Rotary Cutter Does Direction of Travel Matter?

[dadohead]

LOVE the cutter, nice work!
Your 2520 appears to be standing tall also.

Any idea of the weight?

It's got to be 700+lbs but being shorter w/ CG closer to the tractor, it handles  exactly like my 5' rotary. I'll have to weigh it.

Here's a 20" section cut to 4" using full cut width. No slowing, no issues, done in no time. I cant go back.

 

[dieselscout80]

Absolutely right. I have a compact tractor with 20hp pto. NOTHING out there short of single spindle rotarys and finish mowers (I dont have the power for a flail).

So what does a former tractor/mower engineer do in retirement? He builds a prototype mower!

View attachment 875089

Built from an old beat-up used Keen Kutter 3pt finish mower, it has two 3' dia swing blades/stump jumpers from Fred Cain. It has staggered conventional CCW rotation spindles.

View attachment 875090
The mower is offset to the right so BOTH tire tracks are back swept. I've been mowing all spring with this thing and it has exceeded my expectations. I knew it would cut well but was concerned my tractor could run it. It does! I routinely cut 20" down to 4" without slowing.... at a full 6' cut width! Because it is mechanically back sweeping the tire tracks, it didnt need high lift blades or high tip speeds... both huge power hogs. Somebody needs to make these for sub-compact and compact tractors!

Look great do you have any pictures of the underside?

Also how did you attach stumpjumers and blades to the finish mower spindles?

 

[big bubba]

outstanding work Dadohead, this is an example of forum discussion & presentation at it's best

 

[dadohead]

outstanding work Dadohead, this is an example of forum discussion & presentation at it's best

Thanks so much Bubba!

Look great do you have any pictures of the underside?

Here is the underside (front of mower to the right).

All I'm doing is applying finish mower techniques to a rotary cutter. There is engineering going on but ALOT of mower development is "black art". Offset conventional rotation decks cut very well and are ALWAYS the cheapest to produce... so that drove the layout. Just like every finish mower I've ever designed, this mower's front spindle wanted to "hand off" its clippings to the rear spindle causing re-cut (sucks power) and disturbing cut quality. I played with cardboard and duct tape baffles last fall until both chambers started to behave themselves. I replaced the cardboard with steel and painted over winter. The baffle rings show up often in finish mowers. They separate the chambers and create suction WITHOUT adding noise (a big deal for finish mowers... mower sound is regulated in Europe). Note the rings only go up to the blades a little. Just like radiator fans/shrouds, maximum flow is achieved when the fan is just into the shroud a little. ASNI B71.1 (US safety standard) requires that finish mower housings must cover the blades in a very precise manner... doesn't apply to rotary cutters though!

Also how did you attach stumpjumers and blades to the finish mower spindles?

Wow wow wow! NOBODY (family, friends, fellow engineers) has asked me that and it was critical to building this concept! The concept I wanted depended on finding production 3' CCW swing blades/stump jumpers because that size allowed a spacing where the blades could back-sweep BOTH track tires on my 2000 series. Talking to Greg at Fred Cain, he had such an animal. Luckily, they make a 3' rotary cutter just for Christmas tree farms! His stump jumper mounts to a typical 1 3/8" dia 12-spline spindle. SO HOW TO DRIVE THEM? As we talked, he started offering all kinds of parts that they use for their 3' cutter... then he said "need any stripped out Omni gearboxes??? I got a pile of returns I'll give you!" That was it! He threw some gearboxes in the pallet box too.

I cut the top of the gear housing off, milled the top flat, and suddenly I had two spindle housings!

The spindle/pinion gears were hardened so they had to be annealed before the spindle/gear was turned down to 1.500" dia and keyways milled. The spindles got new bearings of course. The next major hurdle was the driven sheaves. For a 13,500 fpm tip speed, I needed a specific diameter sheave (2 belt HB with belt spacing that matched the Keen Kutter driver sheave) with a specific offset. "That's all? No biggy!"

In the 80's I was a journeyman wood patternmaker serving my apprenticeship at Caterpillar. I turned a wood pattern and had a local foundry pour two sheaves in nodular iron. Machine them up, broach in keyways... problem solved!

I can't believe you thought of that question! Nice.

 

[dieselscout80]

Thanks

I like the whole setup!!

Very well executed.

Did you weld the wing on the blades for lift/suction?

 

[dadohead]

Thanks

I like the whole setup!!

Very well executed.

Did you weld the wing on the blades for lift/suction?

Yes but I had a pro weld it. The Fred Cain blades were VERY low lift and I wanted to see if more blade could help. As you probably know, welding blades is typically a no-no (the welders in the Deere prototype shop sure wouldn't do it). A local weld shop will knowing the material then pre-heating... only way I can test the shape. Then I run it only on my property way out in the country. Blade is probably the biggest factor in the DNA of a mower.... and the most difficult to prototype.