heat control

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Hello all, so I posted a few pics and gotten great feed back! I went back to a fresh start w/ thinner gauge metal to learn more about heat control.(from suggestions) I'm using a foot pedal, thickness gauge, tig calc, COMMON SENSE,  and anything  I can teach myself from U all, weldingtipsandtricks, and MANY other resources out there for the time being...I WANT TO LEARN, CORRECTLY!  I wish I could quit my day job(eyeglasses fab guru of 13yrs) to go to school for welding but that's probably not going to happen for a while. Company's expanding. O n did I mention family(wife) biz. So as I referenced to my tig calc & got to practicing last night of course blow through. So I learned some foot control. It just seems as if its too much heat recommended? I know experience comes w/this guys! This is why I stated what amps I was using when those pics/threads(petals to the floor) were created previously, then got replied  too cold.  But was thinking if I'm set to 105amps on 1/8 thickness but only on the pedal about 1/2 way how amps are really being used?Also is blow out related to both speed & amps?  Can anyone help me with what determines puddle size? Anything else anyone can add to help aid in heat control PLEase do! Thanks for reading!
Reply:There are lots of things that control your heat when doing tig. 1st would be the setting on the machine, and the pedal. If you have the machine set at 150 and have the pedal 1/2 way down, you are running at roughly 75 amps (1/2 of 150). Second is arc length, how far your tungsten is from the work.  The farther from the work, the larger the arc is and the wider the area you are heating. Also with arc length is torch angle. A straight up and down torch puts less heat in the plate than a torch at an angle thats "preheating" everything in front of it. 3rd is how fast you are moving. Go slow and you put more heat into the plate at 150 amps then you do at  the same setting going 2x as fast. Also your filler rod will help cool the puddle every time you add filler. Size of the rod also effects the puddle temp, a larger rod pulls more heat from the puddle to melt than a thinner one.As you see it's somewhat difficult to tell you why you are blowing holes at the suggested settings. ( it's why it's been suggested you get some training so someone can look at what you are doing and make comments) From experience with students trying to do alum here's what I think... Most want to hold to large an arc length so they can easily see the tungsten, often 3/8" or larger. You want to be down around say 1/8" or 3/32" arc length. they also tend to use a fairly strong torch angle that throws a lot of heat out in front of the torch. Using a gas lens will allow you to extend the tungsten and keep good shielding, yet see the arc better so you can maintain a tighter arc length. 2nd they don't back down on the pedal fast enough. I mentioned before that everything goes so much faster when doing alum. You have to be backing down the instant you get the puddle going. You can't sit there and look at it and think about it. 3rd most students don't move fast enough once they get the puddle going. You need to be ready and moving adding filler as you go as soon as you get the puddle established. 4th students often don't add filler frequently enough, so they aren't cooling the puddle as consistantly. Usually they are making all these mistakes at the same time and that compounds problems. Usually the student will  counter act all this by trying to run too cold like you are doing. This leads to partial penetration, overheating the body of the material, and not getting the beads tied in well among other issues.This is why we've made comments about learning to get heat control down pat 1st on an easy material like steel, where you have time to think and make changes. Once these sorts of things become second nature, all you have to do is speed up your reaction time. Learning on alum, you have to do all this at once, and it's usually very frustrating because it's so hard to pin point one specific problem thats causing the issues.Remember alum is a great heat sink. It will pull heat away from the bead faster than say steel does. That also means the whole thing heats up faster than steel also. This is why you want to run hot and fast on alum. You want to quickly establish a bead before the alum can suck the heat away, and then try to out run the heat thats spreading out into the plate so that you keep the total heat input down.Last edited by DSW; 07-28-2011 at 06:28 PM..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Alum is put away until I get a lil bit more practice. I'm going to stick w/steel until I've got some more understanding of ALL the important factors, then do the joints/different positions as you suggested. I know this will reiterate all that needs to be clear during this process. I also realize having an experienced overseer would help in this training & please if you are here or local to me, let me know. In the meantime I will continue to look locally for education/teach myself. Thanks!
Reply:Miller's GTAW calc. always seemed a little high on the amperage settings to me. The settings I learned at school were a little more reasonable but that's just my (limited) exp.E.