Pin size and Drill bit/hole size

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Brian.Evans

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Aug 20, 2011
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I know it's been asked, answered, and discussed before, but my search-Fu has left me, I guess.
If I want to use 1/8" brass rod for pins, obviously an 1/8" drilled hole is too small for the rod to fit through. Do I need to spend money on numbered bits or just go up a size to 5/32".

Also, while I have your attention; can I use "pouring epoxy" ie MirrorCoat or EnviroTex to attach scales?
Thanks!
 
Use a #30 bit for 1/8" pins,don't know about that epoxy.
Stan
 
Drill bits don't drill round holes. They drill elliptical shaped holes. If you want precise round hole; drill with an undersized drill bit and follow with a ream of the correct size. That 1/8 inch pin will fit like a glove.
Fred
 
Also, if you don't have the exact correct bit, you can symmetrically grind the pin stock a little thinner by spinning it with your hand as it contacts the slack belt area.
 
medicevans said:
If I want to use 1/8" brass rod for pins, obviously an 1/8" drilled hole is too small for the rod to fit through.
Also, while I have your attention; can I use "pouring epoxy" ie MirrorCoat or EnviroTex to attach scales?
Thanks!
Click to expand...
Drill a hole in a piece of scrap with the 1/8 bit and check it against your brass stock and see what you have. Most new bits will cut a little over. It the brass stock doesn't go (too big) it wont be by much and you can spin it down by chucking it up in your drill press or hand drill and use a piece of 320 grit and spin it down, it won't take much.

I'll be watching to see what kind of feedback you get on the the epoxy. Im still looking for some slow drying stuff and not sure what is preferred .
 
A .125" pin should fit into a hole made with a .125" reamer. Just make sure your 1/8" pin is really .125". If your pins are for handle scales you can go with a one size over drill which is .128". I just can't remember what number it is right now.
 
I do like Stan suggested, Drill all holes with the 1/8" bit then follow up with the #30 (Wire Gauge I believe) Bit. I also use 1/4" pin stock and the #F Bit the same way. usually the steel will expand just enough that you will probably get away with the Fraction bits. But the scale material never fits without making them bigger... IMO
 
I'm just using reamers from USAKnifemaker.com. I found that to be the easiest and since Tracy's a knife maker he carries the logical sizes and types without me having to sort through dozens of other options at a general supply house. I don't generally bother with the reamer on the tang itself though, not unless I've got a particular reason for it such as planning to put a bushing in or something. I use them on the scales themselves so the pins fit perfectly. The tang just gets drilled slightly over sized. I sometimes don't even bother being that precise and just swirl a dremel bit around the edge a couple times after heat treating and call it good. That cleans out the scale and roughs up the surface slightly at the same time it gives enough room for the pin.

The three sizes I use are 1/8, 3/16 and 1/4 for the reamers. I pair them with norseman cobalt bits of the same nominal size. I'm thinking about getting some high quality bits with a more suitable angle for wood and just using them for that but so far I've just used the same bits. If I need to shrink the pins or tubing I actually slip the end just barely into the chuck of my drill and spin them against some sandpaper. That leaves the part in the chuck oversized and you have to be careful to do it evenly, but it works for standard pin stock and tubes if you just need a touch of material removed to get the right fit. With the reamers that's not been an issue for me lately except some tube that decided it wanted to be just slightly over sized on one end of the piece I got. Someone's machine was having issues because it was .250 exactly on one end and .257 on the other over a 12" length. Very odd, but not the end of the world.

How precise things need to be depends on what kind of pin is going there. I'm using more mosaic these days and to make it look good it needs to be a snug smooth fit but I don't want to use a sledge hammer to get the pins through either. The reamer gives me that perfect fit that's snug but easily set with fingers or light taps of a hammer or anything else handy. I can even adjust the orientation of the mosaic with my fingers most of the time if I left enough to get a good grip on.
 
Salem Straub said:
Also, if you don't have the exact correct bit, you can symmetrically grind the pin stock a little thinner by spinning it with your hand as it contacts the slack belt area.
Click to expand...

Or you can chuck it in a drill (hand or press) and either run it on the belt so its evenly turning, or hold sandpaper up to it (or a belt). I've done it both ways but I find that gives me a more even sanding.

I just got a 1/4" reamer from usaknifemaker so I'm hoping that solves my 1/4" hole issues.
 
I was planning on doing the drill press/sanding thing, but I just wondered if there was another way. Guess I'm going to have to make an order with Tracy soon too.

I need better drill bits. It may be time to invest in the common sizes of HSS bits. I'm doing all my current knives and the forseeable future knives in O1.
 
All good advise, but most folks overthink the answer.

The tang hole should always be a little larger than the pin/rivet. This allows for misalignment as well as stretching and shrinking of natural materials. I usually go 50% oversize. A 1/8" pin gets a 3/16" tang hole. It will not matter if this is precise or slightly out of round.

In attaching bolsters, it is very important that the tang hole be larger than the pin by at least 20%, or the bolster may raise up from the tang while peening.
The bolsters should have a snug and perfectly round hole a few thousandths over the pin size. A reamer is the tool of choice.


The holes through the scales should be a smooth slip fit - not tight, not loose. Numbered bits or precision sized bits will work well as long as the tips are kept sharp. Reamers are always a good choice, but the reamer size will be determined by the pin size.



In case everyone does not know it, all 1/8" pins are not .125". The diameter can vary a lot. Best to measure your pins before drilling any holes.
 
That's great advice Stacy, I would never have considered that if someone that had experienced it didn't say so. If you have 50% larger-than-pin holes in the tang, would you drill your precision holes through tang and scale first, so the scale holes are in-line, or do you just do your larger holes in the tang and eyeball the center for the scale holes?
 
I did my first couple of knives (albeit with mosaic pins) where I used the same diameter drill bits as the pins. I got around the issue of fit by putting the pins in the freezer overnight and then doing a press fit while they were still really cold. They started off rotating in the holes but after 10 minutes were solid. I didn't even need to use glue.

PS this probably works better in summer than winter due to temperature differentials. Once the pin is in and at ambient temp. the handle materials and pins have similar coefficients of expansion to retain a tight fit.
 
Could do it kind of like we used to do cylinder sleeves; pin in the freezer and a heat lamp on the blade stock. Of course, with wood and other assorted scale material, one would probably screw something up. Seems like there are easier ways to do it. Thanks for all the answers.
 
Dang it Stacy, I'm trying to make this difficult! Don't come up in here with your common sense and easy solutions........:D















........seriously though, thanks. That makes sense.
 
Ive always wondered why peopel used the number bits and whatnot. ive always just used the bit that matched the size pin. Guess I should look around for a good set of # bits. I have the reamers and some nice drill bits.
 
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