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12022008, 10:50 PM  #1 
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45 Rolling Offset Formula ??
Does anyone know the formula for finding the length of pipe (TRAVEL) between two 45"s. Thought I could remember it but I was wrong.
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12022008, 11:07 PM  #2 
every tool is a hammer

Multiply the center to center by 1.41, the subtract the fittings, I think. I used to do it every day for sump pumps, but It's been too long.

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12022008, 11:40 PM  #3  
Professional Bullshioter

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Buy the pipefitters and pipe weldors handbook. VERY handy book.
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12032008, 12:18 AM  #4 
new nickname:Quaker State

Worked for a guy who said he fired his leed plumber for trying to hold up 2, 4 inch no hub 1/8 bends and measure between them at the same time. AND was on a ladder.

12032008, 03:06 AM  #5 
www.DunbarPlumbing.com

We always had to do a copper jig for the journeyman's test, using the multiplier 1.414 and now they have instead of a lead pour,
3 pipes that are 2" cast iron, ou have to figure out how the offsets work and do your multipliers and if you're right, when you slip on the mission couplings they are either super tight or don't fit at all.
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12032008, 03:11 AM  #6  
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Plumber's and Pipe Fitter's ...  Google Book Search Even has pictures 

12042008, 08:54 PM  #7 
Registered Member

A rolling offset is not a simple offset.
In a rolled offset you need to know the spread A and the advanceB, then it is a simple formula, A squared, plus B squared, the suare root of that sum is then multiplied by 1.4142 and the fitting takeoffs subtracted from that number. that formula is for 45 degree offsets for 60 degree offsets replace 1.4142 with 1.1547, the rest is the same. 
12052008, 01:07 AM  #8 
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12062008, 04:35 PM  #9 
Senior Member

That's how I was shown how to do it. Their is a formula? That makes my life a little easier.
Last edited by Marlin; 12062008 at 04:47 PM.. 
12102008, 04:21 PM  #10 
This space for rent

Um... you folks are making things complicated and Killer, I'm not sure what the heck Spread and Advance refer to.
Think of a right triangle, 45, 45, 90. The two short sides are equal. The long side is calculated by using the Pythagorean theorem. The three sides are A, B, and C, so A squared, plus B squared is equal to the square root of C. Now, think of a vertical pipe that needs to offset 6 inches. You use the 6 inches and multiply by 1.4142, and that will give you the center line to center line distance between the two pipes along the path of your angle, or 8.48 inches, which rounds to the nearest 1/16th of an inch, or 81/2". You have to compensate for the fitting make up distance, which is subtracted from that length. BTW, your offset will always equal your rise and visa versa in a 45,45,90 triangle. A picture is worth a thousand words so... If you were to do as Killer says, 6x6=36, 36+36=72, the square root of 72 = 8.48528. If I then multiply that by 1.4142, I come out with something just under 12. That won't work, even after I subtract for the fitting make up. That's why I got lost. Just multiply the offset by 1.414 and then knock off the fitting allowances or make up and it'll fit like it was made to go there.
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