Mini bulldozer with mini backhoe: Broken bits and backyard recovery

[dremu]

dremu submitted a new Build:

Mini bulldozer with mini backhoe: Video, with my dad!

Friends and family look at me funny when I say we're building a mini bulldozer in our shed. Because, apparently, this is not something normal people do. Seems perfectly reasonable to me

As a bit of background, I've been wanting A Project for some time. Not a life-long project like another Blazer (been there, done that), but a build-from-the-ground-up something. I considered a kit car, but I'm too old and fat to fit in the damn things, and we have enough cars already. The kid wanted a hovercraft (which would be epic, as I could name it Full Of Eels and go around saying "My hovercraft is Full Of Eels") but we don't have a ton of water places on which to run it. I've also really wanted to build a big scale RC model tank for years, but that's more of a life-long project and I don't have the OCD for accurate modelling. And so on and so forth.

But then I _do_ have occasional need (*) for work around the property, so the idea of a farm implement sort of thing came to mind.

* "Need" vs "want" is relative. You guys know how this works.

I also wanted to teach my stepson basic shop skills, some welding and fabrication stuff, and have him make himself useful after graduation until he got a job. Maybe he'd decide he enjoys metal working, maybe he'd decide not, but it'd give him some guidance, and cut down on my chiropractic visits

In the end I decided a tracked implement/machine could be handy, would be fun to build, and would be *kinda* like a tank. I went Googling, didn't find much in terms of kits or really detailed info, but did find one guy who sells plans with some parts pre-cut. Took a while to get all the parts (he's in Canada, so the cross-border stuff was a killer), but eventually we got all the parts, and found excuses to buy more tools, and cut and welded a shit ton of stuff, and several months later, here's the final result:

View attachment 230291

That's said teenager, not me. Somewhere along the thread you'll see the tubby redhead, fear not.

As with my other threads, it'll be pic-heavy with commentary that makes me laugh. It may not amuse you, might just make you think I'm crazy. Hell, I built a fricken bulldozer for my garden

Where I've had good vendors, I'll try to point them out, at least by name if not a full URL. Feel free to post or PM for more detail on any given experience.

Read more about this build here...

 

[dremu]

So, the basic stats: 10hp diesel over hydraulic (i.e. diesel turns a pump, and the track drives and cylinders are hydraulic.) Most of the metal came from the local steel shop; as I mentioned, I did get the laser cut package of complicated parts. I still had to machine a certain number of parts in-house, or farm them out.

As we'll see more below, while it's a mini machine, it's not a toy. Well, not just a toy Should weigh 1600 pounds, maybe a bit more as I've added some stuff, plus rider, as it sits now. I'm contemplating adding a small back hoe to it down the line, make it right around 2000 pounds.

Let's rewind to last fall, then. Broke out the plans, made the first of many, many stops by the local metal shop (they literally greet me by name now, and ask how the project is going) and started cutting square tube:

I'm used to bumper fab or smaller parts on the truck, where you have to balance weight against strength. This machine, everything is over-engineered, one because the guy who designed it is a nut, and two because weight can be an advantage when you're pushing or pulling with low traction. Point being that damn near all the tube is 1/4 wall or thicker, plate tends to be 1/4 or 3/8 ... everything is surprisingly stout.

This is the beginning of the tub; there's another set of tube that goes on top of this. It's not quite square, as the nose narrows in. It's a handsome effect, but not totally necessary and a royal pain to cut and weld. Especially if you suck at measuring as I do. Thankfully this is not a precision machine, and when welding... well, you can fill in the occasional gaps with weld, the sort of thing that makes woodworkers run screaming

 

[dremu]

The kid has a social life and wasn't always around, and even when he was available, the workpieces' size rapidly eclipsed our ability to move them by hand ... so we became very proficient at rigging with the engine hoist. As you'll see, the machine spent half of its build life sitting on the hoist legs.

