[Graveyard]

Hello i'm new to the forum. I spent about 3 hours searching for an answer to my issue for about 3 hours and came up with nothing so hopefully this wont be another pointless thread. Ok so i fabricate fuel tanks for sportbikes. I don't build them from nothing i modify stock tanks. I recently purchased a Large CK pyrex cup kit from Weldfabulous.com and so far i really like it. I mainly weld 16ga cold rolled steel to the existing steel which varies from 22-18 gauge depending on how its been stamped from the factory. So my issue is when i'm welding in one area of the tank on new sheet metal both top and bottom i get this goofy blowback almost like its not getting any gas. I'm running between 20-30CFH on my gauge and its almost acting like i'me not getting gas, i can hear the gasflow so i know its getting it. Once i get past this short 1/2" section it welds great but this has happened on 2 tanks and it's starting to get irritating. I am not purging the tank inside while i weld fyi and i'm wondering if i did if it would help, i've never had to purge them before and i get little to no sugaring so thats why i don't purge. I'm curious if i'm not getting some kind of cross draft inside the tank at this point and its just over powering the gas flow. I've got a couple more to do tonight so i'll see if i can get a pic or a little video if it happens again. This does not happen with my regular #8 gas lense, like i said i just picked up this kit to try and i don't know if its just not right for my application or if i'm doing something wrong. Thank you for any input.

[dirtmidget33]

It sounds like you are creating a venturi vacuum effect. I have never encountered the problem when welding. Matter of fact Jody just mentioned it in his last video. I would try lowering the gas see if that helps. If that doesn't obvious thing would be to use a backing but you can't cause it's a tank so that leaves you with back purge. Is the fit up good or do you have a large gap to fill. Get a good fit up. Just to make sure this sounds like when you start on tanks and not when your closing from way I read it

[Graveyard]

I think that might be my issue, I haven't tried turning the gas down. Here's a pic of what I'm talking about. The fitment is tight and as I use the heat to round the metal with body hammers. So I don't weld them until they are tight so the fitment is less than a 1/16 gap typically. [URL=http://s641.photobucket.com/user/r ... .jpg[/img][/url]

[Braehill]

Graveyard,
You're not by chance introducing some kind of contaminent with the body hammer are you? Back side as clean as the front? Have you tried a 309 rod, it will rule out junk boiling out of the base metal sometimes?

Just a few thoughts.

Len

[gamble]

Have you tried a different collet?
Gas should be at least 25cfh. How far is your tungsten stick out? It could be too close or too far away.

[Graveyard]

Graveyard,
You're not by chance introducing some kind of contaminent with the body hammer are you? Back side as clean as the front? Have you tried a 309 rod, it will rule out junk boiling out of the base metal sometimes?

Just a few thoughts.

Len

I have not tried using the 309 but i'll give it a shot. whats weird is it does this even before i add the rod. i don't believe i am introducing contaminent with the hammer but i'll hit it with a wire brush and acitone anyway. it only does it on this small section and i use the hammer across the entire lenght which is around 8".

[Graveyard]

Have you tried a different collet?
Gas should be at least 25cfh. How far is your tungsten stick out? It could be too close or too far away.

i just bought this kit to try its brand new. i have played with the tungsten stickout on this setup but its around 1/2" to 3/4 and its at that lenght for the entire weld which is around 40" all the way around so again it is weird that it only does it in this one spot. i'm running straight argon at 25-30CFH. thank you for your input.

[Braehill]

Graveyard,
I was welding some seat brackets on a 'bobber' for my son one day and everytime I got to this one spot in the frame I got porosity and blow holes in the weld. I cut it off and cleaned it up three times with the same results. I finally welded it with 309 and it turned out fine. I know a lot of the metals that are coming out of China have garbage in the metal. I've had quite a bit of angle iron that will not weld even with ER70S6 and I have to use 309. I know it's not the answer to everything, but it might let you get through this job.

