Tuesday 5 December 2017

Christmas Advent 3D Printing 2017 Day #4 Faberdashery Translucent PLA's

December advent calendar - modular Christmas tree
3D Printing advice #Day 4.

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.

It's Day #4 of the calendar, and today the gift is designed by Tom Van den Bon - It's a Christmas Lollipop. (I tweaked the design a little for this, read below to find out why) -

What material to print a lollipop?

The choice of filament is obvious for me. It must be multiple translucent colours for this great gift.

Some of the Faberdashery Translucent range of PLA filaments.

Faberdashery have some of the most mouth-watering translucent filaments available anywhere. They basically make printed objects look like ultra-perfect, coloured boiled sweets. Yummy – don’t eat the filament…

I printed the vase (above) back in 2014 with Faberdashery and other translucent colours, they can look really amazing.

I have already told you that Green is my favourite colour. Translucent plastic is my favourite type of 3D Printing filament.

When I look at any manufacturer’s range of filaments, I check if they have a number of translucent (not milky) colours available, this is because translucent filaments are reported to be quite tricky to manufacture. Almost every filament manufacturer (the real manufacturers, not just suppliers/re-sellers) I have talked to over the years says that a good translucent, coloured filament is quite difficult to produce consistently without flecks, bubbles etc. I see it as a strong indicator of quality control, if good quality translucent filaments are available.

Other translucent materials? - 

It’s quite common for PET/T/G materials to come in translucent colours (think of the many coloured plastic water/drinks bottles), but it is not quite so common for PLA to come as translucent. The very first PLA’s I ever used (made in China) were almost all translucent, not opaque at all.

For a frosted/translucent finish, you can use acrylic (PMMA) but that’s considerable more tricky to use. I’ll try to find a day/model to demonstrate out using PMMA at some point during this December advent training series.

The Faberdashery crystal colour pack is a great starting point to make sure you have a little of every colour to hand. It's goes a long way when you use it like I am doing here.

I'm using all Faberdashery colours in this model, for the stick and back I'll use Pearly White. 

Pearly White.

For the many swirls I'm using - Sour Cherry, Orange Fizz, Lemon Drop, Jade Green, Glacial Blue and Aurora.

This lollipop should look good in multiple colours and the design allows you to change colours during the print, for the stick, base and many lollipop swirls.

During model preparation I noticed the STL file had some errors. In the course of fixing those errors I decided to modify the model to have more stepped layers that could be coloured in a rainbow set of translucent colours. 

My version of the Lollipop design uses multiple stepped layers, so more colours can be used.

Printing advice -

I'm using the Prusa ColorPrint program (above) for this one as it will stop at set heights, move the nozzle to the front and ensures you don’t miss any of the critical colour change point.
It's really easy to use, just slice in the Prusa version of Slic3r, upload the Gcode output to the colorprint website and define when the program should pause and change the colour.

To work out what layer heights you need for each step you can load the STL model into a program like Netfabb. See below.

In the above image I have used the Cut Z slider to move the blue lint to where I cant my first colour change. Just make a note of the Z height (here it's 3.2mm) enter that into the ColorPrint webpage as seen above in the previous image.

Do the same thing again for each layer height you want a colour change. (5.2mm above).

ColorPrint also now allows you to use Gcode that has Z-hop (lift) enabled, it's smart enough to ignore all the extra z-hop moves and select real change of print layers.

You don't have to use the ColorPrint program, all it does is adds an M600 Gcode command at the change of layer heights you selected.

You can just look at any Gcode in a text editor (Textpad is great) - then do a search for G1 Z3.200 - this will just you to the Z height at 3.2mm. Just make sure you are selecting the change of layer and not the Z-hop of a travel move. You can ensure this by finding the last reference to the height you want before it changes to a higher constant.

For example, below in Green is an inserted M600 command at the Z3.2mm height.

