Best way to grind welds

[SC Campbell]

I just had the tongue jack area on my Benroy straightened and cracks around the jack mount welded. The welds need to be ground down before painting. What is the best way to do this and how far should I take them down? Thanks.

SC

[Socal Tom]

Why do they need to be ground. Usually a good wire brush will clean them up. If they are ugly, and you are trying to clean them up, then just take off the peaks, but try not to take off the meat of the weld.
Tom

[dales133]

Use a flap sanding disc if you want to smooth them off without removing anymore weld than you have to

[MtnDon]

The best welds need no grinding. That said not all welds fall in that category. I would worry about them if they were a critical structural component. Ugly bumpy welds often lack proper penetration. But if you must grind do a minimal amount.

I like to use an angle grinder.

[Redneck Teepee]

I just had the tongue jack area on my Benroy straightened and cracks around the jack mount welded. The welds need to be ground down before painting. What is the best way to do this and how far should I take them down? Thanks.

SC

Hopefully whomever re welded your "cracks" ground them out to virgin metal before welding them up again? In the welding world there is a saying that is 100% true... "Once a crack, always a crack".... In other words you cannot simply just weld over the old crack....it will crack again. A good seasoned weldor will know how to address the crack circumstances upon inspection. Just my 2 cents worth.

[H.A.]

The best welds need no grinding. That said not all welds fall in that category.

So if we assume the welding turned out structurally good but not so pretty. But one lacking metal work abilities.
You might have an easier go to simply cover & fill the welds with your favourite filler putty then paint.

[SC Campbell]

The welds were done at a welding shop that makes trailers. The cracks were 3 stress cracks about 1" each around the tongue jack. The weld left 3 "worms" in a flat area. I just want to file them down to make it look better before I paint the frame. Thanks all for your help.

SC

[ctstaas]

Hi SC If the welding shop did not grind them down then I would initially think they shouldn't be. Will Bondo work to fix the visuals before painting. For fine grinding of steel I use 36 grit 4 1/2" Al. oxide disks on my angle grinder. For big grinding I use a 9" wildcat. The used 9" disks fit on my angle grinder for hard disk grinding applications. Safety first!
Enjoy, Chris

[skinnedknuckles]

I am with the other posts about not grinding the welds even on the flat areas. You could use a rotary file on a die grinder to "chase" any weld berries and just touch up the weld at the top of the puddles if there are any sharp points otherwise leave the weld alone. They welded past the crack to help support the welded metal and the base metal to help prevent any further cracking. Wire brush the area clean it (not with brake cleaner- have to protect the next welder if it cracks again- heat + brake = toxic fumes ) and put a thin layer of bondo on it, so that if it cracks again you will know it right away.
Paul

[MtnDon]

Somehow the thought of Bondo to it make look pretty bothers me. Reason being if it ever needs welding again the Bondo needs to be100% removed to make an effective and good looking weld. I'd knock off the high points and call it a day. Or grind it all down flat and weld a patch over the area. Depending on the area covered and the size of the patch drilling out holes of 1/2" or so in a few spots and then welding those holes will provide more welded area to spread forces.

[Shadow Catcher]

It is not a critical weld, so if it fails you prop up the tongue. A good weld should look it but there are gorilla welds (strong but ugly) I would go in with an angle grinder and clean it up however do not get it too hot.

[Treeview]

The second best metal working tool after a welder is a good angle grinder.

Many years ago I found that using these wheels makes grinding and cutting as easy as woodworking.

http://www.buyweld.com/63102.html

The wheels are thin so they don't have to cut much metal.

They're made to cut on the edge of the wheel as well as do face grinding to tidy things up.

My 4" grinder gets a lot more work time than my 6".

Tom