Len

[dirtmidget33]

I still think you have a gas issue either venturi effect pulling in air to argon stream or it's creating some type of vortex, could even be do to the shape of tank possible it's causing a blow out issue if gas somehow being forced back at torch. Make sure your torch angle is correct. I take it you never had this issue with regular size cups like a 7 or 8. I have had issues with large diameter cups on outside corner welds before. I was using about 1/2 inch stick out and went to weld outside corner. It welded real bad. Decreasing stick out in that section to like an 1/8 to 3/16 cured the issue. The problem was due to turbulance cause by way gas flowed over the corner

[Graveyard]

Yes I did not have this issue with the 8 gas lense I was using so I'm kinda going along with your Venturi effect idea. I'm going to play with the gas flow and for giggles I'll run a little 309 on one side to check it out. I have more to weld up tonight so I'll post my findings! Thanks again for the input guys!

[Otto Nobedder]

I think that might be my issue, I haven't tried turning the gas down. Here's a pic of what I'm talking about. The fitment is tight and as I use the heat to round the metal with body hammers. So I don't weld them until they are tight so the fitment is less than a 1/16 gap typically. [URL=http://s641.photobucket.com/user/r ... .jpg[/img][/url]

Are you, perhaps, pausing your wrist at this point, and simply advancing the cup, eventually pointing your tungsten way-sharp-forward?

I catch myself doing this a lot... Finding a point where my "prop" is comfortable, and just stretching the torch to keep going, until I have way too much angle...

Just a thought. The inch behind the blowout is a bit "shady" at best, and the HAZ suggests you stopped and started again.

Steve S

[Graveyard]

I'm going to have to attribute this more than likely to the cup setup itself, either its the wrong application for what i'm doing or i am not setting it correctly and the reason i say this is because i've welded close to 300 of these tanks and i did not have this issue till i swtiched. I'm not saying this to be cocky or that i'm the greatest welder in the world because i'm not but the data is there. i swtiched back to my standard 8 gas lense cleaned the area and went on like there was never an issue. i think the 1-1/8" cup is just not for me. i'm going to try out the smaller cups from CK and see what happens. just to give you everything i tried last night on 2 different tanks here they are: I ran the tungsten in with only 1/8"-1/4" stick out, i ran the gas at 20CFH-35CFH and i even used the 309 rod that was suggested and did not have any luck at all. i even close the seam tight, hit it with a buffing wheel and cleaned it with acetone and no luck. then i switched back to my 8 gas lense and it ran a perfect bead with no blow back.

[angus]

1 1/8 th. classic case of latest and greatest. I agree with you 100 percent. if you have done 300 tanks and not had a similar problem it is obviously the wrong product for the application. I have never used a cup that large, in fact I had never seen one and probably wouldn't have if not for these message boards. I do nearly everything with a 7 or 8 cup.

possibly there is a reason to be using one but it would have to be pretty rare case. i have never welded titanium maybe it would be good to use it there.

i would put this up with the ck flex loc torches. i actually bought one. it heated up so bad i could not hold it even though it was rated to 150 amps at 100 percent duty cycle. i ended up getting rid of it and use my regular 17. i do own a ck with gas valve. the bigger handle provides more insulation from heat. may as well throw in that super flex cable too. can easily live without that.

another guy posting about using a 12 cup with scotchbrite in lieu of a diffuser and 1/16 th tungsten and he clings to the belief that this is the best option in spite of the fact several users have advised otherwise.. people have to realize that just because something is used in a demonstration it is not a recommendation for it's full time use. it is shown as a situational solution.

[Graveyard]

Well put Angus i'm just going to put this in the tool bin for a rainy day or a project where it might be of better use. i will say this, when it does weld good the color of the weld is noticably better than with my standard 8 cup. Thanks for the input everyone and i'll be spending a lot more time on this board learning and maybe helping out here and there. So far i'm liking this forum.

[dirtmidget33]

I think it has to to with shape of the joint. Your weld is almost an edge weld Just think it doesn't get good coverage with way gas flows over joint. I did have an issue with the outside corner. when I get chance and have my large cup on there I will try some edge welds see if I get same results. I am just curious.

Edit add on
Yes large cups are not for every job. I like the large push on ceramic over the Pyrex. I think also cause I'm afraid of Pyrex getting crapped up with junk I buy ceramic push on for those lens cheaper than the Pyrex also.

