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Thread: Basic Question - Dial Indicator, Drill Press, Runout

  1. #1

    Basic Question - Dial Indicator, Drill Press, Runout

    Hi everybody... basic usage question here. I finally splurged on myself and picked up a cheap (splurge and cheap? oxymoron?) HF dial indicator set. Actually, I bought it to correctly diagnose my car's brake pulsing problem, but that's a different story.

    Anyway, usage seems really straightforward and I can't really think of another way to do it, but I want to run my procedures by y'all.

    So when setting it up, I need to setup the clamp/holder thing so the indicator is already depressed on the surface I shall be indicating, right? Then I re-zero?

    I setup the kit so the indicator is at like 0.125 or 0.250 or whatever, then spin the dial face to set to zero, then spin the subject piece to find the low spot, etc etc?

    Even though it's a Harbor Freight tool, I don't want to use it incorrectly.

    Anyway, as a test, I put it on my drill press. I have a 3" arbor extension adaptor on it because.... well, no reason, it came with it! The adaptor appears to have .003" runout. My chuck itself appears to have .0015". I'm estimating the "5". The needle goes over the .001" line, about half way to the .002". I was just spinning the chuck... as I'm typing this, I think I should've been indicating on the chuck, but spinning the arbor....hmmmm.... Anyway, If I understand run-out correctly, this should result in about .0045" runout once it all starts spinning together. Is that right?

    Is that excessive? Did I even do it right? I was spinning everything by hand, should I have set the speed to the lowest and run it off the motor?

    Any insight is appreciated. Thanks!

  2. #2
    Join Date
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    I have no idea whether the 2 readings are additive (they may be subtractive), but you could chuck up a rod and measure the runout on that. It's best to have an accurate one, so using a large drill bit upside down (to read on the smooth shank) works. Your dial indicator technique is fine, and I had to buy a new chuck to get my DP down to .005", that's plenty close for woodworking efforts...though I suspect machinists would want it a little closer. BTW, spinning by hand is the safest; but mostly the indicator will bounce so much you likely wouldn't be able to read it. You shouldn't apologize about the HF indicator....it's just fine for most of the stuff done in a home workshop. One more thing, a set of interchangeable tips for the indicator is really handy. Most of them are threaded 4-40 and take tips like these.
    Last edited by fred hargis; 07-07-2014 at 12:51 PM.

  3. #3
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    Another thing you could do is to check how square the DP spindle is to the DP table is to chuck a 90° rod & attach an indicator to the horizontal arm of the rod. With the chuck in the full up position sweep the table & mark the readings at 90° increments, i.e. 12/3/6/9 o'clock positions, on the table. Then extend the spindle fully down & repeat. Compare the readings & adjust the head accordingly.
    Thoughts entering one's mind need not exit one's mouth!
    As I age my memory fades .... and that's a load off my mind!

    "We Live In The Land Of The Free, Only Because Of The Brave"
    “The problems we face today are there because the people who work for a living are outnumbered by those who vote for a living."
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    Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy, its inherent virtue is the equal sharing of misery." Winston Churchill

  4. #4
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    You set the indicator tip as "perpendicular" as possible to the thing being measured. ANY - angle will add error to your readings. The closer you are to "exact" perpendicular" you are the lower the error.

    Also - get the tip as close as possible to - pointing precisely to the CENTER of the spindle" as possible.

    Find the low spot.

    Press the indicator to turn the needle ~ABOUT~ 1/4 rotation - so that it point to the top of the indicator.

    Turn the bezel so that the zero is on the pointer.

    Rotate the shaft one time - 360 degrees.

    The TOTAL reading - the worst case - is called TIR = Total Indicator Reading

    THAT - is your runout reading.


    There are a couple of other tests you can do, but my lunch break is near over and I need to finish eating.

  5. #5
    Hey, there we go!

    New readings make more sense. I knew this drill press couldn't be that good!

    I chucked up a 7/16 drill bit and took a reading off that. Got 0.008-0.009-ish. That makes more sense to me considering this is a cheap Taiwanese press that just turned 30 years old.

    The weird thing is that it almost seems like the true reading was around 0.005 but then there was a bump. The needle oscillated between 0 and 5 for about 180* then upped to 8-9ish in about 45* of turn, stayed there for about 90*, then dropped all the way back down to my zero point in the last 45*. Seems to me, if the shaft was truly following an oval path, the high point should be 180* from the low, not 270-315*.

    Thanks for the tips. I played around with it for 20 minutes or so last night and think I have the hang of it. Enough of a hang for woodworking, anyway!

  6. #6
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    Sooo - after taking that data on runout what does it all REALLY mean anyway?

    Consider HOW a drill works - what it really does, and what our expectations are.

    A drill does NOT cut on the sides of the drill.

    The sides of the drill are called "margins" - do not cut - but really act as a guide to guide the drill along it's path - kinda like a float.

    So - with that in mind - does a drill press really need to be within some high level of accuracy?


    Then again - what is the manufacturers spec for runout?

    And what is required for what we do?

    That .008 does not sound horrible to me considering what the tool does for a living.

    Sometimes the BIGGER - reason is not about the performance of the machine - but rather how we feel about it.

  7. #7
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    Somethings to consider:

    • Was the chuck clean, i.e. did you lightly tap the chuck to "shake out" any sawdust, or whatever, from within the chuck & jaws? Sometimes build-up occurs that can affect the seating of the drill within the chuck jaws.
    • Although the margins do guide the drill in the hole, are the cutting edges (lips) of of the drill of equal length? If not, then that can cause the bit to "walk" & affect the actual cut size of the hole despite the margins..
    • If you have a drill blank, or a long enough dowel, or any uniform "quality" diameter, that would be a more reliable surface to indicate from than a drill that might be cheaply made.
    Thoughts entering one's mind need not exit one's mouth!
    As I age my memory fades .... and that's a load off my mind!

    "We Live In The Land Of The Free, Only Because Of The Brave"
    “The problems we face today are there because the people who work for a living are outnumbered by those who vote for a living."
    "
    Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy, its inherent virtue is the equal sharing of misery." Winston Churchill

  8. #8
    Quote Originally Posted by Leo Voisine View Post
    That .008 does not sound horrible to me considering what the tool does for a living.
    Yup, exactly. 1/64 of an inch is .015625. So I've got a smidge more than 1/128 out of round. This is wood. Drilling a 1/4" hole and ending up with a 33/128" hole is not the end of the world.

  9. #9
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    Well what you are checking is the sum of all the errors.

    At least three.
    1 Total spindle and MT run out.
    2. Chuck arbor and jaw run out.
    3. Any run out on your standard. (The drill bit)

    To see what your drill is really like pull the chuck add set up the indicator to measure the run out on the MT bore in your spindle..

    A better cheap standard than the drill bit is a steel dowel pin.

    I suspect most of your error is in the chuck...

    Garry

    PS
    I have a bunch of 1/4 dowel pins I would send one to anyone wanting one.. Not checked or a standard but usually very true as they are almost always center-less ground..

    Another quick check is to use 2 different diameters in the chuck. If the run out changes then the chuck is very suspect.

  10. #10
    Quote Originally Posted by Garry Foster View Post
    I suspect most of your error is in the chuck...

    Garry

    Another quick check is to use 2 different diameters in the chuck. If the run out changes then the chuck is very suspect.
    Ha, better not be the chuck! Manufacturer says it's good to 0.002 or better.

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