I had decided to make a new model for 2016, mainly due to the increased demand for my blades from the United States. The problem with the 2015 model blade was that all my focus on this blade was to make it as indestructible as possible, without much regard for weight. In Australia all blades were mailed out in a 3kg mail bag, so weight was not a really consideration with this design.
With international mail, prices are broken down into 0.5kg brackets and with the Model-15 blade, it fell into the next higher 1.5kg bracket , because it was just 16 grams over 1kg. Unfortunately this added an extra $17 to the mailing price, which is a lot of money and by shaving some weight off the blade I can reduce the cost of the blade by this amount which is a big saving.
The design of the Model-16 blade has also been influenced by some problems in the Model-15 blade and it is hoped that the new model will rectify these problems without creating new problems. You can read more about the problem by clicking here.
As I have found in the past, solving one problem always seems to expose a new problem and I expect this will be now different. What is important though, is that with each new model, the blades gets better, stronger and safer.
The design of the Model-16 blade will make it a little bit cheaper, a little bit tougher and a little bit safer, without sacrificing cutting efficiency.
Top and Bottom Hubs
The largest change with the Model-16 blade is the shape of the top and bottom hubs.
First off, the slots are only wide enough to accommodate one thickness of anti-fouling blade stop, thus reducing the size of the opening in the hubs and adding that little bit more metal to make them stronger.
The location of the rear anti-fouling blade has been moved back, so the flail-blade strikes it further back along its length. This reduces the impact load, on the hubs, bush and blades.
It was not possible to move the location of the forward stop, but if you don’t cut on the backward stroke, the flail-blade shouldn’t be hitting the forward stop very much. You can read more about cutting on the backward stroke here.
The large bulk of metal behind the flail-blade pivot point has been removed. The idea for this was to help guide the flail-blade back in between the hubs as it was flicked back, which it did very well. What it also did was to absorb the energy from a bent flail blade as it straightened the flail-blade out as it was flicking backwards. The new design will reduce the leverage effect of a whip lashing blade to the hub as it rotates backwards in between the hubs.
The new design also adds more metal where it is needed around the anti-fouling blade slots to improve this weak point.
There will be only one 25.4mm arbor size, as only about 1% of sales are for the 20mm arbor. The larger Stihl and Shindaiwa brush cutter are the only brands that have a 20mm arbor on some of their larger models and Stihl has done such a good job of convincing all their outlet around the world that flail type blades are dangerous, so sales to Stihl owners has dropped through the floor. This has left me with a small stock of about 20 odd blades that I will cannibalise for spare parts and just throw away the top hubs.
The new model-16 Flail Blade, will have a curved uniform width over its whole length, to give the blade more flexibility to bend up and down over its whole length. When it hits a hard object the increased flexibility means, it will no longer put as much bending load on the top and bottom hubs.
The new model will have more area behind its centre of rotation, this will mean that it will fly smooth and flat as the blade rotates. The old blade had more area in front of the centre of rotation and this means that when you think of it as a wing it was very unstable. This meant that as the blade rotated, it would flap its way around and the only thing stopping it from flipping over and over was the top and bottom hubs. This creates another source of vibration and stress on the hubs as they have to retain the flail-blade in its horizontal position.
The extension to the bottom of the blade has also been removed to give the flail-blade more vertical play when cutting. This results in a wider, but unfortunately slower cut as more wood need to be cut away when cutting through sapling trees. I have found that it is very difficult to hold the blade at the end of a weed wacker steady and straight as you cut through sapling tree. The tight fit of a flail-blade in a narrow cut slot, puts a lot of stress on the blade, having a wider cut reduces the chance of binding and the resulting shock loading to the blade and so making for a safer blade.
Since keeping the teeth sharp and balanced is important for efficiency of the BrushDestructor blade, this new model will be supplied with a sharpening jig, to help rebalance and sharpen the teeth after multiple sharpening touch ups or after an impact with a stone that has chipped away one of the teeth.
A video showing how to use this jig will be put up on the How To Page as soon as possible.
The model-16 blade will go back to a single layer anti-fouling blade stop, this is to reduce weight and cost and will also give the operator warning that they are pushing the blade too hard if they are shear them in half.
The anti-fouling blades will now be disposable items like the flail-blades and will be able to be purchased as spare parts like the flail-blades. The aim for this model is not to make the blade stronger, but to make it safer. Making the anti-fouling blades, a sacrificial part will make the use of this blade much safer.
From now on will be sourced the steel direct from the steel mill, where it will be run specifically for me and to my specifications. This will mean that there will be no variations between runs as I had to order many tons of the stuff. Dealing direct has allowed me to stress to the supplier that for me to stay in business and to continue to order more steel, they must supply steel of the highest quality.
It is hoped that that design of the BrushDestructor blade will remain the same for some time now, to allow me to focus all of my time and energy on a BrushDestructor Clearing Machine.
Below is photo of the Model-16 Spare Parts. All parcels are mailed out in 500 gram prepaid satchels and if you choose, you can order option 2, 3 or 4 and get these parts at a discounted price as there is no mailing cost added to their price.
Option-1 – 6 x Spare Flail-Blades Only
Option-2 – Opt-1 + 1 x Diamond Sharpening Disc and 1 x Sharpening Jig
Option-3 – Opt-1 + 6 x Anti-Fouling Blades
Option-4 – Opt-1 + 3 x Pivot Bolt Sets
Click the on one of the links below to go to order page;