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Re-Birth of an EPCO 60 Ton Garage Press

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awemawson:
Several years ago, I was looking for a 'parts washer', won one on eBay, and speaking to the seller to arrange delivery by pallet, he asked if I was looking for anything else. Well I was - I wanted an 'H Frame' garage press, preferably hydraulic. He almost burst into tears and told me the tale of his press. It was his pride and joy and in superb condition, until he had a fire in his workshop. As he had oxy-acetylene cylinders in there the Fire Brigade wouldn't let him enter to save anything, but just let the lot burn, dowsing down as it did.

Eventually the wreckage was pulled out into his yard, and the remains of the press sat there in the rain gently rusting away  :(

Well says I - is the framework still sound - perhaps I can use it as the basis of making my own press. Long story short, I bought it for scrap, he jammed the parts washer into the framework of the press and it all got delivered to my place. It must have been a very intense fire. The aluminium motor frames for the hydraulic pump and platten raise / lower motor had melted and dribbled away  :bugeye:

awemawson:
Now the frame didn't look too bad - one of the channel sections was slightly warped, but after all it would be in tension in use.

The platen that you press against is suspended from four enormous acme threaded rods that are chain linked at the top, and run in bronze nuts in the platen itself. Fortunately when the fire happened, the platen was pretty well fully down, and I was able to raise it with my forklift, exposing the bronze nuts, which were absolutely and completely rusted solid. Huge chunks of bronze about 3" square and 6" long so I didn't fancy making new ones  :(

A bit of research on rust removal methods introduced me to Citric Acid. Rust is bigger than the steel it is formed by, by 7 times the volume, so a little bit of rust will jam threads nicely. Anything you use to de-rust needs to be able to penetrate between the two parts and form a compound that is soluble in water so that gradually things migrate out of the gap. Citric Acid forms Iron Citrate from rust, and this is water soluble. Phosphoric Acid for example, which is a common rust remover, forms Iron Phosphate which is not water soluble and still jams your parts!

Plastic buckets with warm citric acid solution were put under each threaded rod and raised to immerse the bronze nuts. It took several weeks of re-warming and replenishment before eventually I could undo all four nuts.

Then the threaded rods were removed, and put in a capped length of 110mm soil pipe again filled with citric acid. Several days later I had threaded rods and nuts that were perfectly usable  :ddb:

While this was going on, I removed the original hydraulic cylinder with a view to seeing if it could be saved. A might heavy lump of metal  :bugeye:

A few pictures were taken :

awemawson:
That cylinder took several days to dismantle. You can imagine - the hydraulic oil had all boiled off making goo, and the seals had melted into the end cap threads, so it took forever to just unscrew the end cap using heat, cold and much violence - look at the lugs on the end cap and see how they've been abused. It was not a pretty operation  :bugeye:

However, off it came. I eventually found a place in Scotland who claimed to have the right seal set to re-build it, and after the exchange of quite a bit of hard earned cash they arrived. This I think was the first hydraulic cylinder that I'd ever dismantled - nothing like choosing a problem child.

Piston end wasn't too bad, but I made an expensive mistake with one of the seals in the end cap - remember - lip towards the pressure - well I forgot, put it in the wrong way round, screwed it up taking it out, spent more hard earned dosh on another one  :bang:

Amazingly the chromed rod wasn't too bad, and after honing the cylinder bore came up quite satisfactorily.

awemawson:
The original hydraulic pump was toast - just a block of rust filled with aluminium that had dribbled into the chamber when the motor melted. So the hunt was on, but this press needed a very high pressure. 5" cylinder bore 60 tons = about 7,000 psi

Eventually eBay turned up an Enerpac 240 volt three phase unit complete with a solenoid valve set suitable for a double acting cylinder  :thumbup:

So now to look at the platen lifting arrangement.Those long acme threaded rods sit on thrust bearings cleverly arranged with huge springs such that when the press is unloaded they balance the weight of the platen and they rotate on the thrust bearings. However when the load comes on the press the springs compress and the load is taken by shoulders on the rods that rest on the framework. Nice bit of design.

Initially I couldn't work out why my nice new motor, chain drive and cogs hadn't got the guts to rotate things, until I realised that the intense heat of the fire had softened the springs and the bearings were not being used. Careful measurement of the wrecked springs gave me dimensions but not a 'spring rate'. They need to support the platen 'plus a bit' so I weighed the platen (about 100kgs iirc) and had springs custom wound to 1/4 of that when compressed from 1/4" spring steel rod - seems to work  :ddb:

Then it was a case of a bit of grit blasting and spray painting:

awemawson:
So putting it all together, and doing a bit of wiring and plumbing, it turned out like this:

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