Grit / abrasive trapped in stainless steel pieces

Discussion in 'Finishing Techniques' started by euphy, Dec 27, 2010.

  1. euphy
    euphy Member
    Hello everyone, I've got a particular design that is a devil for arriving with all it's nooks and crannys jammed up with the abrasive grit used for polishing the stainless steel. There's a picture attached, this is a ring (for scale).

    P1010009_c_p.JPG

    I don't really know what the material is, I can't decide if it's a mineral or something like a fibrous nut shell. I want to get rid of it, so I'd love to know if anyone has a method of softening it in water so it can be brushed out, or if it's really just a matter of sitting, breaking pin after pin trying to lever the bits out. It gets jammed in pretty hard. I've tried a dremel with a stainless steel wire brush, but it doesn't get the job done.

    Hope someone has tackled this before!

    Cheers
    SN
     
  2. 46021_deleted
    46021_deleted Member
    I'm not sure what it is, but if you can use dental floss and get under the (whatever it is), it should get them out.
    After all, that's what floss is designed for =)

    QX
     
  3. 20201_deleted
    20201_deleted Member
    Looks like it's the plastic/ceramic media. The other final polishing media is ground corn cob impregnated with red rouge. Soaking in water will not help. The best way to get it out is by what you are already doing. You might want to try a sturdier tool like a scribing needle or a dental probe. Or a good size sewing needle will work too. I know this is a real pain in the arse but it's the only reasonable way to get the gunk out. The finishing techs try their best to clean all parts but some things do get past them.
     
  4. euphy
    euphy Member
    I haven't ever been able to decide what the grit is made of, so (this might sound peculiar), but I managed to catch a bit and tried biting it, and it seems soft, fibrous rather than hard like sand, so I'm inclined to think it's the husk rather than the ceramic. I'll try soaking it. If nothing else it might lubricate it's exit while I brush it. If it is the husk (cellulose?), I wonder if I could dissolve it in something (er.. cellulose solvent?).

    It also doesn't taste very special. I must have another gin and tonic to cover it up.

    I'll report back! Thanks guys, hope you're having a good holiday.

    SN
     
  5. 20201_deleted
    20201_deleted Member
    If it's soft then it is the corn cob i mentioned. if you soak it, it will swell up and be harder to remove. Seriously, picking it out is about the best you can do
     
  6. euphy
    euphy Member
    Yes I thought of that just after I plonked them in some water. As it happened, it hasn't done any harm, except made the bits of grit darker so they are harder to see to dig out.

    I ended up using a thin scalpel blade, and putting on some loud music so I couldn't hear that scratching of steel against steel, akk!

    Would also like to say that shapeways customer service have also been in touch about this issue too, so maybe it isn't as normal as I'd thought.

    Thanks folks, help appreciated,
    SN
     
  7. Youknowwho4eva
    Youknowwho4eva Well-Known Member
    I noticed it in some of my pieces and just let it go, figured it was because of my tight gaps.

    I hope you don't often test things that come out of your shapeways items by biting them... lol. With all the chemicals and processes that are involved I definitely wouldn't suggest it.
     
  8. euphy
    euphy Member
    Aye, I don't make a habit of it, except for the aspic jelly support material that comes with the 3D printed pork, that is DELICIOUS.

    SN
     
  9. 20201_deleted
    20201_deleted Member
    Xmas rush in the finishing room might have let a few dirty parts go out the door. Find a jewelers or machinist supply and get yourself a scribe with a slender hardened point. Dental picks are handy too. It is also possible to burn the media off but you risk scorching the part and making a bigger mess.

    -G
     
  10. nervoussystem
    nervoussystem Member
    we've got a couple hundred rings filled with the stuff and have been using T-pins to remove from tiny holes. works pretty well. It's a bit of a pain but I appreciate that the pieces seem better polished as of late so it's a trade off we can agree to
     
  11. 54973_deleted
    54973_deleted Member
    Recently received some stainless pieces with this "grit" in them too, an exacto knife did the trick, bit of a pain to get it all though. Glad you started this topic so I knew what the heck it was!
     
  12. 9694_deleted
    9694_deleted Member
    Wow, so does this happen to (almost) everybody?
     
  13. euphy
    euphy Member
    I've only had it in parts that have particular sized crevices and holes (just the right size to trap the grit), and even then, it's mostly only ever been two or three bits of abrasive. The batch that is in the pic at the top was unusually gritty. On balance, I'd prefer to have to pick the grit out than to not be able to make the design, so it's still a win.

    sn
     
  14. SIXTHSCALE
    SIXTHSCALE Member
    i found i was able to burn the grit out ... but i was planning on darkening the part anyway.... I just used the gas burner on my stove.