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  #1  
Old 05-04-2010, 12:44 PM
dcduct dcduct is offline
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Default plaese help. lol

I have just entered the sheet metal fabrication world,
we have started making square ductwork using 20gauge mild tempered galv.
the size of the sheet is 6'x4'.
the ductwork regardless of size is coming out twisted and we are at our wits end.
If any1 could give us some pointers as to why this is happening it would be greatly appreciated.
kind regards.
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Old 05-04-2010, 08:20 PM
jw223 jw223 is offline
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Dcduct- What are you using to brake it with? Is your brake bending it straight? Is it a pittsburg seam? If so, make sure you are square and flush on the end before hammering it together. Can you post a picture so everyone else can see what's going on? Just a few things to check. If your steel is square to start with, it sounds like either a bending or assembly problem.
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Old 05-05-2010, 11:24 AM
dcduct dcduct is offline
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thanks for taking the time to help,
it is greatly appreciated,
If I run throught the process I use to form the duct,
I can supply some pics tomorrow when I'm back in the workshop.

1. we square the sheet.
2. cut the sheet to size.
3. put through lockformer (pitsburgh lock).
4. measure the size of the sides.
5. put in the folders.
6. remeasure the size of the folds as we are folding them.
(this is where we find the two sides are uneven)
7. join together the duct using a trumpf lock seamer
8. end resullt - twisted duct.
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Old 05-06-2010, 02:46 AM
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Bud Bud is offline
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Is your lock running true all the way in width, it doesn't take much to get twisted ductwork?
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Old 05-11-2010, 08:04 PM
jw223 jw223 is offline
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Try making prick marks in the metal at the points you want to bend it at. After you run the steel through the pittsburg, re-measure and see if the machine is running straight. If it's not, and you are measuring AFTER it's run through, the duct will get twisted when you put it together. Good luck!
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Old 05-14-2010, 01:00 PM
sheetmental sheetmental is offline
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easiest way i know of to check if the pittburgh is running straight -
cut a 6" strip as long as the metal you have. put the end against the infeed guide. run it into the machine. once you have approx 12" into the machine just let go completly. if the head pressure isn't right, you'll know soon enough.
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