I will weigh in on this discussion as I have made a similar reel.

I initially went with a tri-blade configuration, and while it worked well at every low HOC (less than 6mm) as soon as the lawn got too thick it tended to chop and rip rather that cut smoothly. Think of it like an actual saw blade; more cutting tips equates to a smoother finer cut.

Also, I would be pretty wary of having a fast rotating assembly (potentially under a fair degree of stress) without the all the blades physically attached to it. Personally, I think there is a potential for a blade to detach.

100% of the verticutters that I have seen have been mounted on a shaft (hex, square etc) and secured such that there is almost zero chance of blade detachment short of a catastrophic failure.

Just my 2c.

I have had some blades laser cut out of 2mm mild steel and tracked down some 10mm spacers through Golf and Bowling Melbourne. I went with slightly thicker material encase I want to do some deeper verticutting into the soil.

It is now a dead-ringer for devosi's reel, except for the cut-outs in the blade to help clear debris.

Simon

[Linked Image]
[Linked Image]
[Linked Image]