Occasionally when I am mowing, the deck gets a vibration that comes and goes. I figured it was a couple of the blades a little out of balance and when they got in phase, the vibrations were more noticeable.
There is a really nice balancer on Amazon that holds the blades on with ceramic magnets, real deluxe fixture with a $150 price tage.
So after a little thought, I designed a hub on Tinkercad that uses a couple of 608 R2 ball bearings and printed it out on one of my 3D printers. I made a stub with 3D printed threads and a 3D printed wing nut to hold the blade on the jig.
The bearings have no seals and roll very freely.
I used a 5/16" X 3" bolt with the head machined down so it's only 1/16" high and a couple of pieces of steel tube, one 20mm long to separate the bearings and another 25mm long to move it away from the 1" square tube I used for a support that I clamp in a vise.
I pulled one of the blades off and it was pretty close to balanced, only had to take a little off one blade. The other two blades were pretty close too, but now they are all nearly perfectly balanced.
It rotates so freely that even a couple of paper clips stuck on with a little scotch tape makes that blade stop at the bottom.
I figure that with the steel tubing, plastic filament, bearings, bolt, washers and nuts, I have at most $5.00 in it.
If anyone would want the stl file for it, PM me.