Filament question/advice please

Discussion in 'BigBox General Chat' started by Ray, May 11, 2016.

  1. Ray

    Ray Well-Known Member

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    Hi All,

    Sorry this is the wrong place to ask this question, however I have asked another in the General section to see if we can have a Filaments section added to the forums.

    My question relates to a small part I have created in 123D, it is a replacement helicopter rotor for my sons helicopter as the original one fell off and cannot be found.

    It is about 50mm long and the blades are only 2.5mm thick, it is a press fit onto the helicopters shaft, I have the following questions:
    1. What would be the most suitable material to print it from assuming that the blades need to flex a little and take a bit of abuse from a young one (not the TV series), yet needs to be rigid enough that it can click firmly into place on the helicopters shaft?
    2. At present I am using 0.25mm layer height, 3 for top/bottom/perimeter should I use less/more?
    3. I currently have an infill of 30% rectilinear, should I really be aiming for something like this to be solid?

    Screen Shot 2016-05-11 at 11.16.33.png

    I found that I had a spool of ColorFabbs XT, so tried the above settings, but I am not sure if it is durable enough.

    Any advice would be greatly welcomed and if a new Filament forum section gets created I will happily move this to there.

    IMG_0848.JPG
     
    #1 Ray, May 11, 2016
    Last edited: May 11, 2016
  2. Stian Indal Haugseth

    Stian Indal Haugseth Well-Known Member

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    What do you mean with rotor? Is it the rotor blades (propellar) or the flybar (stabilizer) on top.

    I think you will have to experiment but would believe nylon could work pretty good. You need something that does not shatter at impact :)

    I would start out solid and maybe design in hollow tubes along the length to keep as much strength as possible if you need it lighter. Try to get as many straight lines of filament along the length as possible. Maybe increase outer layers and have no infil. Thicker layers bond better and should take more abuse.
     
  3. Stian Indal Haugseth

    Stian Indal Haugseth Well-Known Member

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    Haha! That's not a flyable heli :)

    I think most plastics would do fine. XT should work fine. Make it solid.
     
  4. Ray

    Ray Well-Known Member

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    Haha, no its not an RC model helicopter (those are mine not my sons).

    It more me trying to get my head around which filaments to use in which scenarios.
     
  5. Stian Indal Haugseth

    Stian Indal Haugseth Well-Known Member

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    I only use PLA until I am able to finish my Bigbox. But I have been reading whatever I can on the subject the last year. There is a lot of stuff online.

    PLA should work fine for most toys and it's a safe plastic regarding chemicals but you never know what else they put in. I find PLA a bit brittle and it will not stand up to sun and outside weather over time.

    Creating something to take a beating nylon can take almost anything. I probably will never do much with ABS as copolyesters should be as good or better and simpler to print.

    I believe PLA is still the simplest plastic to print.
     
  6. Sarah Nicholson

    Sarah Nicholson Well-Known Member

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    If you need something to be reasonably strong with a very slight flex to it consider PETG, it's almost as easy to print as PLA and offers good strength, but is much less brittle and has a little bit of 'give' to it. Nylon is much stronger but more of a pain to print and needs special care when storing it (see Henry Feldman's adventures with it elsewhere on this forum).

    As to print settings, I think you're actually pretty well set. 30% infill should be fine unless you need something to be absolutely rigid. I mostly use 2 perimeters but 3 when I want something really strong, and 4 top/bottom layers to get a good finish but 3 should be fine as well. Larger layer heights are better for part strength since the inter-layer bonding is often the weakest part so 0.25 should be a good compromise.
     
  7. Old_Tafr

    Old_Tafr Well-Known Member

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    For strength you need filament to be laid crosswise. Print it with a raft and you will see that the raft itself with one layer north-south, one nne -ssw etc that you get something that is very flexible and can be twisted without breaking, in ABS in this case.

    Depending on age it may be worth looking at what filament isn't harmful if chewed a little ! (with no ref to the Haribo post ! )
     
  8. Ray

    Ray Well-Known Member

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    Thats a good point about health safety when it is for a little one, so for example, ColorFabb XT says the following:

    High strength and very high toughness, Odor Neutral processing, High Tg / improved temp. resistance, Styrene free formulation, FDA food contact compliance, BPA (Bisphenol A ) free formulation.

    Does the bit that says FDA food contact compliance essentially mean its ok for young ones (or older for that matter) if they put it in their mouths? I assume things like Styrene free and BPA free formula also mean it healthier to touch/be around whilst printing?

    I have seen mentioned that ABS for instance isn't great to be around whilst printing, however I am not sure if I have seen mention if its safe in terms of health, although let me clarify the 3 levels of safe/health I see:
    1. Touching the filament and then touching either the mouth or food
    2. Putting the element in the mouth or storing food in it (such as a spoon or cup or child's toy)
    3. Just touching the filament (are there any filaments that you shouldn't even touch without wearing gloves etc.)?
    When I look on the E3D website at their Everyday filaments, it doesn't really mention food safety, at least for ABS or PLA, however, does this mean they are not safe to make toys or object from that a little one could play with, or possibly put in their mouth briefly?

    Update: Actually on re-reading the E3D Everyday PLA/ABS they do say the following:

    Manufactured in the EU at a facility which with we work closely from resin specially formulated for 3D printing, with no mystery additives or possibility of harmful contamination.

    But does the fact that there are no mystery additives or harmful contaminants mean that they are safe in the ways I have mentioned above?

    I would be interested if anyone had any articles about this subject comparing different filaments, as I am sure there must be other people starting out with printing and confused by this sort of subject.
     
    #8 Ray, May 11, 2016
    Last edited: May 11, 2016
  9. Imko

    Imko Active Member

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    I printed lots of toy, parts, train tracks ect all in PLA all at around 20% infill. Raft/Brim only if the shape requires it. None of them are broken and i have 3 kids, 1 = 4 year and 2 almost 2.

    Of course there are materials better suited for the job, but what is the worst what can happen.. printing a second one.

    My vote goes to the "easiest" material you can print with.
     
  10. R Design

    R Design Well-Known Member

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    Additionally:

    - Colorfabb XT is tough as hell (see their datasheet http://colorfabb.com/materials for tensile strength, elongation at break etc.);

    - you might even end up reducing the layer height a bit - since you'll have ample strength and the part is not enormous - in order to make those curves smoother;
     
  11. Old_Tafr

    Old_Tafr Well-Known Member

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    I had not intended to imply the heli blade needed a raft :( just that if you print a raft you will get a megga strong bendy piece of plastic which you may wish to emulate.
     

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