Had a welder tell me to stop grinding my tapers so smooth

I was spending 20 minutes per piece grinding tenon tapers to a mirror finish on mild steel. He pointed out that a rough surface holds flux better and actually gives a stronger forge weld. Has anyone else found that leaving grind marks helps your welds hold?

3 comments

3 Comments

christopher9432d ago

Yeah that "mirror finish for forge welding" thing is a trap I fell into too. Your welder buddy is right, a rougher surface gives the flux something to bite into and helps it flow more evenly across the joint. I used to spend way too much time polishing tapers until a old timer told me basically the same thing. Now I just hit them with a 60 grit belt, knock off the sharp edges, and call it good. The welds are definitely stronger in my experience, less cold shuts and inclusions on the inside. Your mileage may vary of course but try it on a few pieces and see if you notice the difference.

joel_hall171d ago

Hold on, I gotta push back a bit on this. I've been doing it the other way for years and I get solid welds every time with a clean 120 grit finish. The flux issue @christopher943 mentioned makes sense in theory, but in practice I see more flux getting trapped and causing blowouts with rougher surfaces. Maybe my technique is just dialed into the smooth surface thing, but I've tried the rough approach a few times and always ended up with more inclusions, not less.

beth_reed1d ago

120 grit guy here too until last month when @christopher943 convinced me to try 60 and now I never look back.