Build your own finishing mower

pplowery · Sep 21, 2007

Has anybody tried to build a finishing mower or modify one?
How do you match the gearbox to the spindles or does it matter?

sandman2234 · Sep 21, 2007

I built one from scratch(7'6") to pull behind my Ford 1100. I planned on powering it with a 22hp gas motor. Before I completed it, I got an offer to finish it for pto power so I put a 1:1 right angle gearbox on it, and mounted browning sheeves on the spindles and gearbox. The buyer supplied his own driveshaft. The cost of sheeves is the cheapest way of being able to modify the speed which needs to keep the bladetips below the speed of sound. I used standard 5 bolt hubs as the bearing holders.(Trailer axle hubs)
I asked the owner a few years later and he said it was still working fine, except they hit something and bent a spindle. I did build extra spindles...
I don't have a picture of it, as he picked it up as soon as I finished it.
A friend has a Kubota B6000 and we modified an old finish mower that I wasn't using, to run backwards. He bought reversed blades and now he thinks it's a bush hog. I am trying to get him to start building a bush hog before he tears up the finish mower.
David from jax

pplowery · Sep 24, 2007

I am looking for sheaves now. What size did you use for the gearbox? Splined or keyway type shaft or does it matter?

I already have a six splined gearbox for a rotary cutter. I am trying to use that to keep from buying another one.

Did you use straight blades or two piece like a rotary cutter?

pplowery · Sep 24, 2007

Speaking of building a bush hog, I did and it is probably better than anything that I could buy. We have lots of rocks here and it is impossible to get all of them. I have beat the sides into a concave shape and have replaced the blades three times.

It currently resembles a John Deere LX6. I had to do a little welding here and there to keep it together. Otherwise, I am happy with it.

bx24 · Sep 24, 2007

I was thinking about doing the same thing .... then I found one that just needed some TLC and some grease. $400 total ($300 on eBay and $100 in parts), I was up and running with a unit that I bet I could now sell for $600+. I like making things, but I am running short on time.

If you have the time, dive in .... building it will be very rewarding. I had to settle for rebuilding mine

sandman2234 · Sep 25, 2007

I used 1/2" thick blades that I bought at a freight damaged sale place. They were 30" blades, about 3.5" wide, single 3/4" hole in the center. The mower was actually a 7'6" cut with these blades. The sheaves I used were all about six inches. I don't remember what size I finally used on the gearbox, because I had to change it from my original plans when I went from a 3600 rpm motor to a 540/1000 rpm tractor. The new owner probably just ran it in 1000 rpm and it was fast enough to make a good cut. I went over my design intention pretty well with him before we decided to make the switch to a pto power with him being the new owner. Being my first mower, I tried to leave myself plenty of room for change whenever possible.
You might want to take a look at your gearbox and see just how much gear reduction it has. Typically a bush hog has some sort of reduction in the gearbox, and a finish mower has a speed increase at that point. Mine was a one to one gearbox with the speed controled by the size of sheaves.
I used all "taper loc" (actually QD type of taper loc) on mine, because that is what was available in our used parts arena to hold the Browning sheaves to the shafts. They are also available with a keyway which is what I used.
The belts were my "shock absorbers" in case a blade hit something. I only ran single "B" belts for fear of getting too much power transmitted thru the blades. The size of your sheaves will have to be figured out for your application, as you want a pretty fast blade tip speed, without the blade tips approaching the speed of sound. I am sure you can find a normal blade tip speed on a manufacturer's website. Just start with your pto speed and work backwards till you get to the speed of the blades, and adjust the ratio of your sheaves to allow for your intented speed.
David from jax