To coin a phrase from one of my favorite authors, the plans are often apocryphal, or at least mildly inaccurate. There's also a ton of stuff left up to the builder, i.e. "put an engine of your choice, 10hp diesel or 13hp gas or something, in the middle, you know, about here." The plans are really more of a guide than an absolute

Much as though I wanted a nice Kohler or something, I couldn't pass up the ridiculously cheap ($800 shipped) Chinese Yanmar-knockoffs on Ebay. Here we're test-fitting it to make sure it'll fit in the frame...

and that the hood will clear it. Turns out there's tons of room -- you gotta love Cardboard Aided Design.

Finally, the floor of the tub was cut, brushing up on my use of the oxy torch. Again, 1/4" plate, ridiculously heavy ... but it has to hold up the motor and whatnot. (Fear not, it'll also have more 1/4 wall square tube as crossmembers later ) The holes in the corner are drains, as the tub is a catch-all for fluids and dirt. But they're also handy chain tie points.

 

[dremu]

Next up is fenders. In retrospect, kinda wish I'd made them longer, but hindsight is 20-20 and all that. At least they're diamond plate, so nice to walk on. (These are steel, not aluminum, but "only" 3/16 )

And they're welded to the tub

Yes, I'm wearing a welding helmet when taking the photo ... surprisingly hard to take photos through a helmet, in case you wondered

The hood is also 3/16 diamond plate, more I suspect to provide weight balance than to actually protect the motor and pump underneath as that would be overkill even for this thing.

Another hindsight moment, I shoulda had the steel place bend the thing for me, they do fab work and have the machines to do it. However, since it's not a structural piece, we scored the back with the 1/4" cutoff wheel (big grinder ) on the bend lines until we were able to bend it. First we put it flat side down, clamped it to the table, and mini-sledged it, then flipped it, as shown here, and carefully () ratcheted to spec.

There were many, many test-fittings of parts, which are also photo ops and give the kid a chance to visualize what the thing will become. He spent a lot of time denying that random bits of metal could someday become an actual machine. Hopefully now that he's driven it, he'll gain a bit of respect for the old fat man.

The tank under the seat is the hydraulic fluid tank, btw. The motor has its own (smaller) fuel tank; it's basically a self-contained job.

 

[dremu]

Most of the hydraulic stuff came from Surplus Center in Nebraska. Somebody here turned me onto that place for electromechanical goodies, but I only recently realized their hydro selection is amazing and the pricing is good too. Especially for hoses, they're a fraction of the cost locally. Just wish they were closer and shipping didn't take so long.

There's an insane number of fittings, which I could have reduced if I'd had the hoses custom made with specific ends (i.e. 90* SAE6 to straight SAE4). However, as I really had no idea how the lengths would turn out until I ran them, I wanted the hoses to be interchangeable, so I opted for JIC6 ends on all the hoses, and then just adapted to what the valve or cylinder or whatever needed. It's been surprisingly leak-free, only one or two bad fittings and a few I forgot to tighten

Power transmission parts (bearings, pillow blocks, shafts) came from McMaster, duh, and oddly enough, a bunch from Amazon. Sometimes when you order six things, they come in one box. Other times you order a dozen, and they come in a dozen boxes

The kid came in and said "The Amazon reindeer just took a shit on the porch."

Also got a seat rotator for boat seats, and a tractor-ish-sized slider mechanism, cheap, Prime shipping, boom. Not absolutely necessary, but clever to slide the seat fore and aft, and if I do add a backhoe, I can just turn the seat around, don't need a second one.

Speaking of suppliers, I was stymied for a while trying to find a 1.5 fine thread bolt. McMaster, Grainger, Fastenal, nobody had 'em. That's 1.5" diameter, not length. Eventually my Google-fu paid off and I found Zoro.com (not Zorro) who have a wide select AND a decent filter for fasteners. They have the Dr Emu stamp of approval.

Anyway, they had grade 8 stuff in 1.5-12, which looks like this:

It's not so amazing to look at, but when you hold it ... bloody heavy, they are. The bulldozer blade pivots, and that bolt, with some help as you'll see later, is the pivot point.

Which in turn means we need a 2 1/4" socket, which thankfully is easier to source. And it's only 3/4" drive, so I have stuff to drive it, yay.

 

[AJMBLAZER]

'Scribed for awesomeness.

 

[dremu]

Mini awesomeness for now as I'm still outside burning off said woodpile. And the neighbor was taking down trees, so the kids are bonfiring away. I have several dozen more pix to post, fear not.

