Harden tumbler ?

[Roger Fisher]

It may be a minute little thing; but question came up about whether or not the tumbler screw is made a tad softer than the threads in the tumbler to prevent stripping said threads in the tumbler?

It would make sense we do believe!

[D. Taylor Sapergia]

Roger, Chambers' hammer screws, and all the screws for that matter, seem to me to be mild steel.   I've never tried to harden and temper one to check the carbon content.  The tumblers are definitely heat treatable - obviously.  L & R's screws on the other hand, are 6 xc 40 TPI and are of an alloy that comes to you hardened and tempered.  And again, their tumblers are heat treated.  I have never tightened any screw in a lock to the point that the threads peel off.

[jerrywh]

 I temper or case harden all screws and parts of locks. Screws should be tempered about the same as a spring. The threads in a tumbler never strip if it is heat treated properly. It is the screw that breaks off rather than stripping.

[Acer Saccharum]

When threads are used constantly, as in machinery, usually the softer of the two will wear. I don't think there is this issue with a tumbler, unless the parts are too hard, where the threads will chip. Hardness helps the screw thread from deforming under load, and the tumbler screw takes a good bit of tension under full tightness. Hardness will help preserve the screw slot for deforming, too.

If the screw is casehardened and not drawn properly, it can snap.

A through hardened alloy screw must be tempered properly or it, too, will snap.

Tom

[Dphariss]

Roger, Chambers' hammer screws, and all the screws for that matter, seem to me to be mild steel.   I've never tried to harden and temper one to check the carbon content.  The tumblers are definitely heat treatable - obviously.  L & R's screws on the other hand, are 6 xc 40 TPI and are of an alloy that comes to you hardened and tempered.  And again, their tumblers are heat treated.  I have never tightened any screw in a lock to the point that the threads peel off.

The screws are almost surely 12L14 or something very similar. Unless they specifically specify something else. Automatic screw machines are why 12L14 was developed.

Dan

[Blackpowder Barbie]

That's right, all of ours are 12L14 and can be case hardened if folks feel it is necessary.  We don't, but do like to blue them for fantastic appearance sake!    
Barbie