How do I increase pressure in old craftsman air compressor?


Old 08-22-02, 10:19 PM
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How do I increase pressure in old craftsman air compressor?

I have found an old craftsman air compressor that appears in pretty good shape. It's old, circa 1965, but externally looks good. I'm not sure about the model number or electrical engine size, the tank capacity is 8 gallons.

My problem is that the pressure is to low for me to hook up a framing nailer to it. It kicks in at 80 PSI and turns off at 100 PSI.

How dangerous is it to tinker with these things? I would like to increase the pressure to not be less than 100 or more than 120 PSI. There didn't appear to be an adjustment knob on this assembly.

I don't want to create a torpedo, but this old heavy boy looks like it should hold a lot more pressure.

Any thoughts?
Old 08-23-02, 07:37 PM
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Exclamation Not a good idea to adjust pressure.

Old and heavy doesn't always mean stronger.
What you can't see is the corrosion that has been taking place within the tank.
Air compressors generate a ton of water that ends up in the pressure tank. If the maintenance on the air compressor has been good and the tank drained regularly, the amount of corrosion will be minimal.
If not properly drained the corrosion in the tank could be near the point of penetration. This usually occurs at the very bottom of the tank.
Also. A pressure of 80 psi, although a little on the low side for a nailer should still drive a nail into most woods. It is possible that you don't have a large enough supply hose from the compressor to the nailer or the compressor capacity isn't large enough for your tool.
A way to tell is to have a guage at the gun and monitor the pressure as you use the gun. You should be able to nail away and have the compressor at least maintain your cut-in pressure of 80 psi. If it doesn't your compressor is too small.

If you need more info you can post back the details on this unit.
If you are interested I could give you some idea on how to inspect the inside of the tank.

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