Author Topic: Mini Air Compressor ( ST1100\ST1300 ) *  (Read 4983 times)

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Mini Air Compressor ( ST1100\ST1300 ) *
« on: May 20, 2009, 08:06:46 AM »
Original thread can be viewed here:

written by Mike Martin.

Mini Air Compressor

I finally got around to buying one of the $10 Campbell Hausfeld compressors that Wal-Mart sells. A popular item among motorcyclists, it is a bit bulky to take along. There are web sites explaining how to discard the housing and delete the switch to reduce its size. Two such sites are Motorcycle Tires & Wheels by Mark Lawrence and webBikeWorld©. (Most excellent sites, full of info.)

Some sort of bag or plastic container is normally used to store the stripped compressor on the bike. I got to looking at the newly discarded plastic Campbell Hausfeld housing and noticed that the compressor itself might fit inside the storage compartment at one end. Several hours later, the project was completed. These pictures show the process. Click on them to enlarge and read my description.

The advantage to having this compressor mounted in a case is that you aren't as likely to have a finger pinched while using it. Also, you don't have to hold the pump while it's in use. The disadvantage is that it is slightly more bulky than the bare pump.

One other approach: I know two people who have mounted the compressor under the bodywork of their bikes.

This shows the compressor after it has been removed from the case, which measures 6 x 3.75 x 9 inches. The wiring and hose have also been removed. The fan was cut off the shaft with diagonal cutters, and the shaft was cut with my Dremel tool. (Sorry about the poor focus.)

(Are your eyes starting to bother you? The rest of the photos are in focus. I promise!) The case halves spread open. This is what prompted the notion that the storage area might be large enough to hold the compressor. It's hard to see the bulkhead separating the storage area, but it's about 2.25 inches from the left end of the 9-inch-long case

Using a 1.5-inch hole saw on the case. To avoid heating the plastic while sawing, I pulsed the drill so that the saw only turned about one revolution for each pulse. This enabled a clean cut.

Trial fit of the compressor in the storage compartment. I made large holes to allow cooling of the compressor. I don't know whether the holes are enough to do the job, though.

The switch has been mounted using a steel bracket I fabricated. The short orange lead was replaced with a slightly longer length of red wire to reach the switch. The storage compartment has been cut from the original case. The small black part is one of the rubber mounts which has been cut down to fit the available space. It was necessary to use the mount to prevent the black plastic gear from rubbing inside the case. A small worm drive hose clamp is used to secure the shortened hose to the compressor.

The shortened air hose passes through a hole in the upper case. A notch was added for the power lead.

The new assembly. A hole was added for storing the cigar lighter adapter, keeping wasted space to a minimum.

Ta-Daaaaa! The finished assembly of my first version with the wire coiled around it. After sleeping on it, I decided to see whether I could store the wire inside the case. So the next day I worked up a way to do just that. The following photos were taken while I revised the design.

As you can see, the new assembly is about 1/4 the size of the original.

The trimmed rubber block. I used a slowly running saber saw to cut off part of it, and that cut is against the floor tile in this picture. I used a sharp knife to cut off another piece, and that cut is at the lower end in this shot. The knife cut was much easier to make, and I would try it for both cuts if I had do make this part again.

Close-up view. You can see the rubber mount peeking out. It keeps the black gear from contacting the case walls. The bracket for the switch is held in place with one #6 screw and nut. A clearance hole keeps the switch bracket from interfering with the head of a motor-to-compressor mounting screw. The yellow wire tie passes through the knot in the power cord, providing a strain relief for the latest version of my design.

Another view showing the modified rubber mount. You can see the connecting rod inside the compressor. I inadvertently connected the motor leads wrong, but the unit still operates properly. The compressor just has a check valve on the top of the cylinder head for inlet air, so the unit doesn't care about direction of rotation.

You can see where I scribed a line for reference when I used my Dremel with a 1/2" sanding drum to make room for the motor.

View showing mods to the end of the case. The 1/2" hole for the hose is as close to the corner as possible, so the hose clears the motor. The larger hole is for the cigar lighter plug. It must be located so the plug will clear the motor, too. The small notch was added for the first design, for the power lead.

Final design is ready to go! Where is the wire? See the next picture. Dimensions of the new case are 6 x 3.75 x 2.38 inches, not counting the hose. The hose sticks out about 0.75 in.

I had my doubts whether I could keep the original length of wire, which was 11 feet long. It wasn't possible to get the cover on until I fed several feet of wire into the space at the end of the compressor. Then I coiled the remainder as you can see. This is a really tight fit! A notch in the case and the cover allows the end of the wire outside. After using the compressor a couple of times, I found it too difficult to pack the wire away, so I shortened it by three and a half feet.

© 2003 M. E. Martin, All rights reserved
« Last Edit: December 12, 2012, 04:22:49 PM by Tom Melnik »