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Chris Christenberry

Question about hidden pins

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As some of you know, I'm just getting started in this journey.  One of the things I've considered experimenting with is attaching slab handles with hidden pins.  I think I fully understand the "how", but what I'm curious about is "how durable" are they?  I presently use AcraGlass for epoxy and mix it for the full 4 minutes as the instruction say to do.  (I've already learned from experience it's not good to under-mix this stuff!)  :angry:  So are hidden pins as effective as through pins?

Edited by Chris Christenberry

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I run a groove round the center of the pin (on the edge of the belt on the grinder) and add a countersink to both the underside of the scale and the tang so there is a dam of epoxy that locks into the groove in the pin and in any case the pins are more to help with  sheer than to hold the scales on, so hidden pins should be no less secure than through pins all else being equal. I have done a couple this way and had complete confidence in the method. 

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I use the edge of a halfround file to put several notches all over my pins, same idea as Garry, a mechanical lock caused by the glue.

 

With the right glue and some penetration into the handle material I can assure you it's very strong. 

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Yup, guys, I know the "how".  What I was seeking was reassurance it holds well.  I certainly don't want any knives coming back with dissatisfied customers.

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With accraglas and roughed-up pins you will not be getting any returns for handle failure. 

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Thanks, Alan.

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I'm going to disagree to a point with the others here. A pin only adds a mechanical bond in one direction, either horizontally or vertically but not both (unless they are peened). So if you are thinking of pins going through the tang and only partially through the scales then they're not as strong. I prefer to have both a mechanical as well as a chemical bond on my handles. Just my $.02.

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Thanks, Gary.  I was planning on tapping the tang and threading a bolt through the hole and taking a diamond disc on my Foredom grinder and cutting deep recessions randomly around the perimeter of the screw before filling them with epoxy and then putting them into an epoxy filled hole in the handle material.  Of course, I'd still be applying epoxy to the wood and tang.  Do you not think that would be a good bond?

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I think that will be plenty strong.  Eventually I'm confident that you will want to find other methods as tapping the holes is a PITA.   lol

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I'd tap them before heat treating.  I've never had trouble taping holes in soft steel.  Oh well, I've lot's to learn.  I'll keep askin' questions and takin' notes. ;)

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If you want a strong system for attaching scales to a full tang check out corby bolts.

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I've seen them.  My goal was to have no pins showing, and Corby bolts do.

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Just a know-nuttin' newbie talkin' about "what if?";)

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15 hours ago, Chris Christenberry said:

Yup, guys, I know the "how".  What I was seeking was reassurance it holds well.  I certainly don't want any knives coming back with dissatisfied customers.

 

I guess I can somewhat reassure you with one of my own experiences....

I made two knives from 4mm spring steel and the handle shape was based on the Kershaw Skyline, small thin knives with very ergonomic handle with a 50/50 choil.

On the one knife I made the narrow section of micarta at the ricasso area a bit too long, and due to the very flexible blade the micarta let go from the steel.

I was extremely lucky to even notice it, decided it had to be fixed and that was the start of a struggle....

First plan was to hammer out the pins, reshape and glue up again with new pins, I ended up sawing the micarta apart and had to do the lot over. My conclusion was the knife could have stayed like that, the only negative being the possibility of rust in that gap.

 

True enough these pins were all the way through, but not peened. Also have to qualify that the 24-hour epoxy I use makes a very strong bond with micarta, I would not trust the bond on wood quite that much.....speaking from limited experience with wood.

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I have had to remove a couple of handles for one reason or another and at first I tried to drift out the pin but in the end and as a matter of course now if a handle has to come off I use the gas torch and  scorch the handle which send enough heat through to compromise the epoxy and I can drift the pin enough to remove one side which allows for drifting the pin through the tang and the easy removal of the other scale. A thorough clean up of the tang and the countersink of the pin location holes and I am ready to fit up another handle. I had made a few knives with simple plain blackwood handles and got orders for a couple with fancy handles so removed those handles rather than make another pair of blades.

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If you want to see an incredibly good use of blind pins holding the handle scales in place, check this out:

 

 

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If I were to try putting blind pins on a full tang knife, with the intent of using them to hold the scales on, I would use small wood screws.

You could create voids in the tang for the screw heads to sit in the glue and the threads of the screws would hold the scales down and provide shear resistance.

Screw them into the scales a couple of threads before final glue up.

Edited by Joshua States
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Very interesting video.  Thanks for the link.

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