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Need a better oil free air compressors

johansen

Titanium
Joined
Aug 16, 2014
Location
silverdale wa
Friend of mine goes through about 1 schultz air compressor per year.

1hp 1750 rpm 2 cylinders, single stage, turns on at 70 psi off at 105, runs as much as 50% of the time.
"Msv 6" is the number to google.

Problems are the pistons fatigue, the metal springs (flat metal bent a little to expand the ring seals) behind the plastic compression rings wear the cylinder ring grooves into T slots to the point that they are cut off completely in 1 year. This is due simply the inertia of the thin steel ring.

The piston also fatigues to the point the 12mm pressed hardened steel wrist pin will wallow out the piston to 14mm, sometimes.. sometimes not. Once there is about 2mm lost motion the piston wont pump enough air and it will run 24/7 and then overheat which increases the failure modes quickly

In the most recent failure, one piston lost its needle rollers and the seals were nowhere to be found, the connecting rods walked off the bearings to the point they rubbed on each other, the ring grooves were t slots cut 2/3 rds of the way through, the compression rings were at half life, and perhaps most impressively, the circlip that holds the wrist pin in, was loose, because it probably never had much tension to begin with and it vibrated a deeper groove in the aluminum piston. -it could also be the thermal expansion difference between the steel circlip and the aluminum means they fret, as the piston heats up ad cools off maybe 6 times an hour for a whole year.

The 12mm/16mm needle bearings sometimes fatigue to the point the rollers fall out, probably due to grease being lost.

Sometimes the connecting rods fatigue around the needle bearing, and they also sometimes walk off the 6203 connecting rod bearing.

Even if we took these things apart and re greased the wrist pin needle bearing and replaced the seals every 6 months we would only get 25% more life out of it due to all the other failures

Oil free is non negotiable. Any trace of hydrocarbons is unacceptable.


Thoughts? A 2hp 2 stage compressor and a bigger tank is probably a good idea but i want something that does not need new pistons every 4000 hours.

We are going to try making pistons out of 6061 instead of whatever mystery cast aluminum schultz uses. The stroke is just one inch so the acceleration is so low we could make steel or cast iron pistons. The skirt of the piston has a 3/4” wide strip of plastic all around it, it does not wear out because the side forces are very low as the con rod is 4" long. The metal piston thus never touches the cast iron cylinder.
 
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Skip the pistons and get a scroll compressor. Quite a few companies make them down in the 2-3hp range. I don't have personal experience with anything other than a 5hp Gardner Denver scroll but it was flawless for years.
 
It is said Einstein's definition insanity is repeatedly doing the same thing expecting different results. Why after one failure would he buy the same machine.

We're waiting...
 
4000 hours on oil free is not bad. The cost of yours is. California air compressors are quiet and 1/4 of the cost. They are rated for 3000 hours +.
Spend less and get a 2hp. Less running hours.
 
It is said Einstein's definition insanity is repeatedly doing the same thing expecting different results. Why after one failure would he buy the same machine.

We're waiting...
Haha yup. Story time,
To be fair I didn't have room in my garage for a metal bandsaw.
I needed to cut up 12' bars of 6061 for production order's constantly.
So I needed a small fast solution.

small manual band saw with coolant.
one of the metal cutting miter saws
non-ferrous cold saw.

Bought a non-ferrous cold saw returned it after 1 cut.

So RPM speed, I bought the Makita metal cutting saw.
but for Aluminum it was still slow, faster than a automatic bandsaw though.

I ended up buying a $250 Metabo wood miter saw, and adding coolant to it :nutter:

It cut so fast!!!, but eventually the coolant mist ruined the motor, bought another one put a filter on the motor.
this time it lasted way longer, over a year, then went out bought another one.

As you can see for $250 a year, that was extremely cost effective.

Sure now I have a $60,000 automatic horizontal bandsaw.
but the three $250 saw's scenario made me a shit ton of money fast.
 
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I have been running 2x california air 1hp 8 gal compressors for a few years to do small scale glass bead blasting. They are still alive, but are rated for like 5000hrs. Point being; oilless works well if you do not need a bunch of power and you are ok with 5,000hr life. My compressors were only like $250 each... California air 8010 on Amazon now is $210.
 
50% duty cycle seems awfully high. Are there air leaks in the system? Dentists use 3hp & 5hp Powerex rotary scroll. I have a 3hp, that has lasted 10+ years.
 
Powerex oilless is in a whole different universe than the stuff you get at the box store or Harbor Freight. I've got a 47 CFM 3 cylinder Powerex, it's good kit.
 








 
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