shimming less than 0.0004" - Page 4
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  1. #61
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    only picture i got of tang slide part. close up because was having a mill pass lap problem at the bottom of a bore using a 18" long tool holder.
    .
    as you can see the parts i mill are not simple cube shapes
    .
    still not sure why the lap problem. possibly the long tool holder milling harder metal was vibrating more than normal. kind of hard to get a 1.75" dia mill sticking 18" out of spindle to cut extra accurate
    Attached Thumbnails Attached Thumbnails bn_problem_after1st_finish_2015_b.jpg  

  2. #62
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    Wait a minute! Am I the only one to notice numerous suggestions to shim with unstable things?

    paper
    plastic
    paint
    crayon
    embossed/wrinkled shim stock
    Even variable torque (bolts tend to relax with time)

    All these things will move in time; nice flat metal shims is the way to go!

  3. #63
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    Quote Originally Posted by greif1 View Post
    Wait a minute! Am I the only one to notice numerous suggestions to shim with unstable things?

    paper
    plastic
    paint
    crayon
    embossed/wrinkled shim stock
    Even variable torque (bolts tend to relax with time)

    All these things will move in time; nice flat metal shims is the way to go!
    .
    thats why i will order the 0.03mm steel shim .0012" in 1/2" wide rolls. it is the most stable and a difference of a .001" shim on one end of a part and a .0012" at the other end of a part is .0002"
    ....... and both will go in a gap with my body flat on a table reaching in my arm a few feet much easier than a flimsy shim thinner than .001"......... onion skin or plastic shims of only .0004" thickness are difficult to work with, fold over too easy putting in a 0.1" gap

  4. #64
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    You could shellac the onion skin between two shims, and shellac another two identical shims together w/o onion skin.

    I wonder if you could take a 0.005 or a 0.010 shim and put a kink in it. It would than give a slightly different height than an unkinked shim. Would this work?

  5. #65
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    Quote Originally Posted by bosleyjr View Post
    You could shellac the onion skin between two shims, and shellac another two identical shims together w/o onion skin.

    I wonder if you could take a 0.005 or a 0.010 shim and put a kink in it. It would than give a slightly different height than an unkinked shim. Would this work?
    .
    easiest and most reliable is for me to order a roll of 0.03mm steel shim stock.
    .
    a lot of things could work, might work for the time it takes to do the job, but i can cut a 0.03mm shim in 2 seconds so thats the fastest once i have a roll of it

  6. #66
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    Default another picture

    another picture of part i was shimming with 6" dia face mill shown after rough machining
    .
    fixture holds part in 3 different orientation for 3 different operations.
    .
    part resting on 3 pads on ends that i shimmed. normally pads are not all the way on the ends of a part but spaced 0.7 apart of the part length to lower sag amount from gravity
    .
    there is nothing currently under part center. it warped curve shape up in center (opposite gravity sag) after a machining operation on the part bottom. what was once flat was no longer flat or planer
    .
    i ordered a roll of 0.03mm feeler gage shim stock which with .001 and .0015" shims gives a .0002 and .0003" elevation difference
    Attached Thumbnails Attached Thumbnails 210_tangslidehobheadcomponent_2ndop_3b_closeup.jpg   210_tangslidehobheadcomponent_2ndop_3b_smaller.jpg  

  7. #67
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    I thought I was a machinist.

  8. #68
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    Sorry to dig up an old post.... At an older shop I use to use onion paper with great success. I cant find anywhere what I use to use. We had a roll of it about 1 inch wide. Anyone have a vendor for this?

  9. #69
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    I think the roast beef at Arby's is a little thinner than that.

    Zig Zags are about .0005

  10. #70
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    The zig zags work ok, are too small size wise and I don't like the creases in them. I also found that when you put a thin film of light oil on the part the shims stay in place pretty well before you clamp it down.

  11. #71
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    I've never been a fan of thin shims, especially if they are made of a soft material. What has worked best for me are square-washer-shaped spacers of ground flat stock 3/8 inch to 1/2 inch thick. Match-grind to thickness if needed, install, and determine which spacers are too thick, and by how much. From that point, it's a metter of removing the oversize spacer(s), thinning it (them) as necessary, and reinstalling.

    If I recall correctly -- it's been quite a few years since I was the hands-on workerbee -- it takes roughly 100 feet of firm-pressure stroking on kerosene-wetted 240-grit wet-or-dry to thin a spacer 0.001 inch.

  12. #72
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    A human sperm is about .0002 diameter....I would just stack two of those and call it a day.

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    You must be quite the tool maker

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    .001 and .0015 and .0005 are so difficult to use and keep nice it would seem a manufacture would/could make .020 .0201. .0202 and on up to .021. in a set (and a metric set) 1/2" or 1" wide that could be purchased as a catalog item. Likely it could be a low priced set.

    I used to make my own back when doing fancy grinding, along with catalog .005, .010 .015 (and up) with these in different length so easier to identify, I also would mark them with the side of a Dremal point so having a marking that would not distort (like an electric etcher)

    Agree SS is/can be a bugger to grind
    Last edited by michiganbuck; 12-10-2019 at 09:01 AM.

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    ''shimming less than 0.0004" ''

    Use a smaller hammer.

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    Sounds like a place i worked. A guy comes up and asks for some banding. I give him a piece i have handy. He says no, i need some of that thicker banding. Glad i dont work there anymore. And yes, they did it that way for 40 years, and probably still do.

  17. #77
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    Shimming a large block on a magnet does not work with thicker shims, If it was clamped to a angle iron or something that is a different story.

  18. #78
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    QT:[i am just asking, does anybody have a better way of shimming heavy castings of less than
    a .0004" ]
    I don't have any better way..than map it on the plate if that is where it will be inspected.. and then find the the tested amount (of needed take) at the position where it will be machined or ground. looks like that is what you are doing...


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