The only issues that have come back to me, was the failing of the anti-fouling blades and in three cases, failure of or cracks appearing in the Bottom Hub. Although I had expected there to be some failures of the Anti-Fouling blades and the reasons for this can be found in the previous article of failure of the Model-15 bottom hub. I was certain that going back to a single thickness Anti-Fouling blade, would prevent any future failures of the Bottom Hub in the Model-16 Blade.
Even though these failures have proved to be only a fraction of 1% of the Model-16 Blades sold, any failure of one of the hubs is unacceptable. Above and below, are photos from customers with failure of the Anti-Fouling Blades or Bottom hub. If you look carefully at the close up photo on the right below, you can see the seeding of cracks at the end of the slot for the Anti-Fouling Blade. You can also see on the bottom right photo, how the nut guard is starting to crush from the impacts.
I would like to point out, that if one hub should fail, the second hub will carry the load of the flail-blades for long enough to feel there is a problem and stop the brush cutter. In the seven years of selling these blades, I have never had any feedback of a complete failure of the blade where it flies apart in all directions.
Cause
This problem took me a while to figure out, as I had personally done a lot of extreme testing of this Model-16 Blade without any failures of the bottom hub. It wasn’t until I was doing some extreme testing on the Model-17 blade, that the possible cause came to me and then watching every video I could find on YouTube to find a couple that confirmed this theory.
I suspect that the cause of these failures, are the result of bad habits developed after some time using a standard 3 or 4 star metal blade. These standard knife blades, that come standard with most brush cutters are very inefficient at cutting woody material and in fact the only way these blades can cut woody material is to slam them at full revs into the branch. This can be seen in the video above, where a blunt BrushDestructor blades was forced to bash its way through two Australian hardwood stumps. The Model-17 blade when it is finished, will be able to handle this sort of punishment for some time, unfortunately the Model-16 blade will fail fairly quickly when used this way, but it will last a very long time when cutting smoothly through the timber with a sharp blade.
Solution
To this problem will be two fold;
Firstly to no longer use the Anti-Fouling Blades as impact stops, instead use a rubber sheet sandwiched between the top and bottom hubs. Below is the first of what will turn out to be many Model-17 prototypes using a rubber impact stop.
And secondly to remove the large hole opening in the bottom plate, that is there to accommodate the largest standard brush cutter nut guard. It is this large hole in the bottom plate, that has been one of the biggest weak point in this blade right from the very first model.
