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  1. #1

    2 questions from a total noob

    I'm wondering about 2 things before I begin investing time and money in 3D printing? However cool the technology is I really would like to be able to not only print toys.I'm a programmer that have zero experience with 3D design and 3D printing.1) (printer) Say I print a simple tube standing up in the printer, how true is the length going to be? Say 150mm tall and 25mm diameter.15mm bore. can I expect a height difference less than 1mm? Both filament and resin printers.2) (CAD design) Is there cheap software that I could use to design not only a straight tube but one with varying (sp?) outer AND inner diameter while concentric? Like a piece for a woodwind instrument. (plasticwind? )Thanks for any suggestion!

  2. #2
    A 3d printer is a tool. No different than a lathe, table saw or drill press.. Buy cheap china crap and you get what you pay for.
    Need I say more.. Well yes I will.. It is not like printing a word doc.. Not only do you need to design your model for the type of fabrication you plan on using, you need to learn how to fabricate it.. I.E. configure your slicing software...
    In the end the answer is you get what you pay for and you get back what you put in..

  3. #3
    Quote Originally Posted by pslant View Post
    I'm wondering about 2 things before I begin investing time and money in 3D printing? However cool the technology is I really would like to be able to not only print toys.I'm a programmer that have zero experience with 3D design and 3D printing.1) (printer) Say I print a simple tube standing up in the printer, how true is the length going to be? Say 150mm tall and 25mm diameter.15mm bore. can I expect a height difference less than 1mm? Both filament and resin printers.2) (CAD design) Is there cheap software that I could use to design not only a straight tube but one with varying (sp?) outer AND inner diameter while concentric? Like a piece for a woodwind instrument. (plasticwind? )Thanks for any suggestion!
    1.) The tube will be pretty accurate but it obviously depends on the printer you buy. Resin printers tend to be more precise. My measurements always seem to come our near-perfect2.) Generally a printer will come with a software but I would recommend investing a few dollars into a paid software. They are much easier to use.

  4. #4
    To add a bit more since my post was not really all that helpful. The process of FFF print involves slinging a molten plastic string that is about .4 mm wide, depending on your nozzle size, at great speed..
    To get an accurate part you need an accurate machine, one that is built with very close tolerances and made out of a material that won't bend, fex or move out of shape. The stepper motors need to be accurate with the highest number so steps per revolution. Obviously the more more expensive > $1000 USD will be better in this area than a < $1000 machine.
    You have to have the machine calibrated correctly so it outputs the proper amount of molten plastic, too much and your part is too big and your holes are too small too little and every thing is on the other side.. This is not a simple thing.. there is a big learning curve ... like any hobby there is an initial cost, on going consumables and lot of time.. a LOT of time..

    To answer your question, a 2mm tall square wall that has a .4mm wall thinkness, when printed on an accurate printer, that is properly calibrated will be 2mm tall +- .02 and the wall will be .4mm think +-.02. and repeatable.
    When I was in your spot back in Feb I had been monitoring "Top 3D printers" for about 3 years while saving my spare money.. I had decided on a Maker Gear M2 as it was under $2000, been in the top of the prosumer range since it was release in 2012 and I could find no bad press or reviews on it.. It was know to be highly accurate and dependable. It was used by many in a production environment and the manufacture (Made in the USA) was very responsive and customer service was top notch.
    I did not want to deal with hardware issues or an inaccurate machine while trying to learn the Slicer software and how to design part.. I wanted a Top quality table saw that when I put the fence on 2" the wood cut was exactly 2 inches every time. Lots of things to think about when you by a machine..
    Good luck!

  5. #5
    Super Moderator curious aardvark's Avatar
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    right first off - get yourself openscad.
    http://www.openscad.org/

    I'm not a programmer, but i also can't draw. So for me openscad is brilliant.
    You just tell it what you want and it makes it.

    simple cylinder script:

    $fn=100; //sets spherical and cylindrical facets to be 100 - basically makes things rounder
    od=10; // cylinder outer diameter
    id=6; // cylinder inner diameter
    ch=30; // cylinder height

    difference() {
    cylinder(d=od, h=ch);
    cylinder(d=id,h=ch);
    } // end diff (I always comment on my scripts.)



    what I would probably do is set a variable for wall thickness instead of an inner diameter.
    $fn=100;
    od=10; // cylinder outer diameter
    ch=30; // cylinder height
    wt=2; // wall thickness
    difference() {
    cylinder(d=od, h=ch);
    cylinder(d=od-(wt*2),h=ch);
    } // end diff (I always comment on my scripts.)
    If you want to taper the cylinder you can have different start and finish diameters.
    extremely useful.
    Beauty of openscad is you can do things any way you like.

    As far as printer accuracy goes - yeah you should easily be able to get within a mm of the stated height on a 150mm print.
    But also don't be afraid to get the sandpaper and files and drill out for a bit of post processing work.
    I like to print things fast and rough.
    10 minutes post processing versus another 5 hours print time. These days, For me it's a no brainer :-)

    One of the things you will get with more expensive machines is better accuracy. That said - once you know how your particular machine works - you can adjust accordingly.
    I generally get my prints within a few tenths of a mm to the parameters.

