TJ Smith Posted January 10, 2009 Share Posted January 10, 2009 New to mig welding. How much time should I get out of a 40 C/F 75/25 tank at 20 cfh setting. What would be a good cfh in an enclosed shop. Thanks TJ Quote Link to comment Share on other sites More sharing options...
mr d Posted January 10, 2009 Share Posted January 10, 2009 I usually run around 20-25 but your nozzle/lead angle/work angle may dictate a different setting for you. If you are unsure then start at 20 and do some stringers. If it's not sizzling like bacon or you have an erratic arc then try increasing the gas to 25. More is not better. With too high of a flow rate you can actually start drawing atmosphere into the pocket due to the Venturi effect and it will contaminate your welds. As far as how long it will last, I used to know how to calculate it, but I haven't had to do it and have forgotten the formula. If I'm not mistaken 40ft Quote Link to comment Share on other sites More sharing options...
HWooldridge Posted January 11, 2009 Share Posted January 11, 2009 I run about 15 CFH in a fully enclosed shop but I occasionally get some porosity so it's probably a bit low. 20 CFH is 20 cubic feet per hour so a 40 cubic foot tank would last two hours of continous run time. Quote Link to comment Share on other sites More sharing options...
TJ Smith Posted January 11, 2009 Author Share Posted January 11, 2009 Thank you guys TJ Quote Link to comment Share on other sites More sharing options...
Ten Hammers Posted January 11, 2009 Share Posted January 11, 2009 Another fact will be that if you have a basic scratcher torch and must leave the gas on during welding and between welds your usage will be one thing. If you have a Hi Freq start torch with a gas solonoid and postflow your gas usage may be another. My 5 Quote Link to comment Share on other sites More sharing options...
Oak Hill Forge Posted February 10, 2009 Share Posted February 10, 2009 Ten Hammers .... I think you are refering to TIG welding....he's using MIG Quote Link to comment Share on other sites More sharing options...
Ten Hammers Posted February 10, 2009 Share Posted February 10, 2009 (edited) You are correct on the process. I guess I just took the "tank time" as a generic statement for process welding, sorry. No mention of the machine used either. Every time you trigger, the solonoid opens allowing gas to escape. This means that as you learn and trigger excess wire off on a table leg ( or trim with side cutters ) there may or may not be more gas used. Sounds picky but is a fact. While being new and wishing to know what the average life of a consumable ( bottle) would be, it is kinda hard to say. The machine itself will have a rating (duty cycle) so the continuous welding will be factored on that. Since the fella is new to mig, the quality of the weld ( mig ) will also be determined by the setup ( grinding of millscale etc). I am absolutely no expert. I use 75/25 at home shop and roughly 20 cfm. I have welded some outside with dual shield ( fluxcore ) and 75/25 cranked wide open on stainless and carbon with zero porosity. Back grind or gouge and grind the root and make cap passes. Bottles replaced as necessary. The smartest thing I can tell the man is to do what I do. Take a piece of duct tape and put on the bottle by the valve. Write the date on the duct tape with a sharpie. This works for all bottles ( nos,acet,02 and LP). Remove the tape when you fill or replace bottle. :) Edited February 11, 2009 by Ten Hammers Quote Link to comment Share on other sites More sharing options...
tophand Posted February 10, 2009 Share Posted February 10, 2009 I have a Hobart 180 weld pack with a 40cf bottle. In my shop a bottle will last just about as long as a 10lb spool of wire @ 20-25cfm. That is a little subjective, I know. Matt Quote Link to comment Share on other sites More sharing options...
Ten Hammers Posted February 11, 2009 Share Posted February 11, 2009 Tophand, I have a son in law that owns a Hobart 175 handler. I used it while the Miller was getting points replaced. THe Hobart was a fine welder, yes. Plastic rollers compared to the Miller and probobly some other electronic differences but all in all was a good machine. Quote Link to comment Share on other sites More sharing options...
cataulpa_forge1 Posted February 16, 2009 Share Posted February 16, 2009 (edited) Hi Everyone, As it was explained to me for my setup ... I have a Miller MIG 185A / 220 V with .035 solid wire(40lb spool) and what they call a "Q" bottle of AR/CO2 (75/25). I had to ask when I bought my set. The gentleman told me that "at about 18 on the guage was about right. And the best way to set it right was to open the drive roller(wire won't feed), press the trigger and adjust to 18 on the gauge under flow." Yes, the gauge WILL show high when you release the trigger.... that's ok. I have never welded over 20 on the gauge and it seems to work just fine for what I do. I have been welding for about the past 12 years. -- ED/CAT NJ 08088 Edited February 16, 2009 by cataulpa_forge1 Quote Link to comment Share on other sites More sharing options...
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