Benefits Of M6 Wakeboard Binding Inserts: Making Bindings Secure

Schapes Academy - Are Your Bindings Secure? Main Image

Are you using M6 wakeboard binding inserts and bolts to keep your bindings secure? The wakeboard industry has gone through a lot of changes in its development of boards and bindings. The results have been better wakeboard binding inserts and screws on wakeboards. The wakeboard industry has been working towards standards which decrease the cost of manufacturing while allowing products to be interchangeable across brands. This helps wakeboarding grow. The outcome is less hassle for you, the buyer. Much like the wakeboard industry, the snowboard industry has gone through similar changes with insert and binding patterns. The skateboard industry has gone through it with skateboard trucks.  The surf industry has gone through it with fins.

What existed before the invention of wakeboard binding insert threads?

In the early days of wakeboarding, we saw wide 8 inch binding plates. As bindings evolved and materials, innovations, and assemblies were improved, they moved to 7 inch plates. More recently we have 6 inch plates. This drastically reduced the amount of material used as the chassis foundation for the boot upper, which lightened the total weight of your binding. Recently we’ve seen most companies evolve with fin screws and fin hole spacing on boards.  They’ve gone from one single fin hole, then two fin holes spaced 1.5 inches apart. Then finally settling on a 3 inch hole standard that makes swapping fins across boards or finding replacement fins much easier. This is what we currently use.

Early growth of wakeboard binding insert threads

The most recent change has been in regards to wakeboard binding insert threads. Since I can remember, wakeboard binding insert threads have been quarter-twenty (1/4-20) threads, which are a UTS (Unified Thread Standard) measurement popular in the US and Canada. It’s probable that this thread standard was chosen for wakeboards since wakeboarding originated in the US. Over the years,  wakeboarding has grown to be a more global board sport along with surf, skate and snowboarding. The ISO (International Organization for Standardization) metric thread popularity and availability has influenced manufacturers to change from  Standard threads to Metric threads. Let me explain why this decision is the better option below.

Metric and Standard wakeboard binding insert threads

The first major reason for the change is availability. We all know the snowboard industry is bigger than the wakeboard industry and snowboard manufacturers use the same inserts on their boards. Snowboarding moved to a metric standard years ago for the same reasons wakeboarding is doing it now. Since they are bigger, they have more manufacturers producing inserts for snowboards worldwide, which makes metric inserts more readily available and cheaper for manufacturers to purchase in the wakeboard industry. This is a very logical reason to switch. Not to mention tighter tolerances.

The Comparison between M6 Metric Thread and 1/4-20 Standard Thread

Now lets talk about the difference between M6 Metric and 1/4-20 standard threads and why the decision to switch benefits you. We are only going to compare these two wakeboard binding insert threads since they are the main ones used in the market today. Insert depths from manufacturer to manufacturer do vary, but on average are at least 10mm deep. So this gives you at least 10mm of thread engagement if your binding bolts penetrate at least 10mm into your wakeboard. Here’s where you start to see the real difference.

 

Schapes Academy - Are Your Bindings Secure? Thread Engagement

On a one inch 1/4-20 binding bolt with standard threads, the first 10mm of the bolt only yields 9 full threads.  A one inch M6 bolt with metric threads yields 12 full threads. Yes, a small difference but these 3 thread guarantee you a more secure mount. Now, this is a perfect world set up and this usually isn’t the case so I decided to consult one of our engineers. Here’s what he had to say…

From the expert

Thread Failure

“I did a few quick calcs to see what the differences are for the 1/4-20 and M6 bolt thread engagement. Let me start by saying a couple things. First, threads fail progressively meaning they don’t all fail at once. When a screw fails the first thread fails first, then the next , then so on and so forth up the shaft of the screw. It just happens so rapidly that it seems like they all fail at once. With that in mind, you also have to plan for the first thread or so of the screw and the first thread of the insert having flaws as part of the machining process, so we’ll need extra threads to compensate for these first weaker threads.

Minimum Thread Engagement

The typical desired minimum thread engagement depth for any screw size is usually 1.5 times the diameter of the screw. So this means a M6 metric screw with a diameter of 6mm has a minimum thread depth requirement of 9mm (6mm x 1.5). A 1/4-20 standard screw has a diameter of 6.35mm, so it has a minimum thread depth requirement of 9.525 (6.35 x 1.5). So both screw types have a similar required depth but 1/4-20 standard screw has less threads in this distance because standard threads are more course. This may be a reason so many riders are have problems with the screws getting loose. There are not enough threads on a 1/4-20 screw working to hold the screw in place.

