45 Rolling Offset Formula ??
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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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Yup, that's it. I use it almost every day. Bugs the crap out of me to see a journeyman holding a 45 up guessing a traveler.
Buy the pipefitters and pipe weldors handbook. VERY handy book.
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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.
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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.
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.
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.
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.
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Thats only done when you have an air computer...
Sheeesh!:laughing:
That's how I was shown how to do it. Their is a formula? That makes my life a little easier.
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 8-1/2". 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.
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 8-1/2". 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.
Attachments
I provided the formula for a rolled offset, where you are changing both the height (Advance) and the distance apart (Spread), you are doing the math for a simple offset.
No, a rolled offset is offsetting two ways as opposed to a simple offset where it remains on the same plane. In a rolled offset you offfsetting both side to side as well as up and down at the same time using two fittings.
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For rolling offsets you have to find the "true offset".
Take the square root of offset squared plus rise squared. This is the true offset. Take this number times 1.414
It's as easy as dat. I misread the question the first time I posted in this thread.
Take the square root of offset squared plus rise squared. This is the true offset. Take this number times 1.414
It's as easy as dat. I misread the question the first time I posted in this thread.
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I m almost embaressed to say it,I work for a reputable company,1950,and the plumbers hold up fittings.Mind you there not buliding new construction anymore.You guys are ausome.
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790 Posts
.707,1.414,.707
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Take a look see at this link.
Audel Pipefitter's and Welder's ... - Google Book Search
Audel Pipefitter's and Welder's ... - Google Book Search
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I wish to add my .02
As a carpenter we know that to find the diagonal measurement of a squared building you use the formula:
Length to the second power plus width to the second power. Then square that answer, voila! Diagonal measurement. Use it all the time. Should be the same principle here. I dont care if its a rolling offset, or a plain ordinary off set, it is still off set by 45 degrees, so two 45's make a 90, right??
I mean, I look at DA's diagram and it makes sense to me.
As a carpenter we know that to find the diagonal measurement of a squared building you use the formula:
Length to the second power plus width to the second power. Then square that answer, voila! Diagonal measurement. Use it all the time. Should be the same principle here. I dont care if its a rolling offset, or a plain ordinary off set, it is still off set by 45 degrees, so two 45's make a 90, right??
I mean, I look at DA's diagram and it makes sense to me.
you have to account for the distance it moves to the side. look at redwoods diagram and you'll see what we mean. your formula(Pythagorean theorem) works great for your situation but now the 45 has been turned.
Rolling Offsets Story
your running your groundwork and you are headed towards your stack when all of a sudden, out of now where you screwed up!!!!!! You realize you are about to miss your stack and you start crying because you don't want to use an extra 45!!!! so instead you roll the 2 45's to accommodate the offset. the piece connecting the the 45's is a little longer than if it was lined up square but now the boss is happy he saved a 45 and you are happy you get to keep your job. and everyone lived happily ever after because we learned about rolling offsets. The End.
Rolling Offsets Story
your running your groundwork and you are headed towards your stack when all of a sudden, out of now where you screwed up!!!!!! You realize you are about to miss your stack and you start crying because you don't want to use an extra 45!!!! so instead you roll the 2 45's to accommodate the offset. the piece connecting the the 45's is a little longer than if it was lined up square but now the boss is happy he saved a 45 and you are happy you get to keep your job. and everyone lived happily ever after because we learned about rolling offsets. The End.
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