D100 backhoe

Vigo said:

Exciting!

I did a fairly exhaustive rebuild of a small Kubota B670 backhoe over the course of the past year and i think what you start with in terms of the model of backhoe is not as important as its general size (being appropriate), and whether the 'hardest to rebuild' sections are basically intact. Because during your process and with the skills you already have you will find the need or at least strong urge to change damn near everything anyway, so in some ways the starting point is less important to the goal, than actually getting started is! Just buy something and start cutting! Hope that made any sense..

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Thanks, Vigo!

As it turns out, I did get started today, I've invested $550 in steel. That's more than twice what I spent on steel for the loader. But in all fairness, I did find an insane deal on steel for the loader.

But I now have plenty 1x4 steel bar (for the subframe), some 4" wide C channel (for the outriggers) some 6" wide C channel (for outrigger feet) and a bit of 1/2" plate for various gussets and reinforcing.

Let the games begin!

Step one is figuring out how to machine the OD of the outer ends of the axle tubes. Clamping to it cleanly and smoothly is key to successfully adding the reinforcing crossmember.

I'll begin a write-up once I have it figured out.

Bob

Vigo said:

Nice!!


Shark-jumping ahead..

Depending on the radial runout in the existing axles/bushings, and lateral runout of your hub flange.. Could you not just build a tool fixture onto your existing wheel hub and have the thing 'turn itself'? Or at least be located by and spin within the bushing after the axle is removed? Might be easier than making the whole housing spin or fitting it upright underneath some rotating-toolhead thing. I am no machinist so im not very familiar with tooling for 'spinning around the outside of a stationary round piece' but that's the first place my brain goes. Think of a less-crappy version of a brake drum thats been modified with an adjustable bit holder stuck through the side of it to cut the axle tube od. I assume the surface doesnt have to end up THAT nice, as long as it's concentric to the axle and of correct OD.

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That's precisely the lines along which I'm thinking. The trick will be getting it to turn a cylinder, not a cone. And I've been pondering it for a a couple days, and here's what I've settled on:

I don't think I'll be able, without spending hours and hours, but make something that will be adjustable to cleanly turn a true cylinder. It's going to want to turn a cone, because if the sliding head that's mounted to the wheel hub is at all out of square, either in the "in/out" sense, or in the "forward/backward" sense, then it will turn a cone as you move the cutting head across the width of the axle OD.

To deal with that reality, I think I'll just have to make up for it with slow, methodical, step by step machining. I'll have to turn these journals one "groove" at a time. I'll mount up a flat/square 1/8" cutting tool, like a parting tool, and working from the innermost side, turn one clean "groove" at a time. The only thing it requires is that my ability to dial in a cut is accurate, which is to say, the abilty to turn a groove, measure it, and accurately dial in "x" additional inches deeper from that point.

So I'm thinking that I'll find a way to mount a small-ish boring head (from my small mill) as the tool holder. It won't be spinning, it'll just be the stationary tool holder, with a cutting bit sticking down to make contact with the OD. That way I can use the boring head's accurate inward/outward mechnism to dial my cutting bit deeper/shallower.

So I just have to fabricate a flange that can bolt to the wheel hub and mount to a boring head in a way that allows the boring head to slide inward and outward about 2.25" across the face I'll be machining.

Bob

Merchlewitz said:

Bob I was meaning some close ups or even a video of it on a machine.

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Sorry best shot I could find, 646 just has smaller - narrower front tires.. Unless you customize it..
Found a shot of subframe and weight.



Sub frame on tractor

I've made a bit of progress, not a lot:

I've created a jig that bolts to the wheel flange, and as the axle turns, it machines the OD of the boss at the outer end of the axle tube. I'll be hanging a whole new crossmember from those axle tube bosses in order to reinforce/strengthen this non-lbh rear end, so that my 1000 lb backhoe doesn't snap off one of my axle tubes.

But before I can bolt to the axle tubes, I need them to be round and smooth.

So the jig has been created, and I have one side, the easy side, completed. (The driver's side is trickier because you have to work near and around the drive motor. The passenger side is wide open and accessible, so that's the easy side.)

I'll do the other side this week or next, and then machine and fabricate the new crossmember.

Bob