-- A

 

[Bent77]

The kid came in and said "The Amazon reindeer just took a shit on the porch."

Best line. Ever.

 

[AJMBLAZER]

Mini awesomeness for now as I'm still outside burning off said woodpile. And the neighbor was taking down trees, so the kids are bonfiring away. I have several dozen more pix to post, fear not.

-- A

Need to sell my wife on a mini-dozer.

 

[campfire]

'Scribed for awesomeness.

This.

 

[Smokinthehippies]

In to see it end.

Also, just so happened to drive by surplus center in Nebraska about 3 hours ago

 

[nocoasthardcore]

fun.

 

[dremu]

Thanks guys!

As an example of the pieces in the laser-cut package, this is one of the sprockets (there are eight in all) with some of the various tubes for them.

Top left is 3" OD .75 wall DOM, which are for the drive sprockets. They get a keyway broached into them, more on that later. The DOM slugs get welded into the sprockets.

The other two are 3" OD .5 wall DOM for the idlers. They then are machined for bearings which ride inside. This means it was time for a mini-lathe! Couldn't justify the cost/space for a giant one, but wanted something a bit upscale from the Harbor Freight ones. (Actually, those are apparently not bad with some tweaking ) Found LittleMachineShop.com, who sell a range of machines with nice motors with speed control and Japanese bearings, etc etc.

A Bridgeport it's not, but I can do smaller stuff and then roll it away when I'm done. It's amazing, actually, what you can do with one of these. Weird sized washers? Piece of cake. Spacers for the seat? Pfft, no-brainer. Sure, you'd have found a way before, but it's quicker and slicker with the right tool.

Back to the slugs, here's the broach being pressed through:

And yes, those are the Swag Offroad arbor plates. The Chinese cast ones that came with the press scared the living crap out of me. After the requisite several passes for a 3/8 x 3/16 keyway (ie for 3/8 square stock), the net result:

And then test fit with the key and the slotted shaft

That's a 1.5 shaft from McMaster, mmm. The hydraulic motors actually have portals, and then this is the the output shaft from the portal.

 

[dremu]

Rather than being geared, the portals are chain drive, with ~2:1 reduction. Inside:

That's #80 chain. Outside the box is sorta like

Though in the final configuration, the shaft sticks out the other side. This is just a test fitting. The faces of the portals are part of the laser-cut kit, but I had to supply the outer walls. I had my steel supplier roll them:

And then I cut the slots you see. It took me FOREVER to figure out why they're there -- did I mention the plans are cryptic at best? They allow you to get a wrench onto the motor bolts. Don't have to do this often, but you'd loosen the motor to adjust chain tension, then re-tighten.

There's both sides of the portal boxes, and you can see the slotted holes for the motor. The plate to its right has a 3/8 fine threaded bolt to move the motor and tension the chain.

 

[dremu]

When I started into this project, I really wasn't getting the sheer scale of the parts. "Oh, 1600 pounds", I say. Like I have any idea what that means. Then I start ordering sprockets and bearings and such:

and they're huge and heavy and often, not at all cheap. I am very thankful for my exceedingly patient wife who doesn't look at my spending habits

The track sprockets hang on the ends of bloody great carriages, each made from two three footish chunks of 6.25x4 channel. I got my workout shifting those things around, I tell ya.

The laser-cut kit came with ends that fit into the channels and mount the bearings. Then you bend some flat bar across the top

and weld the living crap out of it.

The front end has a slot to allow the sprocket to move as the chain shifts and/or stuff gets stuck

Another laser-cut piece on the inside, with what I think is a good HAZ on this side.

After adding some of the Amazon reindeer shit, here's one test-assembled carriage:

That's three and a half feet of an ass-load of steel and is right about the limit of what I can pick up and move.

 

[dremu]

Somewhere in there I posted about welding hardened steel, namely the drive sprockets. Per the discussion, I heated the pieces up to a coupla hundred degrees and carefully welded them. As they cooled, I peened with the air needler while laughing maniacally, repeating "Heh heh, peen" over and over like Beavis and Butthead. It was a long day. I carefully inspected and saw no evidence of cracking, so apparently I was given good advice and followed it at least sort of well.

