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Thread: Bending formulas

  1. #11
    Join Date
    Jun 2006
    Location
    Ohio
    Posts
    12,665
    Quote Originally Posted by K2500 View Post
    Excellent illustration, I’m just not sure how to use it. What does “r” define?
    It is the radius (r) of the bend to the centerline of the conduit. If you use a triple nickle (Greenlee 555 Electric Bender), it is embossed on the shoe. For most hand benders, it is the deduct for a 90° bend minus one-half the outside diameter of the conduit. Other benders, such as Greenlee hydraulic ones, it should be in the bender's manual (manuals for Greenlee benders can be obtained in pdf format from their website).

  2. #12
    Join Date
    Jan 2009
    Location
    ORLANDO FLA
    Posts
    1,237
    Well we bend lots of pipe everyday with greenlee benders our company has a few . Let me recommend a book which ive had for many years.

    Its called the Electricians Guide to Conduit Bending by Richard A. Cox .
    You can get it at any construction book store ,it has shrink and its great for bending rigid conduit meaning doing all cutting and threading first then do your bending last its a good book if you install lots rigid or aluminum conduit.
    We take our benders when new and start off bending some scrap with measurement from center point to end of conduit in inches per degrees of shrink of take up of each 5 ,10,15,20,30,40,50,60,70,80,90.

    Meaning for each pipe size we kick at these angles and then record on a chart .
    So our guys know what that bender can give them this is great for racks change in direction and when you need to kick and come back to center point of stub ups you know your shrink at that degree from center of bend to end of conduit !! we install lots of large racks and lots of rigid . Formulas are generally good but there is always a need to actually bend some scrap conduit and record what that bender can do it really saves lots of dollars on rigid we do it to all our benders and have a book near by for the bending crew everyone likes this . Its a time savor! heres my work many years ago http://i611.photobucket.com/albums/t...pes001-1-1.jpg Take care be safe
    Last edited by ohmhead; 04-03-09 at 06:00 PM.

  3. #13
    Join Date
    Jan 2007
    Location
    Texas
    Posts
    239
    I always mess up when trying to get shrink for kicks, it has never worked out for me, but any thing that keeps me from having to go find my hardhat[thrown in anger]is a plus.
    Next slow day I'll give your method a try on some scrap.

  4. #14
    Join Date
    Jan 2009
    Location
    ORLANDO FLA
    Posts
    1,237
    Well the method is basic stuff nothing special ,just take each conduit size in its bending shoe kick it up at what ever degree you need and record the shrink at that angle ,you can see it happen without a formula just measure it .

    We use it on underground also in a duck bank a turn in bank then say a group of 90 s stubbing up thur slab .

    We already know at what angle we need in direction and now we know the added or deducted length at that degree to the end of the conduit or how much to add or take away on opposite end due to shrink .

    Just to add most electricians when they bend a 2 inch conduit say a back to back in a electric bender they always deduct and bend that long part up !! we do the short part backwards meaning towards the other first bent 90.

    We have a chart with BB any size measured length for that bender on back to backs we bend the short part and measure as we bring that 90 up meaning a more accurate method and its leveled in the shoe as your looking at it the actual back to back is bent back to back and level before you take it out of shoe you can measure distance of BB length .

    Heres one for free in 555 bender greenlee back to back 2 inch conduit measure from first bent 90 to second mark meaning length of needed back to back distance then add this lenght to mark 9 5/8 of a inch bend up tell me you dont have a perfect BB at that BB distance you needed! let me know what you think ,Take care
    Last edited by ohmhead; 04-03-09 at 10:30 PM.

  5. #15
    Join Date
    Apr 2004
    Location
    Back in Alaska, on a "Jack Bauer" job!
    Posts
    1,708
    With a triple nickel, there are a lot of "alternative bending formulas" to use measuring how much travel, etc. The more one is on the same machine, the better one gets.

    Can't over emphasize that most conduit (over2") is bent use center of pipe for accurate bending.
    Don't let fear be your guide!

  6. #16
    Join Date
    Apr 2008
    Location
    Washington State
    Posts
    14

    Smile Free Stuff

    I am surprised that so many of the responses are not aware of the free stuff section of the Mike Holt web page.

    Go to the free stuff and you will find an excellent download that will give you all the information that you are asking for. If free for the taking so go get it and be informed.

    A simple one to remember is that with the angle of 30degree it carries a multiplier of 2 -- so if you want an offset of 4" -- mark on the conduit that you want to bend 2X 4" = 8" and place the bender on the first mark -- bend it to the 30 degree mark, rotate the conduit, move to the other mark and bend it to the 30 degree mark -- WALA you have a 4" offset -- if you want the take-up or shrink -- you must read the direction found on the download from Mike Holt's free stuff. so if in doubt always visit the Mike Holt free stuff section -- you will be amazed that all of this stuff is free --- yes free. So be smart -- ask Mike 1st he has given us many good things to be thankful for and they are --- YES FREE

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