Large flame cut bevels?

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I am not sure if I am on the right thread here but I am having some trouble creating a clean bevel on some heavy heat treat plate. The material is 5" thick with a 3o degree bevel that starts about 6" back from the edge. The material is gouging very heavy and sometime not blowing all the way through at the landing creating a very ugly and unusable piece of material.Any suggestions on tip size, pressure settings pre-heat temp etc...?
Reply:You need a bigger tip, or more O2.  What size are you using now?DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:As David R said, and...You need equipment sized to maintain that oxygen pressure during the cut.If this is free hand, you need a guide and two very steady hands on that torch.Better look at the tip chart for settings.
Reply:I am using a #8 tip, O2 is at 110 psi, MAP gas at 10 psi. I am using a track burner with an angle head on it.....where might I find a recommended tip size chart along with cutting techniques? I am wondering if maybe I also do not have the right mixture out of the torch head as well, although it's a nice blue flame....
Reply:http://www.weldingweb.com/vbb/showthread...tip+size+chart
Reply:Welcome kevinjwelch,Sounds like you have the right stuff for this cut.For a minute, I thought maybe you were a prankster who joined to kid me.Although you can get by with some compromising; to end up with a premium cut, you need to match the brand and specific series of torch tip, to the work. Pressure and travel speed should be adjusted close to specs.Without checking, #8 sounds too big, also seems like not enough fuel,  and about 30#s too much O2. I'm just guessing, so unless you can afford to experiment, you have to start with the tip manufacturers base specs.Make sure that tank valves are all the way open, to insure high volume flow. Before starting the cut, light up and then open the cutting valve fully, watch for about 20 seconds, make sure that the cutting jet doesn't fade.Pictures would tell us a lot.Good LuckEdit: I just saw tapwelder's links. They'll get you real close.Last edited by denrep; 01-26-2008 at 04:12 PM.
Reply:you probably are but it will help to preheat the plate.  and is the gouging on both bevels or just the one away from the flame. this one -> \ <- or that one becuase if its the far one the oxygen isnt right. and make sure you have a brand new tip or a really clean one.6G zirconium 702 GTAW 2" xxheavy6G P.E.D. carbon steel GTAW 2" xxheavy3G titanium Gr. 2 - Gr. 7 GTAW up to 3/4" 3G 316L stainless GTAW up to 1" 3G carbon steel GTAW up to 1" 3G Hastalloy GTAW up to 3/4"1G tantalum GTAW up to .060"
Reply:I was cutting a bunch of 2 7/8" galvanized plate and I had to clean the tip every cut.  I was using a #5 tip with about 80 psi.  I could knock the slag off with a hammer.I always clean my tip before I start a job.  It cuts so nice.DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:The best way to do it is to use a scarfing tip.It is a tip that has three holes in it and it is wide and flat.It is usually used to romove the backing strip from a welding coupon before it is prepared (cut in thirds) for the bending tests.You could clamp a piece of wood ,cut on a 30 degree angle perpendicular to the cut at the apprproate point and use it as a guide to run the torch tip along it.If it is a piece of flat bar i would just cut it in an abrasive cutoff saw.MAKE SURE it is clamped down!Last edited by Donald Branscom; 01-26-2008 at 06:08 PM.
Reply:On such heavy plate you might consider two approaches.  The first is to have a second torch just heating the surface about two inches ahead of your cutting torch.  At 30 degrees the preheat is being reflected into the air.  My favourite solution for this problem is to cut the plate edge so that the bevelled scrap is underneath.  The torch is in effect aimed at the square cut edge downward at 30 degrees.  The slag and waste falls away from your cut. the preheat is aimed at the plate and is not reflected off.
Reply:I will post some pictures - initially I was cutting with the bevel scrap falling to the ground but it would cause I pretty rough edge at the "top" of the bevel. Cutting from the "top down" produced a nice clean edge at the top but the end of the flame would drag behind the rest of the cut quite signifigantly. I will refer the table and check pressures again....
Reply:Crank up the Mapp pressure a bit for better preheat, lower the oxygen pressure a bit, and take your time, like others mentioned the key is making sure that when using the O2 to make the cut that it isn't dropping too much, have all valves opened fully.(pretty much a reiteration of what others have said)