Tips From The Balisong Collector

Thread-locking Adhesives

More and more new balisong models, Benchmade's 4x series, the Microtech Tachyon, Roton USA's Monarch, are using removable screws for latches and/or pivot pins.

Such removable screws and removable pins allow latches to be removed and/or swapped between Batangas and Manila configurations, blade tension can be adjusted, blades can even be replaced, and -- in the rare cases when it is necessary -- the whole knife can be disassembled for cleaning.

Let me say here that there is almost never a need to disassemble a balisong to clean it or lubricate it. One of the beauties of the balisong design is the openness of the joints. Cleaning can be done very effectively by flushing a solvent (or even just water) through the joint. About the only reason I can think of to disassemble a balisong for cleaning is if something gets into the joints and absolutely hardens in there, maybe paint for example. Once cleaned with water or a solvent, the joint can be dried with compressed air or just by heating with a hair dryer. Most lubricants (certainly Militec and Tuff Glide) can easily flow right into the joint. There just isn't often a need to disassemble a balisong. I am strongly of the opinion that most people do more damage than good by needlessly disassembling their balisongs.

The problem is that whatever can be taken apart can also fall apart unexpectedly. This problem can be annoying when the thing that might fall off is a small, easily lost part such as a screw or latch for an expensive knife. This problem can be significant when the part that might fall off is a handle in motion that might hit some breakable or even hit someone causing some injury. But, this problem becomes downright dangerous when the part that might fall off is a razor-sharp knife blade in motion.

Most balisong manufacturers and custom makers use some sort of thread locking adhesive when they assemble balisong knives with screws. If you disassemble or adjust those screws, you should use a thread locking adhesive too.

The biggest name in thread locking adhesives is Loctite Corporation. In fact, the name Loctite(tm) and the term thread locking adhesive have become synonymous.

Loctite markets a broad product line of thread locking adhesives. But, most of them are sold only to industrial customers. Two Loctite products are sold to retail consumers at hardware, automotive, and home center stores (Home Depot, etc.): Loctite 262 and Loctite 242.

Loctite 262 is considered a "permanent," high-strength thread locking adhesive and is intended for assemblies that are not expected to be disassembled. Loctite 262 is a red fluid.

Loctite 242 is considered a "removable," "medium-strength thread locking adhesive and is intended for assemblies that are expected to be disassembled. Loctite 242 is a blue fluid.

Sometime, automotive and industrial supply stores also sell Loctite 270, a green fluid, that is a permanent, maximum-strength thread locking adhesive intended for assemblies that definitely will never be disassembled. The other Loctite product you may find for retail sale and industrial supply stores is Loctite 222, a purple fluid, that is a low-strength thread locking adhesive intended for assemblies that are not mechanically stressed; it's primarily intended to prevent assemblies from coming apart due to low-level vibration.

If you go to an industrial supply house or if you have access to Loctite industrial products, perhaps through work, keep two things in mind: first, Loctite offers a broad line of thread locking adhesives; the four noted here are just the most commonly found. If you need information about other Loctite products, consult Loctite's website. Second, the color-coding scheme, green for maximum-strength, red for high-strength, blue for medium-strength, and purple for low-strength, is an industry "standard." Many of Loctite's competitors use the same colors. But, this color code is not strictly enforced. Loctite and other suppliers will custom-make any product in any color. Manufacturers of consumer products especially often special-order thread locking adhesive in a color to match the product it'll be used on so that any excess won't show. Clear is also available. So, just because you find a bottle labeled "thread locking adhesive" and it contains a blue fluid, don't assume that it's medium-strength.

A medium-strength thread-locking adhesive, usually blue, such as Loctite 242 is ideal for balisong applications. It's plenty strong for holding balisong fasteners and easily removed.

The screws used on balisongs tend to be very small, #6, #4, or even smaller. For such small screws, only a tiny drop of the thread locking adhesive fluid is needed. In fact, I find that the dropper tip on the bottle that the adhesive comes in generally gives a drop that is way to large. So, I put that drop onto a piece of waxed paper or foil and then use the tip of a toothpick to transfer just a fraction of it to the screw. A little dab will do ya.

There's no hurry, by the way. Eventually, the adhesive will dry sitting on the paper, but that's just it: it doesn't harden, it doesn't cure; it just sort of dries up. Thread-locking adhesives cure, they harden, in the absence of oxygen. There's not much air inside of a tight screw assembly and that's what makes this type of adhesive cure. This explains why when you buy thread-locking adhesive the bottle is only about 1/2 to 2/3 full. If they filled the bottle all the way, then the adhesive would harden in the bottle.

If you don't use too much, medium-strength thread-locking adhesives can be broken loose with hand-applied torque. But, if you over did it on the medium-strength stuff or if you used a "permanent"-strength adhesive, manual torque won't work. This is especially true on balisongs where the screws are very small. If you use the wrong adhesive or use to much, the adhesive bond may be stronger than the head of the screw and you'll break the head of the screw off if you ever try to disassemble the knife again.

