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Thread: Conduit bending table

  1. #11
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    The shop I work for owns several 881 CT's.

    I was assigned to a job recently that called for thousands of feet of 2.5", 3.5" and 4" EMT. I had never installed that size pipe before, let alone bent it. Others on the crew had never used the "table bender" as we call it either. So they brought the bender to the job and our in-house instructor came and showed us how to use it.

    Within a day we were all bending the stuff like we had been doing it for years. The bender is very easy to use. It's the same principles as hand bending but with much larger multipliers and distances between bends.

    Bottom line, you can do some very professional looking work with a large bender.

  2. #12
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    Quote Originally Posted by peter d

    Within a day we were all bending the stuff like we had been doing it for years. The bender is very easy to use. It's the same principles as hand bending but with much larger multipliers and distances between bends.
    .
    huh?

    The mutlipliers are the same regardless of conduit size. The multipliers relate to the BEND - not the CONDUIT. The distances between bends is based on the multipliers, which are consistant regardless of conduit size.
    ie,
    15° = x3.86
    22.5° = x2.6
    30° = x2
    45° = x1.41

    See: http://www.porcupinepress.com/_bending/offsets.htm*
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  3. #13
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    Red face

    I stand corrected. Darn memory again.

  4. #14
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    Quote Originally Posted by peter d
    I stand corrected. Darn memory again.

    Well, you were partially right. The stub up deductions are much greater with the larger conduit. A typical 3/4" bender would have a deduction of 6" for a 90 degree bend. A piece of 3.5" on a 881 would have a deduction around 21" for a 90 degree bend.
    Rob

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    All responses based on the 2011 NEC unless otherwise noted

  5. #15
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    Jun 2006
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    Quote Originally Posted by celtic
    Quote Originally Posted by peter d
    Within a day we were all bending the stuff like we had been doing it for years. The bender is very easy to use. It's the same principles as hand bending but with much larger multipliers and distances between bends.
    huh?

    The mutlipliers are the same regardless of conduit size. The multipliers relate to the BEND - not the CONDUIT. The distances between bends is based on the multipliers, which are consistant regardless of conduit size.
    ie,
    15° = x3.86
    22.5° = x2.6
    30° = x2
    45° = x1.41

    See: http://www.porcupinepress.com/_bending/offsets.htm*
    Quite correct... but I believe peter was referring to multipliers and distances in the small offset range of large conduit when compared to small conduit. For instance, because the centerline bend radius of 4" EMT on a 881 is 21", you cannot make a 30° offset that is less than 10". You have to resort to an offset angle that is less than 30° where the multiplier and distance between bends are greater than doing a bend of the same offset distance using 30°with small diameter conduit.

  6. #16
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    Quote Originally Posted by Smart $
    For instance, because the centerline bend radius of 4" EMT on a 881 is 21", you cannot make a 30° offset that is less than 10".
    Actually, you (probably) can
    Instead of using the "push thru-method", make one bend, remove pipe from bender, insert other end.
    This was a "technique" we came up with when we needed some ridiculous bends on 4" GRC.
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  7. #17
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    Cool

    Quote Originally Posted by Smart $
    Quite correct... but I believe peter was referring to multipliers and distances in the small offset range of large conduit when compared to small conduit.
    Yes, that was exactly it. Thanks for the refresher.

    We had to make a lot of small offsets and that problem came up repeatedly.

  8. #18
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    Quote Originally Posted by celtic
    Actually, you (probably) can
    Instead of using the "push thru-method", make one bend, remove pipe from bender, insert other end.
    This was a "technique" we came up with when we needed some ridiculous bends on 4" GRC.
    Quite true, because you eliminate the straight section between bends required for the bend mark to beginning-of-bend distance—a whopping 8.5"/8.75" for 4" EMT/GRC on the 881. So one could, theoretically, make a 6" 30° offset of 4" conduit on the 881. The minimum 10" offset I mentioned above is from the manual. However, the manual does not explain how to do tail-to-tail bent offsets

  9. #19
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    Quote Originally Posted by Smart $
    However, the manual does not explain how to do tail-to-tail bent offsets
    Isn't that always the EC's complaint: Book learnin' ain't a complete education
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  10. #20
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    Quote Originally Posted by Smart $
    However, the manual does not explain how to do tail-to-tail bent offsets
    Speaking of which, is there something online that references that?

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