Going For A First Try And Need A Littel Help

Discussion in 'Newcomers Lounge' started by fb0195e, Aug 17, 2016.

  1. fb0195e
    fb0195e Member
    Hello

    This will be my first try at 3d printing and I would like to know the minimum wall thickness that can be used to print with metal (jewellery).
    The tutorial at the site says 2mm, but it seem too thick for metal.
    So i just want to confirm that value or if I can use a smaller one.

    (I upload a test file (attached) and got wall thickness issue)

    Also, when I uploaded the file,the site said it was half the size than original, so I had to scale it.


    Thank you

    Julio
     

    Attached Files:

  2. mkroeker
    mkroeker Well-Known Member
    The tutorial (which one did you read?) may date from a time when the only metal was "steel" (actually a steel-bronze composite) that is produced by sintering a print made of loosely glued steel powder. Other metals now available are created by casting from a printed wax master, this process allows thinner walls are finer details and materials that are more corrosion resistant.
    (BTW the size difference you experienced was probably not exactly one half, but a factor of 2.54 - metric vs imperial units ?)
     
  3. UniverseBecoming
    UniverseBecoming Well-Known Member
    To expand on what mkroeker said. . .

    I took a look at your file. Nice geometry! What software did you use to make that?

    It appears that your modeled is in inch units. When we do uploads we check the model units that correspond to the units of the file since this information is not stored in the file when it comes to polygonal based file types like STL or OBJ. You can set the model units here:
    Model units.jpg
    As you get into 3D printing you'll notice that just about everything concerning 3D printing uses the metric system, even though it was first invented in the US. I used to do all of my modeling in imperial units, even for CNC, until I got heavily into 3D printing and then I dropped imperial units altogether and only work in the metric system now. It's still a matter of choice, but it makes things easier if you go metric when you're going to get heavily into 3D printing.

    Your model is not printable in any of Shapeways' metals! :( Don't worry though, we'll get you fixed up and printing in no time. Yes, the walls are too thin, but there is another problem. The cube that you have inside is shielded by the sphere on the outside. What I mean be shielded is a sprue needs to be attached to each part so that it can be filled with molten metal during the casting process. Consequently, what you would need to do is make that cube a part of the outer sphere like you did for the bail. That way the casting crew can simply attach a sprue to the outer sphere and the metal will have a way to get to the cube inside.

    However, before doing that, you'll need to thicken those walls. The cube would be fine if printed in an unpolished investment cast metal since it has a minimum wall thickness of 0.635 mm. The minimum for unpolished is 0.6 mm. There are other investment cast metals that Shapeways offers that do not come with the option of unpolished like platinum, gold and the plated metals. So, if you'd like to have the option of printing in all of the investment cast metals you'll need to increase your walls to at least 0.8 mm.

    There are two other metals that Shapeways offers and those are steel and aluminum. Both of these are done differently from 3D printing a wax pattern and then investment casting and have much thicker wall requirements as consequences of their respective processes.

    But wait! You probably want that cube to be free to move within the sphere! Ok, that is possible in most of Shapeways plastics, in fact it's routinely done in plastic and is one of the great benefits of 3D printing in plastic. For metals however, is gets very difficult. All of the metal processes need a sprue attached to get the metal into the part by either filling a mold in the case of investment casting or drawing it in via capillary action in the case of Shapeways' steel. Shapeways aluminum melts a metal powder in place and therefore doesn't need sprues, but the problem here is it needs support structures to keep the metal from warping while printing and so that won't work because there are no easy ways of removing the support structures that need to be inside the sphere.

    There is hope though. Take a look at this. This is Shapeways' experimental interlocking metal pilot that you need to signup for in order to try it out. It uses investment casting and has the same wall thickness parameters as Shapeways regular investment casting, but you can have up to six separate interlocking parts per order. The thing is though they need to be able to connect one or more sprues to your inner cube. Once you get approved for the pilot you can get your geometry corrected and then see if Shapeways can do it. Shapeways always has a human check your geometry before anything is printed so they will tell you if something is not going to work. The problem would be sticking one or more sprues through your star pattern holes, casting it, AND THEN ALSO, removing the sprues after casting. If Shapeways says they can't do it you might try making the spherical star pattern less dense so that the cube sprues could be worked with.

    Oh yeah, one more problem you may run into with this design. In jewelry design we call this a filigree design. The problem with casting filigree designs is getting the molten metal to flow everywhere to fill up the entire filigree pattern. To make it work lots of sprues are attached all over the filigree to try to let the metal flow in as freely as possible before it solidifies. If not enough sprues are attached the filigree will only partially fill and the result is a casting failure. Thing is though, Shapeways doesn't want to spend all day attaching a bunch of sprues that then need to also be removed after casting. So what you'll get from Shapeways is a rejection notice entitled weak geometry. We all get these various rejections all the time. So, no need to get stressed over them. I remember when I was in your starting out position years ago I received numerous rejections on my first design that I worked on. I wanted to strangle a few Shapeways workers at the time! HAHA! :D Nowadays I know that each of those rejection were justified. What you would do if you did receive this rejection is think about how you can make your geometry thicker or change the pattern so that the metal can flow more readily.

