How was this Mirror finish achieved on stainless?
Close
Login to Your Account
Results 1 to 15 of 15
  1. #1
    Join Date
    Jan 2018
    Country
    UNITED STATES
    State/Province
    Texas
    Posts
    2
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    0

    Lightbulb How was this Mirror finish achieved on stainless?

    How was the finish done on this stainless steel "screw"? It a mirror finish. Im not sure what type of stainless or if is indeed stainless at all. Its pretty heavy, definitely not aluminum, although it does have two aluminum clamps inside of it attached with three bolts. I have seen knife makers like John Grimsmo polish a knife to a mirror finish. Any input?
    front.jpgback.jpgtop.jpgbottom.jpg

  2. #2
    Join Date
    Jan 2018
    Country
    UNITED STATES
    State/Province
    Texas
    Posts
    2
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    0

    Default

    As you can see the inside and bottom were not finished with a mirror finish because it is not required as they will have nothing in contact with them so friction is not an issue. To the contrary of the smooth outer side where it will have foam cups sliding on them and minimal friction is required hence the mirror smooth surface.

  3. #3
    Join Date
    Sep 2008
    Country
    UNITED STATES
    State/Province
    California
    Posts
    1,062
    Post Thanks / Like
    Likes (Given)
    675
    Likes (Received)
    604

    Default

    i would start with progressively finer grades of wet and dry, finishing with 1000 grade, then either polish with a buffer wheel, or use polishing compound with a rag.

    If it was turned then it would be relatively straight forward to get a good polish. A milled finish would take longer. Also if you have to maintain a tight tolerance that will dictate how much material you can remove before polishing starts.

  4. #4
    Join Date
    Jan 2009
    Location
    "Stuck in Lodi", Ca
    Posts
    3,114
    Post Thanks / Like
    Likes (Given)
    1842
    Likes (Received)
    1618

    Default

    I recall seeing some parts that somewhat hand finised to a resonable point then they were "Electropolished". If my memory serves me correct that was the term used. It's kind of like reverse electroplating. There was final polising afterwards.

  5. #5
    Join Date
    Sep 2011
    Location
    Langley, B.C.
    Posts
    1,331
    Post Thanks / Like
    Likes (Given)
    247
    Likes (Received)
    754

    Default

    Any place that does chrome plating could easily polish that--much easier than doing it yourself. That "might" be electropolish
    but I think it's a bit too bright...

  6. Likes digger doug liked this post
  7. #6
    Join Date
    Nov 2013
    Country
    UNITED STATES
    State/Province
    Utah
    Posts
    2,553
    Post Thanks / Like
    Likes (Given)
    704
    Likes (Received)
    1364

    Default

    Looks Chromed to me. Not to say you can't get there without, but that would be the easy(not necessarily cheap) route. I would try to get a hold of the print to see exactly what material it is. I can tell you it ain't 12L14 or 1018 or A36.

    It seems like an obvious Turning job to me, but lately the Mill guys around here seem to think different.

    17-4, 304 and 316 finish absolutely beautifully. With a Wiper insert, high SFM and slow Feed I can get a finish pretty damn close to that right off the machine, with those SS's. I have achieved a 4µin. per the Profilometer.

    R

  8. Likes Vancbiker, Cycle1000 liked this post
  9. #7
    Join Date
    Jun 2015
    Country
    CANADA
    State/Province
    British Columbia
    Posts
    1,054
    Post Thanks / Like
    Likes (Given)
    241
    Likes (Received)
    553

    Default

    Electro-chemical or chemical polishing leave a shiny finish but not precise surface. It is mostly used for decorative, food industry, high vacuum, high voltage - for parts that need polished surface but not perfect mechanical or optical accuracy. Buffing will have a similar effect. If both accuracy and finish are needed, it can be done by fine machining or grinding and then lapping - for example ball bearings.

  10. Likes digger doug liked this post
  11. #8
    Join Date
    Oct 2016
    Country
    UNITED KINGDOM
    Posts
    41
    Post Thanks / Like
    Likes (Given)
    5
    Likes (Received)
    16

    Default

    That looks electro-polished to me

  12. Likes aj liked this post
  13. #9
    Join Date
    Feb 2007
    Location
    Aberdeen, UK
    Posts
    2,929
    Post Thanks / Like
    Likes (Given)
    1041
    Likes (Received)
    1013

    Default

    Quote Originally Posted by billzweig View Post
    Electro-chemical or chemical polishing leave a shiny finish but not precise surface. It is mostly used for decorative, food industry, high vacuum, high voltage - for parts that need polished surface but not perfect mechanical or optical accuracy. Buffing will have a similar effect. If both accuracy and finish are needed, it can be done by fine machining or grinding and then lapping - for example ball bearings.
    Dimensional change from electropolishing depends heavily on initial surface roughness. It removes the high spots, so rough finish = significant dimensional change.

