This should probably be a folder, but it's an old-ish project im going to cover here, as it had some fun adventures.
Why would I need an excavator?
You know, the reasonable/logical part of me entirely understands that there is no definitive correct and universally acceptable answer to this. I can justify it in many practical ways, but purely in terms of necessity, they are all a stretch. At my cabin, this machine could be (and is) used to help around my and my neighbors property - making quick work out of fallen trees and plowing drives/roads in the winter. It's just a 9000lb swiss army knife. Also, who doesn't like just digging holes!?
Buying a machine.
So for all of the research I had done and the time taken to pick the right one, my eventual choice was fairly compulsive. I'd been talking with a guy on craigslist selling a "2018" Cat 303.5ECR mini excavator with about 3200 hours. Complete with a hydraulic thumb, and hydraulic quick connect, the thing was pretty well equipped. and it had a cool screen. To the extent I asked him about things wrong with it, the general consensus was "works great, it has been taken care of and is ready for a lot more hours".
It was a soupy, rainy day when I took the drive down to Gig Harbor, WA to 'look at it'. Such a funny notion, as I'm leaving with 24,000 dollars in cash, an ammo container with 400 rounds of 12ga buck, and an inert russian anti-tank mine telling myself "I'm just looking at it". So I get there, the guy seems on the up-and-up and it's dumping rain. It starts, it moves, it's a little wiggly (play in pins) but all things considered, its expected for a machine of that age. One terrfying thing about heavy equipment is there is no 'registration' for them - so for any given piece of equipment, there is a lot of due diligence needed to actually verify the person selling it owns the machine. In my case, I was a lot more assured here as the guy owned a construction company, which I verified, and we were looking at the machine in the lot of that company. So generally going with the inertia of the situation I had created for myself, I bought the machine. I'd intended to come back with a trailer, but the seller let me borrow his tilt trailer. Either a good or bad sign depending on how you look at it. A few hours later, the machine was rolled into my shop, and the guys trailer was returned. I called it a day and really got spinning on all the improvements/restorations I would do, planning to hit the ground running the next day.
With the machine in the shop, the true horrors started to show. Yes, the boom, stick and bucket pins were loose - but then the following started to be apparent:
- The bushings on the pin that connects the end of the stick to the bucket were completely gone, and the outside of that hole was wallowed/bent out a good bit.
- A hose on the hydraulic quick disconnect circuit was worn out to the point of leaking, and did so readily.
- The ears on the bucket attachment point (where the pins bolt in) were pretty much destroyed
- Most of the bushings from the boom forward were beyond their service life (This I actually expected)
- Just a bunch of other little things.
The rehab
Electronics
I'd put in a massive order for new bushings/pins, so while I was waiting on that and wallowing in a kiddie pool of regret, I took to fitting some electronics on the machine. This was more as a sanity exercise for me as it was my orginally planned "improvement" activity. I restored the original switch control surface and created new circuits for an accessory line and some additional lighting --
The old panel - switches faded (the empty ones had placeholders in there but generally werent used).
The new, restored panel.
Proper-ish harnessing and connectors I'd made for the new panel
This all ran up a harness into the roof to drive these new features:
- A bluetooth/AM/FM radio. Gotta have some tunes.
- Outward-facing strobes on the bars... For visibility ?
- A giant light bar in the front... Again for visibility.
The steel
The parts showed up and I couldn't procrastinate any longer. I needed to deal with all of the linkages and hydraulic mess. So heres what I was working with:
The mounting piece thing had been beat pretty good and likely needed to be either replaced (yeah not gonna do that) or rebuilt.
The bottom of the stick to bucket bushing hole was completely wrecked. Given the extent of damage, getting this re-machined just by iteslf is into the thousands of dollars (heavy equipement work aint cheap it seems).
Seems like it had run so much without a bushing that even the stick itself was deformed...
