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Thread: Giant Calipers

  1. #1
    Join Date
    May 2008
    Location
    Sacramento Area
    Posts
    170

    Giant Calipers

    Harbor Freight sells a 24" aluminum caliper that I have found very useful around the lathe.

    I use it to set the 10% bowl blank thickness without doing any "hard" math. First, get the diameter of the blank:

    P1040191.jpg

    Since the caliper is scaled in both metric and imperial units, it is easy to reset the caliper to 10% of the diameter using the metric scale. I sharpened one of the arms of the caliper and use it to scribe the 10% line. It clearly marks the 10% line and provides a stop for potentially wandering bowl gouges.

    P1040192.jpg

    I also use the caliper to check bowl depth. I first read the overall depth of the bowl blank:

    P1040193.jpg

    I then measure the depth using a stick and metal rod:

    P1040194.jpg

    I can directly read the bottom thickness off the caliper:

    P1040195.jpg

    If you can remember your 10% thickness number you know your target depth. Or use one caliper for depth and one for diameter, and save the brain cells for something more important

    The calipers run about $10 and can easily be cut to shorter lengths, if needed. They are adjustable as well, and the reference arm can work loose so it pays to recalibrate occasionally.

  2. #2
    Ken, thanks for the post!! That is a neat idea, and affordable, too! And, at my age, saving a brain cell is very important!

  3. #3
    Join Date
    Jan 2009
    Location
    Harrisburg, NC
    Posts
    814
    Good idea Ken. I really like the marking of the wall thickness at the rim with it. Instead of 10% I use the easy math and leave 12.5%.
    At $10, thats so cheap it is not worth trying to make one.
    "I became insane, with long intervals of horrible sanity." - Edgar Allan Poe

  4. #4
    Join Date
    Nov 2010
    Location
    Littleton, Colorado
    Posts
    1,320
    Hey thanks a lot for this info, they just build a new HF like 5 blocks from my house, I think I am going to pay them a visit this morning while out running a few errands!

    EDIT - I am normaly very careful about what I buy from HF, you just have to know what it is right up front....lets face it we know they are not known for the highest quality tools & supplies, however I did go and look at this caliper this morning and for what it is, and for the price you just cant beat it, I picked one up and am very happy with it, thanks again for the heads up on this!
    Last edited by Tim Thiebaut; 02-14-2011 at 2:15 PM.

  5. #5
    Join Date
    May 2005
    Location
    Gainesville, Florida
    Posts
    81
    I have what appears to be that same caliper, bought years ago and not from harbor freight. Don't expect accuracy from it unless you check it first. Even though mine zeros correctly, it's off by nearly 1/16" at 22".

  6. #6
    Join Date
    May 2008
    Location
    Sacramento Area
    Posts
    170
    Tim,

    Glad you found it useful. Like you, I generally have low expectations for HF stuff, so I am rarely disappointed.

    I am surprised often enough, though, to keep going back. I saw the caliper a few months ago and thought it was more a novelty than a useful tool. Then I had one of those light-bulb-going-off moments.

    Scott,

    I agree it is not very accurate, and the reference arm on the HF version can work loose and make the normally somewhat inaccurate reading even more inaccurate. It is accurate enough for roughing out bowls, but I wouldn't use it for much else.

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