Performance Testing Air Compressors

I want to add a small compressor to my truck to keep the rear level. It has air shocks but no automatic control.

If I can find a decent priced string pot I can make it fully automatic. for now I need to select a compressor.

I have a few factory ones and a bunch of aftermarket tire pumps. You cant believe the hyped up ratings so I made a simple arduino test rig to sample the pressure every 100 milliseconds and decided to test every one I can get my hands on….

heres the test setup using a battery, pressure sensor, safety cutoff switch and a few other parts…..

and heres the lot of compressors I grabbed from the junk bin and all the cars outside.

There’s this monster from a Caddy Deville.  It even has the solenoid to drop the suspension attached.

A bare frame from a factory air suspension: Not the fastest but its the one I’m using for my suspension.  Its beefy and runs at a lower speed than the others so it will be quieter… Plus it has two 1/8 npt ports on the head that will make plumbing a breeze.. I probably should print up a belt guard for it.,,,,

a very old compressor from the 80’s


what I thought was a cheapie model but turned out better than expected so I gave it a brand new gauge and 3D printed a new cap for the head…..



A left over from a project. Its a cheap aftermarket car compressor with a 3D printed base…

Real cheapo flea market garbage. wouldn’t hit 200psi if I kinked its hose with vice grips…….

A nice $5 flea market one thats going back in my wagon…


A real surprise is the harbor freight model. It was #2

by far the best and most expensive one I have. Its made by slime. Its big ugly and fast and I keep it in my truck


and the results:

  1. Slime
  2. Harborfreight
  3. Interflator

the rest were about even.


MicroBit Brained Robots

I made a few Microbit Robots for the local library coding class.

This one was printed from scratch.

These two used commercial chassis.

They all use a homemade dual motor driver I had posted on Instructables years ago. I originally designed it for CNC use but it works better in a bot.

The first controllers used the accelerometer for steering. Later I turned this old yard sale find N64 controller into a microbit host.

The board is a perfect fit


Upgrading a K40 for Engraving

I decided to swap my K40 controller for a GERBIL from I considered the Cohesion 3D too. I’ve been using GRBL CNC controller with a few custom tweaks to the firmware for some time now but I want to see if the extra PWM resolution makes a difference. I just more familiar with the Atmel GRBL code…

While I was in there I added the Pause/Resume/Abort buttons. I kinda chewed up the label while drilling the button holes and the buttons just didn’t cover the mess. I printed a quick bezel to hide it and it made it look even better…

Just to be safe I also printed a small cone shaped washer for the toggle switch that switches between fixed and PWM control. I’ll label that later…

Simple Air Flow Meter

I needed a simple air flow meter for a project so I went out to the garage and grabbed a MAF that was pulled from a Hyundai.

I used a PIC 18F2550 board I had from another project and a small boost converter to make it completely USB powered.

This particular MAF has the IAT sensor built in so it reports air temperature too.

Just breathing into it shows a decent response.


I tested it with a couple of fans I had lying around. One thing for sure that little fan shroud that a printrbot comes with really impedes the airflow.

I made a huge right angle nozzle  for a laser engraver that showed little drop in flow rate…

LS2 Coils for my Tractor

I’ve been working on my tractor. Still have to replace a hydraulic hose and one axle seal but It drives around fine…

I am still going to convert it to fuel injection but since it has a brand new carburetor first thing I’ll concentrate on is the ignition. It runs great at higher speed but at idle the timing is a bit too advanced.  It will be nice to be able to fine tune the curve. Its going to be running Alpha-N unless I get really bored.

I bought a couple of GM LS2 Truck coils.

I have to make my own harness. I followed the Megasquirt wiring and added a little 10uF cap right at the coil. I read about some issues with noise so I’m using shielded cable for the trigger and plain cable for the power feed.

From the outside they look exactly the same but internally one uses smaller wire with a foil shield.

A little heatshrink tubing on the shield wire

probably should have stripped the black wire then used heatshrink to join it with the shield…. good thing the holes in the connector are oval shaped..

the MSQ forum recommends using a 10uF cap near the coil.

thats as close as I can get it..

solder and tape that upI like a heavy dose of liquid tape then some heatshrink to completely seal it up. ATV sealer works too but oozes more.

Not bad looking. Now just wait for sundown to cool things off so I can work outside.