Stump grinder questions

[Fallon]

Hydraulics are less efficient than a PTO shaft & more expensive. Most tractors top out at around 10gpm @ 2,500psi, which translates into a little over 17hp. So most tractors don't have enough flow, which means needing a PTO powered hydraulic pack, which is $1-2k.

 

[Jim Timber]

The problem with hydraulic rotation is flow. I have 17hp at full pressure, but only 11gpm of flow. As soon as you want to move the cutter, you're peeling off flow from the teeth and losing power in the cut.

With PTO power, I have 58hp at the teeth, and I have full motion control over it. An add-on hydraulic pump off the PTO was another consideration, but then you're talking about several gallons of fluid, another cooler, and you still have the same available power at the teeth.

I have $500 in teeth and pockets.

 

[dickfoster]

Hydraulics are less efficient than a PTO shaft & more expensive. Most tractors top out at around 10gpm @ 2,500psi, which translates into a little over 17hp. So most tractors don't have enough flow, which means needing a PTO powered hydraulic pack, which is $1-2k.

Well for the huge price tags you'd think there is plenty of room in the budget for that. Especially if you're building more than onesies and twosies. So far they look like the highest cost implements going with the least utility.
As far as liability aspects as one said, no more than a backhoe or anything else you stick on a tractor.

Perhaps I'm overlooking an opportunity? Nah don't go there, I'm retired and intend to stay retired.

 

[Jim Timber]

Small market, high materials cost, and slow moving once built.

My friends asked if I was going to start making these for sale; Nope, I'm going to start grinding stumps for hire.

 

[dickfoster]

The problem with hydraulic rotation is flow. I have 17hp at full pressure, but only 11gpm of flow. As soon as you want to move the cutter, you're peeling off flow from the teeth and losing power in the cut.

With PTO power, I have 58hp at the teeth, and I have full motion control over it. An add-on hydraulic pump off the PTO was another consideration, but then you're talking about several gallons of fluid, another cooler, and you still have the same available power at the teeth.

I have $500 in teeth and pockets.

Yeah no matter what you have only the power out that you have going in minus a bit. Simple physics and no math required.

They say the smaller Worksaver can work with PTO power as low as 22HP. Still it's $4700. A Woods TGS50 is supposed to work on even smaller tractors but still costs about $3600. I assume the smaller units take much longer to do the same work. The larger ones take more PTO power and cost more too, much more in most cases. Your's would likely retail in the 5 to 6 grand range. For such simple machines with so few parts it just seems too high to me.

I know you must have knocked yourself out building your very nice unit, Jim. However if these things cost what they should, I expect you would likely have plunked down your money and bought one.

I expected them to cost pretty much what a brush hog does plus maybe the cost of the swing cylinder. What else is there? There must be something I'm not seeing, as you've built one, maybe you know. Are they charging a premium simply because stumps are so ornery?

I wish for the days of good ole dynamite that you got at your local hardware store.

 

[dickfoster]

Small market, high materials cost, and slow moving once built.

My friends asked if I was going to start making these for sale; Nope, I'm going to start grinding stumps for hire.

Well I'd hire ya and pay in beer but you're too far away. LOL

I thought stumps were one of those universal markets. Well I guess you wouldn't expect to sell many in the antarctic but everywhere else has trees and trees make stumps.

 

[Mysfyt]

I was thinking along the lines of a boom that would extend 12". Having never operated one, would this be significant enough to mess with?

 

[Jim Timber]

Beer doesn't pay the mortgage, and my beer is $2 a bottle. I wouldn't load the tractor for less than $250.

I have under $2k in my grinder, and it was a fun build. I don't think I'd buy one if I were to do it over.

 

[dickfoster]

Beer doesn't pay the mortgage, and my beer is $2 a bottle. I wouldn't load the tractor for less than $250.

I have under $2k in my grinder, and it was a fun build. I don't think I'd buy one if I were to do it over.

I said beer not pee in a bottle.:laughing:
Still you'd lose money getting here even at $250. Nice trip though. Lots of people come here and spend their vacations.

 

[Jim Timber]

$250's to get me to leave the property. You'd be better off buying the grinder for $6K. I have a CA environmental surcharge of $20k.