weld bead looks?

[Miggy89]

Im still trying to learn to tig & am able to stick things reasonably well im ok in different positions etc but im having trouble mastering the bead. Most of the time my beads are either very flat or slightly concave & im struggling to get any sort of convexity if i add more filler it looks almost like a mig weld i carmt seem to get the stepped look. so my question is what is a good bead height & is a little concave acceptable in general?

 

[AdrianH]

I may be completely wrong here, but to get the stack of dimes effect, to me seems as though you are, how do I describe it?, putting down loads of spot welds.

Or, not giving enough heat in the deposited metal to flow in the rest, so it sits proud.

Awaiting to get shot down in flames.

I would have thought that a small 'ripple' on the top of the metal to show where you placed filler in would be preferable to the weld. As to get to that stage I would not know.

If anyone on here to ask I guess @Paul. would be a favourite person to pester. His work always seems very well presented, lots of stainless work etc.

Adrian

 

[8ob]

A friend of mine made up a pair of these collectors for me , lots of prep and very little filler rod. Plenty of penetration and no snurgs hanging inside.

 

[hotrodder]

Pics would help us see what's going on. From flat to concave welds and struggling to get any convexity it sounds like you're too hot for your travel speed and maybe the arc length is too long... pics will tell us which or if both are likely.

Ripples in the bead are just freeze lines from each addition of wire whether moving in a step-pause & add a dab-step manner or keeping a steady travel speed while dabbing wire or from torch manipulation*. What people usually mean by the 'stack of dimes' look is typically the result of adding more wire less frequently to exagerate the freeze lines and add a bunch of stress risers. Popular with Septics and twitface users [/tongue in cheek] Should be at least 60% overlap and ideally more like 70-90% overlap of each 'dime' (dab of wire), the later results in a smoother weld where the ripples are more like that exhaust collector i.e. visible but the weld is smooth rather than like the alps with peaks/troughs

* not something to think/worry about for now but when weaving/walking the cup you get a different pattern of freeze lines from the arcs changes of direction whether dabbing wire or feeding it constantly

 

[Richard.]

Miggy the desired tig look your after is a natural part of the process and is created by freeze frames. When you add fill you are as Adrian says adding a tack or reininforcememt to the weld which is a "dime" as they say. Then you move and that "dime" solidifies behind the pool so you add more fill which is another "dime"
Now controlling how far apart these dimes is all down to how fast you travel and how frequent you fill. Hope this helps.

 

[Miggy89]

i can manage similar to the above pic bar my dip lines are much closer together to the point the whole bead looks mig like, i know arc length is ok im holding aroughly 2mm, i think what im doing is letting the pool penetrate too much then now being able to bring it back up & slightly proud of the top i think this because the penetration on the back is far more than whats on top. but is there a general rule for bead height at all or is flat concave convex better than another for any given type of weld?

 

[Miggy89]

Miggy the desired tig look your after is a natural part of the process and is created by freeze frames. When you add fill you are as Adrian says adding a tack or reininforcememt to the weld which is a "dime" as they say. Then you move and that "dime" solidifies behind the pool so you add more fill which is another "dime"
Now controlling how far apart these dimes is all down to how fast you travel and how frequent you fill. Hope this helps.

thats exactly what im looking at trying to achieve but rearly got to get travel & dip timing more insync i think.

 

[Richard.]

thats exactly what im looking at trying to achieve but rearly got to get travel & dip timing more insync i think.

Just don't fall into trap of believing big prominent, shiny, elaborate stacks of dimes are the way to achieve sound welds.
Weld porn seekers may love it but come the day it's got an important job to do you may be pleasantly surprised how far compromised the joint can be because of it.

We can all weld it too cold piling in the filler at really long intervals while swamping the pool with excessive gas flows but if as you say you can achieve a sound smooth weld then I certainly wouldn't say your doing it wrong at all.
Sunken wide welds are probably caused by too much current and travel been too slow.

 

[Richard.]

Not too elaborate but a clean well fused root run on thick 316 I was doing some trails on.
You can barely see the ripples but the important thing is that it's a clean sound pass.

 

[Miggy89]

thats how most of mine are nowhere near as consistant in dip spacing but its good to know im on the rite track & not f'ing it up doing wrong. thanks Richard.

 

[Richard.]

Consistency just comes with practice. Sounds like your defo on the right track then

 

[Miggy89]

thats good to know il keep trying to get some good consistancy & then think about aesthetics

 

[Richard.]

thats good to know il keep trying to get some good consistancy & then think about aesthetics

With weld soundness at the top of your priority list

 

[Miggy89]

of course, is it possible to do multiple passes to get best of both ie good sound weld aswell as exaggerated ripples or is it not worth the hassle. i think its partly because im so used to mig welding that a flat tig bead just isnt the norm to me

 

[Richard.]

of course, is it possible to do multiple passes to get best of both ie good sound weld aswell as exaggerated ripples or is it not worth the hassle

Depends......... Does it warrant a multi pass? Unles your filling a thick joint I'd say not at all. It's only really special Applications, usually exotic metals to X-ray standard where Tig would be used to complete the whole joint.
While multi passing has benifits of extra reinforcement and grain refining if it's done on material much thinner than the actual weld itself it then creates stress points at the weld toes. You certainly wouldn't put an 8mm fillet down 2 MM metal nor would you put an 8mm fillet down 20mm metal. It all needs to be related.

 

[Miggy89]

nothing iv done yet needed multy nor will anything im planning in the near future tbh the thickest material im welding atm is 3mm carbon steel, i was just wondering wether it was possible or even plauseable just to get the desired appearance but if a since a tig weld is generaly "flatter" than mig in any case i think its just a case of getting used the fact that it can be a good solid weld without the extra height that a mig bead gives if that makes sense