homemade air compressor (work in progress, nearly finished)

[spudshot]

i've been stuck with an old air compressor (about 30-50 years old i'd guess) for a while now, and since its so old i dont push it past 70psi, i dont have the money to buy an entire new compressor of a good size, so i decided to attempt to build my own after seeing how my grandfather made his (only goes to 55psi on 1/4hp motor)
first i needed a 2 stroke motor, i figured i'd garbage pick myself a weedwhacker motor somewhere, but when i was looking in my garage i found a very large 2 stroke motor from an old lawn mower. i striped the motor down to the cylinder pretty much, i left the reed valves on though.
next i took the sparkplug out and busted the ceramic out of it, once that was done i tapped the inside of the sparkplug with 1/8" NPT threads.
i found a pulley that fit the 7/8" shaft of the motor and a belt that fit it nicely. now all i needed was an electric motor to power it.
i found a nice 1hp 3450 RPM motor at a farmer's market for 5 bucks, great deal. once it was all cleaned up it was tested and found to work reliably and quietly.
i have a piece of 2x8 i'm going to use for the platform for all of this, and the belt on the pulleys will be tightened by having a hinge on one end of the motor base and having 2 large bolts through the other end, the bolts are through the 2x8, and when tightened pull the motor down, putting tension on the belt.
this project is pretty much finished, i just need to buy a few pipe fittings and a check valve (so the air pressure isnt against the piston)
the primary tank i'm going to be using is a 15 gallon air tank i got at the same farmer's market a few weeks earlier for 5 bucks.
i'm not sure if i want to install a pressure trip switch to turn off the compressor automatically, or if i just want to watch the gauge and turn it off manually, i guess it depends on how cheap i'm feeling that day
once the whole thing is done i'll make a whole how-to for it for people who want to make one themselves, this project will only run me about 30-40 bucks at most, it all depends on how good you are at finding stuff cheap or getting it for free
i've got a few pictures of parts of the setup, i'm by no means finished now, i need alot more pictures to make the tutorial clear i think
http://aircompressorhowto.mypicgallery.com/

the motor might need to be taken for use on a metal lathe i just got, so the tutorial might take a while


EDIT: i've added some new pics, just of the fittings i'll be using to get to the tank, all i need now is a check valve, which i hope to pick up sometime this week

[aturner]

very nice project spudshot. I can't wait to hear more about this as you finishe the project. I will also look forward to the how-to, b/c I would like to give this a try!

[spudshot]

thanks aturner, i hope this one works better than my grandpa's and i can push about 100-125psi i'm trying to get a hold of the last piece, a check valve, but the only place around here wants 15 bucks for it, so it might be a little while

[CS]

I would like to echo what aturner said because im interested in how to do this. 100-125 psi thats extremly good i think for a home made compressor.

[iamthewalrus]

im intruged by this, about how much have u spent on it so far?

[CS]

Why do you have an electric motor hooked to a gas engine? If thats not a gas engine whats the spark plug for? It will proably make sense once some one explains this to me.

[spudshot]

it WAS a gas 2 stroke engine, but i stripped it down, note the pullstart and such are missing.
now that becomes your compressor, when the electric motor turns the pulley attatched to the formerly 2 stroke the piston moves up and down,
normally the pressure built up would be combusted, then exhausted thru the exhaust port, one of the next steps is to close off the exhaust port using sheet rubber and a piece of steel or aluminum. that way pressure builds up there, but instead of the pressure staying there, the sparkplug has had all of the ceramic removed, so theres nothing but metal inside, i tapped it with 1/8" NPT threads. that will be the air output. i have a 1/8" nipple coming out of the modified sparkplug, then going to a 1/4"-1/8" reducer, then to a 1/4" elbow, then the elbow will go to a check valve, but i havent gotten one yet, then from the check valve i'm using a union to adapt different fittings as the output, you can use hose, direct piping, whatever, but i made mine so i can use it on different tanks, it will be mounted on my workbench with some sheet rubber under it so it doesnt vibrate

[CS]

Ok that makes alot more sense I would never think of something like that. One more thing does it take along time to compress the air that way?

[spudshot]

dunno, i'll have to see when its done even if it takes a little while, who cares, its cheap, but it should pump fast with a 1hp 3450 rpm motor on it

[spudshot]

update, i tested it today, no check valve, and the pulley wasnt secured that well, but it pumps air

[iamthewalrus]

how fast does it pump and how well, was it worth it

[spudshot]

it pumped up right away, then the belt started slipping because i dont have the right pulley for it

[joemama]

dude y would u go throo all that work there is one simp solution go to a dump find a frige get the freon comperser (big ball thing) hich 2 wires 2 a box that is on it and put a tube were the presher gose9 metal tube) out the wired leads to a plug it gose to i would say 50 psi is is so much eser ps i did not do thin my friend did but i saw it and used it

get one that dose not have freon in it


i have not tested this and am not liabe for any crap u do with this

[saladtossser]

i was thinking of using propane tanks and a small emergancy compressor.
i need freon...

[taterjim]

I should consider myself lucky or fortunate. I have two compressors a 5 hp and a 3 hp . they will deliver up to 145 psi . which I use regularly. even though 100 is the safe limit.