Sprue And Link Guidelines For Detail Plastic

Discussion in 'Suggestions & Feedback' started by reducedAircraftFactory, Jan 16, 2019.

  1. reducedAircraftFactory
    reducedAircraftFactory Well-Known Member
    With the new pricing models -- especially in Detail Plastic -- it is important to use sprues or links (like those in a chain) to keep multi-part models together and considered one "part". This also helps Shapeways' efficiency, since they can clean and bag the item in one operation rather than trying to fish a dozen parts out of the cleaning output.

    However, it is not well documented what the spruing and linking guidelines are in that material. Versatile Plastic spells it out on the materials page (well, at least for sprues).

    For Detail Plastic, do the sprues need to be 1mm in diameter, or 1.6 mm in diameter, or 2mm in diameter? Is the same true for links? Do sprues need to attach at one point to the real model or (where practical) two? Do the attachment points have to be widely separated?

    There is plenty of folklore on these topics, but I'd like to see these hints directly in the Material Guideline pages. Perhaps it was overlooked because it wasn't essential before the new pricing models premiered.
     
    robs_mw likes this.
  2. stonysmith
    stonysmith Well-Known Member Moderator
    I've always used 1mm sprues. The concept here is to construct something here that can be picked up with two fingers and won't break.
    I have some items that are loose (like traffic cones) and I put them in a completely enclosing cage. At no place do they touch the cage, but also no amount of shaking/turning will cause the any of them to come out.
     
  3. reducedAircraftFactory
    reducedAircraftFactory Well-Known Member
    Not to discount your answer, @stonysmith: your wisdom is always welcome. But I'm looking for something official so that I don't get rejections of customer orders because a tech decides that there is a "hidden" 1.2mm diameter minimum. Now, Shapeways may some day decide to change their minimums -- that's within their purview -- but I'm hoping not to be left vulnerable to the minimum-of-the-day syndrome.

    In the next few weeks, I've got about 200 products in detail plastic to redesign using sprues or links, and I certainly do not want to go through that process twice. I don't want to sprue them with 1mm diameter sprues only to get rejections a week later because there is an unwritten minimum of 1.2mm diameter sprues. (And the same for chain-links.)
     
  4. Andrusi
    Andrusi Member
    As far as I can tell it's completely arbitrary. Sometimes a 1.6mm connection that was fine before suddenly becomes unacceptable because I widened a peghole at the other end of the model.
     
  5. stonysmith
    stonysmith Well-Known Member Moderator
    I'm right there with you.. I know that I've got over 100 to do.

    One huge thing.. be aware of the "barbell rule". Two large masses on the end of a small rod, and the rod is going to break. In some cases, you may have to provide more than one "connector" (sprue) between the parts to keep them from breaking.