Had an interesting day welding up the first end of my CNC table with the Millermatic 250 MIG welder the other day. I had this section all tacked together, so I just had to run beads along the seams in such a way as not to warp the heck out of everything. I got to the shop and clamped my work down flat on the table. I checked the settings on the welding machine and got to it. I ran about an inch of bead before I realized I’d forgotten to listen for the gas… AGAIN. This time instead of turning on the wrong bottle, I’d forgotten to turn the gas on at all. Shame. I need a checklist for this apparently.
I did my penance of grinding out the porous weld, turned on the gas and sat down to try again. This time I didn’t make it an inch. As soon as I struck an arc, I flashed myself in the eyes. Another item on the checklist needs to be to switch the auto-darkening welding mask setting from “grind” back to “weld.”
After rubbing my eyes and blinking for a minute, I finally ran my first bead of the day. I think it turned out more or less decently. The only issue was I had my mask set too dark this time and I couldn’t see where the end of the joint was. As a result I kept going till the arc went out because there was no material underneath it. This left an arc mark as I finally pulled it away.
I welded this originally in the flat position. Note the arc mark to the right resulting from my inability to see I was at the end of the joint. I turned down the darkness setting on my mask to improve visibility.
After the early hiccups, I finally settled down into a bit of a groove. I had the work piece clamped down flat at first, welding flat and moving around to different areas of the piece to keep too much heat from building up in one area and to give plenty of time for cooling. This should help prevent warping. Then I flipped it and did the other sides before turning it on its various ends for the fillet welds.
Got a little skinny in the middle of this one and forgot to leave the gas on the end of the weld for a moment at the end. Think that’s the cause of the dimple.
Not sure how I ended up with this porosity. Had to grind that out. remembered to switch back to the “weld” mask setting this time…
At one point I was feeling cocky and tried to do a vertical weld. I should have waited and reviewed the technique on that as I ended up with a pretty ugly weld with a big droop at the bottom.
Less than stellar results of my first attempt at vertical welding. After this I reoriented my work so I could weld flat until I do some more research and practice with the vertical position. Also note nice cut quality from the Rage II cold chop saw.
I’m not sure what the brown precipitate is on some of these welds. I think I probably need to clean the joints better before welding. I’ll try that next time. Seems to come off easily enough but it leaves indentations in the weld.
So to recap, today I learned:
1. (Again) Double check the gas bottle is turned on before welding.
2. Double check welding mask reset from “grind” to “weld” after grinding.
3. Don’t forget to hover over the end of the bead with the gas for a moment to keep the puddle shielded as it cools.
4. Don’t set the mask so dark that you can’t see where the end of the weld should be.
5. Going to try cleaning the joints with a wire cup brush on the angle grinder next time to see if that gets rid of the brown precipitate.
6. I wasn’t satisfied with how the corners blended together. Next time I’m going to try to weld around the corners and mate the beads up on the flat sides.
While there are lots of ways I hope to improve, I’m pretty happy with how this is turning out so far. It’s cool to be learning and practicing welding on something that’s useful but not critical for life and limb. I’m going to pop in for a minute tomorrow after it’s all cooled off and measure the piece on both diagonals to see how I did at keeping it square. I’ll try to post some pics of that. I’ve got a call in to my steel supplier in Seattle and hopefully next week I’ll get the rest of the tubing I need.
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