Parts requiring the most stiffness?

New Home Forum Mostly Printed CNC – MPCNC Your Builds – MPCNC Parts requiring the most stiffness?

This topic contains 8 replies, has 4 voices, and was last updated by  rkrammes 3 weeks ago.

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  • #114237

    rkrammes
    Participant

    This whole fiasco with Tom inspired me to get started on my burly upgrades and finally get this thing cutting aluminum.  I had some glass fiber reinforced nylon that failed QC from the company that I work for and I figured I might as well use it for some MPCNC parts.  It was really bumpy filament but I got it to print and I think it turned out pretty good.

     

    • This topic was modified 3 weeks, 1 day ago by  rkrammes.
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    #114239

    rkrammes
    Participant

    If I have enough to get through both of the XYZ parts what should be the next priority for stiffness?

    #114380

    Ryan
    Keymaster

    Hmmm, good question. Tool mount I guess. Cool looking fuzzy parts!

    1 user thanked author for this post.
    #115726

    rkrammes
    Participant

    Ok, any other suggestions?  I’m not going to attempt any of the larger parts but I haven’t had too many jams so I might still be able to finish a few more parts.  I was thinking probably feet next?  The feet in the parts list are definitely different than my 529 feet.

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    #115738

    David
    Participant

    If you’re planning to do more printing you might want to think about drying out that nylon.

    I have no personal experiences so take this with a grain of salt but I’ve heard it from a number of 3d printing sources.

     

    Apparently Nylon is super hygroscopic to the point where it can suck enough moisture out of the air in a few hours to cause printing problems.  Apparently a high moisture content causes cavitation in the hotend as the heat evaporates the moisture from the filiment causing small voids and a fuzzy texture sometimes lots of stringing.

     

    Again I don’t have personal experience, but it’s worth looking into 🙂

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    #115740

    rkrammes
    Participant

    Oh, that is absolutely true.  I dry the filament as well as print from a dry box.  In this case, as I said, this filament failed QC and is basically garbage.  I probably wouldn’t spend the cash that this stuff costs but it was free and functionally it should still have the properties I am after.  I believe the way moisture effects nylon (other than print quality) is that nylon loses some stiffness but actually gains “toughness”.  With fiber-filled nylon, nearly all of the stiffness comes from the fiber and it is the toughness of the nylon that allows for a relatively high percentage of fiber in the composite (30%).  GF30PA6 is very rigid, has not warped even in an unenclosed printer, and should not develop stress fractures under load in my non-temp controlled garage.  I will throw it back in the dryer before my next print but if you look at this filament you can see why there is a lot of inconsistent extrusions.

    • This reply was modified 3 weeks ago by  rkrammes.
    • This reply was modified 3 weeks ago by  rkrammes.
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    #115743

    rkrammes
    Participant

    If I was really concerned about surface texture I could be more diligent about printing immediately after drying but prints will never look great with such inconsistent diameter and ovality so as long as it’s not hissing and popping I’m good with it.  I think the parts actually look pretty cool in person.  They don’t feel fuzzy as much as they feel kinda sandy if that makes any sense.

    • This reply was modified 3 weeks ago by  rkrammes.
    #115762

    Aaron
    Participant

    How much more stiff is it? I print just regular nylon, and it’s more flexible than PLA in the same parts.

    #115801

    rkrammes
    Participant

    I believe it is in the same range compared to PLA for rigidity.  PLA is one of the most rigid filaments available but IMO has a lot of other disadvantages when compared to a material like reinforced Nylon.  PA6 is pretty flexible on its own but when fiber-filled its mostly just an incredibly tough binder for the filler and rigidity is determined more by the fill.

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