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#44472 - 11/04/04 09:22 PM Bending A Rolling Offset  
mustangelectric  Offline
Member
Joined: Feb 2004
Posts: 494
Bentonville, AR
Hi,
This is how I bend a rolling offset. How do you do it?

First I measure the vertical distance I need center to center, then the horizontal distance I need center to center.

Then I lay this out on the floor using a pencil or chalk making two perpendicular lines.

I start by making a right angle that is exactly the same measurement as the vertical and horizontal center to center measurements taken first.

Once this is done, I will simply measure the distance between the end points of each perpendicular line. This measurement is the depth of offset to land the pipe in perfectly. This is especially helpful when you need to hit a knockout.

I am sure there are other ways.

-regards

Mustang


Electricity has no respect for ignorance!

Work Gear for Electricians and the Trades

#44473 - 11/04/04 10:39 PM Re: Bending A Rolling Offset  
e57  Offline
Member
Joined: May 2003
Posts: 2,876
S.F.,CA USA
Nice idea..... But seems like you might miss the angle of roll, unless the conduit is un-bent. Often I need to do this on a piece that bay already have a bend on it.

My method is a little less exacting but works well.

Take a small 4-6" scrap piece, and put it on the wall where the conduit you are coninuing would have gone. Mark the back, where it touches the wall on the inside, as a registration mark for the angle of roll. Then measure from the scrap to the outside edge of the KO or fitting that you're aiming for, for you're off-set distance, and mark where your tape touches the scrap. Then transfer this angle to the conduit for a center line, by doing this: lay your already bent or fresh piece on the ground, and put your scrap peice onthe end with the 'against the wall' mark on the floor, then transfer the 'where the tape touched' mark to the one you're bendin, and chalk-line the center line. Then line that up to you benders seam line, or dog leg knotch if you filed one. And bend your distance. DONE (complicated to explain but easier done than said)

Should also take a moment to explain the "dog leg knotch":

Take a scrap piece, and draw two straight lines on it bisecting the center line of the conduit. (One on top, and one on bottom.) And very important to do this exactly, as you'll use this to perminantly mark you bender. Then place it in the bender and transfer your marks to the benders seam line. Once on the hook, one on the top of the hook, and one where the conduit touches the radius of the bender shoe. Then cut a knotch with a tri-angle file, or a hack saw blade.

To use it: Lay you conduit on the floor, as it would touch the mounting surface. Then find the top, by holding a marker or pencil on the top of the conduit, and lock your hand, and side it down the length of of the area to be bent, or chalk line it. (extra careful not to roll the conduit while you do this. ) Then put the conduit in your bender with the line on the knotches for your bends. An old skool anti-dog-leg method.


Mark Heller
"Well - I oughta....." -Jackie Gleason

#44474 - 11/06/04 09:00 PM Re: Bending A Rolling Offset  
Redsy  Offline
Member
Joined: Mar 2001
Posts: 2,056
Bucks County PA
How about taking the square root of the sum of the vertical distance squared and the horizontal distance squared.

Ex:

12" vertical squared = 144"

8" horizontal squared = 64"

144 + 64 = 208"

Square root of 208 = 14.4" offset depth.

Try it.

[This message has been edited by Redsy (edited 11-06-2004).]


#44475 - 11/06/04 11:22 PM Re: Bending A Rolling Offset  
GA76JW  Offline
Member
Joined: Mar 2004
Posts: 193
Suwanee, GA USA
I was showed the same way mustang explained it. Works well when you really don't want to think about it too much.

Sounds like a good idea redsy, but squaring 8 3/4 and 13 5/8 in the field would be a chore. I have yet to carry a calcultor with me. [Linked Image]


"If common sense was common, everyone would have it"-not sure, someone here


#44476 - 11/06/04 11:47 PM Re: Bending A Rolling Offset  
Jps1006  Offline
Member
Joined: Jan 2004
Posts: 615
Northern IL
64-9/16 & 169-25/64

I think it's the square root of 233-61/64 that would get me.


#44477 - 11/07/04 11:23 AM Re: Bending A Rolling Offset  
Redsy  Offline
Member
Joined: Mar 2001
Posts: 2,056
Bucks County PA
Sorry, guys.
I should have mentioned that a calculator is necessary. Unless of course you're "Rainman"

Wapner at 7!
8 fishsticks!
Uh-oh, fart!

JPS,

It's worse than that.
You need to square the first 2 numbers before adding them. Then take the square root.

If you have a place for a small calculator, though, it is worth it.

[This message has been edited by Redsy (edited 11-07-2004).]



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