Wrench for slitter nut 2

[madojabe]

I'm redesigning the spanner type wrench that's presently being used to tighten a nut that has a 5 1/2 -6 T.P.I. thread. I'm going to a box-end style and am trying to decide what would be the best material to use. I want toughness along with some hardness.
We've made one of the spanners out of 4150 pre-hard and wasn't totally satisfied.
This nut will be made with a wire EDM machine, so I can heat treat the block prior to machining. It will have a handle that is attached.
Weight is a consideration, also.
The nut this wrench is used on is tightened with strikes from a 15 to 18# sledge hammer. Not real scientific but it works.
I'm going to the box-end style in the hopes of reducing some of the stresses that are induce in the tightening. I'm planning on making the handle about 12 inches longer, also.
Any help would surely be appreciated.
Jim McCutcheon

 

[TVP]

What was wrong with 4150? Not enough strength? Poor fracture toughness? What were the mechanical properties that you obtained with the 4150? You are obviously proceeding along the right path with a heat treated alloy steel. Other factors like wear resistance, corrosion resistance, etc. need to be considered as well.

 

[unclesyd]

Most tools are made from Chrome-Vanadium alloy steels. The more common one are AISI 6140/6150. A trade name is
CR-V 6140.
Making a slugging wrench is fraught with problems and it starts with the name.

One approach to get around the slugging part is to use a
"Supernut". Information can be found at:

http://www.superbolt.com/