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  1. #1

    Printed plastics long-term durability questions

    Hi, I have been trying to absorb as much as I can regarding 3D printing over the last couple of weeks but I need some clarification on exactly how durable 3d printing is.

    I would like to print usable bespoke parts for airsoft/paintball guns. I have watched a few "durability" videos on youtube but I have a few reservations in regards to long-term life of 3D printed plastics when exposed to regular use (abuse) sunlight and stresses. A lot of videos show people hitting things with hammers and dropping them fresh out the printer but how would this same items hold up after 5 years of dropping, sunlight exposure and stresses. How does the stronger plastics (nylon, ABS) etc hold up? My main concern is obviously delamination on areas where they might be stresses. They might not show up right away, but cracks might show up later down the road. Also, is there a way to reinforce objects during or post printing?


    Thanks

  2. #2
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    Reinforcing during printing, not so much. The markforged printers can and do this by turning the printed part into a semi typical fibre composite. But no machine you're going to have on your desk for hobby use will be able to do that.

    Reinforcing after printing, sure. Wrap it in fibreglass, carbon fibre, whatever you want really. You could print hollow and fill it with resin, etc. Lots of options here.

    Abs is the most uv sensitive of the common 3d printing plastics, I can't think of any others that are noticeably uv reactive. That being said I doubt this is really much of an issue with airsoft items, most of the plastic parts on those are already probably abs. Nylon is hygroscopic so it will absorb moisture which affects its properties (flexibility/strength). Its relatively rubbery compared to other filaments so I personally don't find it too useful.

    Finally, abs is actually one of the weakest 3d printing plastics. Pla is one of the strongest. Which one is more suitable for a given mechanical application is another question, but pla is stronger despite what so many people will tell you.

    The best plastic for your applicstion (and therefore how the 3d printer part performs) really depends on what you want to print. Any examples of what you're looking to 3d print?

  3. #3
    Thanks for your reply


    I am interested in creating full kits that use donor parts. Stuff like clam-shells for lower receivers, stocks and shrouds etc. I would also need to print some switches like mag releases, fire selector and some of the trigger mechanism. Basically all the stuff you could get away making with a polymer on a real firearm. Much of this will be held together with screws or pins. The reset of the items like barrel, bolt, regulators, gearbox (for airsoft) will be purchased separately. The exterior of the guns would have to be impact resistant and relatively light while the switches and trigger assembly would probably need to be more wear resistant.

  4. #4
    Super Moderator curious aardvark's Avatar
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    if it's for commercial items then you probably need to start looking at the more expensive end of the market.
    ninjateks armadillo is a phenomenal filament. made of polyurethane, but almost as rigid as pla and ridiculously tough. Also very easy to print with. Some of the other super tough filaments, like polycarbonate - are total bastards to use.
    Also worth looking at is innofil's pro1 a super tough pla.

    polymakerss polymax is also worth a look.

    Now you can get cheap pla for as low as $15 a kg. It might work for some of your parts. You won't know till you try.
    https://globalfsd.com/
    have an american site and do samples of most of the more hi-end stuff so you can test it without coughing up a lot of cash for something that might or might not work.

    Other than that trakyan is spot on :-)

    I've had a pla poop bag holder in the garden - fully exposed to the english weather - for about 4 years.
    Apart from a sligh lightening of the colour (it's red) it's as new. Every now and then I give it a flex to check and it hasn't broken yet :-)
    I aso have bird feeders that have been outside for a similiar length of time. All pla all absolutely fine.

  5. #5
    Thanks for the suggestions. What would you suggest I do for a printer. I have been looking at models like Creality CR-10, Taz 6, Raise3d N2 as I would like to have a larger print volume. From what I can tell there seems to be no definitive answer to what printers to go with as they all seem to have their strengths. I don't want to waste $600 dollars on a printer like the Creality if it won't suit me and at the same time I don't want to drop 5 grand on a N2 if I don't need to.

  6. #6
    Super Moderator curious aardvark's Avatar
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    formlabs t-rex 2+
    http://www.formbot3d.com/formbot-lar...ize_p0018.html
    Huge build volume, but the independant dual extruders really open things up.

    If you're making parts for 'guns' then you're restricted in design options. So quit frequently you will find yourself needing to use supports.
    A normal dual extruder would work, but they are fairly finickity.
    With an idex system you massively cut down on print times and material wasted in dribble walls.

    Use a soluble support material and all you do is throw the part in a sink or warm water, and the supports dissolve away leaving clean print surfaces.

    couple of other options in the way of idex machines.

    BNc3d sigma, and my current favourite 3d printer the leapfrog bolt - which is around the $6000 mark - but totally awesome :-)

    The raise has standard dual extruders, which really are a pita. I tedn to spend extra time designing things that don't need support rather than use dual extrusion or supports.

    If I had an idex sustem - things would be different :-)

  7. #7
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    My advice on big printers is generally "you don't need a big printer".

    Aside from big prints taking ages, and most people don't have the patience to put up with that, 3d printing (or at least fdm) loses practicality for mechanical parts above a certain size. For a small plastic part it might be plenty strong, for a big one it usually isnt. On a big print you've got so many more possible shear points (the layers) and the large size of the print makes it act like a big ol' lever for all the moment loads within the part. So a 10 N load on a small part and 10 N load on a large part are not the same. All of the big prints I've seen (I.e. Those you'd need a build volume like the cr-10) have been cosmetic and non structural, I reckon there is a reason for that.

    For the record, my main printer right now has a build volume of 150x150x130 and I find it perfectly adequate. Occasionally I wish it was a bit bigger, but only by 10-20 mm.

  8. #8
    Super Moderator curious aardvark's Avatar
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    I'll concur partially on that.

    My replicator clones are 220x150x150.
    It's not really big enough.
    The he3d k200 delta is 200x about 265.
    And I have made one thing that needed to be cut into 4 to print on that (viking helmet).

    The thing is, A large volume printer will still print small stuff as well as a smaller printer, but a smaller volume machine won't print the occasional large item.

  9. #9
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    Can't say I've ever had to print a viking helmet, but I guess everyone's use case is different. That being said I personally dont have the patience or desire to print large decorative items. All of my mechanical prints I keep small for three reasons: strength, material, time. The amount of time I've spent trimming my cnc's printed parts to save material usage and I'm still not done with trimming parts here and there.

  10. #10
    Engineer ralphzoontjens's Avatar
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    If there are major forces coming across the part, it is likely to delaminate at some point, however if you can construct the part so that forces are in line with the print planes rather than across it (peeing the layers) it is very possible to print strong and durable parts. Keep in mind that 3D printed parts are about 5 times weaker than their injection molded counterparts, so design wall thicknesses and more internal structural features accordingly. Ditto advice on outdoor use as CAardvark, I have a few parts outside for 3 years now as a test, the PLA remains fine!

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