what size reamer for 1/8 inch pins

Nathan House

Nathan House

Joined
Feb 14, 2000
Messages
1,204
I would like to know what is the best size
reamer to use to get 1/8 inch pins in the holes,thanks for some input
 
Nathan-

If you drill the hole with a #31 or #32 bit you can then just ream it with a 1/8" straight flute reamer to get an exact hole.

The thing you have to remember, is the pin stock might not be exactly 1/8"

I have always drilled an exact hole and then lightly countersunk the hole to create room for the pin to expand. Many makers have been telling me they drill the same size or slightly over (as the pin stock) and then pound the hell out of the pins.

Do what I'm doing, try different methods and see what works best for you.

I order short bits from places like Travers because the shorter shank has less chance to walk or drift. And for a very crucial hole, I center-drill it first, to get a positive place to start the hole.

Just my two cents.
Nick
 
Not being to sure of your application, you can also get under/over reamers. Many of the machine tool suppliers sell reamers that are under or over the standard size. Sizes can be had in a few .0001's to a few .001's. These are often used to accomplish press fits between parts, slip fits and "pre-plating sizes" for parts that get various coating or plating treatments.
I drill and pin mostly with carbide drills that are exactly .093 and .250. Once all the holes are through the handle materials and tang I ream them with .003 oversize carbide reamers for a NICE EEEEEEEASY fit with NO glue gaps. It only takes a second to ream them, the carbide stands up to G10 and carbon fiber very well. The no fuss fit makes it worth it!!
Neil

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Talonite, new pics, knives in stock!

blackwoodknives.com
 
Oh Yeah, the old oversize pin problem... I wish someone would make pin stock in .125, not .126 or .12x. For handles, I just drill a #30 hole (0.1285) and it works fine. For bolsters, I'm a bit fussy. I hand sand the pin stock until it goes into a .125 holes snuggly. All the holes in both the blade and the bolsters are drilled to 0.125. I then use a 2/0 tapered reamer to taper the top half of each hole in the bolsters. On small knives I don't bother doing this since it is less critical. I just use the parallel holes. On large knives where there might well be flex that can work bolster pins loose, I feel I need the tapered holes. Once I crush the pins in those holes (I use a 4# hammer), nothing is getting loose, ever.

BTW, sanding the pin stock to size is not as bad as it sounds. It takes maybe 5 minutes with something around 120-180 grit.

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Jerry Hossom
www.hossom.com
 
Aint this amazing!! Nathan asks a seemingly simple question and we get all this info from it. Wow!! Jerry, do you taper your pivot hole too?? Where do you buy your tapered reams?? Thanks and take care! Michael

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Always think of your fellow knife makers as partners in the search for the perfect blade, not as people trying to compete with you and your work!http://www.nebsnow.com/L6steel
Buzzards gotta eat, same as worms!!!
 
A 1/8 pin will not fit in a hole drilled by a 1/8 inch drill bit. One of two things can be done. Either use a precision reamer or a slightly over-sized drill bit. Here is a list of the pin sizes and the drill bits I use.

Pin ...... Drill bit
3/32 ..... 2.40 mm
(.0937) .. (.0945)

1/8 ...... 3.20 mm
(.1250) .. (.1260)

5/32 ....... #22
(.1562).. (.1570)

1/4 ...... 6.40 mm
(.2500) .. (.2520)

One other method that some folks do since not all pin stock is exactly the same is use a micrometer and measure the diameter of the pin and they purchase the appropriately sized bit and tape it to that pin.

I obtained all of my drill bits from Wholesale Tools. Another source is MSC at http://www.mscdirect.com/

The drill bits above work for me very well. Not too much slop as when I was using strictly "number size" bits. Drill bits are cheap so I get 3 or 4 of the same size when I order them.

C Wilkins
 
From a machinist's point of view, your question lacks som vital information. Do you want a slip fit or a press fit? In my limited experience with handle material, I would shy away from a press fit ( typically .123" to 124" for a 1/8" pin which yeilds a .0005" to .001" press fit). Pressing through would likely result in chipping the edge of the hole in the handle material.
More likely, you would want to have the pin slide freely into the hole where it could then be epoxied or peened to hold the handle material. Another consideration is to check the actual size of your pin. There are sometimes variations in pins that can be decieving. DO NOT USE A CALIPER to measure round stock! It won't be accurate 100% of the time due to variations in the way we hold things. If you want a true measurement, use a micrometer ( we don't let anyone use a caliper to measure critical assemblies at my shop, there's too much room for error, micrometers work even with different people using them.)
The other thing is that drills, even factory fresh drills, rarely drill round holes! They may look round, but if examined under a comparator, they show themselves to be all sorts of interesting shaped, from ellipsoids to triangles! A quick check to see if your drill is off center, start a drill in a piece of material and drill down only a couple of thousandths, see if the mark is triangular, if so, the drill is uneven and won't drill a round hole. We resharpen all drills in my shop as soon as they come out of the box. We use a diamond wheel machine that costs about 3K and ONLY sharpens drills. This is the only way we can assure concentricity from one set of holes to another. ( I will sharpen up to 10 drills free of charge for any member of this forum, email me for information). Also, the point geometry is something that is often overlooked. There are better geometries for particular materials that are different from the standard 118° - 135° point styles. We can also change over drill geometry to suit a particular need. As you can see, drills are a lot more complicated than one would first suspect!
 
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