Gopher 5 Star Digger Restoration

[Old Operator]

I am restoring this, the slew system had failed, & an old Twose backhoe slew system was added by past owner. This moved the Kingpost 21'' forward & added much weight putting it off balance, so could hardly keep rear wheels on the ground. I have built a new slew post & built up the fixed slew table with bead pad welding. I got measurements of the post from another owner & also built 2d mock ups to prove the geometry - the boom ram when closed must not pass below the horizontal, & boom rear must be vertical when this ram fully open. Also the 'modification' had meant that only 7/13th of the ram was used to move boom through its arc. The new post is welded with E7018 root run whilst hot, then built up to leg length with E6013. I had the original slew rams & chain as spares. Seen here is the New post fitted on top of the new thrust washer. I still have to get & fit the plate wheel sprocket underneath so we will have power slew. The boom geometry has been tested under power, lift ram is 3 deg. above horizontal when closed, & boom rear stops in the vertical when ram fully open. This means the rear of boom will not touch the spool chest. Next job is to mock up this valve support & the removable seat support before welding all if sound.
To get this far was only possible because I got the back gear going on my Victorian / Edwardian large lathe. It bored a 3'' dia. hole in 2 off 20mm thick plates, did same in nylon table washer, & bored the 'bucket pin tube' holes with a cutter off ebay.
I am going with a boss & cross pin underneath - rather than the original design with two small keyways @ 90 deg apart, - this often failed on these machines. Granted this is a 'wheelbarrow machine' but do you restore old British engineering or put your faith in something 'Carter'. There is a small type Gopher on sale in Leeds (50mm rams) for £2300 good order, Powerfabs often sell on Ebay for more than they cost new! The Powerfab is still made under the name Otas in Eastern Europe. These machines are quite prized in France where towing laws are different. Info on the Lathe repair & Pic here if anyone interested

Braze steel gear onto hollow grey cast iron shaft

Hi I need to braze a replacement steel pinion onto a hollow cast iron shaft. The pinion is now ground/machined off & the new one a smooth push fit on. I am not sure if the shaft & pinion were once one casting or that the latter was heated & interference fitted (shrunk) on, as there have been...

www.mig-welding.co.uk

 

[Old Operator]

Sorry original pic did not load - this is how I bought it, weight was massive. I have also repaired the engine cowl - allowing a new clone part pull start to be fitted - covering a dangerous open wheel. This meant making a little plate getting it MIG welded in to a depression in the cowl, then using the new pull start to give the hole centre - I drilled & tapped the 'filing exercise' plate so repairing where the stud had been ripped out. I did all this while the engine ignition was removed for chassis welding, as had to disturb it anyway. Note that under the 'modification' the man no longer slewed opposite to the arm but was fixed, very wide weaves on this mod made me nervous of it failing. Some info here on the model (Mine is the 5 Star - meaning power travel, there was also a 'Boss' - same bigger 60mm rams but only towable / walkable both 11Hp) Also the smaller original model of about 7Hp http://www.oilyhands.co.uk/gopher_towable_diggers.htm Machining kept me quiet in lockdown, Pete
Pic below is how it was when bought, one above shows it back to original slew post design - with part I made & view of 'arch' workshop, I do weld nearby but totally away from the machine in another 'arch' !!!!

 

[Old Operator]

Got the machine back together, is now 'dry' i.e. no leaks, fully slews 180. I re bushed the dipper head pivot using an aftermarket nylon bush made for a JCB 8014 (needed slight outer skim so as to interference fit into dipper) Made a pin for this bored & threaded to take an M6 grease nipple, as there seemed to be no provision to grease this area. Did similar thing on main slew as likewise it lacked the ability to be kept greased (so made up a 'snorkel' tube to take grease into the vertical slew pivot bush). We now need to go for a test dig up the side lane - once the road works outside the arch finish - as ques of traffic there just now. It has been a lot of work but worthwhile I hope. Note the wheel is off for security reasons- stored elsewhere. Everything coulored black I have fabricated myself, including the improved sprocket carrier arrangement underneath (as this was a weak spot on these machines.)
Hope to get some footage on youtube of it digging

 

[Mogman]

Looks a neat bit of gear and fabrication

 

[Old Operator]

Thanks for the interest all, here is a pic of one of the slew post side plates being bored out on the old lathe. I drilled 6mm pilot holes vertically - then set up the plates on the table with the tool post removed & a piece of angle added & trued. This allowed a true bore with the ebay cutter for the heavy wall bushes. Was middle of winter during lockdown. Shed unheated apart from primus stove burning CH oil