    Anyway, once you get the hang of it it gets pretty darn fun! Almost anything you can draw up in 3D can be sitting in your hands a week or two later and that's super fun and also SUPER ADDICTING! :D
     
    fb0195e likes this.
  4. fb0195e
    fb0195e Member
    Hi
    thank you for your answer
    I used 3D Max and cm units.

    sorry to know that can't use metal for it.
    Will check the other parameters.

    thank you
     
  5. NoahLI
    NoahLI Well-Known Member
    you should be able to print that in aluminum which allows for interlocking parts. Polishing plating and/or anodizing afterwards can create interesting finish. I doubt the model will work for interlocking metal pilot as the spaces are not large enough access and remove the temporary sprues after casting.

    If you want to do other metals: bronze/brass/silver, printing the outter sphere in halfs then soldering together afterwards should work.
     
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  6. mkroeker
    mkroeker Well-Known Member
    Aluminum allows for interlocking but not enclosed parts (needs sprues for overhangs etc), also the (casting) alloy used appears to be unsuitable for anodizing... not sure yet what to make of James' intimidating wall of text, the easy way out would probably be to print in "strong&flexible" nylon and spray with metal effect paint.
     
    fb0195e likes this.
  7. NoahLI
    NoahLI Well-Known Member
    Ah right. I was thinking anodizing only for aluminum. but since that material is not possible, it's out of question as well.
     
    fb0195e likes this.
  8. UniverseBecoming
    UniverseBecoming Well-Known Member
    Good ol Max! Thanks!
     
  9. UniverseBecoming
    UniverseBecoming Well-Known Member
    I got bored. :p
     
  10. UniverseBecoming
    UniverseBecoming Well-Known Member
    Oh yeah, welcome to Shapeways forum Julio! :D
     
  11. Digitallake
    Digitallake Member
    Newbie question... When designing interlocking metal parts do we place sprues in the 3d model or is that something that is done to file by 'staff' after analyzing the file?? Thanks!
     
  12. UniverseBecoming
    UniverseBecoming Well-Known Member
    Yes. That is something that is done by Shapeways both for the interlocking and also the regular non-interlocking 3D printing. One thing to keep in mind when designing for interlocking is, there needs to be ways that sprues can be attached and also removed. They are removed by first cutting with a cutter similar to a pair of dikes and then the sprue is also ground down to the part surface with a rotary tool. So room is needed to remove the sprues.
     
  13. Digitallake
    Digitallake Member
    Thank you!
    Is there a 'hard' dimension that one should allow for that ...say a hole of X diameter as a minimum?
    Thanks in advance!
     
  14. UniverseBecoming
    UniverseBecoming Well-Known Member
    No, but Shapeways should come up with something along that line. I have diamond saws that are about 5 mm in diameter and can reach an area about 15 mm deep to cut a 1.5 mm sprue. I'm sure most jewelers would have similar cutters, so I would think at least that small. Seems like one could make a special flush cutter from a pair of needle-nose pliers that could get into an even smaller area. I guess one would have to submit a design and see what Shapeways has to say about it. Shapeways' support address is service@shapeways.com

    A thing to keep in mind concerning the 50% off sale is if one submits a design and it is later determined that the design is not printable or even if it was some mistake by Shapeways that caused a problem, in these instances Shapeways will not honor that initial sale price. I know because I had Shapeways make a mistake on a order that I made and when the smoke cleared the initial incentive was revoked. Consequently, one needs to be extra careful when placing an order by at lease checking with Shapeways first so as to minimize not getting into that scenario.

    50% off all orders on Interlocking Metals
    Terms & Conditions
    • Promo code INTERLOCKING is good for 50% off all models in Interlocking Raw Brass, Interlocking Polished Brass, Interlocking Raw Bronze, Interlocking Polished Bronze, Interlocking Raw Silver and Interlocking Polished Silver.
    • Code is valid 3 uses per customer with a maximum discount of $150 USD per order.
    • If you order a design during the promotion period that cannot be printed, we cannot apply discounts to future orders (even if these designs are repaired).
    • Code cannot be combined with other discounts or offer codes.
    • No cash value.
    • Orders must be placed before August 31, 2016 at 11:59pm PDT in order to qualify for this promotion.
     
  15. Digitallake
    Digitallake Member
    Yes... I noticed that incentive just yesterday.. and thought I could maybe
    take advantage of it. (and I'll try) But given that I'm new to this it's probably not going to go as I'd like : ).
    Thanks for the details.. they help a lot!
     
  16. UniverseBecoming
    UniverseBecoming Well-Known Member
    If you want, you can send me a private message of what it is you're working on (if it's not proprietary) and I'll help you with it.
     
  17. Digitallake
    Digitallake Member
    Thanks for offer.. I will if I can 'pull it together' in time!
     
  18. UniverseBecoming
    UniverseBecoming Well-Known Member
    Ok, sounds good. :)