Welding stainless nut to mild tube, how much radius for lip?

TraditionalToolworks · Mon Aug 10, 2020 3:15 am

I have some stainless nuts which are 1/4-20, and the outside of the flats are .430".

The way I was thinking about it was I have .180" difference. Originally I was planning to drill 5/16" holes, providing 1/16" which would give me about .032" on each side if I center it. This would also leave about 1/16" for the lip where I will weld the nut. If I was to split the difference the lip to weld to will narrow. When you weld nuts on a tube so you can use a machine screw, is there a rule of thumb for how much material to leave open and/or how much lip to leave before you stand a chance of blowing the edge of the hole out?

Seems 5/16" would be safest if I can get it centered. On my welding cart I used stainless flange nuts for the rear wheels, but for the front casters I'm just using stainless hex nuts. I will heed cj's advice and use anti-sieze on the screw when I weld, like I did on the flange nuts. I probably only need 3 tacks/welds, one on every other flat of the hex nut.

Any thoughts?

cj737 · Mon Aug 10, 2020 6:57 am

You really don’t need much weld to keep the nut connected. Personally, I just put tacks on 3 sides with a dab of 309 or 312. There’s not that much stress in that application as the nut flange is what prevents the bolt from pulling through.

I do coat the bolt with antisieze, then thread it into the nut when I tack. That keeps everything fully centered and prevents the bolt from fusing to the nut.

TraditionalToolworks · Mon Aug 10, 2020 1:17 pm

cj737 wrote:You really don’t need much weld to keep the nut connected. Personally, I just put tacks on 3 sides with a dab of 309 or 312. There’s not that much stress in that application as the nut flange is what prevents the bolt from pulling through.

I do coat the bolt with antisieze, then thread it into the nut when I tack. That keeps everything fully centered and prevents the bolt from fusing to the nut.

Gonna use that same Tensileweld I have (312), and will do just that.

Should be able to get to it tonight, hopefully.

BillE.Dee · Mon Aug 10, 2020 2:29 pm

Hey Alan,,,that Tensileweld stuff...IS it the same thing as 312 and the mfg is using a fancy name or is it something special? I've been looking around and really can't decipher anything special. Just asking out of curiosity because I believe I have some 312 taking a nap in the shop.

TraditionalToolworks · Mon Aug 10, 2020 2:37 pm

BillE.Dee wrote:Hey Alan,,,that Tensileweld stuff...IS it the same thing as 312 and the mfg is using a fancy name or is it something special? I've been looking around and really can't decipher anything special. Just asking out of curiosity because I believe I have some 312 taking a nap in the shop.

Yes, AFAIK, it's 312. At least that is what my LWS told me about both Washington Alloy Tensileweld and Harris Super MissleWeld. I have to admit, Super MissleWeld is a much cooler name!

I'm told both are 312, with high percentage of nickel.