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Having a bit of a time tigging some 3 inch pipe. I am working for a cert sometime in the near future. I am walking the cup as my method of a cap pass. Some of you think this is a bad idea and some of you think this is a good idea. Personally, I was unable to even test for a job one time because I didn't know how to walk the cup- so this is what I am doing. Anyway, I have a 3/32 tungsten, with 3/32 wire. Amps around 100. I keep undercutting the edges of the weld. I ve included a picture to show my problem. Any suggestions? Thanks. Attached Images
Reply:Its probably a combination of you being to hot and not being filled enough before you start your cap. I like to fill mine to within 1/16 of the thickness of the pipe before I lay my cap, any more than that and I have a hard time filling it all in esp. when walking the cup.If I remember last time I walked out a cap I was at maybe 60-70 amps. There was a decent amount of heat still in the pipe but 100 seems a little hot.Edit, looking at the top of the pipe, if thats all the farther you have it filled in before you lay the cap on you need to fill it out more.Have we all gone mad?
Reply:Cleaning the pipe 1/2" back from bevel on each pipe should help. Contamination from paint, rust, or whatever else is on the pipe causes it to undercut on cap. Tig welding requires shiny clean metal.
Reply:Yes, and to add to what was stated above, hold your edges a little more. Turn the heat down about 10 amps from your fill passes to do the cap. It looks like you havent got it filled out enough, tried to fill it and cap it at the same time and as a result ended up cooling the puddle in the middle while undercutting on the edges.Were you feeding the wire when you did that? Welder is set too high. What machine are you using? My welder at home puts roots in at 55 amps (syncrowave 180) and my welder at the hall where I test puts roots in at 95 (xmt 350) both miller machines. The xmt has a lift arc setting which I think is why that is happening. (Maybe someone on this board can shed some light on this)
Reply:I am using a Maxstar 150. Nothing fansy about it. I ll try some of the suggestion mentioned and I ll post an update tonight. Thanks for the responses.
Reply:Tye : Did you have any luck with the cap?
Reply:Your amp is to high, you might want to lower it maybe about 80-88 amps for root and then 5 amps up for hotpass then cool it down a bit and go 90 amps for the fill and 75 to 80 amps for caps. make sure your feeding enough to cover every pass, you are ready to cap once your fill up is flush, never cap when your fill is not flush enough. good luck
Reply:Originally Posted by AlinkwelderYour amp is to high, you might want to lower it maybe about 80-88 amps for root and then 5 amps up for hotpass then cool it down a bit and go 90 amps for the fill and 75 to 80 amps for caps. make sure your feeding enough to cover every pass, you are ready to cap once your fill up is flush, never cap when your fill is not flush enough. good luck
Reply:I am needing to do this..... so I appreciate the added info...Weldandpower Lincoln 225 AC,DC with Briggs 16hp gas engine.WW2 era Miller TIG. |
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发表于 2021-8-31 23:29:38