Hoback Rolling Detent (HRD)

Using The HRD:
The HRD system was designed to create a smoother operating system for liner/frame lock folding knives. It was developed by Jake Hoback in early 2009.

A normal detent in a folder is a pressed-in ball bearing either .062 or .092 wide. It drags along the blade, keeps the blade in the closed position, and lifts the lock off the surface of the blade to keep the lock bar itself from dragging on the blade, thus creating surface friction.

The HRD system uses a rolling ball bearing to do all that a standard detent does, but with substantially less drag. There is greatly reduced wear, it is user-replaceable, and it has slightly-adjustable tension.

It is fairly easy to build this system. First, you will need to buy the detent here. When installing the HRD, make sure to leave at least .05" between the threads of the hole and the lock face, so you do not risk decreasing the strength of the lock face.

Tap your detent hole with a M3x.5. Insert the detent and adjust the depth of the screw to the desired height you would like the bearing to protrude. 

Keep in mind that with very little friction, the bearing will not leave much of a mark on the blade, so when you are trying to locate your detent hole in the blade, use a sharpie to mark the path then run the blade open and closed several times to assure you know where to place the hole.

The blade in the above picture has had the HRD installed for 6 months, and you cannot feel the detent arc at all. The HRD system will allow some adjustment to the tension by increasing or decreasing the depth the bearing protrudes.

Notes:  When placing the detent hole in the blade, if you very slightly offset the hole rearward of the pivot .003-.005, from the center line of the detent arc, this will allow more adjustment of the set screw. This happens due to the lock bar moving further away from the blade, the more the set screw protrudes from the hole, thus creating a shorter lever and pulling the bearing further into the hole.

We recommend greasing the HRD system with thick oil. Jake prefers to use "way lube," which is very sticky and stays put very well.

If you want a very stiff detent, Jake has had great success with allowing the last .003 of the body of the set screw to drop into the detent hole in the blade -- this gives it great action. Be sure to very slightly round the edge of the detent hole, so that it does not wear the body of the set screw too much.