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Up Topic Welding Industry / General Welding Discussion / my latest tig problem
- - By rtnnhazel (*) Date 09-28-2007 03:05
i own a 51 chevy pickup and it is the whole reason i bought a tig machine. i have been trying to weld patches and seams and hopefully chop the top. i use 1/16" cold steel (i dont know if its cold or not but it is steel). the 50 year old steel the truck is made out of what looks like 20 gauge. im not really sure how to transfer inches to gauges. my welder settings are as follows: 40-50 amps, 1/16 2% thoriated tungsten, i use a foot pedal, using 1/16 evdur or silicone bronze as filler, 100% argon @ 15 psi. i am getting a tear drop on the end of my tungsten, my tungsten is turning black and im burning holes in the steel. im holding the tungsten about a 1/16 off of the work and im sure contamination is one of my problems as i dont have the steadyest hand yet. i wonder if im running too many amps? i have .040 tungsten also would that help? i also clean the metal with isopropyl alcohol. the welds are butt welds. would a different type of weld help,such as on overlap? i know its a lot to think about and i appreciate any help you may have. im getting really frustrated. i can post pics if it will help. thanks, robert
Parent - By OBEWAN (***) Date 09-28-2007 12:09
Make sure you are using DC Electrode negative polarity (dc straight).  MIG is a better process for sheet metal body work.
Parent - - By Kix (****) Date 09-28-2007 12:25
What kind of machine are you using for yor tig welding?  Is it one that you can switch from tig to stick on the machine without switching your cables?  It sounds like your torch is hooked up to the + terminal and your ground is hooked up to the negative cable.  It sounds like a simple fix so fill us in on just a bit more detail.
Parent - By rtnnhazel (*) Date 09-28-2007 23:42
im running my ground on the positive terminal and my torch on the negative terminal. my machine will do stick but it is a different cable. so yes i have to switch cables. it is an htp dc/hf 130. i use the high freq for everything and have never tried the touch start mode. do you think that would help?
Parent - - By jd369 (**) Date 09-28-2007 23:53 Edited 09-28-2007 23:55
I would like to know what machine you are using as well, if you have a post flow setting then it may be set to low (too short of a time) if your tungsten is turning black. It could also be that your tungsten is extended too far from the cup, a "good rule of thumb" to follow is that the tungsten shouldn't protrude any further then the measured internal diameter of the cup. So if you are welding with a number 7 cup (7/16 dia) then your tungsten shouldn't protrude any further then 7/16". Are you using a regular collet body or a gas lens? You mentioned your shield gas is set to 15psi, are you sure you don't mean 15 cfh. I want to make sure you are using a proper flow meter and not actually running 15 psi out the torch as this would definitley cause some contamination with air being drawn into the stream.
  What cleaning methods are you using prior to the alcohol wipe? Is the steel clean and shiney on BOTH sides of the butt joint prior to welding? This is important as the contamination on the opposite side that you are welding will still get into your weld puddle if not cleaned.If your material has mill scale on it it will cause contamination and needs to be ground/sanded off, I use a small disc sander to prep the steel to clean off rust paint undercoat etc. The alcohol is probably over kill for body work if it is nice and shiney but it certainly won't hurt. I like to use tig for body work myself and find it works very well.
  Butt joints are a good choice, the 1/16" tungsten is an excellent choice as well. Do you have a remote amp control like a foot pedal or thumb wheel? If not then you may want to get one if your machine will allow it, you will have much greater control while welding. Does your machine have high frequency start/ lift start/ or scratch start?
Obviosuly the aforemention polarity is something you will need to check as well, DCEN is what you want to run it on. I think at 40-50 amps on DCEP with 1/16" tungsten it would ball up quickly and you should see that this is not right, if you don't touch the filler wire to the tungsten or melt it into the work piece it should stay reletively sharp.
Get back to us
Good Luck
Jim
Parent - - By rtnnhazel (*) Date 09-29-2007 15:00 Edited 09-29-2007 15:12
the machine i use is an HTP DC/HF 130. it is a 130 amp machine i am running dcen. the ground lead is on the + terminal and the torch is on the - terminal. thanks for correcting me i am running 15 CFH not psi using an argon flow meter. i use a pyrex cup with a gas lens with about 3/8 sticking out. i have a full set of alumina cups but wasnt really sure what all the numbers meant and which application to use them with. i do use high frequency but have never tried the touch start method. i do have a problem where i will get a puddle going but my filler will just ball up on me and not flow into it. the steel is 50 years old and not very clean, i can clean the side i am welding on but the back side is very limited space so i cant get it very clean. i use a foot pedal with my machine. i also use the ground of the magnet type the kind where the ground wire is attached to a magnet instead of an actual clamp. can that be causing my problems? does anybody else use those?
