How to weld near threaded holes

ONDGAS · Sun Apr 30, 2017 4:16 am

How would you guys tackle this?
I was going to get a stainless bolt and have it sitting flush with the end of the hole and hope it doesn't do too much damage and hopefully just run a tap through it after.
Any ideas? Possibly have the bolt a touch past the thread?

cj737 · Sun Apr 30, 2017 6:02 am

If you choose to use a bolt, I'd steer clear of stainless. The heat alone in the metal while welding can lock the bolt in permanently. You can do that, but you'd better use some AntiSieze or other release agent to get the bolt back out. Another option would be to make a quick bolt from ally that won't weld to the base metal.

And of course, weld it up and if need tap open the hole afterwards to clean away conflict. Obviously, clearance for the head of the bolt is a concern.

Sun Apr 30, 2017 6:34 am

If it is merely to stop spatter getting in there, just roll up some paper or card and ram it in there. Wet it a little to reduce burning, and it should come out nicely at the end.

ONDGAS · Sun Apr 30, 2017 7:06 am

Sorry I should have clarified, that is a aluminium pipe getting welded to aluminium flange and when finished a bolt will go from the other side so the head of the bolt is fine for clearance

Does this change your mind on using a stainless bolt in the hole to help save the hole... keep in mind my alloy welding is best described as a combo of chicken shit mixed with Fidos butt

cj737 · Sun Apr 30, 2017 8:00 am

ONDGAS wrote:Sorry I should have clarified, that is a aluminium pipe getting welded to aluminium flange and when finished a bolt will go from the other side so the head of the bolt is fine for clearance

Does this change your mind on using a stainless bolt in the hole to help save the hole... keep in mind my alloy welding is best described as a combo of chicken shit mixed with Fidos butt

Yes it does. Still, some release agent on the threads is a good practice. And try not to muck it up!

ONDGAS · Sun Apr 30, 2017 8:06 am

Thanks I'll definitely put some anti seize on it, I have to wait till tomorrow to get some bolts their a weird fine metric thread and I'll give it a go. In sure I've seen Jody do a alloy build up with stainless behind the work piece , is this a fool proof way as the AC won't puddle the stainless or can you still do some damage with enough heat? Reason I ask is I have to start the puddle happening on the thick flange so I worry I'll damage the bolt and not get it out again

exnailpounder · Sun Apr 30, 2017 8:19 am

ONDGAS wrote:Sorry I should have clarified, that is a aluminium pipe getting welded to aluminium flange and when finished a bolt will go from the other side so the head of the bolt is fine for clearance

Does this change your mind on using a stainless bolt in the hole to help save the hole... keep in mind my alloy welding is best described as a combo of chicken shit mixed with Fidos butt

Your idea will work fine. AL won't adhere to SS so you can just back out the bolt when you're done. You might have to chase the threads on both pieces since you'll get a little oxidation from the heat on both metals but I think your idea is good but it doesn't look like you're going to have much room for a bolt head left over...AL welds are big.

ONDGAS · Sun Apr 30, 2017 8:31 am

Thanks, all good with bolt head the bolt head goes from the other side

mcostello · Sun Apr 30, 2017 9:13 am

Could use a set screw if clearance is a problem.

Sun Apr 30, 2017 12:24 pm

In place of anti-seize lubricant, which contains oil and will off-gas/burn, I'd dip the bolt in Maalox, which is water based, and will give you the same release.

$0.02

Steve

Oscar · Sun Apr 30, 2017 12:36 pm

Whatever you do, I hope you have done this weld before, such as previous identical work, or mocked up exact practice pieces. If you're practicing ON the projects, well.......

'Stang · Mon May 01, 2017 1:14 am

ONDGAS wrote:How would you guys tackle this?
I was going to get a stainless bolt and have it sitting flush with the end of the hole and hope it doesn't do too much damage and hopefully just run a tap through it after.
Any ideas? Possibly have the bolt a touch past the thread?

Are you going to tig weld it, or use mig? If tig- spatter should be no problem. If you are going to use mig, then just wrap that section with the threads with heavy kitchen aluminum foil. Hope this helps.

Olivero · Mon May 01, 2017 6:32 pm

Just weld it, run a tap through it. You will have to regardless, I have done plenty of welding near threaded holes, welding nuts, pem nuts, all kinds of nuts, stainless mainly but have done some aluminum. I have tried putting bolts in before, in stainless, they gall (i think its called) and your screwed. Aluminum seems to not really care unless you get too close.

For this, considering its aluminum, I would just weld it and run a tap through it after, spatter or not, still gonna solve it for you. No need to risk a bolt getting locked in, even though alum and ss won't fuse, the threads around the bolt can get screwy and you will have a jammed bolt in there regardless. At least I think that can happen....

Weld it, run a tap through it, the end.

Mon May 01, 2017 6:45 pm

Olivero wrote:... I have tried putting bolts in before, in stainless, they gall (i think its called) and your screwed...

The trick is not to use a stainless bolt in a stainless thread. A yellow Zinc Chromate bolt with never-seize or Maalox on it will release nicely. I rarely have to tap a nut I've welded on this way.

Steve

pgk · Wed May 03, 2017 12:33 pm

I'll have to give that try, thanks for the tip Steve.

Pete

Otto Nobedder wrote:
Olivero wrote:... I have tried putting bolts in before, in stainless, they gall (i think its called) and your screwed...

The trick is not to use a stainless bolt in a stainless thread. A yellow Zinc Chromate bolt with never-seize or Maalox on it will release nicely. I rarely have to tap a nut I've welded on this way.

Steve

xryan · Mon May 15, 2017 9:50 pm

If I was doing that, I wouldn't be putting any bolt in there, definitely not stainless, not a steel with zinc chromate bathed in Malox, Pepto-Bismol or anything else.

The stainless will gall even in aluminum. The oils and the zinc chromate will burn off.

Just TIG weld it, run a tap through when you are done, it shouldn't even barely have to cut a thing if it's welded properly.

Olivero · Tue May 16, 2017 9:29 am

Otto Nobedder wrote:
Olivero wrote:... I have tried putting bolts in before, in stainless, they gall (i think its called) and your screwed...

The trick is not to use a stainless bolt in a stainless thread. A yellow Zinc Chromate bolt with never-seize or Maalox on it will release nicely. I rarely have to tap a nut I've welded on this way.

Steve

I'll have to give it a shot next time, normally I just run a tap throught it in the end but this sounds pretty easy.