Attaching scales

K

KWHunter

Joined
Feb 18, 2008
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How do the hidden bolts work? I have a knife that needs new scales and I would like to do it myself but don't know how.
Thanks for your help.
 
KWHunter said:
How do the hidden bolts work? I have a knife that needs new scales and I would like to do it myself but don't know how.
Thanks for your help.
Click to expand...

If you are talking about "corby bolts" you drill a hole all the way through the scale for the shaft of the bolt then counterbore a larger hole partially through the scales for the head.
 
With Corby bolts, it is easy and looks good. Easiest way is to get the step drill for the size bolt you will use. The supply catalogs that sell the bolts, sell the matching drill bits. I use Corby bolts on 95% of my full tang knives.

Here is a simple tutorial:

When making the blade, drill the holes in the tang for the bolts. Make them about 30-50% oversize (1/4 for a 3/16,5/16 for a 1/4,etc.) to allow some wiggle room. Don't make them the exact size of the bolt shaft.I also drill extra holes in the tang to allow the epoxy to reach from one scale to the other (and it lightens up the knife a bit).

After the blade is finished, hardened and tempered, and all work is done except final sharpening, cover the blade with tape up to the ricasso ( to protect it from scratches and you from the blade).

Sand to shape and polish the ends of the scales at the ricasso by temporarily taping them together and sanding/polishing as a solid block ( don't worry about the sides, they will get shaped in the final sanding/grinding). This will assure both sides being the same curve. It would be hard to sand and polish this area once on the knife.

Now, tack one scale in place on the tang with a drop of CA.( Use a drill press for all drilling) Drill a pilot hole, about half the size of the shaft hole, in the center of the tang holes for the bolts (drill from the tang side, obviously). Temporarily tack the second scale on with a drop of CA, being careful to align it with the first scale. Drill the pilot hole through from the first scale side. Now, re-drill these holes for the bolt shaft size. Remove the scales (use a thin,sharp blade, and they should pop right off) and clean off the CA with some acetone. Drill the step hole in the scales with the step drill on the drill press.When properly drilled, the female bolt will go through the scale and tang just enough to slightly enter the other scale by maybe a 1/16-1/8 of an inch ( with a thick tang this is sometimes not possible, but with a thin tang it works well). I like to drill all the female rivets holes in one scale,then drill only one male hole in the other, temporarily insert that bolt, and then drill the other holes.Check that the bolts go in all holes and will thread together smoothly.Once all is well, disassemble the scales, clean everything with acetone, mix up some slow cure epoxy, put on rubber gloves (you will really want to !) , and apply epoxy to the scales, and bolts (don't get epoxy in the female bolt hole, though). Slip in the female bolts (use a toothpick to remove any epoxy that gets in the hole) and set this scale on the tang. Place the other scale on the female bolts and insert the male bolts. Get each bolt started and them slowly tighten all bolts until just snug. You don't want to crank down and squeeze out all the epoxy or warp/crack the scales. Wipe off the extra epoxy, wait about five minutes, check the bolts to see if any need more tightening. Come back in an hour and, using acetone, wipe off any epoxy that is on the ricasso and front of the scales ,then set aside to dry for 24 hours ,or more. ( A tip here is to dye the epoxy the color of the scales. It makes any gaps or goofs invisible. Use the powdered dyes from places like K&G, they are beter, IMHO, than the liquid dyes).

Once dry completely, saw/grind off any excess bolts that are sticking out. DON'T GET THEM HOT while doing this, or it may make a discolored ring around the bolt in the scale material. (This is especially a problem with stainless bolts) GO Slow. Sand/shape/grind/file the handle to the desired shape (again, avoiding getting the bolts overheated).Finish/shape/polish as you wish.
Stacy
 
Stacy,

Very good write up. I've just purchased my first stock of Corby bolts and will be using them on one of the next blades I make. Very excited to try and great tips! Thank you!
 
Thanks Stacy,
great post. I think I meant hidden pins, pins that do not show on the scales. I saw on eknife made like this on another forum (not sure if I can post the link here).
How do they hold the scales on the tang if not riveted or somehow fastened?
Thanks.
 
If you're going for hidden pins, then the holes are only partially drilled on the inside of the slabs with pins through the tang, but only long enough to reach into the slab so the slab fits flush. Follow Stacy's directions by temporarily attaching the scales with CA and drill through the tang hole just deep enough into the slab to insert the pin. Remove slab and repeat on the other side. Either epoxy or solder the pins into the tang, coat the pins, tang and slabs with epoxy (yes, wear gloves!) and clamp both slabs onto the frame. Clean up as Stacy described and finish being careful not to sand through the slab into the pin.
 
Thanks again.
Corby bolts: the heads of the bolts gets ground down and then polished as the handle takes shape, isn't it so? So they have a more decorative purpose than attaching the scales as they don't positively fix the scales to the tang.
 
KWHunter said:
Thanks again.
Corby bolts: the heads of the bolts gets ground down and then polished as the handle takes shape, isn't it so? So they have a more decorative purpose than attaching the scales as they don't positively fix the scales to the tang.
Click to expand...

you are right about grinding off the head, but I have heard that they are among the strongest of knife fasteners (and pretty too)
 
Corby bolts come in sizes 3/16, 1/4, 5/16 wide and several lengths. They are the strongest mounting system. Available in Stainless, nickel, brass.They are cheaper in bulk, but not costly even when bought by the unit. Isn't $5 worth knowing that your handle will NEVER come off .

If you are using hidden pins, they are just there to align the scales and prevent side movement. They don't add much structural strength. If you do that type of mounting, drill lots of extra holes in the tang. The epoxy bridges that go from side to side through those extra holes are much more structurally important than the hidden pins.
Stacy
 
KWHunter said:
Thanks again.
Corby bolts: the heads of the bolts gets ground down and then polished as the handle takes shape, isn't it so? So they have a more decorative purpose than attaching the scales as they don't positively fix the scales to the tang.
Click to expand...

When you put the Corby bolt on the Knife with the Lip you left inside the Scale with the counter bore it creates an added measure to prevent the handle from coming off in the event the glur or epoxy fails. I do not know why someone would do it but I believe you could hold a handle on with just the bolts. it just would not be as tight or look quite as good. They are very nice added feature if you are going for more decorative then you would probably go Mosaic pin or just a design using smaller pins. and even then your get a great deal of strength depending on how you attach them.
 
I use the corby bolts for all my full tang working knives. They hold the scales very tight but not too tight if they are adjusted correctly. They also look great engraved. If you have a metal lathe you can drill the ends out and put a mosaic pin inside of them so you get the strength of a corby but the beauty of a mosaic.

Hidden pins are simply short pins and epoxy under the scales. Be sure to dovetail the scales to make the epoxy lock. Several is better.
 
OK I'll bite. What is "CA" which seems to be for temporary attachment of scales for drilling. I really need something like that!

Phil705
Winthrop WA
 
For hidden pins, I use threaded rod. Gives a bit of purchase for the epoxy. Just my .02. Have fun!
 
one thing I do is also drill small angled holes on the INSIDE of each scale. I am hoping that the epoxy will cure and this will act like an internal pinning device. Cant say it works but I still do it anyways :)
 
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