[How-To] Fill (weld) holes in 1" steel plate

[rabler]

I'll second (or is it third) using a copper plate underneath, something like 1/2" thick and not too small. Aluminum may also work? (both do a good job of wicking away heat). Clamp it up and move it around for each hole. It'll help the weld fill in the bottom, and will help retain shielding gas.

 

[682bear]

I have plug welded 3/4 inch holes before... successfully...

The specifics were a little different, in my case the holes were around 3/4 inch deep and they were blind holes. I set the MIG up for 3/8" thick steel, IIRC, and started at the bottom corner, working in a spiral around the sides of the hole. I adjusted how fast I moved until the weld was just meeting in the center of the hole, and continued until the hole was filled with a low crown on top.

It worked pretty well, and was fairly easy to do... but I never had to do any drilling or cutting intersecting the holes, so there may have been some inclusions in the weld.

-Bear

 

[FOMOGO]

I would weld around the o.d. on one side at an angle as deep as practical until that side is closed up, flip and weld up the other side. Run .030 solid wire and 75/25 gas, and run the second side in hot for good penetration. Lots of ways to go about it, but that would be my approach.

 

[keeena]

Great feedback folks. I think I'm narrowing in on a solution which takes some plusses from the various options. I'll plug the bottom ~1/4" to 3/8" and then fill the rest with weld. This should give me a healthy bit of fully welded material on the top half of the 1" plate which should be sufficient in case there is an overlapping hole in the future. And it sounds like hitting this depth will be easier than a full 1" depth.

If I machined a chunk of copper with a 3/4" diameter boss sticking up 1/4" to use as a temporary plug backer: would this not stick to the weld? This would then give me the option to fill from underneath if I ever wanted to in the future.

 

[Aukai]

I have not checked on sizes, but would a pipe tap threaded from the bottom, and screw in an Allen head pipe plug till flush(or more) then fill the hole from the top?

 

[Cadillac]

Or make plugs for each hole a touch oversized and a .250 short. Freeze plugs and one by one drop in hole flush with the bottom. Then once installed and a .250 from the top filler weld that .250 void.
You plug will be shrunk fit in the hole and the weld will permanentLu affix it and fill to top surface.
Trying to fill a 3/4” hole 1” deep is a challenge. The wire will arc to the closest side and inclusions will almost be guaranteed. Filling a .250 won’t be tough.

 

[AGCB97]

I couldn't find where or if you said about how many holes you want to fill. I hope you don't have too many to do.

I've plug welded holes but not just for filling as I was attaching plates together from the bottom (not overhead) so there would not be welds seen from the top). I turned the heat up higher than normal and just started in the middle bottom of hole. The molten puddle spreads to the sides. Shielding gas is trapped in hole so you can use a long distance between torch tip and bottom of hole.

The backer would be a good idea since you have no bottom to start. If you're worried about warpage, just do it in stages with cooling between. Experiment if you can!

 

[MikeInOr]

Thread the hole. Put a 45 degree taper on the end of the fill rod. Fill in the fillet left by the taper with weld. You could probably get away with not even threading the hold and fill rod.

Filling the entire hole with weld you will either get really bad penetration and a bad weld or the sheet will get so hot that it will warp. Filling in a fillet on each side should give enough penetration that you could grid the weld flat and still have a strong weld and hopefully not warp the sheet.

There is always JB weld too. Epoxy in a plug with JB weld?

 

[deakin]

i see no issue with plugging and drilling an overlapping hole. that is how cast iron cracks are repaired in the automotive business. (lock-n-stitch)

 

[Eddyde]

Yep, there is no problem with partially overlapping threaded plugs: