meaning of light fab ±** ；heavy fab ±**

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I read this from a drawing. It is about the tolerance requirement.What does it mean?what is light fabrication and heavy fabrication?what are the differences between them?Waiting your help.Thanks.
Reply:I would say that anything 1/4'' to 1/2'' and under would be light fabrication and anything above and beyond 1/2'' would be considered heavy fabrication....Lincoln pro mig 180Lincoln Square Wave Tig 300/wp 20/home built water cooler Victor, Purox, Harris, O/A welding/cutting setupsVintage Craftsman drill pressVintage Craftsman/Atlas 12"x 36'' lathe7''x 12'' w/c band saw Everlast 140 st
Reply:I haven't seen those words on a print, but I have seen working tolerances.Say the print calls for 2.250" -.001 +.005, which means the piece needs to be 2.249" to 2.255" to be acceptable.Not sure if that is the correct answer, but without seeing the print, it's the best guess I have.Semper FiJesus may have been a Carpenter, but his dad was a Millwright" A grinder and a can of paint, will make a welder what he aint' "I've done so much, with so little, for so long, that now I can do anything with nothing!
Reply:Originally Posted by Meggie ZhuI read this from a drawing. It is about the tolerance requirement.What does it mean?what is light fabrication and heavy fabrication?what are the differences between them?Waiting your help.Thanks.
Reply:traditionally speaking anything under 1/8" is light fab and anything over 1/8" is heavy fab.Vantage 500's LN-25's, VI-400's, cobramatics, Miller migs, synch 350 LX, Powcon inverters, XMT's, 250 Ton Acurrpress 12' brake, 1/4" 10' Atlantic shear,Koikie plasma table W/ esab plasmas. marvel & hyd-mech saws, pirrana & metal muncher punches.
Reply:I was recently given a weld test for a job described as "light fabrication", basically make stuff out of thin-walled tubing (e.g. fences, gates, etc) instead of the 3 and 4 foot wide I-beam drops we cut up and practiced on at school. As to how thick can be "light" and how thin can be "heavy" I have no idea.XMT304 (school)SP125+ (home)HF 4x6 BandsawGood judgement comes from experience and much of that comes from bad judgement.
Reply:I gotta +1 to Dualie, 1/8" from the mill is classified plate, thinner is sheet.What's the callout on the tolerance difference?Matt
Reply:I would say if you can pick it up with a HF engine hoist it is light fab...if it breaks the hoist, it is heavy fab.
Reply:Originally Posted by M.RedHawkI would say if you can pick it up with a HF engine hoist it is light fab...if it breaks the hoist, it is heavy fab.
Reply:Originally Posted by Matt_MaguireI gotta +1 to Dualie, 1/8" from the mill is classified plate, thinner is sheet.What's the callout on the tolerance difference?Matt
Reply:Originally Posted by M.RedHawk View PostI would say if you can pick it up with a HF engine hoist it is light fab...if it breaks the hoist, it is heavy fab.