The center tube is the DOM slug from above, and then there's the three convex reinforcement pieces partway out.

Eagle-eyed viewers will note that I'm only partway through, stopping for a photo op and a stretch, as not all the sides are welded.

The idler sprockets are basically the same, just mild steel and have the thinner DOM with the bearings in them.

 

[UpnAdam]

You never disappoint!

 

[dremu]

So the sprockets are test fit on the carriages, and one of the two chains hung:

That's CA557 ag chain, which is roller chain, but a bit longer pitch than the ANSI stuff. The tracks will be two pieces of plate, one of which will be welded to these chains, and then an outer one which can be replaced as required from wear or catastrophe. Though thus far I'm not sure what would injure the plates, as I've driven over rock and concrete and a burning woodpile.

To locate the tensioners, I had to stretch the chain out fairly taut. The plans suggest a come-along, though I used a chain hoist. My shop doesn't really have much to attach to, but then I do have two fairly immovable objects ...

one end on the hitch on the Ferd, and the other to the rear axle of the Blazer. The chain hoist is behind the Ferd, and isn't yet taut (when I finally got it, the whole thing actually lifted off the ground )

One of the local CK5'ers, 4X4HIGH, came by, I do believe the day we welded the carriages to the crossmembers to the underside of the tub. It's REALLY hard to explain the thing, even with pictures, when it's sitting upside down

The crossmembers are 2x6, .25 wall, and are further reinforced with gussets of 1/4" plate. I could have named this thing "Because 1/4 Plate", I tell ya.

At the front there's the two hinge points for the blade (more laser cut brackets, plus .25 wall bushings), and so to keep them aligned I stuck a piece of 1" rod through:

Was a bit hairy to get out once it cooled, but the hinges are aligned, yay.

 

[dremu]

Flipping the tub ONTO the 55 gallon drums was interesting enough, but once it gained the two carriages, it took some gymnastics with the engine hoist and both of us hustling to get it back upright. Never gonna flip it again, no way, no how.

Finally it's starting to look like a thing. The portals and motors are hooked to the drive sprockets, the idler sprockets are in place and have the tensioners on, etc. There was a TON of planning required for this, to decide which thing has to be welded before which other thing, etc. The plans only loosely set out a build order, and basically show you a bunch of drawings and say "build it like this, you know." The guy's the king of the Jedi Mind Trick, I tell ya. Gave us good practice in thinking things through and only sometimes did I have to re-do something repeatedly. Like the portals, the first one of which I think I assembled eight times. At least the second one only took me twice

Here's the two strands of chain mounted up:

Then it was onto the tracks. I so badly wanted a tracked vehicle, as opposed to wheeled ... and yet cutting 140 plates and 210 bars and drilling over a thousand holes was somewhat daunting. (Okay, it was mind-numbingly frightening!) Let's just say that I'm thankful that the kid likes repetitive tasks, I did a bunch even though it drove me batty, and neither of us will do it ever again

 

[dremu]

Also sprung for a bandsaw, as I clued in that the chopsaw wasn't going to cut it, as it were. What I didn't get, until I used it, is how much easier angles are with the bandsaw. The chopsaw deflects on anything other than 90* -- hell, it deflects cutting 90*s on really thick stuff. But the bandsaw, albeit slow, will do whatever, right on target. We chunked out a LOT of pieces of plate for the tracks:

Shift flat bar to stop, apply a little oil, start cut. Wait, lather, rinse, repeat.

Every day the stack grew larger

I'd also posted about how to cut holes in this much plate. Ended up with a carbide hole cutter in the desired size, but first we had to do pilot holes

Plus the four corner holes, which even with a step bit are tedious. Insert workpiece into jig, oil, drill a corner, flip around, oil, drill the opposite corner, turn over, oil, drill third corner, flip around, etc.

Did drop the press to ~125RPM with what I call the "drill press doubler", a Drill Press Reduction Kit from Rogue Fab. Great guys, took care of me when I had a problem with my kit. Crazy low speed makes all the difference when drilling thick metal.

And the stack of final form pieces grew: