Welding nuts or bolts to metal

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Let us say we want to weld a nut in place against a piece of metal. The nut would then be used to receive a bolt to hold parts together.

Do you position the nut by just placing it against the metal, or do you put the bolt in place with the threads only flush and weld, using the bolt to align the position and placement of the nut?

Do you need to do anything to the bolt to keep it from sticking to the nut from the heat? Do you take the bolt out while the weld is still hot, or let it cool before you remove the bolt?

Is it best to weld on one flat (one side) of the nut, two sides, or a full weld encircling the nut?

Just trying to get some opinions on how YOU would do it.

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Posted · Report post

Normally, I whittle down a stick and screw the nut on until its flush, then two spot welds on either side for placement. Then full weld around the nut. If the stick burns, no biggie.....

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Kinda carried over from the welding spatter thread. I never-seize the whole bolt, put it in place and wipe off any never-seize that will get in the way of the weld. Helps the bolt release from the nut AND keeps the spatter off of the threads. I usually just weld on two opposite flats, but have welded around the whole nut depending on the application. And ALWAYS ALWAYS ALWAYS grind off any coating that is on the nut or bolt before welding. ALWAYS.
-Aaron @ the SCF

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Posted · Report post

nice tip about the stick Moose.....I've always used a bolt in the nut to position the nut and keep it's thread clean, then welded all the way around the nut....then took out the bolt and half the time threw it away. Usually tack weld the nut in place, remove the bolt, then finish welding all around...I use a mig

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Posted · Report post

like Aaron said i always clean/grind the coating off before welding! but most of the time i drill & tap it

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I weld all the way around a nut with a bolt in place to keep the threads clear. I use duct tape on the bolt so I can save it.
Finnr

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First of all, I’m careful not to use any bolts with a coating (like cadmium that will hurt you if you weld it). But I tend to put the bolt in, tack it, take the bolt out and complete weld all the way around. I have yet to get spatter in the threads on the inside of the nut. Having said that, if I’m welding a bolt/stud to a part, I always cover the threads with a piece of tube or something to keep the spatter off.

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Posted · Report post

Mooseridge's tip about using a stick to hold the nut in place and keep splatter off the threads is a very good one.

I recall several years ago doing a repair for my father-in-law that required welding nuts in place.He picked up a stick and did that very same thing. I hadn't thought of that idea.Seems that when I'm welding, I think of metal........not sticks.

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Posted · Report post

In my experience , its almost easy with the size of bolts we use. I have done structural steel for over twenty years. With structural pieces and stairs we would sometimes have to tack on nuts for a blind connection , usually tight in a corner where the wall prevents the connector from getting a hand in behind to hold a nut. The size we use is almost always 3/4 inch bolts and nuts.
I use a 3/4 inch flathead bolt , set-up for a countersunk hole. It has a round head , and is set-up to be used with an allen wrench. Our holes are usually punched , if not I drill the holes , then put the bolt in with the tapered head on the opposite side of where you need the nut , the taper will center the nut in the hole. I just hand tight the nut , just to keep it from wobbling. Then a little shot of spatter spray , I weld two opposite sides of the nut . I dont need an allen wrench to loosen my bolt , because i welded a handle on it , it gets hot after a couple of holes. Hope that helps......c

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Lets say you have a 1/2" hole and you want to weld a 7/16" nut centered on it. If you had a lathe you could turn a stub to stick thru the hole from the backside with a small 1/2" shoulder to line up the hole then the stub would have a small end turned to fit the ID of the nut and the same height to hold the nut while you tacked it. Thats how we did it in the sheetmetal shop when we had hundreds of holes to do and they had to be perfect...Bob

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Posted · Report post

A tapered drift should aid in alignment.

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Lets say you have 3/4" pipe and a hole drilled in it (next sized over 3/8). Take a setup bolt ( 3/8 x 2 ) and put a nut down to the bottom of the threads. Dip the exposed threads in some vaseline or whatever you use for nozzle gel. Place the bolt through the hole and place another nut in the end of the pipe and tighten the nut thus holding the bolt tight in the pipe. Set the bolt paralell to the table and make down welds on the outside nut from each side. If you have a hundred of these to do, the man may object to your procedure ( time ). Then you do same ( nut on bolt to bottom of threads, then dip in grease ). Take a pair of # 17 t vise grips and weld a piece of angle on the bottom jaw ( to recieve the pipe ). The top jaw goes on the bolt head and close the clamp. This holds the bolt firm in the pipe and weld as noted. Remove the bolt with a pair of pliers. This actually works better than the nut inside but you need dedicated clamp for the procedure or grind the angle off. IF the weld makes it into the threads you may work back and forth with a wrench to save the nut. Experience will tell you how big of hole to drill for the bolt to pass through. If you need to put a nut on the corner of a piece of square( for strength ) you can make passes on the edge of where the nut will be welded ( since you have exposed threads that are hard to not weld). Let the color go from the weld and then make another pass to the nut thus attaching the nut and not welding the threads. You can also try and tack to the outside of the square corner to hold the nut first. USE grease( whieither nozzle gel or Vaseline) to dip the threads. Yes it will smoke. All in your needs. A pipe clamp ( call them Pony if you wish ) with the sliding end removed is helpful for plate. Make the pipe 6-8" long ( for a very short clamp ). Black pipe. Keep this for many shop uses. Remove the sliding end and tack the pipe beside the bolt to be held ( tack on the bolt side ). Unscrew the clamp and place a piece of rod or square from your collection between the clamp and the bolt head. Screw the clamp tight to hold the bolt/nut down to weld ( this is out of position issue that works nice ). Twist the pipe to remove and grind. PUT THE SLIDER BACK on the pipe ( I never lose stuff do you ? ) As noted a piece of broken pallet or whatever else will hold the head of the bolt down if gravity or position is in your favor. Sometimes you just got to Clampett, Jed.

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Clampett Jed !
I Hate That I'm Old Enough To Get That Joke!
Well Got'ta Get To The Cement Pond For The Turtle Race!

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I also might add that if you have an issue for centering, wheel bolts ( or studs ) and nuts work nicely. The back of the leg vise in the shop is mounted to the table with them ( studs through plate from the bottom and nuts on top, plate then welded to table ). Alignment of holes was critical to keep plate square for good joint to weld but fairly close worked nicely. I'll rustle up a pic if I can.

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Posted · Report post

I weld all the way around a nut with a bolt in place to keep the threads clear. I use duct tape on the bolt so I can save it.
Finnr


I use the exact same method except I use masking tape in place of duct take, we don't have duct tape laying around the shop or I would probably use it.

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