Stump grinder tractor

jeepnmatt said:
do you have the old starter? is it rebuildable?

Local shop just rebuilt a starter for a JD tractor for a friend for $200, and the one for my 97 CTD Ram a year ago for about the same price. Not cheap, but they use good parts.
Click to expand...
I do but it is pretty rough. Thinking about using a belt driven starter/generator from a club car golf cart. Rated a 25amp, should be plenty for my needs.
 
Drilled the holes for mounting the teeth, they require a 41/64 hole. Came out pretty good, not perfect but all of the teeth bolt in place easily.


IMG_5126.jpeg


IMG_5124.jpeg


IMG_5127.jpeg
 
Got the new starter and it was not even close. I ordered the completely wrong part number by 2 digits, oops. Able to return it but they didn’t have the one I needed.

Getting desperate I found a NOS PRESTOLITE MBG4124, one of two available anywhere. It was a small fortune.

IMG_5130.jpeg
 
Added some angle pieces to the front end to help push brush/trees away from the tractor in tight areas.

IMG_5145.jpeg

IMG_5142.jpeg


Installed the drive belt for the PTO. Pretty tight but still going to add an idler.

IMG_5147.jpeg

IMG_5148.jpeg
 
Beginning stages of the pivot joint for the swing arm. The pivot axis will be inline with the axis of the u joint. This will allow for the most travel with no driveshaft slip, as well as easier to rotate the head 90 degrees.


IMG_5323.jpeg



IMG_5324.jpeg
 
back woods said:
Didn’t really want a used gearbox. Then I found this one for pretty dang cheap with the right ratio, 1:1.47. With a 3” engine pulley and 7” PTO pulley this ratio will net me the target 2200rpm (grinder speed) between 3400-3600rpm. 2200rpm is the target rpm because that is what the Dosko grinders posted above run. The wheel I am going to run will be spec’d the same as the Dosko unit 14”x3/8” with 8 cutters.


IMG_4632.jpeg
Click to expand...

IMO you will be unhappy with that joint and driveshaft setup (if it is only flexing one ujoint), especially if you are running at 2200RPM.
Watch this video and note the speed difference in the first example, imagine that on your cutter head:


IMO, you need something that keeps both ends of the shaft parallel and lets the two ujoints cancel each other out.
Also (if you indeed plan to spin the cutter to throw chips out to the front), you will want to be careful about something to catch the chips/stones or they will be thrown through walls, windows, people, etc.

Speaking of speed, if the wheel OD at the cutters is 17.5" (14" wheel plus 1.75" of bracket), with a 2200RPM wheel speed, that's 10,000FPM at the cutters.
Looking at a random Vermeer, it is 4611FPM with a 1100RPM cutting wheel and a 25HP motor: Vermeer SC30TX Stump Grinder - Compact Stump Cutter Design (also, note that they throw chips towards the machine)
If the 14" is the OD at the cutter, 2200RPM is 8069FPM at the cutters.

Also, that gear box is rated for 540RPM, running it at 3600RPM may not hold up (even with less than half of the rated HP)...


Aaron Z
 
  • Like
Reactions: PAE
aczlan said:
IMO you will be unhappy with that joint and driveshaft setup (if it is only flexing one ujoint), especially if you are running at 2200RPM.
Watch this video and note the speed difference in the first example, imagine that on your cutter head:


IMO, you need something that keeps both ends of the shaft parallel and lets the two ujoints cancel each other out.
Also (if you indeed plan to spin the cutter to throw chips out to the front), you will want to be careful about something to catch the chips/stones or they will be thrown through walls, windows, people, etc.

Speaking of speed, if the wheel OD at the cutters is 17.5" (14" wheel plus 1.75" of bracket), with a 2200RPM wheel speed, that's 10,000FPM at the cutters.
Looking at a random Vermeer, it is 4611FPM with a 1100RPM cutting wheel and a 25HP motor: Vermeer SC30TX Stump Grinder - Compact Stump Cutter Design (also, note that they throw chips towards the machine)
If the 14" is the OD at the cutter, 2200RPM is 8069FPM at the cutters.

Also, that gear box is rated for 540RPM, running it at 3600RPM may not hold up (even with less than half of the rated HP)...


Aaron Z
Click to expand...

Thanks for the video and your input. Somehow I knew all that and even saw that video before but it was absent in my mind. I have some designs in mind for what direction to go next

The blades cutting direction will throw the chips back at the machine similar to the other machines.



When I put up the specs of the AGND I was incorrect about the max gov. speed of 3600rpm, it is actually 3200rpm, this slows things down a bit. With the clutch this gives me an operating rpm of 1900-3200 (engine RPM). This gives gives the gear box an input rpm of 815-1370rpm. Higher than rated but not extremely higher.

The Vermeer you posted has a hydraulic powered grinding wheel. From what I have seen belt driven units run at a higher rpm. Reading around about belt vs hydro some people think the smaller hydro units are under whelming in comparison to the inertia that belt units provide. I personally dont have the experience that is just what I have read.

Ya. I own a sc30tx. It's a good machine for a small company but if you
Are a larger company or are stumping every week I would go with a larger machine for tree extra 8k. The 30tx loses a lot of power because the cutter wheel is hydraulically driven and not belt driven like the larger stumper. I do some pretty large stamps with it but it takes a bit of extra time.
I rented that toro piece of **** and it was garbage. I didn't even consider it when I bought it.
Click to expand...


