Rotary Cutter Blade tip speed

SPYDERLK · May 24, 2013

A 540 blade rpm youre going to run beyond the sharpened area at about 6mph. I often mow a little faster than that.
larry

Hollow · May 25, 2013

the old grind said:
I agree that tip speed could be a bit over-rated, nice with a finish mower's sharp blades on soft grass, but some of us will distinguish between a field and a lawn. Hogging brush relies quite a bit on flywheel effect of rotating blade mass, where sharper blades would indeed nick/gouge more easily. (How neatly must we manicure what we're cutting from stem to leaf?)

Forward speed, like pass width, determines how much uncut material goes under the blade tip per revolution. We adjust 'feeds & speeds' when machining metal to get the best match-up. Cutting is cutting, and cutting wider with less HP is but a matter of what gear/speed we choose to compensate for the width cut or tool diameter, to draw a ~ parallel. No absolutes here, just getting a feel for what works best. If you bog down, then gear down. Not rocket science, and no calculator or spreadsheet needed.

Thumbsup

JHTFarmer · May 29, 2013

Just looked through the specs of the Bush Hog line of single spindle rotary cutters. Didn't see any correlation with increasing blade tip speed and cutting ability. In fact, appears inversely proportional:

SQ 172, 2 inch capacity, 14,963 fpm

Model 286, 2.5 inch capacity, 14,877 fpm

Model 296, 3 inch capacity, 15,268 fpm

Model 326, 3.5 inch capacity, 13,966 fpm

Model 406, 4 inch capacity, 10,179 fpm

Except for the model 296, blade tip speed generally decreases for this line of cutters as they go from light duty to super heavy duty... What does go up, though , is the mass of the cutting blade.

TomSeller · May 29, 2013

Like engines, there is nothing like displacement.

Midniteoyl · May 29, 2013

JHTFarmer said:
Just looked through the specs of the Bush Hog line of single spindle rotary cutters. Didn't see any correlation with increasing blade tip speed and cutting ability. In fact, appears inversely proportional:

SQ 172, 2 inch capacity, 14,963 fpm

Model 286, 2.5 inch capacity, 14,877 fpm

Model 296, 3 inch capacity, 15,268 fpm

Model 326, 3.5 inch capacity, 13,966 fpm

Model 406, 4 inch capacity, 10,179 fpm

Except for the model 296, blade tip speed generally decreases for this line of cutters as they go from light duty to super heavy duty... What does go up, though , is the mass of the cutting blade.