    It's not just the machine that can effect this though. Different filaments have different expansion and shrinkage coefficients.
    So abs - for example, is a real bastard, and best avoided :-) Up to 1% built in shrinkage.
    Pla is much better and with decent pla the shrinkage is barely noticeable - it's one reason pla is generally preferred (plus it doesn't stink and generally makes stronger and more durable prints than abs).

    Then you have the flexible filaments that don't shrink at all.
    And I find that any of the inclusive filaments (wood, metal, stone etc) also have no measurably shrinkage.

    3d printing is a delicate balance between getting the filament to adhere to the build plate while printing, and releasing from it after. Different brands and colours of filament will all behave individually. You then need to balance that with the extrusion speed and temperature and how fast it's cooled.

    The larger the bead you extrude the faster you need to cool it before it slumps and deforms.

    Consequently the most important piece of software is the slicer. The thing that takes your model and turns it into thin slices of gcode that printer and use.
    I recommend simplify3d for about 99.9% of printers.
    If you go for a replicator dual clone. Then I recommend flashprint (which is free) - just handles the makerbot clones much much better than anything else out there.

    So that's that aspect.

    As far as resin versus fdm.
    Resin is messy, apparently smelly and needs post processig: washing, hardening under uv light etc.
    Fdm is actually much better - generally a model comes out and that's it done. If you've used supports then you'll need to remove them. But generally if you design it yourself, you almost never need to use supports.
    FDM is pretty clean, the filament is generally fairly cheap and material wise there is more choice than you can shake a forest of sticks at.
    Also with a multi nozzle or a 2-3 into one nozzle, you can mix different colours and materials in a single print.

    That said resin machines use much thinner layers than fdm and consequently can produce injection moulded quality prints.
    It all depends what you are mostly going to print.
    You can get resin machines from $100 (olo/ono) on up these days. So getting a cheap one for the odd print isn't out of the question.

    For example my klic-n-print replicator clone is currently setup with flexible and rigid pla. So I can print objects with flexible hinges, built in seals, valves etc.
    Having two seperate extruders does come with a bunch of issues but also lets you use 2 materials with completely different printing parameters.
    Mixer nozzles require filaments that print at the same temperature - so bear that in mind.

    So the important thing: what sort of budget are you looking for ?

    As far as fdm machines go I'd say Build quality wise they tend to max out at around the $5-10,000 mark.
    After that you're pretty much just buying print volume.
    That doesn't mean you can't get a a really nice machine for under $1000. If you're prepared to bolt a few pieces together yourself - you definitely can.
    You can also get a fairly serious print volume as well.
    have a look at this: http://www.formbot3d.com/formbot-lar...ize_p0018.html
    Gets round the dual extruder issue by having two independant extruders. IDEX.
    This makes dual material prints soooo much easier. All the hi-end industrial fdm machines I saw at tct this year have adopted The Idex setup.

    The t-rex is what we call an i3 style. Printheads go left to right and up and down while the printbed does back and forth.
    You then have the cartesian printers where the print head goes left and right and back anf forth while the bed goes up and down.
    Last setup is the delta, where the printhead does everything.
    I'm currently running one of each :-)
    The delta is my personal favourite. But the i3 setup has a lot going for it too.

    Then there's things like bowden extruder (filament is pushed through a long tube) and direct drive where filament is pushed through a really short tube directly on top of the hotend.
    Bowden setup is fine - but you don't want it on a large machine.
    One of the advantages of the i3 setup (designed by joseph prusa) is that you can have direct drive extruders but print at faster speeds than a standard cartesian machine.

    So have a look at openscad and give us a budget to work with.
    No matter what the budget, there will be something in there we can recommend :-)
    Last edited by curious aardvark; 10-08-2018 at 06:40 AM.

  6. #6
    Thanks a LOT guys, you have all been super helpful!
    I'm an instrument builer (as well) and to be able to make prototypes with 3D print could be a big timesaver for me.

  7. #7
    You don't need an expensive 3d printer to get great results, I am an engineer/machinist by trade and use my printers for mechanical prototypes. I have a wooden frame Makerfarm i3v, at the time of buying a $500.00 machine and a Anet A8 $75.00 with a chinesium acrylic frame.

    Both of them print better than my daughter's schools engineering class MakerBot z18 and Lulzbot Taz 3d printers. If you spend time putting the machines together using machine square, calipers, and a good ole tape measure you will have a machine that can usually hold tolerances well. Setting up software and calibration is also critical, take your time.

    Most any 3d printer you can buy in 2018 will give you some nice prints.
    With that said whatever you chose to buy make sure you buy something with good customer service or a large community for troubleshooting and improvement.

    For design, I use Fusion 360 with a free student license very intuitive and easy to learn.

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