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In electric arc welding I'm mostly self taught.

"In the school of self taught the price is about right, but the labs are pure xxxx" (to quote my self)

That said, for every weldin project I've alway relied on advice, instruction, and equipment provided by older and more experienced friends. Until a couple of years ago I had access to a 400 amp DC welder and a sage craftsman of vast experience. He and the equipment have faded into history unfortunately.

Today I have a brand new Hobart Stick Mate that recommends max 165 amps at 20% duty cycle although 205 is the rated max.

I'm putting together a treadle hammer and need to weld 1" plate to 4" square tube with a wall thickness of 1/4". Plates are the hammer and anvil with 1" hardy hole.

The 1" Plate will be 4 1/2" by 4 1/2"

I'd like advice on Rod (size and type) , amperage, joint preparation, and preheat of plate if necessary.

Thanks in advance for your help

Edited by Charlotte
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Hi Charlotte. It would be nice to know if your machine is AC, AC/DC or DC. Aside from that, I would use 1/8" 7018, with about 300-400F preheat. Depending upon how hot your machine runs, between 100 and 120 amps. If you are getting undercut, turn it down. If you can't keep the rod from sticking, turn it up. If you have a DC welder, use electrode positive. If you have only AC, be sure to get 7018AC rods. 7018 likes to be run slightly uphill. It tacks well in the flat position, and can weld flat, but it is much easier to use if the item to be welded is inclined at about a 15 degree angle or more. If you must weld true vertical, you must turn the heat down a little.

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When I took the 1 inch plate certification class, 7018DC, the teacher had us keep a 400 degree F tempil stick around, and wait for a while if the weld area got over 400 degrees. Can anyone verify this? I still weld between 300 and 400F, and been having good luck. Also, the weld Charlotte describes will warp the 1 inch plate towards the weld, maybe some 90 degree gussets would be appropriate, and welding smaller length beads here and there, as opposed to running the entire 4 inch fillet at once.

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If you read Charlotte original post she is only welding 4 1/2" sq. plate to 4"sq tube. gussets will not fit anywhere. The preheat for the 1" is a little high...250-300 is adequat as you are only welding to 1/4". A 1/4" bead all the way around will hold all the tube will hold. You are going to have 1/4" exposed to the 4 sides anyway.... 1/8" E7018 is the best choice of rods, amps at 125 to start with, may need to tweek depending on your machine. (good rule of thumb for amp setting on E7018=== 1/8"=.125" = 125amps, once agian, may need to tweek to fit machine....
Tack on corner, sq piece, tack opposite corner, weld opposite sides to each tack, have fun!
mike-hr post on 1" preheat is good IF you are welding 1" to 1". Code requires preheat with 1"+ ==350F

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Interesting point Jimmy. For strucural welding, even tacking should be done with 7018. If tacks were made with 6010 or 6011, they should be ground off before filling with 7018. A treadle hammer is subject to impact; far more destuctive than the static loading of structural steel. Finaly, if you read Thomas Deans post above, you will see that there is only room for one pass or two at the most, making it even more important to use no 60xx weld at all.

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