Polyamide

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A polyamide is a polymer containing monomers of amides joined by peptide bonds. They can occur both naturally and artificially, examples being proteins, such as wool and silk, and can be made artificially through step-growth polymerization or solid-phase synthesis, examples being nylons, aramids, and sodium poly(aspartate). Polyamides are commonly used in textiles, automotives, carpet and sportswear due to their extreme durability and strength. -- Wikipedia.

In our case we use Aliphatic polyamides-family.

First polyamide to be used was under the brand Nylon, technically a Polyamide 6.6

Other kind of polyamide in common use is Polyamide 11, known under the brand Rilsan, with better mechanical properties and slightly lower water retention.

What is available under Nylon name on the 3D printing market are blends of different kind of polyamide, with undisclosed contents and wide variety of properties.

Contents

Caution

Just as with any other thermoplastics (such as ABS) used in a FDM-3D printer context, please make sure you have adequate ventilation in your workspace and/or the knowledge to go with it.

Article over at Instructables outlying the safety risks of printing with materials such as: ABS, pure polyamide , and trimmer line.

Overview

Advantages of Polyamide:

  1. It can be very inexpensive to acquire, at less than half the price of conventional filaments. This is because the plastic is readily available as weed wacker (line trimmer) line.
  2. It is readily available. Hardware stores everywhere sell weed trimmer line in many different sizes and colors. See below for a list of Internet sources.
  3. Prints are flexible and wear resistant.
    • Unlike ABS and PLA, PA is far less brittle, and therefore stronger.
    • Has self lubricating properties which are useful for printing gears or nuts for screws

Disadvantages of Polyamide:

  1. It is more stringy than ABS or PLA. Overfilling the part will make a gooey mess with strings everywhere.
  2. Bed adhesion is more problematic.
    • It does not stick to PEI at all, and tends to warp more than ABS or PLA on glass. Cardboard or blue tape + gluestick or heated Printbite work for the most part.
    • Printing on cardboard necessitates more cleaning steps.
  3. You must dry PA before printing for a clean finish.
  4. Cheap trimmer line can be more inconsistent filament to print with.
    • Diameter of round filament is comparable to other cheap 3D printer filament w/r/t tolerances.
    • Diameter of the other shaped filaments need to be calculated.
    • Required print temperatures also vary. Some lines require > 265C to get good interlayer adhesion on thin walls.
    • Some premium trimmer line is impregnated with other materials to improve its strength.

Print Surfaces

  • Cardboard (heated)
  • Glass + UHU Glue [1]
  • Printbite (heated)
  • Bluetape + gluestick (low heat, ~60C)

Instructions

Steps for printing Polyamide:

  1. Get 0.105" trimmer line. This will work with a 3mm extruder. Make sure it is PA. I got mine on amazon here.
    • 0.065" is appropriately-sized for 1.75mm extruders.
    • 0.090" is also usable for 3mm extruders (and is easier to find at my local big box store), but can have more problems with retraction.
  2. Dry the filament by putting it in an oven at 300 F(~148.88°C) for 3-4 hours. Don't dry all of it at once especially if you live in a humid climate. I dry enough to last a week. If you do not dry it, the extruded material will get all foamy and make your parts very bad looking. This is due to the evaporating steam. It will also overfill the parts because of the bubbles in the filament. This will cause your part to look stringy and blobby.
  3. Put the dried filament in a ziplock bag, and put some desiccant with it to keep it dry. I used some "closet desiccant" I got from Walmart, with the ziplocks that have a slide thing.
  4. Feed the filament out of the bag and into your extruder.
  5. If using a cardboard build platform:
    1. As seen in the video, make a bunch of little clamps to go around the outside of your bed. I just used some pieces of wood with holes in them and some small bolts that go through the table. You could also print something that would probably work better.
    2. Cut a piece of cardboard to size, so that it fits under all of the clamps. Slide the cardboard in and screw the clamps down. You can use pieces or cardboard multiple times, and on both sides.
  6. Go to http://forums.reprap.org/read.php?1,70471,page=3 for the slic3r settings (config.ini). You will need to get your heated bed up to 120°C and your nozzle up to 245°C. The given printer settings are not going to work for everyone, so experiment.
  7. Calibrate the height you want to print at. The closer to the cardboard you are printing, the more adhesion, but the more cardboard you will need to get off of the bottom when the print is done. It will also make you use cardboard faster. On the other hand, if you don't care what the parts look like, it doesn't matter.
  8. Start printing :)

Cleanup

  • Use a rotarytool(dremel) with a fine wire brush attachment to take off the cardboard stuck to the bottom. The wire brush should take off the cardboard quite easily, but not damage the PA.
  • Option 2:
    1. Get some drain cleaner from the store.
    2. Make sure it is the stuff with Sodium Hydroxide and not Sulfuric Acid.
    3. Use rubber gloves, and add a small amount of water to a container, then pour in some drain cleaner.
    4. You only need to have enough to cover the bottom of the part.
    5. Put the part in the solution, again using gloves.
    6. Let it sit for about 15 minutes, then take it out and rinse it off.
    7. Use a wire brush to brush off the wet cardboard.
    8. You can use the above option to clean it further.

Other Notes

If you have empty spools, it can be convenient to respool smaller packages of trimmer line onto them.

Videos

The newest video is without cleaning the cardboard off as in the instructions above.


Newest Video:

Older video:

Sources of filament

Check the Printing Material Suppliers-list with user reviews and report your findings.

Known vendors
Printer Playground


http://www.amazon.com/dp/B001BKZT1S/ref=pe_175190_21431760_M2T1_SC_dp_1

http://www.amazon.com/Weed-Eater-952711559-0-080-Inch-2000-Foot/dp/B0010XRBXA/ref=sr_1_2?ie=UTF8&qid=1295391377&sr=8-2

Further reading