You cannot use the locknut that came with your grinder to tighten two blades! You can use the manufacturer’s locknut to tighten one blade only. Their locknut has a 22mm shoulder which will not allow it to tighten two blades. We designed the Universal Nut with its flat base and hexagon head specifically for the purpose of holding any double blade combination. Using a 13/16(21mm) spanner, socket or crescent wrench, its much easier than manufacturers two pin spanners. It can also be used to tighten other accessories.
We have never had a chain break, discs crack or blades fly off the grinder, contrary to some of the myths out there. Not one has ever been returned through customer dissatisfaction or manufacturing defect. The simple truth is that the chain can't break because it doesn't move independently like a chainsaw, which rotates on a bar. The chain on every one of our products rotates as one unit locked between the top and bottom discs, the total assembly being secured by the lock nut which is further secured by its clockwise tightening when the motor turns anti clockwise. The chain can't go anywhere as it spins in conjunction with the discs. Another design feature ensures the blades never heat up due to the cooling effect provided by the four holes and slots in each disc, maintaining their long life. The discs also have a patented anti kickback clutch action when the chain hits an immovable object like a nail or wire, however, do not force the blade and twist it in the wood during operation. Like any other cutting attachment, if twisted hard or rapidly against the sides of a deep cut you made in the wood, the forces exerted could induce a kickback.We are very proud of our excellent safety record.
Please keep in mind that you MUST always use caution with any power tool. The biggest danger is complacency and lack of attention to the work. We have been told many times by users that they have been lulled into a false sense of security to the danger because the tools do such a fantastic job. You must always be alert and be aware that the blades travel between 10,000 - 11,000 rpm at three times the speed of a chain saw and with twice as many teeth!