That being said the lower gov. rpm of 3200rpm changes the operating range of the wheel to 1200-2000rpm.
 
Thought about it for a while and remembered I have a shaft with a double cardan joint. (Below). Correct me if I and wrong but the double cardan should fix the ujoint phasing issue. The shaft has the incorrect ends though. One end is a 1" keyed shaft collar and the other is a 1-3/8" 6 spline female connection. The 6 spline end is correct but on the wrong end of the shaft. In order to work, the double cardan end needs the 1-3/8" 6 spline (with detent) and the other (at the gear box) needs to be 1-3/8" smooth (shear pin).


1738283385646.jpeg



Pictures are blurry but I cut the 1-3/8" 6 female spline off and replaced it with 1-3/8" smooth ID collars with a cross drilled hole. For the double cardan end I cut off the 1" collar and rewelded the 1-3/8" female end to it. Both welded good and came out very straight.

866765035309360257.jpg


-2850991121095352096.jpg


-4577775210625240795.jpg
 

Attachments

  • 1738283337059.jpeg
    1738283337059.jpeg
    3.7 MB · Views: 76
PAE said:
Found the video.

Click to expand...
That would be pretty slick for row pines or trees with tap roots that don’t sprawl. Would probably get some good business with one since a lot of people recognize them from the internet and think they are cool.


Got the starter in the mail, it is the right one this time. Dang thing cost me $400 but I needed it pretty badly. Anyways got it installed and boy does it crank. Previously I had know the spark plug threads were a bit muffed but it was still sealing. Well, was getting a no start, pulled the plug and the threads are toast. Luckily there is a great small engine shop down the road from me. Dropped it off for them to stick a helicoil in it, problem solved there. With it apart I chased all the head bolt threads and cleaned up the deck surface a bit.

The to-do list is getting smaller to get this thing going. Swing arm and mount are almost done, I’ll grab some pictures of those.


A little back story on why I am building this. Last year I started a stump grinding outfit so I could build a house. This year our goal is to have it close to done by fall 2025. The house is a 40x30 (20ft tall) Quonset hut, all steel. Last year I put together a small shop for my equipment which is a 40ft high cube shipping container with a 14x40ft lean-to. Currently waiting for the snow to melt to get back at it all with my dozer. In the meantime time getting this grinder done is important because it will be a valuable tool for the business once spring hits.
 
Last edited:
Here is the start of the mount plate. The swing arm will weld directly to it. It will be tied into two of the 5/8” holes on the on the gear box on the wheel side as well.

IMG_5385.jpeg


IMG_5387.jpeg


Swing arm setup, ground the yokes to get the travel right where I need it. Will be able to cut around 6” below the soil.

IMG_5388.jpeg

IMG_5391.jpeg
 
Took a bit to find the sweet spot for the shaft length. There is about 12” of up and down travel, 6” below grade and 6” above. This will be more than adequate for my needs. The problem is that 6” off the ground isn’t high enough to load on a trailer. To fix this there will be a “travel mode”. Shaft is removed, the lift cylinder is moved to a different mount hole and the arm can be raised to over 12”. With the shaft removed and arm up the tractor can be driven using the entire rpm range.



KIMG1005.jpeg
 
First spin up with the grinding wheel today. First impressions are it is very smooth, no vibrations throughout the frame. Clutch engages real nice, everything is pretty straight and spins well. A little scary with no guards. Frame rate makes it look like it is spinning slow.

 
Getting close to completion, these pictures are a couple days old. Cylinders are mounted up, had to get creative and use a doubled up tractor joint to keep from binding. Once doubled up I had to lock out half of the movement in the joint. It works good, I’ll get better pictures.

Ordered a new seat and steel for the blade guard that should be here soon.


IMG_5600.jpeg

IMG_5599.jpeg
 
Weather has me slowed down a bit, wanting to get finished up next week so I can paint it and put it to work.

My air filter setup was less than optimal and decided that it wouldnt work well in harsh conditions.

Found these air filter assemblies on Ebay. They are the same as what our JD Gator with a diesel Yanmar runs. They do a good job and at $50 I decided it is well worth it. Two stage filter with in inner and outer element.

1740845570069.jpeg
 
CarterKraft said:
Can't wait to watch the live action
Click to expand...
Me too! Waiting for the snow to melt. Got around 160” this year, lost a lot of it in the past few days. Looking like it should be gone in a week or so. After shakedown I’ve got a job with 27 stumps ranging from 5” to 48”. Hope it works good or I’ll have to pickup a small walk behind unit.
 
Just a video of it spun up, maybe 1/3 throttle. Must have straight cut gears, it’s loud, I like how it sounds. Dipped it into a piece of OSB and it threw chips into the operators station pretty bad. Can’t be having that happening. Went down to the local tractor manufacturer (lucky to have them 5 minutes away) and found what they call “Georgia mat”. It is relatively thin material, heavy woven fabric (likely synthetic) with smooth rubber coating on one side. $40 for a 3’x3’ piece. Plan to build some light frame work that it attaches to and creates a 2/3 surround of the cutting head. Far enough away that it can’t get sucked it but close enough to prevent chips from going upwards.

 
You must log in or register to reply here.
Top Back Refresh