Capillary pull alongside the weld

[ojh]

Is there a way to minimize the capillary pulling of the base metal alongside of the weld seam? I am using a -2 filler rod with tig, when I metal finish I wind up with additional grinding of the base material to eliminate the seams from the capillary pulling.
Thanks, Oj

[Chris_Hamilton]

What size is that? Not familiar with that nomenclature. One reason why the English don't use filler rod is for the reason you listed.

Only thing that can help is use a smaller rod (ideally around the same size as the sheet you are welding) and use it more sparingly. That will lessen it but it won't eliminate it.
I think you need to plan to shave/grind the backside if you are going to use filler and plan your weld areas accordingly. Try some .035 MIG wire if you haven't already.

[crystallographic]

Originally Posted by ojh

Is there a way to minimize the capillary pulling of the base metal alongside of the weld seam? I am using a -2 filler rod with tig, when I metal finish I wind up with additional grinding of the base material to eliminate the seams from the capillary pulling.
Thanks, Oj

how about pre-stretching the metal edges?
Or using an old sonic weld vibrator during the weld process?
Just guessing ....
otherwise, minimal amps + minimal rod dia + adjust polarity + freq. ....

[hot rivet]

Do you have a picture? when i try to visualise what you are saying all i can see is an undercut weld which is a manipulation/setup error.

[Chris_Hamilton]

Originally Posted by hot rivet

Do you have a picture? when i try to visualise what you are saying all i can see is an undercut weld which is a manipulation/setup error.

Screenshot is from David Gardiner's DVD. Illustrates what the issue is when using filler rod.

[BTromblay]

Originally Posted by ojh

Is there a way to minimize the capillary pulling of the base metal alongside of the weld seam? I am using a -2 filler rod with tig, when I metal finish I wind up with additional grinding of the base material to eliminate the seams from the capillary pulling.
Thanks, Oj

Hi,

The under cutting along your weld seam is more than likely caused by being to hot. Try an initial TIG welding setting of 1 Amp per thousand of an inch, example (.040" thick= 40amps) if in a aluminum add 10% to your current setting. For the use of filler rod in 19 gauge steel, I prefer a 1/16" diameter rod with a 1 to 1 dip rate approximately. 1to1 example (1" of filler rod for every 1" of travel).

I recommend to people that I have trained in the past, to start with a test coupon approximately 12" square, sheared in half. Weld, evaluate, shear, weld, repeat and so on. You want to verify that the heat affect zone (HAZ) / (the discoloration) is consistent and parallel to the bead and that you have full penetration on the backside. The larger coupon is used to give you a realistic result when building bigger parts. Small coupons heat up quickly and require more accurate temp control on behalf of the operator.

With practice and some basic instruction you can make a consistent weld bead that is fast, clean, full penetration and no under cutting that can be planished and fully disappear.

Let us know how you do. Hope it helps.

Bill

[crystallographic]

FYI - "Negative weld volume" is what the weld engineers term "post-weld shrinkage."

Not sure if capillary action is a recognized welding feature, metallurgically speaking.
At least I've never heard or read about that??

[crystallographic]

FYI - "Negative weld volume" is what the weld engineers term "post-weld shrinkage."

Not sure if capillary action is a recognized welding feature, metallurgically speaking.
At least I've never heard or read about that??

[ojh]

Originally Posted by BTromblay

Hi,

The under cutting along your weld seam is more than likely caused by being to hot. Try an initial TIG welding setting of 1 Amp per thousand of an inch, example (.040" thick= 40amps) if in a aluminum add 10% to your current setting. For the use of filler rod in 19 gauge steel, I prefer a 1/16" diameter rod with a 1 to 1 dip rate approximately. 1to1 example (1" of filler rod for every 1" of travel).

I recommend to people that I have trained in the past, to start with a test coupon approximately 12" square, sheared in half. Weld, evaluate, shear, weld, repeat and so on. You want to verify that the heat affect zone (HAZ) / (the discoloration) is consistent and parallel to the bead and that you have full penetration on the backside. The larger coupon is used to give you a realistic result when building bigger parts. Small coupons heat up quickly and require more accurate temp control on behalf of the operator.

With practice and some basic instruction you can make a consistent weld bead that is fast, clean, full penetration and no under cutting that can be planished and fully disappear.

Let us know how you do. Hope it helps.

Bill

Too much heat, that's a possibility. I'm welding 19 & 20ga, my machine is set at 70% of the 5 - 60a range so I could be too aggressive on the pedal, I use ER70S-2 x .045 filler rod, I keep the rod ahead of the seam and pull metal from it if I need it.

[ojh]

Originally Posted by crystallographic

FYI - "Negative weld volume" is what the weld engineers term "post-weld shrinkage."

Not sure if capillary action is a recognized welding feature, metallurgically speaking.
At least I've never heard or read about that??

I'm doing a fender now and will post a photo. You are probably right that the amount of metal pulled isn't a factor, its just the thought of removing base metal.
I can be stoopid at times.