Thread gages and Hardcoat Anodize
Close
Login to Your Account
Results 1 to 11 of 11
  1. #1
    Join Date
    Feb 2017
    Country
    UNITED STATES
    State/Province
    Maine
    Posts
    85
    Post Thanks / Like
    Likes (Given)
    64
    Likes (Received)
    42

    Default Thread gages and Hardcoat Anodize

    So I need to source some gages for an upcoming job. The customer requirements state a .001" type 3 hardcoat, no masking. So, I sent off the thread sizes and that plate spec to a couple thread gage shops. Within a day I hear back from them both. The thread gage dimensions don't agree between the two shops...
    I pressed them both to confirm that these were gages for .0005" buildup, to which they said both said yes.

    Hardcoat puts .0005" into the material, and .0005" external. I know it's a 4:1 ratio on the P.D, but I'm uncertain of the math involved to calculate the following:
    Major Diameter
    Pitch Diameter
    Measurement over wires

    Thread sizes are:
    1.187"-16 3B
    .250-28 3B


    The lead time on one of the shops was 9-12 weeks, the other was half that. But, I don't even know which one is the correct dimension. Would rather solve that before dropping $600 in gages only to find out they aren't correct.

  2. #2
    Join Date
    Jun 2020
    Country
    UNITED STATES
    State/Province
    South Carolina
    Posts
    79
    Post Thanks / Like
    Likes (Given)
    30
    Likes (Received)
    23

    Default

    You have me confused if you are making internal threads I don’t think you can use wires . Also it’s been my experience that internal features get less buildup you should talk to your finisher . Either way you should add or subtract .002 form your pitches depending on inside or outside . .001 from either major or minor depending on which one . When you send the parts if you have finish gages send them to the plater with the parts to be safe.
    Good luck
    Pete

  3. #3
    Join Date
    Feb 2017
    Country
    UNITED STATES
    State/Province
    Maine
    Posts
    85
    Post Thanks / Like
    Likes (Given)
    64
    Likes (Received)
    42

    Default

    Thread gages. This is a question about the proper dimensions for plug thread gages used to check an internal thread that's been hardcoat anodized. I spoke to the plater and he passed the buck off to the thread gage company. He's like "man, I just coat parts for a living, I don't know none of that stuff"

  4. #4
    Join Date
    Jun 2020
    Country
    UNITED STATES
    State/Province
    South Carolina
    Posts
    79
    Post Thanks / Like
    Likes (Given)
    30
    Likes (Received)
    23

    Default

    Sounds like you need to find a different finisher . Over the years I’ve made tons of parts and never had a problem my customer sends the parts to a place in conetict. It’s a pretty precise process and they should be able to control it so I don’t see why they can’t give you better guidance.try asking a different vendor also if they certify for mil spec or aviation they would be a better bet.
    Good luck
    Pete

  5. #5
    Join Date
    Feb 2017
    Country
    UNITED STATES
    State/Province
    Maine
    Posts
    85
    Post Thanks / Like
    Likes (Given)
    64
    Likes (Received)
    42

    Default

    That doesn't do anything to answer my question. I need a thread gage to make these parts. Plater tells me it's .0005" buildup on a surface (+/-.0002). I go to two thread gage manufactures and give them that info. They provide spec sheets for approval. Those two sheets SHOULD be the same numerical values. They aren't. How do I calculate which one is correct? On thread 60 deg angle, the ratio is 4:1 of growth. I have a general idea on how to cut (and measure) external threads to compensate for coat (measuring over wires), but I don't know if that's a 1:1 translation to thread gage dimensions. For example, a 1/4-20 plug gage will not thread into a 1/4-20 ring gage. They are different. So, on a plug gage, what are the dimensions I need to learn?

  6. #6
    Join Date
    Jan 2014
    Location
    Temecula, Ca
    Posts
    3,302
    Post Thanks / Like
    Likes (Given)
    1401
    Likes (Received)
    4316

    Default

    I have a customer who uses Precon preplate gages. We've never had a problem, so you might want to check and get a third quote from them. Don't cost nuthin.

