another handy tip

I needed a lot of 3/8 nuts welded into my T bucket frames for headlite brackets', exhaust hangers, seat belt anchors, tail lite mounts etc , etcs. I either buy black uncoataed nuts or sand blast and sand to remove the cad or zinc coatings. i drill the pilot hole then use a uni-bit or step bit for the final hole. they give you a round hole. I drill the hole so the nut will not fit thru the hole, screw a bolt and washer onto the nut and tap it into position with an interference fit. the washer is there so you don't pound the nut and bolt both into the hole and lose it into the frame tubing, with the proper interference fit you can align it square and weld it in. the unibit chamferes the hole so you get good penetrarion on your weld and you can grind the weld smooth, knowing it will hold.

I,m going to use that to anchor my seatbelts Thanks DH

You should try Nutserts, same result, lots less work!

We have used a lot of Rivnuts, they have a .060 flange that holds the part above the surface, we used a lot to install roof luggage racks. truck mirrors, etc they sometimes will not seat properly if there is any sealer on the underside of the metal It can soften on a hot day and your inserts are then loose. on parts that only require medium torque they work great. I prefer seatbelts anchor plates under the floor and tacked into place or fastened to a sturdy crossmember. The factory repair spec was to use stainless poprivets.to replace defective welds.