Go inside linerlocks to judge its operation and workmanship.

For those who truly appreciate the custom knife, particularly the variety of folders, there is beauty in the function as well as the aesthetic qualities of the piece. Nowhere is that functional beauty more evident than in the intricacies, tolerances and precision of a well-made linerlock.

Inspecting the inner workings of the linerlock presents an opportunity to evaluate its operation and determine the degree of expertise that has gone into the finished product. In assessing what goes into the best of linerlock construction, top makers agree that the critical connection between spring and blade is the most obvious indicator of a particular lock’s capabilities. To be sure, there are other aspects to consider in the evaluation of the well-constructed linerlock, and these should never be discounted. But first things first.

Blade-Spring Relationship

“There is more to proper linerlock construction than just the blade-spring relationship,” agreed Ethan Kolar, a custom maker since 2020 with about 65 percent of his work devoted to the linerlock. “There’s a lot of small things that work together to make the knife function as it should, but the blade-spring-lock relationship is the most crucial part of the knife’s functionality as it is critical to a safe and user-friendly knife.”

When Maverik Murdock watches his linerlock work, blade and spring functionality is his primary concern as well.

“The lock fit is probably the first noticeable portion of a well-made linerlock folder, but it is a small part of what makes an overall good knife,” he explained. “The lock fit, or timing, is a good thing to look for as a sign of attention to detail from a folder maker, though there is some personal preference on how the lock fits.”

Murdock has been making custom knives for 15 years and folders for the last five with about 60 percent of his current output in linerlocks.

“Other good signs of a well-made linerlock are good fit and finish with the materials used,” he observed. “The blade should be centered between the liners when closed. This is a sign of proper pivot construction, good bearings or bushings and good alignment of the liner, back spacer and blade. Smooth travel when opening and closing the blade is also good.”

Repercussions Of A Bad Relationship

In the event the linerlock fails the first critical test and the function is flawed, there are consequences.

“If the lockup engagement isn’t correct, it will do one of two things in my experience,” Maverik began. “If there isn’t enough engagement, it could create an unsafe and unstable lock as there isn’t enough lock contacting the blade, which will run the risk of the blade coming back on the user’s hand. On the other end of the spectrum, too much lock engagement can crowd the user’s thumb or thumbnail, making it difficult to release the lock and decrease its service life as the lock has less area to wear into before it has sloppy lock engagement. The most common types of incorrect lock interfaces, I would say, are the two I’ve listed. However, in my opinion, over-engagement is more common than under-engagement as it is easy to both grind more material than is needed for proper lock engagement and the blade taper angle can be easily canted less than is necessary.”

If the spring extends beyond the optimal position, the condition is commonly described as “overtravel,” and the knife’s function is significantly impaired as time and use progress.

“If the lock bar has overtravel or over engagement, it generally isn’t dangerous to begin with because the angle change on the lock bar isn’t high enough to compromise the compression strength of the lock under normal working conditions,” Murdock explained. “But that does depend on the construction of the knife and materials used. Overtravel generally just means a shortened working life of the lock mechanism where it would need to be replaced sooner than a properly timed lock. The problems with overtravel begin to show up with the reach to the far side of the lock. If the lock bar fully reaches the other side of the lock, there comes a point where it no longer has contact with the blade when open, or has minimal pressure where it can bind.”

Other Linerlock Concerns

K.C. Gray has been making custom knives for a decade and collecting them for 30 years. He produces about 100 knives per year and roughly half are linerlocks. His perspective on quality workmanship includes the vital connection between spring and blade as well as other factors.

Interface

“That interface is the prime concern,” Gray observed, “and people usually talk about it in terms of ‘percent of lockup.’ Basically, that is how much the lockbar travels across the lock face toward the opposite liner. Everybody has their own idea of the ideal number. Some like as little as 10 percent lockup. I think most makers would say 40 to 50 percent would be the correct range. Too little lockup and the blade can slip off the lockbar and close. Too much and the lock will stick or even light wear will cause the blade to wiggle. So getting the lockup in the sweet spot in the middle is a sure sign the knife was well constructed.”

Detent

According to K.C., other critical elements should be considered in the overall quality of a particular linerlock.

“Other things to look for would be the strength of the detent holding the blade in the closed position,” he advised. “It should be firm enough that the blade doesn’t fall open when lightly shaken. But it can also be a problem if the detent is too strong. If it’s very strong it can make opening awkward and dangerous. Thumbs can slip onto the cutting edge or the knife can be dropped more easily. Another thing to look for is the centering of the blade between the liners. It should be bang down the middle except in chisel-ground blades.

Clearance

“Something else,” Gray continued, “is whether there is enough clearance between the liners for the thumb to get purchase on the lock to disengage it. If the blade is thick, often no relief is needed. But a thinner blade will usually need some relief cut into the opposite liner. It’s usually a sign that the maker thought the design through thoroughly.”

Other Aspects To Look For In Linerlocks

Of course, there are attributes to the well-made linerlock that are not necessarily visible. The feel in the hand and the ease of simple repetition in opening and closing contribute to the best linerlock experience.

“The blade motion when opening and closing should be smooth and consistent through the whole opening/closing cycle,” Murdock related. “Some makers like more or less drag on the blade, but it should be consistent. If the drag is excessive, it can be a sign of improper pivot sizing or too much lock bar pressure. The blade should have little or no side play when open. If it does the pivot may not be tight enough or the working surfaces may not be in alignment. The blade should be centered when closed and should be tight against the stop pin with a firm enough detent to prevent accidental deployment.”

Kolar also acknowledges the telltale signs of poor construction that are not necessarily readily apparent on sight and warns prospective buyers to consider these red flags.

“There are a few limited signs of improper construction that can’t be seen by the eye,” he commented. “Sloppy blade lockup oftentimes is very difficult to see as it doesn’t take very much for the blade to rock against the lock. How tight the blade pivots is another, as well as whether it has side play in the blade, and this is something that you can usually only feel. A good simple rule for cases such as these from both the maker and the buyer standpoint is to go with your gut on what you feel. A lock should lock up tight with no horizontal side play and no vertical lock play relative to spring size. Smaller springs can compress easier than larger.”

Questions To Ask When Buying A Linerlock

When buyer and seller meet, the evaluation of a prospective linerlock should include more than just a consideration of the knife itself. Buyers should engage the maker in conversation and ask a few questions. A healthy dialogue always enhances the experience and gives the customer confidence in the decision to plunk down hard-earned money.

“Ask about the liner material,” Gray offered. “It’s almost always titanium in custom knives. Ask what angle the lock face has been ground to. Most often seven to nine degrees is used. Ask if the blade runs on bearings or washers. And just ask if the maker can explain the materials used and why he or she likes those materials.”

Murdock agrees. “If you are talking to a maker about his work, he should know the process and materials used and should be confident in what he does. It’s good to ask about the materials and why they’re used. If you can see the work in person and look at these points and the fit and finish, that’s a great place to start.”

The making of a quality linerlock requires attention to detail and presents challenges that go well beyond a simple aesthetic. While eye appeal is always a factor, the proof of the linerlock’s worth is in its operation. Informed buyers can help themselves in taking the time to understand the attributes of linerlock mechanics and the skill that is present in the finished product. Then, the unbeatable combination of beauty and optimal use can be attained.

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