What did I do? Hardened Iron

Aug 08, 2010 2 Replies
A

Hi Guys, Once in a blue moon welder here. I made two brackets with 3/16" x 1-1/2" angle iron. All went well, I drilled some holes and checked fit, then when I went to drill the holes larger, it seems like the iron is hardened and I can't drill it. I did water cool it after welding, but it seems like my first set of holes drilled ok. When I went to redrill, it was to hard to drill. I tried heating the whole thing up to dull cherry red and let it cool slow, but I still can't drill my holes larger. What is going on? I need to know before the next blue moon :-)



MikeK


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J

Dull drill?

Seriously though, one frequently drills a hole with a smaller drill and all goes well. then tries a larger drill and it doan work! Usually a matter of cutting speed.

Cheers,

John B. (johnbslocombatgmaildotcom)

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M

Welding and plasma does a number on steel and if it can harden it will.

If I need nice holes, I drill them. If the holes are nor drill size I use my cnc plasma to cut them. But I learned not to punch pilot holes for a drill press - the metal hardens nicely.

A grindstone - like a cone might grind the holes a bit larger and then a drill can take over. Or if sheet - try a cone drill.

I'd drill the holes before welding and if not - use a cone drill - or get a round file and open the hole up a bit then try a drill.

If stainless - drill first no matter what. Chrome oxides are tough!

Mart> >

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