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  • #61
    The wedge is only so thick.... these had about 0.8 inch to pull, so the wedge could break the "bond" created by the long tiome in position, but there was still a long pull. And the parts were tight, so it was a hard pull as well.

    As for yield point, not ignoring anything... if you recall I mentioned "not taking a set", which clearly would indicate not reaching the yield point. I try not to spout tech terms here if I don't need to, it's a bit elitist unless it is required for clarity..

    Bottom line is that if the same size, with same studs, and holes in same places, as certainly the case with the OTC vs HF, (a particularly poor design, as I will point out), you can expect the same amount of bending per unit pulling force. That will distort the bearing races the same amount, due to loading at two points on the outer race.

    Noe, if you look at the Snap-On, there is a key feature THAT COSTS NOTHING but improves performance.

    The OTC and HF have the puller stud holes out in the middle of the thing, midway between the "wedge studs" (the ones pulling the two halves of the "wedge" together). It's a HORRIBLE design.

    The S-O has the holes over near the "wedge studs".

    What that placement on the S-O part does is instantly convert the strong bending force on the "wedge studs" to more of a shear. The lever arm from puller stud hole to the "split" in the wedges is cut by a factor of between 2 and 3..

    Instead of a strong bending force on the wedge studs, tending to bend them in the space between the wedges, the bending is more along the body of each wedge, from stud to stud. The studs resist movement by more of a shear and far less of a bending action.

    There is no reason the company that made both the OTC and the HF could not have done that.... Any possible patents ran out years ago.

    I am strongly tempted to drill and tap holes over where they should be.... But so far I do not know what the thread size is, I may or may not have a tap for it.
    CNC machines only go through the motions

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    • #62
      On the other hand, by placing the pull points on the diagonal, the jaws are forced to tip, concentrating the pulling force unevenly on the jaws possibly causing them to fail.

      Ideally, the separators are used on a hydraulic press with proper platens to take the pulling forces, in which case the drawbolt location makes no difference. When used with a strongback and jackscrew, there will be tradeoffs.
      Jim H.

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      • #63
        Originally posted by J Tiers View Post
        But so far I do not know what the thread size is, I may or may not have a tap for it.
        Well'' I ponied up for the $70 XXR Branded set (stickered "Made in Taiwan"). (1/2 the price of the OTC set).

        It feels well made ..the clamps are heavy, with a very smooth silky finish to them. Hard to a file and not cast.And a mix of both metric and imperial threads.

        The connecting bars threads are 3/8 (0.360) x 16

        The clamps are 10mm x 1.0mm and 12mm x 1.25mm and the drive screw is a 13mm x 2.0mm
        YMMV.
        Rob

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        • #64
          Originally posted by JCHannum View Post
          On the other hand, by placing the pull points on the diagonal, the jaws are forced to tip, concentrating the pulling force unevenly on the jaws possibly causing them to fail.

          Ideally, the separators are used on a hydraulic press with proper platens to take the pulling forces, in which case the drawbolt location makes no difference. When used with a strongback and jackscrew, there will be tradeoffs.
          Very doubtful......

          I do not see the 'forced to tip" at ALL.....

          If anything, the insanly stupid positioning of the OTC and HF holes CLEARLY "forces them to tip"..... I'll take your "maybe possibly might could sometimes tip" over the "known to be stupid and will bend and tip every single time" OTC and HF setup.....

          It's the same forces, just a LOT less of them with the better pullers. And no cost to the change.

          Somehow I doubt HF and OTC have a better idea than Snap-On and everyone else that makes "real" tools. HF does not talk to mechanics, they look at competitor catalogs for ideas.... or maybe only at what their suppliers present to them.

          Whatever... The HF did pull it, did the things you suspect they cannot, and nothing broke....
          CNC machines only go through the motions

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          • #65
            OTC has been in business since the mid twenties, about the same time as SnapOn. They were innovators in tools, primarily for the automotive trade as was SnapOn. They do not make knock off copies of other manufacturers tools as HF does, but have been making "real" tools of their own design, under their own patents for decades.

            https://home.comcast.net/~alloy-arti...y.html#pullers

            As far as tipping vs bending, the bolts might bend due to pulling forces with the pull bolts centered between the drawbolts. The jaws will always tip, causing the puller to assume an X configuration when pulling force is applied to the off center location.
            Last edited by JCHannum; 08-08-2014, 10:18 AM.
            Jim H.

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            • #66
              I know how to end this>>>

              Jim, you are right.

              There, does that help?
              CNC machines only go through the motions

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              • #67
                Heck, it could end (unlikely) with "hey Jerry, Jim is right".
                Last edited by lakeside53; 08-08-2014, 11:47 AM.

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                • #68
                  There is not really a right or wrong, just two sides to the coin. In a reasonably low pressure, infrequent pulling application such as yours, the discussion is pretty much moot. However in shop where they might be subjected to real work, the HF unit is potentially a waste of money while the OTC stands a good chance of being a useable unit.
                  Jim H.

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