A (line) boring story
Fitting the new pins in and fixing the hydraulics was easy as it was really just heavy metal legos.. Though pressing in and removing bushings with hydraulic rams will never cease to terrify me and the holes in my shops drywall can justify that terror. Really what i needed to figure out was the end of stick hole. With a new bushing, I can see just how out of whack it is:
So I need to add some metal in. The industry-approved way to do this is to build up a layer of weld, then use a special tool called a line bore to bore out that hole and remove that buildup until what you're left with is the original diameter. This needs to be both portable (able to be attached to something like this excavator stick) and precise, as even a degree off in the angle of the bore and the pins wont line up. So I came up with a plan that made use of what I had lying around and my deep deep dislike of spending money on specialized services.
While the outsides of the bore were pretty well borked, the 3-4" in the center of the bore were still nice, round and axially sound. So with a defunct drill press I had banished under a shelf, I set out to make my own boring bar setup. With that setup, I would bore the diameter the outside of the hole was wallowed out to back into the hole maybe 2" or so on each side. I would then machine a bushing whos OD was that diameter and who's ID was the outer diameter of the bushing. I could then press both of these in and in theory be set, at least for the life I was going to give this machine.
The most difficult part of things like this is the setup -- the whole measure twice, cut one thing... With anything metal, especially machining, fixturing is key, and flexibility is the absolute enemy. I'm already using an incredibly underpowered drill press, so to get as much of its power into the bit as possible, the whole assembly mounted on the stick needs to be rigid. In additon, I need a way to locate my boring bar perfectly along the center axis of that hole. Tackling that first, I put the 3d printer to work making a piece whos OD was the ID of the unaffected center bore and with an ID of my boring bar. I could then use this to snugly fit my boring bar in the middle of the stick and build my line bore setup around that.
From there, I could machine some holes in the boring bar to put machining inserts into, and attach that to my disgraced drill press
With some all-thread, I then could make 4 support lines that on the other side secured the boring bar into a bearing. I could use the nuts to fine tune the alignment, using a long micrometer to at least confirm consistent spacing from the upper pin ( to ensure it was at least parallel as that's what it connects to)
We can then start very very lightly making chips. As I hunted down flex/vibration, I would simply apply weld. After one side was done, I would move the cutters to the other side of the boring bar and feed the drill press the other way to cut the other side. The first cuts werent pretty, but as I honed in how to run this ugly machine I made, I was able to get a passable surface finish!
With the holes bored out, and generally unknown if my fixturing actually produced a good, parallel bore, I measured out the diameter for each side (they were different IDs), and made some bushings on the lathe. I set out to do about a 3 thousands press fit, which i dont think im talented enough to actually hit, but I think i got close!
After getting a good soak in some dry ice, I rushed to press them in. Interference fits are scary things as you know damn well that once it gets a little bit in, that you're committed. As the part starts to warm up (and especially given my rough machining marks), that it isnt going anywhere. So youve just gotta push it harder. Thankfully it all went okay, albeit snapping another 3/4" allthread rod and sending the end into my wall again... But it was as I was trying to get an extra hundredth of an inch to give the grease seal some room to clear the edge. All things considered though, with the line bore removed and some paint slathered on and the seals in - it looks okay! At least better than it was.
Making quick work of the other metallurgical issues on the stick end, everything surprisingly went back together and with some shims was factory tight!
The rest of it
After that, and getting the rest of the pins/bushings done, I could really get going on making her look pretty again! First was 'taking' all of the dents out of the valve house cover... There was a lot there, and it wasnt a perfect filler job but it'll do.
Got a little improvised paint booth set up and laid down some farm paint and a good clear coat over it
For how cold it was when I was laying down the paint and how little prep I did, I was very happy with the outcome!
After some decals and additional TLC, it was ready to take the trip to its forever home! Oh I forgot to mention - I also added an external plug that on the inside is connected to a battery tender. This in combination with adding a battery cutoff switch inside the door gives me the ability to easily keep the battery in good shape for easy winter starts.
