How do I prevent the crater at the end of a stick weldment?

When I start a weld, for instance a fillet weld, I end up with a big goop when I start, and a crater when I'm done. Sometimes they aren't as pronounced, but I have yet to develop a technique for either problem. I was making some parts today that had fillet welds of about an inch in length, and they just look abysmal, with a big marble at the start and an empty crater at the end.

Since the crater at the end is the biggest problem; how do I prevent (or fill in?) the crater at the end of a fillet weld?

This is with a basic buzz box, not a fancy machine.

Thanks,

Jon

Reply to
Jon Danniken
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Linger a little longer on the end with the welding rod?

Reply to
Ignoramus16320

Thanks Gunner. So should I be reversing the rod angle as well, or just the direction of travel?

Jon

Reply to
Jon Danniken

Thanks again Gunner, I'll give that a try next time.

Jon

Reply to
Jon Danniken

What he said, just be careful with 7018 so you do not break the arc, or you will have a big repair. Keep your eye on the puddle, and the end of the stick in it.

Steve

Reply to
Steve B

You mean that unsightly pile of rusty (s)crap on the side of my garage covered in welds two to three welds deep? That's my retirement fund!

Jon

Reply to
Jon Danniken

As someone explained here - probably years ago - on the backward journey if you do it quickly you are not melting, so you are not reliant on shielding yet. The 7015/7016/7018's take a moment to get the shield up and running, don't they? So doing the backward travel also means you don't have porosity at the bead-start location. The rod is hot, the arc is formed and the shield is formed.

So it's kind of strike a bit down the weld, travel quickly back as the arc starts to burn clean then quickly land down with a short arc and start your run. That run with a puddled weld-pool absorbs and melts away any small amount of crud from the burn-start and makes the location of the arc-strike history when you run over it.

That's all well when you are doing the usual in-the-shed stuff - snapping the flux off the end of the rod and striking it again.

What's the recommended technique if you are on a big-bucks job with a "free issue" of premium welding rods? Then you never restrike a rod. Throw away and get another with the graphite(?) starter tip (the black blob) every arc-strike. What's most recommended then? Strike at the location you want to run from and get going? Or still strike ahead, run back, dip to short arc and run?

Reply to
Richard Smith

I first learned stringer bead technique in '71 from a friendly main steam pipe welder, who found an extra helmet for me and explained in detail not only everything he was doing but everything he had to do to qualify for the job. Failure of one of these high stress, high temperature welds will kill everyone in the engine room and disable the ship, so requirements are very stringent, with near zero flaws allowed in the radiographic inspection (often called X-ray but actually gamma ray sources were used). In the event of failing radiographic inspection, rework can easily take a week and cause a ship to spend extra time in the shipyard at $30,000 per day or more, so consistent flaw free welding is highly valued.

While I routinely use the backing up technique in welding low carbon steel, where small flaws are irrelevant, in high integrity SMAW welding backing up is a bad idea. The start and stop of an SMAW bead will always contain flaws; the start is likely to leave inclusions and there will always be a crack at the unavoidable exit crater. So for high integrity SMAW, nothing is left in the finished weld except for metal deposited by a fully established arc with proper position and travel speed; all else is ground out. So since you will grind out all starts and stops, you want them to be as small as possible. Strike and establish forward motion as quickly as possible, and pull away forward at the end rather than back up.

The other key to flaw free SMAW is to never weld over any sharp angle which could trap flux - always smooth all corners and irregular or rough spots out with the grinder first. 1/8" thick (maximum) unreinforced wheels work best, wire brush after grinding to remove any residual grinding grit which could otherwise be left in the weld.

The free lessons I got from this welder worked out really well for me during a year in a shipyard on the USS Saratoga, where I was reassigned from valve overhaul to welding after doing a weld the supposedly best welder from the hull tech shop said was impossible. Welding 12 hrs per day 7 days per week is a good way to improve your technique :-).

Glen

Reply to
Glen Walpert

Glad to be back and conversing again about these things again. Read your post with great interest. Rgds -- RS

Reply to
Richard Smith

Usually just strike the arc, hold a long arc to avoid much metal transfer for a moment until everything is up to temp. than just do it.

Reply to
John B.

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