Stump removal

I put a half quart of my $1 walmart clearance SJ rated synthetic 5w-30 oil in it and it tied to fire on the 3rd pull.
So I filled it up all the way (holds about 1.1qt of oil) and I'll mess with it some more next week.
The shaft dial calipers in at about 0.999 inches in a few places so the shaft isn't messed up, chewed up, ect.

 

Stump grinder rentals here starts at $300 a day.

 

I told some people at work I was building a stump grinder and I'm already getting jobs lined up.
Also looked up cutter head speeds it looks like the fastest cutter on the market spins up to 4,800rpm.
So I'll probably try a 4 inch pulley on the cutter head and a 4.5 inch on the engine with a 5L106 belt between them if that sounds oddly specific at this point its because that's the size I'm going to upgrade my riding mower deck belt to.
That will get the cutter head spinning damn near 4,000rpm.

 

I wish my ole pops was still alive ,, we could sure have built some of this stuff. He was an engineer ,, and could understand those rpm changes with pulleys and stuff. Its amazing how smart that man got in that 5 year period of time when I was 16-21 . RIP Pops ,, luv ya .

 

Oh pulleys is easy, that's redneck math.
Even if you go same size to same size the cutter head speed should still be quite satisfactory, then make those pulley sizes about the same as a riding mower so you know they can carry at least several horse power.
I said 4 and 4.5 inches because they should be big enough and I have one or both in my junk collection.
I'm over driving the cutter head just to try but with cutter teeth every 90 degrees may end up under driving the cutter head and switching the big pulley up front.

I did end up saving the little 5.5hp tiller motor after I put about $100 in it.
Needed a gas tank, cylinder head, the head needed a valve job, cylinder head gasket and a carb to air filter spacer, that's why the air filter wouldn't fit...

I did order a 9.5 inch diameter, half inch thick A36 steel circle with a 1 inch circle cut in it. So its over 9 inches so it won't fit on my buddies lathe, so I'll have to figure out a way to turn it my self. But it's bigger and bigger is better and $25 cheaper. No way I'm going to spin an unbalanced death wheel up to 4,000rpm. I'll have to figure out a way to turn and ballance it my self.

 

Looks like I'll have a 112mm triple belt pulley on a taper lock up front, driving the cutter head shaft. So I'll have to put different size pulleys on the engine.
112mm is 4.4 inches so I'll try a 5 inch riding lawn mower pulley on the engine that had its splines stripped and I bored out to fit on a tractor supply shaft drive hub.
I also bought a second 112x3 taper lock pulley if over driving the cutter head doesn't work as well as I would like and I'll drive it 1 to 1.

Oh man I was looking at the harbor freight 22hp predator engine, they cost $900 now.

 

I ordered the greenteeth 700 series cutter pockets, pocket bolts and wearsharp cutter teeth. About $300 worth of shit. Got a few extra pockets (pockets are the cutter holders), a few extra pocket bolts as the bolts are specialized counter sunk 1/2 Allen bolts and a whole extra set of cutter teeth. I could have done it for about $200 with no spares.
Ha, no spares, who does that anymore.
I think china virus proved the only logical outcome to the just in time global supply chain.

 

I think I'm going to call my stump grinder "collateral damage".
I'll spec the front with enough room for a 6.25 inch double 5/8 pulley, you know just in case.

 

Sounds great ,, I'd love to see some pics when you're done.

 

Well I found my stump grinder. The dokso 620-20.
Weighs about 400lb, fairly heavy construction, has a 14 inch cutter head with 700 series greenteeth every 90 degrees, a 20hp V-twin, is towable.
Regular price of nearly $7,000 on sale for a little bit over $6,000.
Seems like a lot of money for a 3/8 thick cutter head.
Now mine will have a 11hp engine unless I start stump grinding on the side.
If the gx390 is holding me back real bad I'll upgrade to the 22hp predator or maybe the 35hp briggs and stratton.
The 20hp 14 inch cutter head spins up to 2,500rpm. So I should probably follow suit and under drive mine too, shoot for about 1,800 to 2,000rpm my cutter head is going to be around 12 inches.

 

The cutter pockets are going to make the cutter head about 12.5 to 13 inches hole to hole. The cutter pockets are bigger than I thought they would be. Add cutters and the cutter head will be about 14 inches tip to tip. I'll know when the cutters get here tomorrow if they show.

 

I was looking at stump grinders again. Looks like you get stamped sheet metal unless you are willing to spend more than around $4,000.

I got the frame cut and laid out using quarter inch wall 1x2 rectangular steel frame. I'll make the motor plate out of 1/4 or 5/16, have to get some from the welding store.

So far I'm at:
$200 for the used gx390
$300 for the cutters, pockets, bolts, plus plenty of extras.
$50 for 1'' Pillow blocks, with extras.
$60 for the 9.5 inch cutter head and 1'' rod.
$100 for taper lock bushings, taper lock sprocket to use as a flange to drive the cutter head, taper lock pulleys, several extra pulleys since I don't know exactly what my drive ratio will be.
The axle will hopefully be made out of what's in my trailer, bearing, spindle and related parts box.
Well the parts box is empty so I'll have to buy that shit.
That's a lot of money to not blow up stumps, I'll be doing jobs with the stump grinder.

 

Yeah but I don't need to buy, transport or store the boom if all I'm doing is making my stumps take flight.

The stump grinder frame got cut, laid out, mocked up, welded up.
Now to cut and weld up the 5/16 stainless steel motor plate. I have a 1/4 or 3/16 stainless steel Dimond tread c channel ladder step thing, well I got a whole bunch of them, I'm going to cut one up and form it into the chip shield and it should look cool.
Ran the GX390 for a few minutes, it starts right up and runs great.

 

I put a bid on a 10hp 400cc diesel engine I would likely use on the stump grinder for no other reason than it would be cool.

 

When they said "half inch cutter pocket bolts" I assumed that meant the bolts were 1/2 inch thread. They're 1/2 inch allen head....
I held the 1/2 drill bit up to the threaded pocket hole and it wasn't even close. I measured the bolts with the dial caliper, they measured 0.615'' and that's really close to 0.625 which is 5/8.
Well I don't have a 5/8 drill bit for drilling steel so I ordered 2. I'll pilot hole all the cutter pocket holes with a 3/8 then punch them out to 5/8 when it comes in.
I bought new old stock, made in USA, because f china.
The torque spec is 180ft.lb.

 

You don't break 5/8 drill bit, 5/8 drill bit breaks you.
I am mocking up the cutter head for final cutter lay out. Looks like the cutter head diameter is going be about 12 and 3/4 inches in diameter and about 3 and 5/16 wide. May need a reverse cutter pocket.

 

$30 more for two 5/8 twist drill bits.
$108 for a 1 and 1/16 spindle and 5 on 4.5'' axle kit (no wheels or tires yet).

I got all 8 cutter pockets lined up with all 8 holes on the first try. I only had 1 cutter head plate so I had to make it work.
Just waiting on the machine shop they said my sprocket hub will be ready friday. All they need to do is score a 4.5 inch circle.