M204 S1000
G1 X122.752 Y116.452 F7800.000
G1 F6240
G1 X122.135 Y115.491 E-0.43439
G1 F6240
G1 X121.956 Y114.657 E-0.27247
G1 F6240
G1 X121.927 Y114.494 E-0.05313
G1 E-0.04000 F2100.00000
G1 Z3.350 F7800.000
G1 X134.891 Y92.234 F7800.000
G1 Z3.200 F7800.000
G1 E0.80000 F2100.00000
M204 S2000
G1 F2585.558
G1 X123.758 Y103.367 E0.53295
G1 X123.502 Y103.998 E0.02301
G1 X123.238 Y104.768 E0.02757
G1 X123.002 Y105.558 E0.02792
G1 X122.800 Y106.356 E0.02785
G1 X122.595 Y107.409 E0.03632
G1 X138.605 Y91.399 E0.76639
G1 X139.365 Y91.285 E0.02602
G1 X140.588 Y91.159 E0.04162
G1 X141.770 Y91.113 E0.04003

This will make the printer move to the front and push out the filament, wait for to load another one, feed and then start printing again after you press the button (as long as your 3D Printer firmware supports M600 commands).

First colour change from Pearly white to Sour Cherry.

Sour Cherry done, nest is Orange Fizz - just continue until it's finished.

From the side you can see the colour changes, but from the top it's a multi-coloured Lollipop!

The Tree is looking really nice.

What settings did you use? - Faberdashery PLA is really easy to use. I use 194 Degrees C for Translucents. 

Print speed - it's good from 10-150mm/sec. Works fine in Direct drive or Bowden extruders.

Why use it? - PLA is an eco-friendly Bio-plastic. It's UV stable and works very well as a 3D printing material. Originally developed by Natureworks as a bio-plastic made from corn starch. many different grades exist. It can also be made of potato starch. 

It has a low glass transition temperature (~50 Degrees C) provides no warp in most situations. You don't need a heated bed, but it can assist when printing big (+150mm wide) objects.

Don't print in very low temperatures (below 15 Degrees C).

You can easily re-form post printed 3D objects with a hairdryer or heatgun, handy when you need to bend a tentacle or whatever.

Is it strong? - Yes, PLA has good strength, but can be a little brittle in it's raw form. Most manufacturers add impact modifiers to make the plastic more impact resistant. As with a lot of materials colour is added at around 2-5% volume, you can get both translucent and opaque PLA's from a wide range of manufacturers.

Is it easy to use/print - Yes. It can be quite runny (like honey) if you put the temperature up too high (~218+) I would recomend sticking to around 190 for normal printing speeds ~40mm/sec and if you do go fast ~120+mm/sec then consider putting the temperature over 210. My max temperature for PLA is 218. After this point it will start to rapidly degrade inside the nozzle. PLA will leave residue over time and it can be one of the most tricky to remove. The best method is with an Nylon Atomic Pull (Google it).

Do you have to dry it before/after use? - No. PLA is one of the few materials that can sit around at normal ambient temperatures, and not have a significant effect on printing capability. That said, keep it sealed, dry and away from strong light for maximum shelf life. Some people report that PLA becomes brittle over time, I have had every problem you could imagine with many materials, including a roll of PLA shatter over one summer. But it's very unusual.

Do i need a 'special' nozzle? - No, it's not abrasive, I have used it with all aidderent sizes of nozzle from 0.25 to 1.6mm - It will work fine with Stainless, Hardened steel, Copper, Ruby or Brass nozzles.

Does it smell when printing? - Yes. Usually just a slightly slight sweet smell, like popcorn. Unless it has a lot of additives, then it may smell more.

Does it come on a eco friendly spool? - No, But it comes on No spool! - Faberdashery coils filament in ~400mm diameter rings, they have a low bend radius and feed really well into 3D printer extruders. They have minimal extra packaging so you pay for the material not spools, cardboard and heavy delivery. Top marks for being enviromentally friendly. You just need to be careful in use so the coils do not tangle. I hang them over a big 400mm wide spool in use.

Conclusion for Faberdashery PLA  - It's very good material with the highest quality production you are likely to see. Some people really don't like the lack of a spool, but that can be managed if you are careful.

Day #4 Is Completed. Again it turned out exactly as I wanted, a Rainbow lollipop of multiple colours printed on a single extruder machine using ColorPrint M600 Gcode commands. Easy, and good fun.

The story for this one is all about how to design and print multi-colour objects with a 'normal' single extruder 3D Printer.

Join me next time for Day #5

Thanks for reading.


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