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  1. #1
    Engineer-in-Training
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    Which material for CNC hold-down clamps?

    I found out from the thread at https://3dprintboard.com/showthread....ayers-Adhering that PETG may not be suitable for CNC hold-down clamps because PETG may break instead of flexing. In fact, one of the clamps broke as I tightened the screw. Also, which material for mechanical parts?

  2. #2
    Super Moderator curious aardvark's Avatar
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    nylon would probably be your best bet.

    That said - pet-g is weird stuff.

    I've got a scraper I made from esun white pet-g. And it's phenomenally strong,
    The miniture gears I made from blue colorfabb xt - were incredibly strong.

    Everything else I've made from pet-g has been crap.
    And for the life of me I can't remember what settings I used for the gears and scraper :-(

    I think the trick is to print very slowly and in very thin layers. The scraper was printed at 0.1mm layer height. Even my dad only managed to break off the leading edge up to the 0.3mm thickness mark. We were trying to change an awning on a motorhome, made the scraper to remove glue.
    My dad is one of those people who looks on the phrase: 'virtually indestructable' as a challenge :-)

    So yes pet-g can be superstrong, IF you get the print settings right. And given how much of a bastard printing in nylon is - it's probably worth persevering with the pet-g.
    Or any of those I mention below.

    Mechanical parts - depends entirely on what you're making and what your printer is capable of. I love pla.
    But if you have a heated bed enclosure and a high temp extruder - then things like poly carbonate and PEEK are incredibly strong.
    Bear in mind that PEEK runs at around $800 per kilo.
    Polycarbonate is a 'slightly' cheaper at $40 for 750gms :-)

    Now pc is also a right bastard to print with. you need the heatbed very hot, the extruder around the 260-280 and it doesn't stick to anything that well.
    Oh yeah except the sheet of buildtak you get with the polymaker pc-plus. It sticks to that like it's been epoxied. I never did get the test print off the buildtak. I managed to seperate the buildtak coating from it's base layer. But not the print from the top coating.

    It's also worth looking at ninjateks armadillo. That's a hard polyurethane that prints like pla and is incredibly tough.
    Also bloody expensive. https://ninjatek.com/products/filaments/armadillo/
    Around 60 a kilo

    This stuff sounds good - I've never seen it in the real world or had any to test. But I'll see if globalfsd have any. http://www.polymaker.com/shop/polymidecopa/

    Nylon 645 sounds interesting.
    Just ordered 10 metres. Finding a nylon that will print easily would be fantastic.
    Last edited by curious aardvark; 04-09-2018 at 04:03 PM.

  3. #3
    Engineer-in-Training
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    WOW! Buying the
    ninjateks armadillo
    filament is like buying a Rolls-Royce car. I can't find out how high the hothead with all-metal nozzle will heat on my PowerSpec 3D Pro (Flashforge Creator clone). Is eSun PLA+ filament good?

  4. #4
    Super Moderator curious aardvark's Avatar
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    well compared to PEEK they're practically giving armadillo away with a box of crackerjacks :-)

    Never used any pla+ Always found standard pla to be sufficient for what i needed.
    Esun filament is usually pretty good.

    I am curious to see how this nylon 645 behaves. With the exception of MYMAT nylon (which is also bloody expensive) I've never had and success with any kind of nylon.

  5. #5
    Engineer-in-Training
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    I got the eSUN PLA+ filament in the mail today and a test print of a small box looked good. I got a piece of paper listing the filaments sold by eSUN. There's a filament called eAL-fill. Is this good?

  6. #6
    Engineer-in-Training
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    I thought that I have under extrusion on some parts of the 3DBenchy boat like the exhaust stack and the box behind the cabin. I can break off the stack and there is a small gap on top of the box that should have been filled. I think that there is a setting in Simplify3D that is supposed to fill in the gaps.

  7. #7
    Super Moderator curious aardvark's Avatar
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    eal-fill will just be an aluminium coloured filament.
    It's good if you want something that's does look really metallic. But not so much if your think it's going to be stronger because it's got metal in it.
    It's not :-)

    As fars a s the nylon 645 went.
    Yes it prints easily, yes there's great layer adhesion and no discernible warpeage - but it doesn'ty stick to printbite.
    Probably the cleanest print I've yet had from nylon.
    So as far as I could tell from the limited print I got before it unstuck itself - it really is as good as they claim :-)

  8. #8
    Student
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    For my CNC I use PETG. I haven't had any problems with filament I use and I use some of the cheapest stuff out there. The thing I learned with PETG is to cool it as fast as you can while printing. Before I started cooling it fast the prints were not as strong, now I have prints that I couldn't break unless I really abuse them and they don't chip off or crack , they bend and twist first. Also , play with the temps, my current filament works best 216C , higher it doesn't cool fast enough and lower the layers don't bond well. Print something like a long rectangle with a few layers and 20% infill and try to break it, alter temps till it bends but not breaks is how I do it. Even a few degrees can make a difference, 210C didn't work and neither did 220C, 215C was close, 216C was just right. I use a bed temp of 70C and print on glass + hairspray (aquanet) . I sometimes break the glass removing a print it adheres so well, cheap $1 picture frame glass from dollar stores laid on top of 3/8 inch glass bed.

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