Thread: Micro Petrol Air Compressor "Project Loan Out"

Old mate with the pump in plan A said to go pick it up tomorrow despite not answering a call or txt all day and night thought he had sold it as the add was only removed today

The old pump is dooable if i go that route i just opened it up and it is a one sides crank bearing, i can remove the copper or brass mass from the shaft than cut the shaft back, machine the shaft to fit the bearing and slide the bearing housing and shaft support back if i do this i will leave a small shaft protruding out the front for the pulley

Originally Posted by shedhappens

That motor will do nicely, make sure you get your belt ratio right as compressor pumps are not built for drag racing.
Do you know what motor and pulleys were attached to that compressor pump?

Not so sure it will do as well as hoped. Motors for water pumps are generally an extended shaft with a thread for the impeller and no keyway to suit a pulley.

On mobile will edit this in a sec on laptop no way to upload pics without data cable

Ok went to pick up that small 3/4th hp pump it was a decent size pump and 3/4hp 3 phase it had 2 belt pulley and the whole pump was seized old mate pulled off a few you can do this..... to palm it off but it was nothing more than rubbish

i came home and worked on my pump i pressed it apart than put the shaft in the lathe and reduced it to what i thought was acceptable 15.08mm put it in the press and bent the shaft had to pull it out remove the bearing put it into the lathe to find the high spot and mark it than back into the press horizontally to bend it strait than back into the lathe and a final machining to 14.84mm the bearing pressed on perfect i than pressed on the other bearing and pressed it all together to find out i am hopeless at calculations lol i'm about 11mm short i will do some more machining tomorrow and make it fit properly

had to make a custom die to fit over the shaft to press the small bearing on as the bearing was so deep down the shaft i had problems making the die as my lathe tool couldn't quiet cut thru half of the die on each end but finally there i am buggered

the chinese shaft cut like an absolute mess that steel is shockingly cheap and nasty

Few more pics fellas only part i need replacing should be the bottom cylinder gasket i will likely make one since these compressors are use abuse and throw away its likely no one will carry spares

A bit of precise cutting and shes bolted together had to retread the 100mm long bolts and cut them down to roughly 35mm shes all bolted up and feels tight and smooth to rotate

i get a lot of chatter and need to reshapen the tool on the lathe when parting steel so i will just cut the shaft with a angle grinder, the original fan is going back on too but i have not worked out how yet o even how to direct the air over the cylinder and head

Been working out the best way to cut out my gasket either using the scissors or ball pin hammer gasket sheet is 2mm or 2.5mm thick so it is quiet thick and hard to cut, picked up some paint the other night gloss fire red and white gloss i thought about painting the tank red and pump either red or white but unsure if i can get into the nook and cranies with the spray gun and make it look tidy without runs plus getting a good cover also picked up a wire brush wheel for the grinder was the cheapest option, paint stripper is mighty expensive just to be washed away
Paint says to thin with turps so i need to pick up a bottle on a friday night nah i'm not a drinker lucky, paint is epoxy enamel

Took about 40mins to re-assemble

Unsure how to delete these 4 sideway pictures if admin can delete would be good thanks

It keeps rotating my pictures bugger

The little petrol engine arrived at the crack of dawn had to be close to 7am started pulling it apart this afternoon took off the water pump, the impeller and housing i left the little brace on the engine crankcase as the bolts were very tight so likely loctited, i sanded down the tank i tried to strip all the paint off with a flap disc but man that was a mission so mostly sanded the paint and just took off the flaky rust and sanded around the rusty areas still a few spots to sand and use a wire brush than i need to tape her up and get ready to lay down some paint (big air compressor still hasn't arrived)

just now i put a small length of scrap aluminium along the top of tank just to get a feel for how it will look all together than sat the pump and engine on top looks pretty cool i reckon i think i may need to block off the original outlet port because its right under the engine and use the inspection port as a outlet, not to sure how to mount the pressure piston idle/throttle mechanism i may have to make a plate coming off the air filter bolts the throttle is quiet stiff to move so it may be a problem

i will likely run the rank at max 115psi and throttle up at 90psi it was pressured to 120psi when i bought it asa running electric air compressor

need to fab a plate for the pump and engine to sit on i was thinking of using my left over half a sheet 4mm alloy but not sure if the sides will bend in my sheet metal bender may have to weld it

Make sure you get the direction of rotation correct for the compressor or it may not oil correctly. I would also strongly suggest that a taper lock pulley is your only option on the motor given there is no keyway in the shaft.

Hey Kryn i was thinking of making both pulleys my self and using a lock screw and loctite on the shaft its only a littme pump and engine so i am thinking the loctite may hold

In a bit of a sticky situation here something i didn't realize idle down piston mechanizems throttle back at pre set 145psi my pump is only rated for 120psi cut off so the idle down piston would have to kick in at 120psi i cannot find one that low i can only find unloader valves which vary in psi some unload at 90 to 125, 100 to 130 right thru to 140 to 175psi

anyone know of any options?

Originally Posted by gazza2009au

In a bit of a sticky situation here something i didn't realize idle down piston mechanizems throttle back at pre set 145psi my pump is only rated for 120psi cut off so the idle down piston would have to kick in at 120psi i cannot find one that low i can only find unloader valves which vary in psi some unload at 90 to 125, 100 to 130 right thru to 140 to 175psi

anyone know of any options?

As far as I was aware you could adjust the cut in/out pressure to what you require.