Corby bolts vs solid pins

M

mitch8

Joined
Oct 11, 2010
Messages
180
What is the benefit of using a corby bolt over using a solid pin? From what I've seen the corbys seam like more work and just look weathered more quickly because you can see the threads after some aging. What am I missing here?
 
Corbys are bolts that hold the handle on. They are one of the strongest fasteners for handles.
Unpeened pins only provide resistance from lateral forces. Peened pins are strong, but not as strong as bolts.
 
And that's why the thick portions are so tall? So you can file away a lot of brass without the threads showing like they do in a loveless handle. Things are starting to click here. Thanks bill.
 
I've put handle scales on a few knives with these bolts. I pre-determine how thick to make my scales plus the blade tang, and carefully measure the depth of the hole in the female bolt. then I figure out how far to recess the bolts into the scales so that once ground down I won't expose the hole in that bolt. Some people don't worry about this and let the hole be exposed but I prefer not to, just personal preference. I carefully countersink the scales, mix the epoxy, and put it all together. This leaves a lot of material sticking up that has to be cut off. I usually saw off most of it with a hack saw then the rest comes of with the belt sander.

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Corby bolts compare to peened pins the way bolting together a picnic table compares to nailing it together.

If you are seeing the threads show on the handle, it either is Loveless bolts, which use a round nut and a bolt, or the Corbys were not properly installed. My rule of thumb is to leave half the handle thickness of 1/8" (whichever is less) as the shoulder thickness. In most all cases this gives superb strength and ease of finishing the handle. Corby bolts come in a good variety of lengths and width sizes to fit any handle you would normally make.

Probably the biggest advantage of Corby bolts is that they eliminate the need for clamps. (Using 1 hour epoxy) You put the epoxy on the tang, and a little bit in the holes through the scales, insert the corby parts....and assemble the handle. Tighten only snug, wipe off excess epoxy, check the sides for gaps and alignment, tighten/adjust a tad more if needed ( Do Not Overtorque).... and set it aside to cure. You can handle it, wipe it clean, etc. with no worry about messing up the alignment or under/over clamping.

As said, once the epoxy is cured, there is no stronger basic handle.
 
I'm trying to get comfortable with Corbys- it seems like you need a pretty chunky handle for the proportions to work out right and not show thread...they're tapped in about 3/16, so using Bladsmith's formula you end up with a pretty fat handle- 3/16 + 3/16 for the threaded part, + enough wood for the shoulder + 1/8 for the tang. That ends up being 3/4 plus a little so the bolts don't show, which is on the thick side for most any knife handle.
What am I missing here?
I guess I could trim some off the threaded part.
Andy
 
elementfe said:
3/16 + 3/16 for the threaded part, + enough wood for the shoulder + 1/8 for the tang. That ends up being 3/4 plus a little so the bolts don't show, which is on the thick side for most any knife handle.
What am I missing here?
I guess I could trim some off the threaded part.
Andy
Click to expand...

The shoulder on the female side of the Corby is about 3/16". The hole in the tang should be slightly larger than the Corby, allowing the shoulder to go in the tang hole for alignment. If you want 1/8" of the fat end of the Corby remaining, then minimum thickness would be 5/8" (1/8" bolt + 1/8" shoulder +1/8" tang + 1/8" shoulder + 1/8" bolt.) You will probably have to trim the shoulder on the female Corby and teh threads on the male end to make sure you don't grind through the female end and it still has enough clamping force on the scales.

randy


If you really want a headache, put these on a tapered tang. :)
 
DO check the depth of the female with a toothpick or something. I've come across some that were drilled much deeper than needed... grinding them flush and coming into a ragged hole in the middle will make you say bad words... you can guess how I found that out.

rwn2000 said:
If you really want a headache, put these on a tapered tang. :)
Click to expand...

Tapered tangs are no problem - just drill the tang while still flat, taper it, and drill the scales while they're clamped onto it and the whole thing is vised and/or shimmed so the centerline of the blade is perpendicular to the drill. It's harder to describe than it is to do.
 
Has anyone ever had a problem with either peened or unpeened simple pins coming loose on a handle that's been epoxied?
In my experience the only time simple pins have allowed the handle to come apart has been with thin blade stock where the tang flexes or when a knife has been put in a dishwasher (you just can't hammer "no dishwasher" into some thick skulls).
 
james terrio said:
DO check the depth of the female with a toothpick or something. I've come across some that were drilled much deeper than needed... grinding them flush and coming into a ragged hole in the middle will make you say bad words... you can guess how I found that out.



Tapered tangs are no problem - just drill the tang while still flat, taper it, and drill the scales while they're clamped onto it and the whole thing is vised and/or shimmed so the centerline of the blade is perpendicular to the drill. It's harder to describe than it is to do.
Click to expand...
No, I know that part. I'm talking about fitting the Corby's so they're not too long at the butt end of the knife, keeping the different sized pieces separate. Just a lot to keep up with for my little brain, lol.

randy
 
Randy, you're over-thinking it a little. It's an easy matter to grind down the male/female parts to the length you need, and to drill the overbore in the scales to the correct depth. Measure twice, cut/drill once.

My best advice is to get a couple and play around with them, it becomes more clear when you have them in hand. Heck, send me your address and I'll mail you a couple to mess with. :)
 
fumbler said:
Has anyone ever had a problem with either peened or unpeened simple pins coming loose on a handle that's been epoxied?
In my experience the only time simple pins have allowed the handle to come apart has been with thin blade stock where the tang flexes or when a knife has been put in a dishwasher (you just can't hammer "no dishwasher" into some thick skulls).
Click to expand...

Unpeened pins....yes, and that's why I only use corby bolts any more.

Never done peened pins in handles.
 
watercrawl said:
Unpeened pins....yes, and that's why I only use corby bolts any more.
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I feel compelled to mention this yet again... I view epoxy as mostly a sealant, and rely on mechanical means to hold my knives together. The right adhesive for the materials used can be extremely strong by itself! But I prefer using both methods whenever possible. Under-promise and over-build.

Having said that, I'm also pretty well convinced that properly peened pins give very close to the same holding strength as threaded fasteners.
 
james terrio said:
DO check the depth of the female with a toothpick or something. I've come across some that were drilled much deeper than needed...
Click to expand...

The only ones I have ever used came from Pop's. They have always been consistent, and are not drilled/threaded too deep. I have had to shorten (male and female ends) to use on a thin blade with thin handles, but not a problem.

I also use the "countersink" (is that the correct term?) that he sells. It is a near perfect fit. I use both the 1/4" and the 3/16" diameter sizes. They work great.

In addition, I think Pop makes his own Corby bolts. Good people for sure.

Robert
 
james terrio said:
Randy, you're over-thinking it a little. It's an easy matter to grind down the male/female parts to the length you need, and to drill the overbore in the scales to the correct depth. Measure twice, cut/drill once.
Click to expand...

For the knife I showed in post #7, I ground off between 1/16" and 1/8" of the female part after I took the first photo. I think there was still plenty of depth for the male part to fit but that part is easily ground off to if needed. I measured lots of times and did a good test fitting before applying the epoxy.
 
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