Parent - By Lawrence (*****) Date 09-29-2007 15:18
If that magnet is within about a foot of your welding arc it can cause havoc.
Parent - - By aevald (*****) Date 09-29-2007 18:32 Edited 09-29-2007 21:24
Hello rtnnhazel, as Lawrence conveyed to you, the use of the magnetic ground attachment can be highly detrimental to arc stability, go to a standard clamp system. I believe the other issue for you is the cleanliness issue, whenever TIG welding, the joints have to be ABSOLUTELY clean, one of the other responders to this thread said that as well. Quite some time ago I was following a conversation on a particular topic where GMAW and TIG were being compared, an interesting point came up, with the wire process, the filler metal, due to the use of DCEP current concentrates the majority of the heat at the end of the wire where it is melted and then transferred to the base metal, this causes very minimal dilution of the base metal, thus the cleanliness of the base metal has a lesser effect on the finished weld in some ways. The TIG process on the otherhand utilizes DCEN current, in this case the heat is concentrated in the base metal and provides the heat to melt the base metal and melt the filler rod to form the weld bead. Because of this, the base metal has more dilution with the filler metal and also requires the base metal to be much cleaner. I hope this explanation somewhat explains why you may be having some of the difficulties you are experiencing, as you aren't able to clean the weld joints as they probably should be cleaned in some cases. The balling of the filler rod can possibly be caused by a couple of things, if the torch angle is laid back too far you may be directing too much heat towards the end of the rod causing the balling. If you don't quite withdraw the rod away from the weld pool quite far enough when dabbing the filler rod this can also occur, care must be taken though when withdrawing the rod from the pool, if you are using a dabbing motion take care not to withdraw it too far, this will cause oxidation of the end of the filler wire and upon adding the rod back into the pool will introduce this as a contaminant into the weld pool. As much as I hate to say it you may want to consider a different welding process on certain parts of this work, especially if you can't clean the parts correctly. Best regards, aevald
Parent - - By rtnnhazel (*) Date 09-30-2007 02:38 Edited 09-30-2007 02:42
i appreciate your reply. do you think running dcep would help the because it woould get hotter? or is there a way to get the metal clean without a grinder or flap disc? again i appreciate your help with this. also from what you have written i believe i am to blame for some contamination, i have always been completely removing the filler from the welding area. i will try to keep a better eye on this.
Parent - By aevald (*****) Date 09-30-2007 02:54 Edited 09-30-2007 02:57
Hello rtnnhazel, if you try to use the DCEP polarity you will end up having the tungsten ball up excessively on the end, DCEN is the correct polarity. It simply boils down to using the correct process for a given situation. If you have no other choice for the welding than TIG try to clean everything as well as you possibly can, also try laying the filler into the joint and use only enough heat to get it to melt and bond to both sides of the joint. This can be a little tricky but with a bit of practice you may end up with satisfactory results. I don't exactly recall the diameter of the filler wire that you said you are using, for this work you might either try to get some .045 diameter filler or simply use some .045 diameter GMAW welding wire and cut it into 10" or 12" lengths. If you have a dremel tool see about getting a fairly small ball-end carbide burr to fit it and use this to do some of the cleaning of the joints that you will be welding, although this could be rather time consuming. Best of luck and regards, aevald
Parent - - By DaveBoyer (*****) Date 09-30-2007 04:10
I guess from the filler metals You mentioned that You are TIG brazing. Have You tried steel filler wire? and how did that work? 70-S6 mig wire might work due to the de-oxidisers in it, I don't know. I guess that You are using an un fluxed rod, where if You were gas brazing the flux would be working to break down the iron oxide [rust] on the underside of the material.
Parent - By aevald (*****) Date 09-30-2007 04:34
Hello Dave, thanks for noticing that he was using silicon bronze, and to you Robert, I was referring to using a mild steel filler as DaveBoyer had mentioned in his post, although the silicon bronze will react similarly to contaminants and possibly even worse. When using silicon bronze filler with the TIG process heat can have a big effect on the puddle, how it wets out and ties in, and it also requires a great deal of cleanliness. Regards, aevald
Parent - - By Tommyjoking (****) Date 09-30-2007 17:32
Robert I hope this helps clear up some things for ya....lot's of things have been covered so I won't have to make too lengthy a post (whew!)