    We make some parts out of 17-4 that have close tolerances that are electropolished after machining. As long as the surface roughness out of the machine is in the 0.2-0.4µm ra out of the machine, then the dimensional change during polishing is in range of several µm only.

    OP's part certainly looks similar in finish to our 17-4 parts after electropolishing.

  14. #10
    Join Date
    Nov 2002
    Country
    UNITED STATES
    State/Province
    Texas
    Posts
    3,087
    Post Thanks / Like
    Likes (Given)
    1443
    Likes (Received)
    670

    Default

    As others have said, it is probably electropolished.
    With the exception of the fin at the bottom, it could also have been burnished as the final step in the turning process.

  15. #11
    Join Date
    Jan 2014
    Country
    UNITED STATES
    State/Province
    Washington
    Posts
    3,036
    Post Thanks / Like
    Likes (Given)
    581
    Likes (Received)
    1529

    Default

    Quote Originally Posted by litlerob1 View Post
    ......17-4, 304 and 316 finish absolutely beautifully. With a Wiper insert, high SFM and slow Feed I can get a finish pretty damn close to that right off the machine, with those SS's. I have achieved a 4µin. per the Profilometer.
    I think this is pointing the right direction.

    One screw machine place I installed several Citizens at would routinely do an 8µin finish as turned in stainless. Feeds were sometimes as low as .0002" per rev when cutting a .04" diameter.

  16. #12
    Join Date
    Aug 2006
    Location
    Wisconsin
    Posts
    1,510
    Post Thanks / Like
    Likes (Given)
    644
    Likes (Received)
    569

    Default

    Looks like a diamond polish to me. Any mold shop can do that on almost any material.

  17. Likes Greg White liked this post
  18. #13
    Join Date
    Dec 2008
    Country
    UNITED STATES
    State/Province
    New York
    Posts
    8,536
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    2275

    Default

    certain carbide inserts leave a shiny finish when sfpm is high enough and ipt is in the minimum range often .0030" ipt
    .
    cratex rubber abrasive sticks i hold in plastic hand holders (same used for abrasive stick polishing of molds) and hold against part spinning in a lathe. if acts like a rubber eraser and smooths finish. they come in coarse, medium, fine
    .
    also just using a buffing wheel parts can be hand held against to make shiny. the softer the abrasive the more it blends corners or effects shape, profile, tolerances. the harder it is the more it will true up the profile. just saying if cosmetic finish usually do not worry about removing .0005"
    Attached Thumbnails Attached Thumbnails shinymilling.jpg  

  19. #14
    Join Date
    Aug 2013
    Location
    Chicago, IL
    Posts
    618
    Post Thanks / Like
    Likes (Given)
    421
    Likes (Received)
    239

    Default

    Abdat60 - It looks a bit "cloudy" to me, like a foggy mirror...is it? If so, that would be vibratory finishing...different cutting/polishing medias used with different pastes/additives can smooth out machine marks and even shine them up like what I think I see. I do not think you can achieve a "perfect" mirror finish with that process but if it looks like there are microscopic dings a smudges on it when you look closely that could be your scumbag.

  20. #15
    Join Date
    Dec 2008
    Country
    UNITED STATES
    State/Province
    New York
    Posts
    8,536
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    2275

    Default

    Quote Originally Posted by Nerdlinger View Post
    Abdat60 - It looks a bit "cloudy" to me, like a foggy mirror...is it? If so, that would be vibratory finishing...different cutting/polishing medias used with different pastes/additives can smooth out machine marks and even shine them up like what I think I see. I do not think you can achieve a "perfect" mirror finish with that process but if it looks like there are microscopic dings a smudges on it when you look closely that could be your scumbag.
    .
    i have seen shiny surface where you could see a tape measure in reflection but not like you can read the small letters in reflection
    .
    buffed parts often a object with zebra stripes is held and you look at reflection to see how straight the zebra stripes look in the reflection. if distorted its cause part is not perfect or distorted
    .
    picture buffing to mirror finish
    Attached Thumbnails Attached Thumbnails buffingshiny.jpg  


Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •