Old rotary cutter turned post hole digger?

[thoner7]

I recently destroyed the deck on my old beat up rotary cutter. The gearbox and 3 point linkage is still all good. Let me run my idea past y'all.

it looks like I could fold the legs of the tail wheel and parts of the 3 point frame and make cradle for the gearbox, that would hang plumb from one bolt. I have an 8 foot section of 2x4 steel tubing which would be one the 'top link" and hinge off the original rotary cutter 3 point assembly and pins. My gearbox cradle would hang a pivot from the other end of the steel 2x4.

I'll buy an auger and figure out that connection to the spline on the gearbox. Either find something that mates easily or weld some adapter straight to the stump jumper pan.

the only problem with the gearbox would be the gear ratio. I think it's roughly 1:1.3 or something. From what I've found online is post hole auger boxes are more like 2:1.

So my rotary cutter gearbox would definitely spin the auger faster. But that's no different than using a lower gear ratio, at higher RPM, I think.... My tractor is 50 horse at the pto so I'm not really worried about being geared too high.

would this work or am I crazy

 

[Doughknob]

Crazy......

 

[texasranger556]

I'm all for a project but have you priced an auger in your area? I picked up a gently used Danuser 3 pt mount PHD with 24" auger for $500 a few years ago. I see them pop up for sale periodically. I can't imagine you could build something for much less than that with similar usability. If I were to build a custom PHD it would be hydraulic drive and reversible.

And you're right, you'd have to reduce the gearing somehow. I'd guess mine is somewhere around 2.5:1 reduction. It's not so much power/torque as it is ability to control, at least in my limited experience.

 

[ROUSTABOUT]

I recently destroyed the deck on my old beat up rotary cutter. The gearbox and 3 point linkage is still all good. Let me run my idea past y'all.

it looks like I could fold the legs of the tail wheel and parts of the 3 point frame and make cradle for the gearbox, that would hang plumb from one bolt. I have an 8 foot section of 2x4 steel tubing which would be one the 'top link" and hinge off the original rotary cutter 3 point assembly and pins. My gearbox cradle would hang a pivot from the other end of the steel 2x4.

I'll buy an auger and figure out that connection to the spline on the gearbox. Either find something that mates easily or weld some adapter straight to the stump jumper pan.

the only problem with the gearbox would be the gear ratio. I think it's roughly 1:1.3 or something. From what I've found online is post hole auger boxes are more like 2:1.

So my rotary cutter gearbox would definitely spin the auger faster. But that's no different than using a lower gear ratio, at higher RPM, I think.... My tractor is 50 horse at the pto so I'm not really worried about being geared too high.

would this work or am I crazy

It could work. Seen plenty made with auto rear ends. Maybe turn the gear box around and drive from the blade side. Only if auger bit fits the drive side. You need to make a hitch so that it dangles. Check how a factory PhD hitch is made. We used an old home made one for years. Got a factory one, still think the old one did better. We used the pieces cut out of livestock panel for shear pins. Auger needs to mount on a smooth shaft with a good bolt through it. That way you can disconnect it if it threads into the ground and you need to get it out. Pto don't have reverse.

 

[jaxs]

Crazy,both impliments are dangerous at best,home brewed is equivemlent to a death wish. There's a market for pto shafts,gearboxes and tail wheels,sell them and put money towards a digger.

 

[thoner7]

Yes it should be easy to dangle with the existing metal. Good idea with turning the gearbox around. Although I'm not sure how to re-mount it without looking at it.....

 

[Redlands Okie]

I will agree with the control comment. I usually use my PTO 2 point Aulger with the tractor at idle and its still plenty fast, if not to fast many times. Roots will get you into trouble fast for example.