Welding

[KUBOTA OWNER]

I have some heavy 1/2 plate that was from a scraper blade off a plow. welded it up to use to make a thumb for my b21 backhoe. I checked to see
if steel was to hard to drill of cut and it seemed ok. but now i am having a very hard time drilling 1/2 hole, even 1/8" is hard. --- can I heat it to red hot
to remove the temper? or should I blow some messy holes with a torch ??
----{old mech. with a new love for tractor.} ---would appreciate any help.

 

[Rob-D]

I have some heavy 1/2 plate that was from a scraper blade off a plow. welded it up to use to make a thumb for my b21 backhoe. I checked to see
if steel was to hard to drill of cut and it seemed ok. but now i am having a very hard time drilling 1/2 hole, even 1/8" is hard. --- can I heat it to red hot
to remove the temper? or should I blow some messy holes with a torch ??
----{old mech. with a new love for tractor.} ---would appreciate any help.

What you did was harden it (must be a higher carbon steel, 1040?). this can even happen from drilling especially when the material doesn't have a way to dissipate the heat efficiently so use a lubricant on the bit.( I use wax stick lubricants in the shop.) Sometimes you can reheat a piece red hot and cool it gradually to allow you to work it but if you are working with a large piece that is difficult to get red hot it's not so easy. What you should do is look at the color where you are trying to drill. If it looks purple or even tan then you probably hardened it.
You can drill it with a carbide drill or like you say, if it's not critical blow a hole through it!. Sometimes the down side of that is the metal becomes brittle and is prone to cracks.
Rob