Something a bit different- excavator arm

I thought members may be interested in my completed excavator arm, something I have wanted to build since being a small boy.

I have scaled it from a die cast Kubota model I have and it was never my intention to make a replica model, just somethig that looked OK and I could play with. At the moment I am running it at a 100 psi at which it seems to have more than enough force. During some early experiments I used up to 150 psi and apart from a few tubes blowing off it held together.

My main concern was that the 4mm tubes used would be so restrictive as to make the speed of operation too slow but it is OK and 'to scale'.

Going to get some cat litter so I can have a play.

BEAUTIFUL, it will give hours of fun, Lego did a 360 tracked digger some years ago that worked by pneumatics. Small hand powered hydraulic systems often work at 10,000psi. Noel.

A fascinating and very unusual project!

There may be a lot in modern engineering that could inspire model-engineering versions, but perhaps the older machinery's attraction is the "works" working visibly, not hidden away.

The only other example I can think of in this genre, and I forget the constructor's name unfortunately, is a sizeable model of one of the huge walking-draglines formerly used in the Northamptonshire iron-ore quarries. Its builder operated it from a full-scale replica of the prototype's driving-seat and controls, and a video-camera in the model cab gave us a scale driver's-eye view as it gracefully moved heaps of cat litter about. That display also answered for me how those excavators actually "walked" - slow hops with both feet down.

Back in the 1960s, something rather thinly called "fluidics" was all the rage for some years, but probably replaced in most applications by electronics. It took the hydraulics as used in earth-moving machines a stage further into the realms of logic-circuitry for controlling the power hydraulic or pneumatic systems. I don't know if any model-engineers have experimented with fludics, which usually use compressed-air.

Very nice indeed, have you thought of going the whole hog and making the rest with working tracks and dozer blade which many had fitted

The chap who did the walking one did a tracked one before, he used to be at Harogate most years.

Steve

Excellent! I wonder if it would fit on the back of Four Stroke Fred's tractor

Very nice. My grandkids would love to get their hands on that.

Steve.

Excellent workmanship. Be proud!