Stump Grinder Build

[woodlandfarms]

So I have been playing with the idea of a stump grinder for a number of years. The issues are cost for a new one (3 to 7K depending on how you go) or getting lucky with a used one. My tractor is fully hydraulic (like a skid steer) so it limits me on where to purchase one.

This all said, I finally had enough saved up to build my own. I am no engineer, and this has the wife in complete fits. the spinning wheel of death is her assumption.

Anyway, so this is the start of it. I am happy to take notes, but pretty set in my design. I think will compete the project in the next two weeks.

The implement is based on 6" C channel and Ship Channel. The wheel is custom made 20" with Green Teeth cutters. It is driven by a 4.6 cu motor turning at 800RPM based on my 18 GPM/3000PSI PTO circuit. The wheel runs sideways. Meaning you roll forward and back for the cut, you do not turn.

Costs to date
120 for the C Channel - Attach plate already exists but if you bought, add another $50.
160 for the motor (Surplus Center)
60 for the shaft (Ebay)
70 for the pillow blocks (Ebay)
350 for the green teeth (Kinda Ebay)
320 for the spinning wheel of death (This is being machined for me)
70 for the Love Joys (Ebay)
30 for the hub (Ebay)
250 for hoses and connectors (OUCH) I never budget correctly for these. (Local Hydraulic store)
50 for odds and ends so far (bolts, drill bits).
75 for poorly purchased parts (motor mount and hub for wheel)

Not included is the new plasma cutter and welder

 

[J_J]

Are you going to do yours like this video, or off the side of the bucket?

https://www.youtube.com/watch?v=GlA-NKNzmLc

I would suggest to use joystick tilt also with front and back movement.

 

[oldnslo]

No mechanical engineer either but hope your pillow block bearings will take the radial thrust load of shoving the wheel of death into the stump.

Be sure to allow some form of safety run down protection for the wheel of death when you shut it off. I don't have a clue on if there is some "standard" time in which it is supposed to stop but a 20" wheel at 800 RPM has some serious inertia.

best wishes on getting this build and in operation

 

[J_J]

His PTO solenoid is an on off setup.

I would suggest a relief valve across the motor.

 

[MossRoad]

I take it the spinning wheel of death will go on the shaft between the pillow blocks inside the rectangular box at the right end and the motor to the left bhy the lovejoy?

To echo the concerns of the above.... I would have put the shaft THROUGH the steel and used bearings on each side rather than pillow blocks. If the pillow block casting fails, there's nothing to contain the shaft other than the other pillow block. At least if its through steel, that MAY contain it a bit longer should the bearing or bearing holder fail. I'm not an engineer, but I did sleep at a Holiday Inn one night a few weeks ago. :laughing:

Good luck with your project. Scary scary project.

 

[downsizingnow48]

I'm not an engineer either. Pillow blocks are rated by the manufacturer for dynamic load and RPM so an appropriate version can be selected for a specific application. Most are for relatively tame applications (eg blower fan), but some are designed to handle severe shock loads and heavy vibration. The 20" wheel of death will have plenty of that. Will the grinding motion be up and down or sideways? Pillow blocks will not be happy with much in the way of bending or axial forces.

 

[woodlandfarms]

Are you going to do yours like this video, or off the side of the bucket?

https://www.youtube.com/watch?v=GlA-NKNzmLc

I would suggest to use joystick tilt also with front and back movement.

Yeah, saw this a couple of years ago. Yes, like his.

 

[woodlandfarms]

His PTO solenoid is an on off setup.

I would suggest a relief valve across the motor.

JJ. I have considered the relief on the motor, but I don't think I need one. The PTO Circuit should cover this as Power Trac has designed. My mower does not have a relief valve on it. What am I missing?

 

[woodlandfarms]

So..... The Pillow Blocks. I don't disagree with any of your concerns. But pretty much every design I see uses Pillow Blocks. I asked the manufacturer when I bought them and they pointed me to these, with thick webs and the legs are fully cast. In looking at other versions, the part that goes around the bearing was thinner, especially toward the foot (the part that connects to the steel bars). Also, the foot is solid. The thinner version the feet are open to save on steel cost.

Does this mean I got the right ones? Nope. Does this scare me, given I am a filmmaker and not an engineer, and have no clue about Hydraulics? Eyup.

Keep it coming guys.

Oh, if I feel the Pillow Blocks are not going to survive, I planned for the use of blocked bearings. It would take a new motor mount, but I have enough room on the 6" C Channel to fit a new bearing in if it needs to happen.

I mixed my design from downloads taken from Baumalight and Rayco. Rayco loves pillow blocks.

 

[Tor Arne]

JJ. I have considered the relief on the motor, but I don't think I need one. The PTO Circuit should cover this as Power Trac has designed. My mower does not have a relief valve on it. What am I missing?

A lot of flywheel effect, I'd install a check valve between the hoses to the engine so it can freewheel down to stop.