Back to back bends using (1) 10 ft, 2" conduit with an old Green lee 855 beder

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maghazadeh

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Campbell CA
Hi everyone,
I am going to bend a 90, a kick, and second 90 on one 10 ft length piece of 2" EMT conduit using an old Green lee 855 smart bender with standard pendant. The same bends will be applied for 6 different runs of conduit. I will do the two 90 bends plus adding shrinkage for a 22-1/2 degree kick bend (between the two 90 bends), then at last I will bend the kick bend to avoid dog leg.
I have the instruction book that came with the bender, and there is plenty of information to bend 90, offsets, 3, 4 point saddle, and U-bends, but reading the special bending chart is confusing to me.
For a 90 stub up for a 2" EMT the chart says Minimum stub length = 18-3/8" and deduction (take up) for the mark #1 is 16-3/8".
The route that the conduits will take is;
50" straight up to the top of first 90 (out of cabinet) changing from vertical to horizontal plane.
Horizontal distance between the first 90 and the second 90 is 46" from outside-to-outside the conduit.
A 22-1/2 degree kick between the two 90 bends, changing direction in the same horizontal plane. ( shrinkage is 3/16" for every 1" of rise for a 22-1/2 degree bend) my directional change and/or rise is 11" so shrinkage that will be added to the length between the two 90 is
(11" x 3/16" = 2.0625"). So roughly 48" between the outside to outside of 90s.

As an example: back to back bends for a 3/4" EMT conduit, for the first bend measuring the same direction as bending deduct 6". Second bend, bending opposite direction to measuring add 3". these numbers will give a desired distance from outside to outside of the 3/4" conduit.

Question #1: Can I use the same principle as the example above for a 2" EMT?? Meaning for first 90 (50" - 16-3/8" = 33-5/8" bending mark #1).
Bending 2nd 90 opposite to measuring direction and using (half of deduct / take up amount 16-3/8" divided by 2 = 8-3/16") so,
distance between the 1st & 2nd marks outside to outside is ( 46" + 2.0625" shrinkage + 8-3/16" adder for 2nd mark = 56.25" or 56-1/4")

Question #2: does the calculation and steps above seems right to you?

Question #3: Is outside to outside measurement correct method for this size conduit?

Question # 4: Can you think of any easier way to achieve this challenge other than cutting the conduit between the bends and using couplings??
I'm pretty sure there are bunch of smart ones out there, so please help. Thank you in advance for any help I get.

Best,

Max
 
When measuring for the second 90 in a back to back bend, using half the deduct and flipping the conduit around is only a close approximation and the margin of error goes up a lot as conduit size increases. What you want is the gain.

For example with a 3/4 conduit the deduct is 6 inches and the gain is like 3.125, which is nearly half your deduct. Another example with 3 inch grc, the gain is 10.75 (or 10.25 can't recall) while half the deduct is 12 with the table bender. It's close, so it depends on how accurate the second needs to be. If you could move the support to where the conduit lands then use half the deduct

The gain is found by using a scrap piece of conduit. Measure the overall length, ex 60 inches. Now been a 30 inch 90. Now measure both the stub and leg. So let's say your stub came out perfect at 30 inches and your leg 35. Add them together you get 65, now subtract 60 inches (what we started with). You come up with 5. Your gain is 5.

This is used when you don't have enough length of the conduit on the back side of the bender up execute your bend. This sounds like your situation.

Question 2 you look good and added shrink which is the biggest gotcha that everybody neglects once in awhile

Question 3, yes always use outside measurement

Question 4 you could use your new found gain knowledge to set up another equation to be more accurate
 
a cam track table bender is easier to use than those things! but, it has a plus because it makesroom for back to back... if the bender has a back to back mark you could just use that...pencil your first mark, do not bend, then bend your 22deg then slap it on the gear and pencil the back of the second ko then bam... for room clearance issues make the first pencil mark into the typical take up stub (3.25? I forgot ) and use the back of bend mark for #2. the bigger the pipe (and thicker). you sometimes cant go wrong with back to back marks. less mistakes.

save the first marked pipe with the 22 as a template.
always mark the ko's with the bent pipe. if possible. it will look better.
always level out the shoes,,then keep a 6" piece of shallow and strap with you- place your magnet torpedo on a stub end (as long as it has vert and horizontal bubbles) Then start your bends. never have another dog leg again...I ddont use those screw on nifty levels, well not for what they intend it for. I have more control over this way.
if this post doesn't help you im sure the post above and all the rest together will provide an a
 
Bend your first 90. Then make your mark for your second 90 off the back of your first 90, plus the 2”(ish) of your shrink for your kick. Then put your kick on it followed by the final 90. Cut off the remain length of pipe or leg to the desired length. Bending both the 90/ first on 2” will make more difficult, if even possible, to put the kick in after the fact.


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Tank 728, Rambojoe, and Eletctric matt Thank you so much for your reply.

FYI, I did it the way I described and it did work great. I didn't have to cut any pipe and no dog leg.
Thank you again and have a great day.
 
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