Rings Sizes And Shrinkage?

Discussion in 'Jewelry' started by debdeb, Mar 26, 2017.

  1. debdeb
    debdeb Well-Known Member
    Hi Jewelry Makers,

    Wondering if anyone adjusts their models for shrinkage before printing? 90% of my prints have been too small. A few even by a full ring size.

    Thanks,

    Deb
     
  2. virginia_gordon
    virginia_gordon Shapeways Employee Community Team
    Hey Deb,

    Which materials have you noticed your prints being too small? Cast metals?
     
  3. debdeb
    debdeb Well-Known Member
    HI Virginia,

    I have 6 cast pieces in my possession at the moment. They are silver, 14k gold, 14k rose gold, raw brass, polished brass and raw bronze and are all consistently 1/4 size small. They were all ordered in a size 7.

    For printed steel, I have 9 pieces that vary in ring size. They all range from 3/4 of size too small to 1 sized too small.

    If a customer purchases frome the Shapeways platform, is there QA done to ensure that the ring size is correct before being sent out?

    Thanks
     
  4. Ontogenie
    Ontogenie Well-Known Member
    Hi Deb,

    From what I understand, the sizing quality control is pretty much left up to the designer with the reason being that the design itself influences the amount of shrinkage (width of band, thickness of band). You're going to have to play around with it a bit, and when you notice that one ring design is consistently 1/4 size smaller than you had planned, make sure that the file that corresponds to that size when the customer orders it is 1/4 size larger. In my experience the cast metals are pretty close to their nylon plastic prototypes, but the stainless steel is kind of a wild card depending on the design. I'm trying to nail that one down at the moment so I can feel comfortable offering some stainless steel rings. I would love to see someone do a controlled study on metal shrinkage with rings and give us absolute guidelines for design, but I think it's just not an exact science at this point. Shapeways does offer a money-back guarantee and incorrect ring size, regardless of the reason, is covered under this guarantee from what I understand.

    It's good to know that all of the cast metals that you tried, even the unpolished ones, came out at about the same size. Thank you for doing that experiment so I don't have to! And did you really order two pieces in solid 14k gold and 14k rose gold? Wow!

    Kimberly
     
  5. debdeb
    debdeb Well-Known Member
    haha! No, I didn't. They were plated. Oops.
     
    Ontogenie likes this.
  6. Ontogenie
    Ontogenie Well-Known Member
    Whew! For a minute there you had me thinking I wasn't properly devoted to my craft because I've never printed in solid gold. :D
     
  7. gordonlardi
    gordonlardi Well-Known Member
    typicaly with castings (silver,brass gold) i add .2mm to the inner diameter, With printed metals i add .5mm to the i.d. this is a result of quite a bit of trying and the results are quite accurate. No one can use a printed ring that is to small but a precious metal ring (not plated ) can be enlarged and polished again if the details are not too delicate.
     
    Digitallake and EvieL like this.
  8. Digitallake
    Digitallake Member
    Thanks, I was wondering the difference between silver and gold plated? ..and how if there is a formula for each that
    differs?
    Basically i want to be able to test each size variant in the cheapest castable metal before ordering more expensive precious metals... ordered a 14k and had to order a second a 1/4 size smaller. Which i completely take responsible for but I need to dial it in so that doesn't happen again.
     
  9. Muzehack
    Muzehack Member
    I think that 3D printed metals, like the Stainless Steel will shrink because of the sintering process. Basically once the ring is printed it has a lot of air spaces in it that will be filled with bronze during sintering to give it strength, but there can also be some shrinkage of about 2-3% from my understanding. Gold and Silver are cast from 3D printed wax prints I believe and as a result there should be little shrinkage. Someone correct me if I am wrong. I have gotten the same ring in stainless and silver and the silver was very close to the same size as the model whereas the steel had shrunk about 2%. So I guess you need to make your models about 2-3% larger for stainless vs silver/gold.
     
    josephbrowne_ce01 and Ontogenie like this.
  10. gitfiddlerno1
    gitfiddlerno1 Member
    In the silver section of materials they specifically talk about shrinkage, however, for some reason they have two versions of their text, not sure if thats due to polished versus unpolished:
    1)
    “Your model may shrink about 0.25 mm plus 2.5% after casting and finishing.

    For rings the inner diameter is accurate within +/- 0.1 to 0.15mm. On average, the model shrinks about 2.5% after casting and finishing. We do our best to polish the internal diameter to match your model file.”

    2)
    “Your model may shrink about 0.15 mm plus 1.5% after casting and finishing.

    For rings the inner diameter will be 0.125 - 0.15 mm smaller than your design. On average, the model shrinks about 1.5% after casting and finishing. Scaling up your model by 1% will make your design closer to your desired size.”

    I didn't’ investigate the more precious metals, although I would expect similar results. I also believe the ammount of shrinkkage is tied to the size of the object
     
    josephbrowne_ce01 likes this.
  11. havilahpmusic
    havilahpmusic Member
    Hi,

    This is a random one.

    I created a silver pendant and had it printed. Shapeways printed me the wrong size and so they refunded me for this. I resubmitted the order and asked them to reprint the same design. The design came and this time it was a totally different material than the one I paid for. No one answers my emails on Shapeways nor do they get back to me regarding this. Any suggestions as to what I should do?
     
  12. mkroeker
    mkroeker Well-Known Member
    Make sure that their email replies did not end up in your spam folder, shapeways customer service is usually quick and efficient. The print in a different material sounds strange - was it just a question of surface quaility (polishing), or actually a different metal ?