Instructables
Picture of Waste Plastic Pump
This instructable is focused on techniques for reusing / welding waste HDPE plastic. If you want to rework old bottles / containers and make things out of them, please keep reading.

The techniques are demonstrated by showing / describing how I built a 1.2 V NiCd AA battery powered pump which is chemically tolerant for use in circulating an acidic bath. I considered using ABS and PLA for their 3D Printed appeal, but the material would not have survived. Using a windshield washer motor was also considered but rejected since I have no way of knowing what material was used in its manufacture.

Although HDPE is notorious for its shrinkage when cooling, this instructable shows how it can be used to make something useful.
 
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Step 1: Sourcing HDPE

Picture of Sourcing HDPE
00B - Harvest.jpg
Most household cleaning products and non-transparent pill bottles are made of HDPE. It can be identified by its resin identification symbol, a triangle with a two inside. Once I found a decent container to use, I did the following:
  1. Removed stickers with Goo Gone
  2. Washed with Soap
  3. Dried Overnight
  4. Cut Continuous Square Sheets with Scissors
  5. Saved Handle with Utility Knife
  6. Cut Scraps into 1/4" (inch) Chips
This instructable only deals sheets from step #4
If you want to reuse the leftover chips from step #6, try:
Tip: Don't use bottles used for smelly compounds. I used a laundry bottle and noticed that when heated, it emitted the smell of laundry liquid, despite having cleaned it. If you can obtain, hydrogen peroxide bottles are a good source of HDPE, they're also infrared blocking which is great if you want to use IR LEDs, most other HDPE is transparent to infrared.
Tex Arcana6 months ago
I like this, but you sure went a looooong way to get there. how long did this take you to make?
vreinkymov (author)  Tex Arcana6 months ago

That's true, it took a few days with lots of trial and error. It did teach me a lot about plastic soldering.

LaserDave10 months ago
Great instructable, for showing both how to recycle plastic to make your own custom parts, and for showing how to do plastic welding. Even if some people are not interested in reclaiming plastics, the welding instructions may be more interesting and will permit repairing their broken plastic articles to keep them from being turned into recyclables themselves.

Just one clarification though... Spinning a permanent-magnet motor will produce a voltage at its terminals in the SAME way a generator does, and measurements of this voltage has nothing to do with "back-EMF". This generated voltage will not indicate the polarity expected by the motor. If the measured current draw is different for each direction, it may be caused by a worn brush/commutator assembly or worn bearings. It may also be caused by an electronic circuit used to "snub" or reduce the electrical noise thrown off by the motor.

The phenomenon of back-EMF (reversed Electro-Motive Force) is produced by switching the current to a coil on and off, the result of the magnetic field building and collapsing upon its own windings. (The majority of back-EMF occurs when the energised inductive circuit is broken, but there is also a smaller amount coming from energising the coil too.)

When a motor rotates from its applied current, the commutator/brush arrangement constantly energises and cuts power to the coils on the rotor (armature). As this cycles at a frequency directly proportional to the RPM, the voltage of the back-EMF is also proportional to the speed. Depending on the characteristics of the motor's coils, the back-EMF voltage being generated is usually much higher than the motor's supplied voltage.

Just thought this info might be helpful to someone, no offense or negative vibe intended.