Grex AOS368 Pneumatic Sander

[Tom Hoffman]

Just bought a Grex AOS368 pneumatic sander at the Sacramento Woodworking Show. Not really happy. Even the slightest pressure causes the thing to stall and stop spinning. Don't know if I got a lemon, or if I'm doing something wrong. I've checked other posts regarding this sander and most everyone seems to be very happy. Anyone else having this problem? I have more than enough air capacity

[Harlan Coverdale]

Sounds like something is restricting the airflow, or you got a lemon. I run my Grex around 80 psi, but even at 40 or 50 PSI, I doubt I could stall it.

[Rick Lizek]

What about your compressor.? How many HP and cfm at 90 lbs?? These things use a lot of air.

[Harlan Coverdale]

What about your compressor.? How many HP and cfm at 90 lbs?? These things use a lot of air.

Just to pick nits a little, the horsepower really plays no part in the equation. You could have a 10 HP motor hooked up to a 2 CFM pump, and it won't be enough to run the Grex. ;) The Grex wants about 8 CFM at 90 PSI, but the more air your compressor can put out the better, just to keep from tiring out the compressor too badly.

[Tom Hoffman]

Rick: Don't have the specs right at hand, but I have a large 80 gallon Campbell Hausfeld compressor, so I doubt it is getting starved for air.

Others out there: If you have the Grex AOS368, I would appreciate someone doing a test on their's to see how much downward pressure it takes to stop the disc from spinning. Mine stalls out with just slight downward pressure especially when applied at an angle to the surface (not flat to the surface).

I'm making Christmas presents like this: http://www.eagleamerica.com/product/401-8338/gift_making_ideas which have compound inside curves made with a dish bowl router bit that need sanding.

I bought the Grex with the thick spongey pads thinking I could get into the curved sidewalls

[Rick Lizek]

Had to ask about the compressor.
sounds like a defective air motor. Is there a valve to adjust the speed. Many sanders have that feature. I'd call Grex or swap it for another unit, It should not stall out that easy.

[Ken Fitzgerald]

Tom,

It doesn't matter if you had a 400 gallon tank...it's the cubic feet per minute of air and the pressure that you are getting to the sander that matters.

Your hose being too small could restrict air flow and it would happen. Typically the only time my Grex stalls is when the air pressure gets too low. Then I have to wait for the pump to catch up.

[Stephen Cherry]

The easy answer is to get a small air pressure gauge at the inlet of the tool and make sure it is up to around 90 psi, while running.

Air sanders are real consumers of air- they require a big pump, motor, and heafty air lines.

[Chris Parks]

Also make sure the airline is at least 3/8". Any smaller will affect the power available but it should still run and not stall immediately as your is doing.

[Callan Campbell]

If you hold the Grex Sander and look at the top side of it, you'll see a flat blade screw sitting in the middle of the valve retainer assembly nut.
This screw is adjustable, it SHOULD be in the "in-line"/lengthwise position with the body of the tool. Once you have it off that angle, it starts to limit air to the motor inside, so you stall easier. The screw/valve is designed to act as a mechanical air regulator if you don't have a regulator handy on your air line.
Happens all the time with air tool assembly, someone doesn't line up the valve in the right place and the air tool runs "weird". Check it, and turn it while running the tool to see how much difference it makes. If the screw IS in the "straight" ahead position, then contact Grex to see what they want to do. I've dealt with them and got great response to a simple question I had about the same sander. Worst case if your set-up and hose are OK, it's just a tool under warranty that they'll take care of.
As far as I know, Grex works hard to make great tools and keep a good reputation with both woodworkers and the construction people.

[Tom Hoffman]

Thanks to all who took the time to comment. Much appreciated. My compressor is rated at 10.2 CFM @ 90 psi and the in-line adjustment is correct. I played with it some more today and got discouraged. I think I'll send it back to Grex and have 'em check it out.

[Chris Haas]

send it back, then buy the harbor freight one for 24 bucks i have one and love it.