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Mandrel Center Hole Size

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  • Mandrel Center Hole Size

    I purchased a set of expanding mandrels (0.5 - 1.0 inch). The center holes are only 1/8in in diameter.

    Click image for larger version  Name:	61aty8nTCyL._AC_SL1143_.jpg Views:	0 Size:	79.1 KB ID:	1874877

    Riten has a document on their site titled Center Hole Specifications. ( https://www.riten.com/wp-content/upl...nter-specs.pdf )
    According to that document these mandrels are limited to parts weighing less that 1 lb.

    They are listed as Lathe Mandrels, are they actually grinding mandrels?

    I am concerned that they would only be suitable for holding bushings.

  • #2
    Grinding and light lathe work, turning down bushings and that sort of thing, the same as solid lathe mandrels.
    I just need one more tool,just one!

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    • #3
      I can see the reason for the hole size on the small end of the 1/2" mandrel, but the entire set has 1/8" center holes.

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      • #4
        Bushings for sure. Just dont ask more from the tool than it is built for. Look like a nice set. JR

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        • #5
          If you do a little math, you will rapidly determine that ther is no consistency to the numbers. Slightly larger actual areas are allowed considerably larger pressures, NOT in proportion.

          Between 1 lb and 500 lb allowable, there is a 500:1 difference. The area difference is 19:1. The "stress on E" is 26:1. The shear stress is 32:1 Not a linear relation at all.

          If you use a solid center, use their numbers. If you use a rotating center, you can easily move up an entry, to 10 lb. I have a similar set, and have had no issues at the higher numbers. I use a rotating (ball bearing) center.
          CNC machines only go through the motions

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          • #6
            Originally posted by J Tiers View Post
            If you do a little math, you will rapidly determine that ther is no consistency to the numbers. Slightly larger actual areas are allowed considerably larger pressures, NOT in proportion.

            Between 1 lb and 500 lb allowable, there is a 500:1 difference. The area difference is 19:1. The "stress on E" is 26:1. The shear stress is 32:1 Not a linear relation at all.

            If you use a solid center, use their numbers. If you use a rotating center, you can easily move up an entry, to 10 lb. I have a similar set, and have had no issues at the higher numbers. I use a rotating (ball bearing) center.
            Now how come phukin drunk Poulice dont come after you? Hahaaa

            Haa, kidding. I like!!! JR

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            • #7
              Originally posted by J Tiers View Post
              If you use a solid center, use their numbers. If you use a rotating center, you can easily move up an entry, to 10 lb. I have a similar set, and have had no issues at the higher numbers. I use a rotating (ball bearing) center.
              Thanks for that information. I have a couple of rotating centers and will make sure to use them on larger parts. I considered opening up the center holes and decided it would be difficult keep them as concentric as they are now without regrinding the shaft.

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