First the metal gauges:  http://www.engineersedge.com/gauge.htm

WAY TO GO DAVE!!!  I have been waiting for someone to pick up on the filler being used here.....

Robert that's the first thing I want to address is your filler.  I assume this choice was made from the standpoint of reducing shrinkage/warpage/distortion of your base metals.  As Dave has already said by using that filler you are actually going for a brazed joint not a welded joint.  The whole idea is to get your steel dull red (both pieces) and then add the bronze into the arc....it will flow in quickly ....move forward and repeat.   This is easy to do with an oxy-acetylene rig and tricky to do with a tig.    IF YOU ARE bringing that steel to melting temperature as with normal tig welding I can imagine that bronze is virtually boiling....the  melting point temperatures are quite different....silicon bronze will melt at around 1760F and your steel will be around 2600+.    This difficulty will be compounded by the fact that you have two very different thickness of steel as you mentioned.  40-50 amps is appropriate heat for welding (melting) 1/16 steel but is way to hot for 20 gauge which is approximately half that thickness.    20-30 amps is more appropriate for the thinner material for welding.  Here are some pointers for making this work out;   Since you are not needing to bring that steel to melting temp lower your heat range quite a bit.   Your metal will have to be absolutely clean and free of rust, scale and oil anywhere near where its being heated front and back.  Lap joints will give you the best results with your thinner piece top on the torch side.     Use a large gas cup and more flow say around 20-25cfm.  You may want a lighter shade lens (9) so you can clearly see the steel just when its starting to get red....not getting the steel too hot is very important here.

If you were to abandon the bronze and go for a more conventional weld then ER70-S2 or ER70-S6 would be a good choice.   This also will not be quite as sensitive to cleanliness as trying to tig braze.   1/16 diameter filler is too large...A good rule of thumb with TIG is for your filler diameter to be no larger then your thinnest piece to be welded......if your truck body is 20 gauge then that means an .032 filler or smaller.  Your heat range should be 0-40 for welding 1/16 to .032 material.    Stick with the 1/16 tungsten just have it nice and sharp.

To address your tungsten and process issues:   Weld steel DCEN (DC negative).  Use your start mode on your high frequency....leaving it on continuous is just going to help erode your tungsten quicker.   At 40-50 amps as you mentioned there is no way you are melting your 1/16 tungsten (on DCEN anyway) so you are probably getting contamination on it.  Hold your tig torch like a big pencil and try to brace your elbow or forearm where you can and this will help you stay more steady.

