Flat wrenches

[TomG]

(09-27-2012, 09:32 AM)Wawoodman Wrote:

(09-26-2012, 09:30 PM)TomG Wrote: Mike,

If you are going to the trouble of making a tool, go the extra mile and harden it. It'll hold up better for its intended use and it won't get all beat up from getting knocked around. You can either make it out of O1 to begin with and then harden and temper it with a torch, or you can save some money and make it out of mild steel and case harden it afterward. Either way you'll end up with a much nicer tool.

Tom

Tom,
Details, please! By "mild steel" is there a specific number you mean? I use Online Metals for supply, since they are 10 minutes from me. And how do I case harden?

Oh, joy! New things to learn!

Mild steel is anything that contains too little carbon to harden on its own, 1018 is a good example. To case harden, you heat the part to a dull red and dip it in a carburizing compound (Kasenit is a common brand) then re-heat it to a cherry red color and hold the temp for a few minutes to allow the carbon to soak in, then water quench. The cherry red is the key here (around 1400º). Overheating can warp or damage the tool. Another good way to check for the proper temp is to use a magnet. Mild steel becomes non-magnetic at the critical stage.

Case hardening works well for tools because only the surface gets hard. The tool gets strong and durable but it doesn't get brittle.

Tom