The Shop > Tools
Compressor quandry
John Rudd:
Pete,
For me it is becoming a money magnet, but on the whole it could be worth it.....it should easily run my shot blasting kit ( pot and cabinet ) where as my other compressor is a shade too small...
The remaining parts of the compressor are in good nick, the other piston assy is ok, as is the crankshaft/bearings and seals.....there isnt too much left.....
BTW, a replacement pump from MachineMart is £180..... Ouch!
I think once this is fettled it will be a good compressor worth £300, they are over £550 new.....
AdeV:
--- Quote from: John Rudd on July 16, 2016, 10:29:44 AM ---So what about the gudgeon pin? Would EN8 be any good?
--- End quote ---
I imagine it would want a heat treatment and grind to final size after machining, but there's no reason a replacement gudgeon pin wouldn't work; except, aren't you going to have to machine it over-size to take the wear out of the small end? In which case you're going to end up having to very carefully ream the piston to take the larger gudgeon pin... which sounds like more work than the bush...
John Rudd:
I can bush the con rod little end......bore out to clean it up, machine a bit of pb bar, drill out and ream to size.....
Piston could be machined from solid, just found a billet of 75mm ally bar...the bosses for the gp could be reamed to size....
The gp made from EN8 machined to fit the little end and piston bosses....
Does this sound doable?
Else I could buy a new piston and gp and just fettle the con rod....
AdeV:
Is the gudgeon pin damaged?
If not, I'd be tempted to bore the conrod, make an interference-fit phos-bronze bush, freeze the bush & warm the conrod in an oven (maybe to 150 degrees C? Perhaps some material experts could give you a safe temperature to heat it to which won't adversely affect any heat treatment it's had); install the cold bush in the hot conrod (it should just drop in, if you got your sizes right); when it's all returned to normal temperature, trim the bush and ream to the exact right size (I guess a tight sliding fit on the gudgeon pin? Or maybe it's a press-fit, depends if the little-end rotates on the pin or if the pin is designed to rotate in the piston...). Either way, the bush should be very tightly held by the conrod, and being phos-bronze it will be fine to let the pin rotate in it.
If the pin is damaged, but the little end can be rescued; then depending on how much meat is available on the piston pin bosses, I'd be looking to turn a slightly over-sized pin, clean up the small end, and bore out the piston pin bosses to take the larger pin.
Only if the whole lot is knackered, ovalled, etc, would I write off the piston & the pin.
chipenter:
EN8 is good can be machined fully hard but the incerts don't last very long , get it neer to size before hardening .
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