Good Luck
Tommy
Parent - - By rtnnhazel (*) Date 09-30-2007 18:25
i never thought of it as tig brazing the guy at my local welding shop said most car guys use evdur so i bought a pound. so i guess in a sense i have never done any tig welding only brazing. i will get some er70-s6 im told it wets a little better. if i am to kep a butt weld should i concentrate the heat more on the thicker metal and weld into the thinner. i hope i worded that right. i am really hoping the filler change will solve most of my problems. i will go pickup some up now and let you know how it turns out. thanks, robert.
Parent - By Tommyjoking (****) Date 10-01-2007 01:37
Robert any bronze you already have stuck will have to be sanded off before trying to weld  over the same area...this should not be difficult with a small grinder/sander as the bronze will be above the surface of the steel
Parent - By aevald (*****) Date 09-30-2007 18:37
Hello Tommy, nicely put. All of those little nuances and details all add up to either success, partial success, or failure. The real trick is to have all of the pertinent information and then be able to figure out how to put it all to good use. The only tough thing about this situation and many others, is not being there to witness and help with the problem. Best regards, Allan
Parent - - By discusswelding Date 09-29-2007 20:17
you can find all your answer to tig welding here.     http://discusswelding.com/forum/forumdisplay.php?f=4
Parent - - By ctacker (****) Date 09-29-2007 21:15
Looks like my ignore function is finally gonna come to some good use!
I personally think 1 post about your website should be sufficiant to let everyone know about it!
Parent - - By aevald (*****) Date 09-29-2007 21:28
Hello ctacker, I do believe a different introduction onto this forum would gain a better response to this individual. I am always leery when I see something like this and then I go to the bio page and don't find any sort of information to identify who this person is in any way. Can we all say "SPAM"! Regards, aevald
Parent - - By ctacker (****) Date 09-29-2007 21:36
hows that spelled? SPAM? i been to that website,and find this forum much more informative and professional,maybe every member here should go there and advertise this forum!
Parent - - By aevald (*****) Date 09-29-2007 21:48
Hi again ctacker, you might just have something there. Regards, aevald
Parent - - By Kix (****) Date 10-01-2007 12:49
Could this be as simple as he needs to swap the cables back.  I mean if you have a machine that can be switched from elec - to elec + on the machine then the leads do not need to be switched ever.  You need to put your torch back on the + witch you say is on the negative lead now and put your ground back on the negative terminal and switch your machine to elec -.  Try throwing in on elec + for sits and grins the way it is now and see what happens.
Parent - - By aevald (*****) Date 10-01-2007 13:48
Hello Kix, I believe this particular machine is a DC only inverter for stick and tig w/hi-freq and touch start capabilities, I don't believe it has a current selector switch, but if it does, I see where you are coming from. Definitely something to consider with regard to tungsten issues. Regards, aevald
Parent - - By Kix (****) Date 10-01-2007 15:53
http://www.htpweld.com/products/tig_welders/tig130.html.  This is all i could find on the machine and it's not a very good picture of the bells and whistles, i'm thinking that you are correct about it not haveing any current selector switch.  I just thought i'd throw that out there just in case.;-)  Sometimes it's only that simple and no money has to be spent. lol
Parent - By aevald (*****) Date 10-01-2007 18:18
Yes Kix, you're absolutely correct it is those simple things that will sometimes catch you off guard. Regards, Allan
Parent - - By SWP (**) Date 10-01-2007 13:18
I don't think its been mentioned yet, but when TIG Brazing with Everdur, YOU DO NOT MELT THE BASE METAL!  Use the arc to melt the everdur, do not melt the base metal.
Parent - - By rtnnhazel (*) Date 10-02-2007 01:08
no my machine does not have a current selector switch it is a somewhat basic machine but more than enough for what i am trying to achieve.besides it all i could afford on an electrician apprentice budget but we all make do with what we have. i didnt know that you dont melt the base metal with everdur i think i will abandon the evdur for a while in concentrate on the .035 70-s6 and the 1/16 70-s2 i bought. the s6 is on a spool is there any tricks for working with it off of a spool? i was thinking of mounting it so i could just pull it off as i need it and feed it straight into the puddle. thanks for all the input, robert
Parent - By Tommyjoking (****) Date 10-02-2007 09:50
Robert you could try that method with the spool but....what I do is just pull of loops in my hand till I have say 20 or so then just cut it with a pair of snips.....I take it and straighten it by working it thru my hands.   When its curved or straight off the spool you will tend to have problems feeding it right where you need it and often times it will jump in your fingers when you feed it and hit the tungsten.   Do go back and check and make sure those leads are on the correct polarities....if they are backwards your tungsten will melt as soon as you step on the pedal.    If you refer back to my first post it will give you a bit of detail on running the bronze for future reference.
Up Topic Welding Industry / General Welding Discussion / my latest tig problem

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