Mowing Nuances of finish mowing

[Volfandt]

How to get the best cut possible out of ones machine is a major topic in many threads now, so I thought I'd share mine mowing w/a BX23 and 60" MMM.

Theres several keys to obtaining a great finish cut.
A well tuned tractor, a properly balanced mower and good properly sharpened blades.
These are all necessary but so is operating the machine at the proper pto speed.
With the tractor & mower mechanically sound, the key to a great finish cut = blade tip speed. The faster the blade tip speed, the better the cut.
This is evidenced by the fact that all commercial mowers have much faster blade tip speeds than consumer mowers. I recall reading on several sites that consumer blade tip speeds are regulated to be slower inorder to be safer. I don't know how factual that is, I mean I don't know if a blade tip spinning at 14k fpm being is any safer than one spinning at 15k rpm but thats the logic from what I've read.

In any case blade tip speed is directly purportional to engine rpm, i.e. the faster an engine spins, the faster everything it powers spins, i.e. the pto(s). Simple logic.
Hense, if one requires the best finish cut his machine will produce, one needs to operate the machine at the rated blade tip speed which is achieved by operating at the engine's rated pto speed.

The owners manual provided with my BX23 and RCK60B-22BX MMM provides the necessary data for me to assertain how to operate both at their rated speeds to obtain the best finish cut.

The BX23 is rated @ 3200 rpm to get it's 22hp output.
To obtain 2500 rpm at the mid pto the engine is rated at 3125 rpm.
To obtain the 60" MMM's rated blade tip speed of 14271 FPM (2647 rpm), the engine must be spinning @ 3125 rpm.
If one is powering a 54" MMM with their BX23, a blade tip speed of 14527 FPM (2969 rpm) will be obtained @ 3125 rpm.

A couple things jump out at me when looking at these specs.

1) The BX23 doesn't have to be running at WOT (3200 rpm) inorder to achieve the "rated" blade tip speed. Just a notch or two below full throttle (the 3 O-clock setting) will do.

2) The 54" MMM achieves higher blade tip speeds than the 60". Those that are compareing both can use this as a good indicator that the 54" should produce a slightly better finish cut.

3) Since the BX23 produces the MMM's rated bladed tip speed at less than WOT, it should use less fuel, run cooler, produce less noise and be more durable than a comparable gasoline engine powered mower, be it consumer or residential.

Conclusion, those operating their BX engines's rpm either slower or faster than the rated outputs are not getting the optimal performance out of their tractor and MMM setup.

Course there are many other variables involved, but this is just the "tip" of these nuances

 

[EddieWalker]

Interesting post. I just bought a used 7 foot finish mower, but haven't used it yet. I still need to fix two flat tires on it, but I'm very curious to how it will work and how I'll like the results. I'm very hopeful, but understand it will take some trial and error to get it right.

Do you have any tips or recomendations on sharpening the blades?

Eddie

 

[Volfandt]

Hey Eddie.

Do you have any tips or recomendations on sharpening the blades?

I hand sharpen mine with a course file. I lock 'em in a vise and spend about 10 minutes or so per side. I barely touch the bottom, only to file down a pit or where it's bent by hitting something. I file on the top. I don't put a razor sharp edge on them, but I get them sharp enough to cut ones finger if one mishandles them (don't ask )

I used to put a razor sharp edge on my blades with my bench grinder (hand grinder on my bush hog) and found that the blades dulled faster than if I didn't put so much of an edge on it. I can't tell the diference in finish cut either. I now mow @ 3 1/2". The grass seems healthier but the dandelions seems to thrive more. I may go back to 3" but I'm still cipher'n.

I changed over to gatorblades mid last summer and so far I haven't had to lay a file to them yet.

That 72" should make shorter work for you.

 

[Lockport]

I changed over to gatorblades mid last summer ....QUOTE]

Volfandt:
That's what I need to do. Do you happen to have the Gatorblade part # for the RCK60B-22BX, which I guess is the deck you are using?

 

[vrman]

Another tip for finish mowing is keeping up with the grass. The taller the grass is, the slower you have to go to get that good cut, or you'll end up going over it more than once.

Oh, and another one, cut the grass in different patterns each time. For instance, I do north-south, then east-west, then sw-ne then se-nw.

(Check my sig for the blade #)

 

[Qrazy]

My tip...

Properly inflated tires....My old mower would have a slow leak on one rear tire...I could tell when it was low by the uneven cut Not sure how that would work with a 60" floating deck...But a tip none the less

 

[crbr]

Do you have any tips or recomendations on sharpening the blades?

Eddie

Flat (bench) grinding wheel, a good eye, pair of leather gloves, safety glasses, and a steady hand. Done deal.

 

[cp1969]

Within common sense limits, I've not found the tip speed (pto rpm) to have much effect on the quality of cut.

Of course, I have a gear tractor and revving the engine up increases blade speed, but it also moves the tractor across the ground that much quicker, so the net effect is....?? Other than getting done quicker, I can't tell any advantage to running at rated PTO rpm when something less does just as good of a job mowing with less noise and ruckus.