Thread Pitch

As thread pitch moves from course to fine, the slope in the fit goes down. When making a courser 1/4-20 threaded hole, the actual % thread is about 55%-60%. That means the hole drilled in the insert is sized so that the tap only uses the outer 55-60% of the tap teeth to cut threads. Threads are not full depth and therefore, are more loose. This is done because it is difficult to make 100% threads with course pitches.

As you move to a more fine thread pitch like the M6, the % thread is more like 75% so 3/4 of each thread face is in contact between the screw and the insert. The fit of the M6 has less slope and tends to better stay in the tight condition as compared to a course thread. A fine pitch thread tends to stay in place better than a course thread since the % of change per rev is less for the fine thread.

What does this all  mean?

Simple. The choice of M6 bolts for the boards will provide a better fit of the bolts to the inserts, which will improve the bolt retention and be better for keeping the binding hardware locked down. This improved fit comes from having more threads engaged between the bolts and inserts as well as the better machining of the insert threads associated with the M6 size compared to the 1/4-20.”

Kevin Kimball
Engineer
Humanoid Wakeboards

The angle of threads in binding screws

To go along with what Kevin just said and if you look closely at the illustration, the angle of the threads, referred to as lead, are steeper on the 1/4-20 standard screw than that of the M6 metric screw because the M6 has more threads packed into the same distance. Since M6 has a shallower angle, it has less chance of wanting to slide along that angle and loosen. If you thought of the threads as a slide, which threads would you be able to slide down easiest, up or down? The answer is the 1/4-20 standard screw, which means they have a greater tendency to loosen when compared to the M6.

Safety First.

Now that you understand why metric threads are better from an engineering stand point, let’s talk about how to properly tighten screws when assembling your board. First, the most important thing to remember is that you should always check your binding screws before every ride, no questions asked. Every ride. They always have the potential to loosen regardless of the type, M6 or 1/4-20.

If you ride with loose screws your bindings can skip teeth, which can abruptly twist your knee, ankle or leg in general when you land. This quick change of your stance angles can cause injuries. That’s why it’s smart to keep screw drivers in your boat or vehicle if you travel to the cable park. Most cable parks have tool tables or tools available there, but don’t count on that. Also, most of these tools available at the park are usually pretty beat up from regular use, so you are better off bringing your own screw driver. Make sure it’s the proper type of screw driver. What’s the proper type you ask?

Get the right tool for the job

Most people have seen different size screw drivers, but don’t really pay attention to the actual sizing needed for the screw they are using. They just grab the nearest screwdriver and crank away. What they don’t realize is that each size screw head has an ideal corresponding screw driver size requirement to achieve proper hold.  It also stands to decrease wear on the screw head while tightening. More simply put, the proper screw driver will allow you to get your wakeboard binding screws tighter and the screw heads will last longer. Most manufacturers like us supply you with “Phillips” head screws, so the screw drivers we will be talking about are Phillips.

Tool Size (#) Fastener Size
#0 0-1
#1 2-4
#2 5-9
#3 10-16
#4 18-24

See the chart to the right. Our binding screws size sits in the 10-16 range on the chart and requires a #3 size screw driver, which is pretty large. If you use a smaller size screw driver on our M6 screws or even on 1/4-20 wakeboard bindings screws you can quickly wear down the head.

 

Using the wrong tool increases wear

Check out the illustration to see three M6 heads of the same size, the first tightened with a screw driver that was two sizes too small (#1), the second tightened with a screw driver that was one size too small (#2) and the third tightened with the proper #3 size Phillips head screw driver.

You can really see the difference in wear on the heads. More importantly, you feel the difference in how much tighter you can tighten the screw using the proper #3 size screw driver. I was able to to get almost another full 360 degree turn out of the proper combination and this means that my bindings are tighter to the board resulting in a safer assembly.

Schapes Academy - Are Your Bindings Secure? Screw Driver Wear

Right Tool, More Response

Heel lift in your bindings causes a slower board response. Decreasing heel lift has  been a challenge for manufacturers since we are limited to only one central row of inserts on the board. So for now, we will have to max out the performance of M6 inserts and bindings screws. Next time you grab your board to take a set, make sure you grab the proper #3 screw driver. Crank your screws down tight for a better response while keeping your safe.