Equipment

Sub-Compact Stump Grinder Ep. 3

The stump grinder is finally ready for a test run!

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One thing the test run showed, was that I needed a way to better tension the belts. I added tensioning screws to the bottom of the arm, which allow me to push on the pillow block bearings. You can see in the pictures above, how loose the belts are. But even with the belts loose, and starting to slip taking a heavy cut, the test run was still a total success.

For the finishing touches, I fabricated a guard for over the cutting disc, this will keep some of the flying debris at bay.

The hoses got routed and secured to the frame, to make things nice and tidy. The PTO shaft safety chains where permanently installed.

And finally, the grinder received a yellow paint job.

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This will conclude the stump grinder build.

I hope that some people are inspired to build their own machine.

As always, if you have any questions, please feel free to leave a comment and I’ll get back to you.

Yogi

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Sub-Compact Stump Grinder Ep. 2

Before I begin with showing how I made the parts, I’m publishing the drawings for the main three components of the grinder. This is not intended as plans to follow and build one, it’s there to guide and help you design your own. It can be a tremendous help, to have something to start from and then design and alter from there.  They are not 100% complete either, as I made the drawings for myself to work from. I always feel having a set of drawings in the workshop makes life a lot easier. One could argue that would be an unnecessary step, as I have 3D models available, and I designed the whole thing, so why paper drawings? I find myself referring back to the drawings a lot, double checking dimensions, pondering (and maybe refining) the design, and even a place for a quick note…

 

Frame.pdf               Yoke.pdf               Arm.pdf

 

Lets make some parts:

I didn’t have a way to chuck up the cutting disk in the lathe, as my chuck is simply too small. Instead, I machined it on the mill.

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Some of the brackets are machined and ready for welding.

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Milling the slots for the pillow block bearings. This will allow me to tension the belts.

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A few shots while I was welding the arm.

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The frame is test fitted on the tractor.

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The welding on the main components is finished, ready for assembly.

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First mock-up with the hydraulic cylinders.

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Yours truly, checking the travel of the hydraulics. Nothing binding, everything moves free.

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The pulley need to be adapted to fit the gearbox.

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Cleaning up the outside diameter of the cutting disc. Again, due to the size of my late, I mounted the disc on the shaft, which I then chucked up in the lathe.

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The cutting disc and shaft with the pillow block bearing are installed on the arm.  The disc got also the Greenteeth pockets mounted. For more information on the pockets and teeth, see: www.greenteeth.com

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Thank you for visiting my shop.

If you have any questions, please leave a comment and I will get back to you.

Yogi

 

Sub-Compact Stump Grinder Ep. 1

I have been cutting down a lot of trees on my property, to expand the yard. The clearing of the trees has been going well, but  I needed to find a solution for the left over stumps. It became very clear to me that grinding would be the preferred method to deal with them.

I started an evaluation process, to figure out how I would proceed. The following are some of the options I considered:

  • Rental Equipment. Renting a stump grinder seems very economical at first; especially if there are only a few stumps to grind, but as the “yard expansion project” will extend over a rather long period of time, and I’ll be working on it as time and weather allows, it would become less so.
  • Hand Operated Sump Grinder. It takes a lot of effort to operate one of those, and for just a stump or two would be a good option. For the amount of stumps I have to grind, I would prefer something more mechanized. The least expensive one I could find was around $2000. A lot of money for a gas engine on a steel frame.
  • Second Hand Professional Machine. It’s a big investment. The asking price for any used stump grinder I could find was upwards of $5000. These machines are purpose built an would do a wonderful job, but it’s just not in the budget. Also, those machines are rather large, and I would not have a good place to store it when not in use.
  • 3-Point, PTO Driven Grinders. That’s the ticket! Powerful machines, using the tractor PTO, and hydraulics to operate it. But here comes to problem: My tractor! My tractor is a Yanmar SC2450. The tractor falls into the sub-compact category. Even though the tractor has a cat-1 hitch, hydraulics with a 24 hp engine, I felt all the commercially available grinders would be too big for this little tractor. The cost of purchasing such unit is prohibitive too, as they start at around $4500.

In the end, I decided to build my own version of a PTO driven stump grinder, that would be properly sized to fit my tractor. Aside from building a stump grinder that fits my tractor, It will also be the least expensive option.

First, I modeled it in 3D CAD.

StumpGrinderCAD1

I also modeled the hitch and PTO of the tractor to ensure that the drive shaft will clear the frame in all possible positions.

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Some of the design considerations:

  • The frame is to be lowered to the ground for grinding. This will transmit the cutting forces into the ground, rather than into the tractor.
  • The gear box is from a rotary mower, turned horizontal.
  • The cutting disc is a compact 11 inches, as this is the largest size for my small lathe.
  • Greenteeth carbide teeth and pockets. www.greenteeth.com
  • Belt drive to increase the cutting disc rpm, to make up for the small diameter disc.
  • Off the shelve hydraulics. www.surpluscenter.com

 

I’m ready to start cutting metal, which we’ll see in the next episode.

Thank you for visiting my shop.

If you have any questions, please feel free to leave a comment and I’ll get back to you.

Yogi