible.
On extremely delicate materials, like MOP and some ivories, this method is the only option that avoids the high risk of damage in riveting the pin.
On more robust woods, some folks peen a good size head on the rivets to hold the scales snug to the tang as the epoxy cures. The peened head is ground away in the shaping of the handle. Most of us just use clamps and avoid the mess and risk.



Here is a great tip:
We all regularly are faced with the dilemma that an 1/8" pin will not usually fit in a hole drilled with an 1/8" bit. The wood fibers expand after the drill leaves the hole and it is too tight for the pin to pass without being hammered through....which is a bad idea. If we take the next bit in our set, 9/64", the hole is too sloppy. We often just let the epoxy fill the gap on the sloppy hole and move on.
Having an expensive set of tapered reamers is the machine shop answer to this, but the average hobbyist does not have this option.
But, there is an answer. Make your own tapered reamer.
First drill a piece of scrap wood with a dozen or more 1/8" holes for your rivet stock. Check to see if the holes are too tight for the rivet stock, which is what you want.
Take a 9/64" bit and chuck it in a hand drill. Run it slowly against an a cheap HF diamond sharpening stone to make it taper just a bit. Run it down one of the holes in the wood after a few passes of the diamond stone. If the rivet goes through too loose,mark an "X" on that hole, and taper the drill some more. Keep checking a new hole until you like the fit. Once it is tapered to the right amount, it will re-drill 1/8" holes to a perfect fit for your rivet stock.
Place the tapered bit in a plastic tube or small zip-lock bag and label it.
BTW, It is a good idea to always get your rivet stock from the same supplier, as exact sizes can vary.
You can do this to make a reamer for each size rivet you use.
 
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