problem with grapes

Hi. I am just learning how to stick weld, and I have been having some
problems with grapes (I think that's the correct term). I have tried
running stringer beads on scrap plate and bar, which seems to be the
first training lesson, and these seem to be working out OK. They are
straight and clean, and seem to have decent penetration.
So, I tried working on a real job. This was welding a slotted brace
to a steel strip. The strip was a few feet long, and the brace was
1.25" x 4" with a slot in the middle. Both pieces were 3/32" thick.
The brace was kind of ragged, being made with blacksmithing techniques
(sequential application of slotting punch, and knocking the biscuit
out from the back side). So, it was a little ragged. There was about
a 1/32" gap in the middle, and I tried to fillet weld the piece with
3/32" 6013 with AC. Tack welds worked fine, but when I tried to run
the bead, I burned a hole through the place with poor fitup. I
probably need to improve my hot punching technique, or use a swage.
Anyway, there was a post on USENET, I believe by Mike Graham, saying
that blow throughs can be fixed by sweeping the rod back to the hole,
then backing off to allow it to cool. This would be repeated until
the hole was filled. Although this technique seemed to work, and it
filled the hole (sort of like an interrupted whipping motion), it
produced these hot sizzly balls which landed on the metal. These
things were HOT, and some of them landed on the work surface and
burned for awhile. After everything cooled, they turned out to be
metal balls which stuck really hard. They are really ugly, and not
like slag balls, which can easily be chipped off with the hammer.
When you file them, they turn into raised half balls with a shiny top
face, still really ugly. They don't seem to affect the strength of
the weld, which works out, but is there any way to avoid them? OK,
don't blow through, and try to achieve good fitup, but once the deed
is done, is there a way to avoid producing these things. Oh yeah,
they look like they will burn through clothes/gloves.
Thanks,
Eric
Reply to
Eric Chang
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They will. What you have is called welding spatter. Grapes are a different thing, drops of metal hanging off the backside of a butt weld joint due to too low a travel speed.
Too much heat, too long an arc, irregular electrode motions will all cause spatter. Some rods produce more spatter than others too. It is part of welding. Try turning the amps down about 20%, maintain a tight arc and consistent travel, and most of the spatter should go away.
Gary
Reply to
Gary Coffman
Does it look like buck shot (splatter), you can knock it off with a cold chisel. Place the chisel point at base of the ball and strike with hammer. To stop splatter from sticking coat your metal with Pam or other cheap no stick cooking spray.
Reply to
Lance
Eric, it sounds like you were running too hot. How many amps were you running, and on what sort of machine? Also, how big were these "grapes"? You will normally get some splatter in stick welding, and it will be worse if you are running too hot. The way that you describe the splatter "burning" makes it sound like you were getting the metal so hot that it was *literally* burning. That is too hot!
FWIW, I would run around 70 amps for that size metal and rod -- on my machine. But note that different machines will perform differently, or perhaps will not be completely accurate in how they set the amperage, so your mileage may vary ...
Yes, you can fill a hole in the manner that you describe, but I normally wouldn't try it with 6013; it is easy to get all sorts of slag inclusions. 6010 (if you have DC) or 6011 (AC or DC) will work better for this, because it is "fast freeze," it has minimal slag, and it will penetrate through that slag easily. You do have to learn how to use these rods; they are agressive ... but they are great for dealing with poor fitup problems.
Hope this helps ...
Andy
Reply to
Andrew Hollis Wakefield
Sometimes what looks like grapes can be bubbles caused by rust, oil, paint, or other contaminants in the weld area. They will be hollow, and you can watch them boil up and cool.
Just a variation on grapes.
steve
Reply to
SteveB
Yepper's too hot! splatter is common in welding, if the machine is set right, your travel speed angle of rod to the work piece and arc length are correct, than your slage covering the weld should lift up and off, or after 5 min of cooling just fall off, the splatter those tiny metal balls should take little or no effort at all to dislodge, if you need a chisle and hammer to crack them loose your just too hot in your settings, when your burning through your work piece, your too hot in your machine settings, or too slow of travel speed and or a incorrect arc length, the object when welding is watching your puddle and listening to the arc and the machine, they will tell you when your running sweet and when your not, play play play
Reply to
rodney johnson
Hi Larry. Thanks, I did not think of a cold chisel. That should do the trick. This is splatter, but a much more severe type of it. Usually, those little balls do not stick, and can easily be chipped off with the chipping hammer. I think that the problem is due to poor technique and I need more practice. Doing a normal weld is no problem; the splatter is easy to deal with. I think the problem in this case is that I am whipping the stick forward and preheating the area ahead of the weld. Then, when I whip back to the area where the weld is taking place, any splatter which lands on the now hot region ahead of the weld sticks real good.
Thanks, Eric
Reply to
Eric Chang
...
Hi Gary. Thanks for the helpful advice. I will try your suggestions, but when filling in a blow through, it is difficult to maintain consistent travel, or else the hole just seems to get larger!
Eric
Reply to
Eric Chang
Hi Andy. I am using a Miller Thunderbolt, dialed to just below the 75 amp line. I will try to back off a little in the current. I did notice that 6011 was a little more well behaved on how it filled spots, and it was easier to see the puddle. But I did not have any 3/32" 6011, and besides I heard that 6013 was good for thinner stuff.
I picked up a lot of this 2 mm stock as scrap, and I will practice more on some non-critical jobs. Maybe just running some more long laps and fillets.
Eric
Reply to
Eric Chang
Sure, but if you follow the suggestions, you won't be getting blow through.
Gary
Reply to
Gary Coffman
Eric, if the normal stringer beads are working okay, but it is just filling in the hole that is causing the problem, then you may be okay at 75 amps ... but certainly doesn't hurt to try dialing it down and see what you get. I welded up some brackets from old bedframes, probably around 2 mm or so, and was surprised that I was burning through at 75-80 amps; I think I had to dial it down to around 65.
On the other hand, in a recent discussion along these lines, someone talked about using 6013 at a relatively high heat, but moving very quickly along. This requires perfect fit-up, as I recall. I haven't had a chance to try it out ...
Meanwhile, I wouldn't hesitate to use 6011 on 2mm stock. Do you have it in 1/8" rod? If so, give it a whirl. Particularly if you have any fitup issues, or any dirt, rust, paint, etc., 6011 is great. You do have to use it with a "stitch" motion, or you will burn through in a hurry. But I have used 6011 even on very thin stock (less than 1mm) and had pretty good results. This rod features "fast freeze," thin slag, and ability to hold a long arc; all were helpful when using it on thin material.
I have found that I can usually switch between 1/8" 6011 and 3/32" 6013 at the same amp settings -- for a given size rod, you will need a lower amp setting for the 6011, but switching the sizes of rod lets you use the same amperage. Or so I've found in my relatively limited experience ...
Hope this helps; have fun!
Andy
Reply to
Andrew Hollis Wakefield

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