Nozzle size v. Amperage

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Hello All:  If one is operating a plasma cutter at less than 95-100% of its capacity should the nozzle size be reduced accordingly? In other words use a smaller nozzle for lower currents and thinner materials? Cannot seem to find reference to this, maybe it is something you are supposed to know from early childhood . Thanks for reading.  Burt
Reply:Burt, you are creating a plasma and don't think the nozzle would have any effect.  JohnSMAW,GMAW,FCAW,GTAW,SAW,PAC/PAW/OFCand Shielding Gases.  There all here. :
Reply:Burt, in theory yes, in practicality only larger expensive machines have this consumable available (sized tips).
Reply:Burt welcome the the forum. Like already said one size does most. Plasma cutters are rated in metal cutting quality. Small machines like my Spectrum 375 xtream I cut 28ga to 5/8" the thinner the metal the better the cut. Remember if you are buying one more amps = thicker cutting ability. Mine is 27 amps and it cuts 1/2" decent 3/8" awsom. I have cut 3/4" and if sucks. Steel Thunder Welding LLC. St. Thomas VI USAMM350PBOBCAT 3MAXSTAR 150 STH375 EXTREME PLASMA6.5 HP COMPRESORDEWALT 18, 24, AND 36 VOLTO/A TORCH SETAND SO MUCH MORE I DONT REMEMBERALL IN MY 2005 2500HD EXTENDED CAB L/B
Reply:Thanks to all for their replies.  I will stick with the nozzles that came with the unit and play with the other variables (height, amperage and travel speed). I have been experimenting with 14GA mild steel and some 1/4" Stainless Steel (Grade unknown) and found that if I move the torch at a pace that "feels right", the 14GA takes 25A and the 1/4" SS is best at 35A.  Still working it out since my machine is Asian rated at 50A.  One other issue I  have is I am using a Hobart "HOOD" auto-darkening helmet with the shade set at 9 for Plasma Cutting and at 11 for MIG (75A el-cheepo) and can barely see where I am. I remember Stick welding back in college and being able to see the puddle thru the fixed #10 lens,  Am I expecting to see too much?  Don't see how that is possible since if you can't see, how can you follow the seam?  Bear with me on these basic questions please, I have read a bunch but no real experience and there are no classes available at the local community college. Take care.  BurtLast edited by fluvannabear; 02-05-2008 at 02:49 PM.
Reply:I would get some goggles or turn your auto hood off (you can turn the sensitivity down to accomplish this) for cutting, I think it's 5 or something when it's off. For the MIG, adjust where you can see the puddle, for me that's about 9.5-10 for low amps like you're running.HH 187Miller Bluestar1EAHP AlphaTig 200X
Reply:If you have a drag nozzle, a hood is not required.  The arc is under the steel you are cutting.  If you hold an arc, thats different.  JohnSMAW,GMAW,FCAW,GTAW,SAW,PAC/PAW/OFCand Shielding Gases.  There all here. :
Reply:In order to produce the best cut quality at the fastest speed with the least amount of drosss and haz (heat affected zone)...then you must closely match the nozzle orifice size to the material thickness and power level you are using. The plasma cutting nozzle's primary function is to constrict the arc......meaning to compress the energy and incease the velocity of the ionized gas. A 20 Amp nozzle has a smaller diameter orifice as compared to a 40 Amp nozzle. If you use a 40 Amp nozzle at 20 Amps....you are not producing anywhere near optimum energy density (measured in Amps per Square inch)...therefore the cut quality will not be optimized.Hypertherm has a line of "FineCut" consumables for their Powermax units which use a specially designed nozzle that dramatically increases the energy density...borrowing technology from their industrial HyDefinition mechanized plasma systems....these FineCut consumables provide extremely high quality cuts on materials thinner than 3/16" at relatively low power levels.Jim Colt
Reply:Thanks to everyone for their replies. (Greyhorse) I will get a pair of Shade 5 "sunglasses" for cutting, tried today with clip-on sunglasses and they were not too bad but still a bit bright.  Setting my hood at 9 seemed to work better with the MIG than I remembered.(weldgault) I do not have a "drag nozzle" as far as I know, I understand I can put the nozzle I have in contact with the workpiece at a cost of more rapid wear.  Have made a standoff piece that slips on the end of the torch and spaces the nozzle from the work as well as serving as a surface to contact my templates edge. Made it from 1" copper water line and trimmed to shape. (jimcolt) I will investigate Hypertherm for their FineCut consumables in case they will fit my torch.  Doubt if I can afford their torch.  All my cuts will be manual and high precision is not needed as much as minimal finish work.  Thanks again guys.  Take care.  Burt