SMAW Hot pass.

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just some questions on running hot passes with SMAW and 3/4 tp 1"plate. At school I have using alot of 3/4 plate for practice welding for the verticle up cert.  I am mainly using 1/8 7018,  I have been running 120 amps for pretty much all the passes I have been doing, and I was thinking about starting to run hot passes to really get the base of the metal to full penetrate and just had a few questions about it. How much higher should I be setting the machine on the hot pass and is their any other changes I should make. I would be asking my teacher but the first week all we do is go over the same safety stuff I have heard to the last 2 years.  I am getting close to doing my cert test and want to do it once and do it right.
Reply:I am curious as well. How big should the land be and how much of a gap? I think the land would be around 1/8" and the gap maybe 1/4"-3/8"? The guy I worked with ran the root with 1/8" and the rest with 5/32". I was thinking 5/32" would get that test coupon pretty darned hot? No? Dave
Reply:I don't think you need a hot pass.  When I took my test, the inspector had to see my root pass before I could continue.  With 6010 sure, 7018 if applied correctly shouldn't need a hot pass.  I run 7018 as hot as I can and keep control of the puddle every pass.I can do a 3G with 3/32 7018 on 3/8" prepared plate with a backer.  I can do the test, I have not taken it.  I do have a 3G with bare wire and Co2 cert.DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:What test are you preparing to take? The AWS and D.O.T. differ slightly. I can tell you right away for the D.O.T. test, you are using the incorrect size rod. Also, they allow you to pre-heat both your rod and your material. This keeps you from turning UP your machine and once your material gets hot, it won't drip as you go up on the vertical.John -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.com
Reply:im going for the AWS cert, and I know the inspector has to check the root pass, and I am setting a 1/4 inch gap and I want to say a 3/32 landing with a 1/4 inch backer bar.
Reply:The 7018 1/8 rod has a range of 90-150 amps. So, depending on the machine settings you're going to have to adjust it some. For the 1" plate, I would start at about 140 and work my way down. It easier to be too hot and burn in, then be too cold and have your rod stick. (at least for practicing and adjusting your machine) John -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.com
Reply:That is an interesting joint description! You have a landing as well as a back up bar? In any case, the amount of power you can feed a vertical joint like that will depend on how well you can stay in control of the puddle, to avoid having it drip out on you. In the field, this can be corrected, but, that will end your test plate!! So, by all means, practice before hand with your amperage settings until you find the limits of what you can control. Control is everything.City of L.A. Structural; Manual & Semi-Automatic;"Surely there is a mine for silver, and a place where gold is refined. Iron is taken from the earth, and copper is smelted from ore."Job 28:1,2Lincoln, Miller, Victor & ISV BibleDanny
Reply:I am a little confused on the term hot pass, is this after your initial root pass? If so I would only run a "hot pass" if you observe a wagon tracks effect meaning you need to flatten the middle to avoid inclusions. One of the best tools to help with heat control is to buy the HF infrared thermometer. You then wait until the temp cools to a point (at the top of you plate) that will produce the same result each time. Now you have a amp setting and temp control now its travel speed and travel angle control.
Reply:First off, I've never really considered the term hot pass to apply to 7018 except to maybe designate the pass after the root.  An uphand 6010 hot pass is a special technique to wash out the 6010 root's wagon tracks while depositing very little metal.  With a 7018 root on a backing bar there should be no wagon tracks.  The next pass and those following would simply be run as hot as to still be controllable.Next admittedly I've never done a backup test that involved having a land.  Is this an option at the welders choice?  If you are not allowed to use a grinder during the test , then I would say to do away with the land.  The reason being as that you are liable to leave a heavy shelf  when you breakaway on the root.  On the restart it will be difficult to assure complete penetration to the inside corners on the  backing bar.  This is usually where they call for a root bend test.  If this test has to be done with a land then I'd be more concerned about practicing a tapered breakaway on the root then the hot pass.
Reply:well mybe landing is such a good way to describe it, its not really a full landing like I use with open back but when I am cleaning off the mill scale I will grind slighty on the edges and mybe a little more on the botton edge of the plates. Ill take pictures of it when school starts back up.