  7. #7
    Join Date
    Mar 2017
    Country
    LATVIA
    Posts
    772
    Post Thanks / Like
    Likes (Given)
    213
    Likes (Received)
    450

    Default

    anodizing grows perpendicularly to the surface - I suspect that is where your "4:1 ratio" comes from, if draw cross section of your thread in cad, add half of the total thickness of to the thread slopes, draw in tangent circles to new slopes representing thread wires, measure distance between the circles and you'll have your distance on the wires, then add the necessary +/- thread tolerances for those sizes and you'll have your true gage dimensions

    I'd do the numbers, but I'm from metric land, so it is a bit too much of a work for me to look all the necessary stuff up and make the drawings

    considering the larger thread size and its standard tolerances, I think you should be fine with a standard thread gage for that thread, the added thickness of the coating (which is quite low for a hardcoat...) would still should be well within the standard tolerances for that thread granted you hit the size close to middle of the tolerance, smaller fine thread would be another matter

    p.s. more of a note to the designer of such parts - depending on where the holes are on the part and how the part is positioned in the tank, it is entirely possible for blind holes oriented downwards to have the plating only maybe a diameter deep - this is because the hole may be filled with air or rinse water and may not have enough of flow around it to replace the rinse water with electrolyte (no electrolyte = no oxide growth), and a gas ir formed during the oxidation process - this pushes out electrolyte/water out of downward facing blind holes which leads again to low or no plating inside the holes

    through holes (of reasonable size) should be fine and have very similar thickness to the outside of the part

  8. #8
    Join Date
    May 2011
    Country
    UNITED STATES
    State/Province
    New Jersey
    Posts
    2,802
    Post Thanks / Like
    Likes (Given)
    275
    Likes (Received)
    1530

    Default

    Quote Originally Posted by upm2019 View Post
    Sounds like you need to find a different finisher . Over the years I’ve made tons of parts and never had a problem my customer sends the parts to a place in conetict. It’s a pretty precise process and they should be able to control it so I don’t see why they can’t give you better guidance.try asking a different vendor also if they certify for mil spec or aviation they would be a better bet.
    Good luck
    Pete
    Was that supposed to be Connecticut?

  9. #9
    Join Date
    Jul 2012
    Country
    UNITED STATES
    State/Province
    Washington
    Posts
    3,359
    Post Thanks / Like
    Likes (Given)
    1369
    Likes (Received)
    1483

    Default

    I went through some of this a while ago. After trying to figure it out using trig I finally modeled it in cad, which finally showed me what I was missing, it's complicated. As others have said, and my anodizer, the size of the threaded holes really needs to be tested with sample parts as it is not something you can estimate accurately. As you know that 28 tpi 3B is going to be the fun one to get right so you better make the holes dead nuts on the center of the tolerance to give your anodizer as much room as possible. If it was me I would be specing the size of the thread gages a lot tighter than 3B, maybe half the tolerance or less, for the threads before anodizing, once you figure out what that size is with your anodizer. Another vote for sending finished thread size thread gages with the parts to the anodizer too since their work will be your biggest variable.

  10. #10
    Join Date
    Jun 2020
    Country
    UNITED STATES
    State/Province
    South Carolina
    Posts
    79
    Post Thanks / Like
    Likes (Given)
    30
    Likes (Received)
    23

    Default

    I’m a good machinist but can’t spell sorry

  11. #11
    Join Date
    Jan 2014
    Location
    Temecula, Ca
    Posts
    3,302
    Post Thanks / Like
    Likes (Given)
    1401
    Likes (Received)
    4316

    Default

    Quote Originally Posted by upm2019 View Post
    I’m a good machinist but can’t spell sorry
    looks like you spelled sorry ok

  12. Likes Liberty_Machine liked this post

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
  •