[motox]

you can try damning up next to it with some foil
if you think its a gas coverage issue. might help
craig

[gamble]

how about a picture of how you have it installed? i've seen many people put things in backwards (collets, heatshields etc) and that causes issues

[kiwi2wheels]

I'm going to have to attribute............ i ran the gas at 20CFH-35CFH and i even used the 309 rod that was suggested and did not have any luck at all. i even close the seam tight, hit it with a buffing wheel and cleaned it with acetone and no luck. then i switched back to my 8 gas lense and it ran a perfect bead with no blow back.

Why are you running so much argon flow ? 12 cfh is a more usual number. Too much flow can cause turbulence and introduce atmospheric contamination.

[dirtmidget33]

with 1 1/8 cups it's normal to run 20 to 25cfh. you have to run it that high because of amount of volume needed for coverage. If running short stick out and welding a fillet you might get by with 12. on tubing and irregular surfaces where argon can not be trapped you have to run higher cfh. I do not like term gas saver for these, Yes lens are more efficient with gas usage but with these large cups it requires a lot of gas.

[ESENTI]

Good to know few things myself , since i have bought a ck large diameter ceramic nozzle 1-1/8 , but i have not tried yet . I thought is too big so i ordered the newer version ceramic nozzle #12 that fits to the above large diameter for this which is 19.mm aprox . Who is a better version of 1-1/8 or 28.mm . Actually it is new on the market and is not readily available in Europe where i belong ( greece ) . Never the less it is hard to weld on an edge since the space surrounding is empty space , better would had been is in a controlled area or a chamber or at least in a quiet corner in a shop without any air draft and very short tungsten stick out.keep up the good work esenti ...

[Wes917]

For what your doing here, I'd be using a 7 cup and gas lens. Only time I use the jumbo lens' is when doing titanium work, and even then a gas lens and 12 is usually sufficient.

[Superiorwelding]

you can try damning up next to it with some foil
if you think its a gas coverage issue. might help
craig

I am with Craig on this one. Before you give up on the jumbo gas lens try to build a dam around your weld path and see if that changes anything. With that joint configuration your argon will fall away quite fast. If that works I still don't see the benefit of using it. You don't want to set that purge dam up every time.

I usually use a 26 gas lens with a 12 cup for my SS work. I have the jumbo but I think I need a new diffuser, doesn't cover like it used to.
-Jonathan

[Oscar]

The joint edge looks clean (ground off), but I see no evidence of any other cleaning. Did you take a flap disc to the 1/4" of metal from the edge of the joint? Can't see swirl/grind marks.

[ESENTI]

I will put it this way , the difference between fail and success is a tinny detail some time so tinny that can not be noticed ( great napoleon ) . So I think is the tig procedure , a shortcut to make thinks faster does not help.Now that im more experienced i pay better attention to details something i could not see before.Cleaning is very very important . Recently
I weld a flat surface thick steel and the protection was excellent so good that i was surprised .The gas had nowhere to go but
where you weld .If this is an edge and void sideways then protection the gas is an issue , if it is thin too so much worse if it is
inox and gets red hot you can easily guess the oxidation will take place.So reduce the tungsten stick out increase gas flow no drafts as this is possible in the shop like the cooling fan of the inverter machine for example and good choice of cup , then watch out carefully the weld puddle to see if has the right color afterwards then you are getting somewhere . Me personally
I saw this large diameter gas lens so nice and i thought to try it and see but then i saw that is too big so i ordered the #12 ceramic cup I am curious whats the use it to full tig power 230 amperes in my case .Since the small diameter gas lens will boil
definitely. Another idea of the dam is to use plates at the sides holder-ed in place with magnets.Few thoughts of Essenti ..

[Graveyard]

I'll try and answer all the questions that came up. As far as cleaning goes i meant that i was cleaning off the steel with a buffing wheel and Acetone. this is 16ga cold rolled steel so i cant grind on it too much or it will thin it and these tanks get beat up pretty badly with the way they are used. i tired this several differnt ways. i tried the tungston in and the gas flow low and i tried it with the gas flow high and it did not change the results. i am in a closed atmoshere with no drafts. I have welded this exact joint almost 300 times with my #8 gas lense without this issue. once i swtiched back to the gas lense in the same exact environment with the same conditions and same steel i experienced no issues. no i do believe it is a matter of turbluance and the shape of the steel opening. once i get to the edge i close that gap with a boddy hammer as i go. as far as putting the unit together backwards or incorrectly i will try and upload a photo but i don't believe i could have put anything together backwards.