Monday, 18 December 2017

Christmas Advent 3D Printing #Day 17 Advice for making reference test prints using a Polyalchemy Elixir sample pack

December advent calendar - modular Christmas tree
3D Printing advice #Day 17

For the background and introduction - Day #1 Post click here

Christmas Advent 2017 Download on Thingiverse here - designed by Tom Van den Bon  With some help for each day by the South African Makers team.


Day 17 gift is designed by Shaun Nadan -  It's a Christmas Poo Emoji.


I really didn't want to print this in a brown coloured material. I contemplated gold, but I don't have any, so I turned the Christmas Poo, into a Christmas 'Unicorn Poo' Emoji instead.

This is what a Polyalchemy Elixir sample kit could look like. (not all colours available)

As I recently discussed the need for material samples in Day 15, I decided this poop emoji was a good advent gift to demonstrate the sort of thing a user could do with a sample materials / colour pack from a filament manufacturer. Also look at Day 4 Lollipop - that was a Faberdashery sample pack.

What could you make with a sample kit like this?

I'm delighted to say I have already had some messages and questions from manufacturers about the need for samples packs. Some have now decided to start introducing them in early 2018. Keep an eye out.

If you are a 3D printing filament manufacturer, why not offer sample packs for sale? And how about a competition for anyone using a sample pack in an interesting or innovative way... over to you.

My calibration 'chip'

I'm also going to take advantage of this post to talk about printing out sample test objects. Printing a sample object in a new material, or different colour can be a useful way to check what a material looks like, and also how it performs. 

Cubes and small complex objects are often used to check a 3D printer.

Above is my test set for checking, warp, de-lamination, flex, break and twist of a 3D print material.

The 3D Benchy designed by Swedish designer Daniel Norée @DanielNoree ,
is often used by people to test out a new material, or as a way to check a 3D printer is operating well.

I have only ever printed out around two or three 3D Benchy's. I really don't have the room to keep a whole fleet of them, and I don't find it completely useful as a material sample. It's great at testing a new printer / nozzle / hot-end / extruder setup.

The test 'chips' above allow you to see opacity, and various fine features of a material print.

I have made my own 'materials test chip' to print out, store and use as a reference for material and machine / setup capability. You can get the test object, along with some other useful test parts from My Youmagine page here.

Being able to check a mechanical part can fit, is useful.

I also designed the 'chip' to allow a short section of Filament (both 1.75 and 2.85mm) to be inserted and stored with the test print. 

Back to the Poop...
Bringing this right back around to 'unicorn poo', I guess a multi-coloured poop emoji is a valid way to demonstrate a materials range, and keep as a reference print. It's at least a good talking point.
I'm just using the M600 Gcode command to switch filaments at regular Z height intervals.

Day 17 completed - with added googly eyes.

Print advice - (What makes a good material test sample)

Why can't I just use a 3D Benchy? - You can if you like. But I like to be able to check opacity, colour, fine details, and surface finish. I also need to be able to store them in an easy way.

Why print test objects anyway? - Well you have to test something when you get a new material. It usually takes a few goes to dial in the correct slicing, temperature and flow settings. A good test object should help you do that.

How can you test the strength of a material with a print sample? - The easy way is to first check the raw filament strength. Do this by bending first slowly, and then a quick snap. You should also be able to feel, the sort of plastic it is, hard, 'chewy' soft, stretchy.

Bending filament will only give you a first insight into the material. The material may also change state from amorphous to a crystalline structure after heating. A filament can go into your hot-end 'chewy' and come out like glass.

I also print off a number of 'dog bones' see images above, to allow me to test each sample in a home made jig. I can twist, snap, bend, impact and pull these samples apart, to gain a better indication of strength after printing.

Any other advice?- Yes, try out different test objects. Over the years all manner of test objects have become useful for all sorts of things. One really great object is the Hollow calibration pyramid found here. this object was one of the first things I used to setup and tune early 3D printer developments. If you can print this object well in every material you have, congratulations you are getting somewhere.


Days 1 to 17 of the Advent Christmas Tree.

Day #17 is completed. We had family star-wars day today, the last Jedi is really a rather good film.

Today's story can be about shiny unicorn poop? or maybe the importance of a good test object...

Join me next time for Day #18

Thanks for reading.

Rich.

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