Comealong Wrench

[Quarry Dog]

Hey all, It's been a little while.  Been reading alot of the forum and books from the early 1900s.

   I'm considering making a 2 3/*" wrench made heavy enough to undo nuts on a large rock crusher at a quarry.  The only source available is asking 200$ or more for it and I'm reasonably certain that I could make it for about half that and make it stronger, although heavier.  The last wrench was a combo wrench and had a tooth on the open end broken off.  I'm surprised that the box end didn't go first as thin as it was.  The ring on the back will be made heavier and smoother (better for pulling), and the head on the open end heavier, and after I ask a few mor questions I may just make it a heavy box end if it will still serve it's purpose.  My primary concerns are the type of steel to be used, and proper heat treating.

   Given it's (ab)use it will be under considerable stress hence why I'm forging it solid, keeping the metal as thick as possible and using fairly thick stock.  I've been reading and it seems that alot of people use steel from old leaf springs such as 4130/4140/etc.  I would prefer to use fresh steel as i would be more certain that it would not have any surprises from past abuses, and I think I'd have trouble finding 3/4" leaf springs anyway.  Would 4130/4140 still be a good steel for a wrench of this size?  I also imagine that the entire final product would need a fairly uniform springy temper to prevent everything from bending out of shape under these stresses.  What would be a good method of arriving at this temper?  A temp stick and a torch or Brittle harden and cook an hour at 700F or 800F (I can't think of anyone with a furnace), or just oil quench for a few seconds and draw temper from the inside? How would this best be done with a piece of steel this size?

[jmccustomknives]

4130/4140 would do ok for this project however I have no knowlege of it ever being used for leaf springs.  That steel is usually simple carbon steel or modern springs a version of 5160.  The best steels will be chromemoly tool steels.  The advantage will be the easier heat treating of the lower carbon steels.  You could call your local truck shop to see if they have any leaf springs lying around.  If you have a plasma cutter or any good with a torch you could cut that thing right out.  Those springs are usually 5160 or 6150 and are around 3/4" thick.  Using a torch will cause a hard zone so you'd need to clean it up and try to temper it out.  I can't say that's the best way to do things, but hey whatever works. ;)

[bigfootnampa]

I sometimes come across wrenches of this general size range in antique shops or at flea markets.  They are not as rare as you might imagine!  You should be able to use the "greasy stick" method to temper such a tool to spring temper (around 800 to 900 degrees Farenheit).  Search here as several threads have covered it.  eBay is another possible source for a bargain tool that would be ready made!  

[VaughnT]

The forging seems rather straight forward to arrive at that shape.  My biggest concern would be the heat-treating.  For a commercial application where someone could be hurt by a wrench breaking at the wrong time, I'd want to have it professionally heat-treated by a firm that specializes in that type of thing.  Better safe than sorry.