There are all sorts of myths about how to remove fasteners held by thread-locking adhesives. Here's what it says on Loctite's own website:

The application of heat is needed to remove a fastener that can't be removed with a hand tool. Temperatures of 325F and above is needed to break down a standard [thread locking adhesive], 500F for high temperature [thread locking adhesives]. A heat gun or propane torch is commonly used to do this process, and careful disassembly should occur while parts are still hot. Once apart, and cooled, use methylene chloride (Chisel #79040) to remove cured excess material. Always wipe down the fasteners with clean up solvent to remove the wax film that Chisel #79040 leaves on the surface.

(350F = 177C and 500F = 260C.)

Chisel #79040 is a solvent product that Loctite sells specifically for removing their thread locking adhesives. It's a somewhat hazardous material and I've never seen it offered for retail, consumer sales. Methylene chloride, the major active ingredient in Chisel #79040, is available for retail purchase at automotive supply, painting, and home center stores. It's a nasty solvent chemical, so be careful using it. Follow all the labeled cautions and directions. Wear eye protection that completely seals around your eyes; common glasses aren't good enough because the chemical and splash around the sides and this stuff can permanently blind you if it gets in your eyes; please take no chances on this (my website is not yet available in Braille). Wear gloves. And work outdoors or in some other well-ventilated area. Be especially careful with methylene chloride on any balisong that has exotic insert materials or that has painted or coated handles. Even blade coatings could be attacked by this stuff. Methylene chloride is a nasty, powerful solvent; please be very careful with it.

Anyway, as you can see from the Loctite text, heat is the key to removing a screw held by thread-locking adhesives.

Some people seem to know that heat is the key, but they don't know how much. Some people try boiling knives to get the thread-locking adhesive to release. Boil all day if you like, it won't do any good. Boiling water is only about 212F. You need 350F. The same is true for hair dryers. They don't get up to 350F either (and it's a good thing they don't or your head would be burned).

Loctite recommends a torch. That's a bit much for the small screws usually found on balisongs. A common technique that works well for small screws such as those in balisongs is to hold a hot soldering iron on the screw for several seconds before attempting to remove the screw. Remember, soldering irons are very hot (typically about 700F), so be very careful.

Keep in mind that if you apply excess torque to a screw, you risk damaging or even breaking off the screw head. This is especially possible with the small-size screws used in balisongs. I've heard of people trying to remove #4 screws held by thread-locking adhesives who have had the head of the screw break right off leaving the body of the screw locked in the assembly. When this happens, the simple task of removing a screw suddenly becomes an expensive job for a skilled machinist. So, don't apply excess torque.

Breaking off screw heads is especially easy with the Torx (tm) or Hex-head screws that are popular in balisongs these days. So, be very careful. These screw head styles are specifically designed to transfer torque forces to the screw very effectively. This can be a good thing and a bad thing.

When you remove a screw that's been held by a thread-locking adhesive, there'll be some residue of the adhesive on the screw. That residue will interfere if you try to put the screw back into the same hole or into a different hole. This is especially true for fine threads. Furthermore, new thread-locking adhesive will not set properly if the parts to be bonded have residue from previous applications on them. So, that residue must be removed before the screw is reused. A wire brush can often remove remove the residue from the screw. But, there's also residue in the hole that the screw came out of. The only way to remove that residue is with a solvent such as methylene chloride or Loctite Chisel #79040. Notice that you then need to remove the residue left by the methylene chloride or Loctite Chisel #79040 using another clean up solvent. This step is especially important if you want to reassemble with a thread-locking adhesive as the residue from the methylene chloride or Chisel will interfere with the new thread-locking adhesive.

Other residues on the surface of a screw or inside the ferrule, the female part of a Chicago fastener, will also interfere with the hardening of thread-locking adhesives. The surfaces have to be clean. Lubricants are a big problem. But a lot of people like to lubricate their balisongs. It is especially important when you reassemble a balisong using thread-locking adhesive that you clean both the screw and the inside of the ferrule. Cleaning the inside of the ferrule is very difficult.

I sometimes see balisong artist saying that blue thread-locking adhesive isn't strong enough and that they have to use red. I'm convinced that this is because they're not getting the parts cleaned well enough before they reapply thread-locking adhesive. There are two dangers here. First, if the parts aren't cleaned, red adhesive isn't going to work well either. They are risking a failure of the adhesive with all of the resulting dangers outlined at the beginning of this essay, i.e. the spontaneous disassembly of the knife). Second, if one time they do accidentally get the parts clean, they will be applying a much stronger adhesive than necessary and will have great difficulty disassembling the knife at a later time.

The conclusion here is that the consequences of disassembled balisongs falling apart in your hand during manipulation demand a thread-locking adhesive on the screws. Thread-locking adhesives carry their own set of complications. As a result, if you have a balisong with removable screws, it's probably best not to disassemble it frequently. Assemble it into the configuration you want, apply a medium-strength thread-locking adhesive, and leave it assembled.

Here are two screws removed from a Benchmade Bali-Song. You can see the thread-locking adhesive residue on them.

This picture will give you some idea of how much thread-locking adhesive to apply when you're assembling a balisong. Enough to cover two to four threads is plenty.

If you do use a thread-locking adhesive, understanding that adhesive and how it works -- and doesn't work -- will help you achieve the best possible results.