Edge Retention/Rolling Test Stand

[Jan]

We're sharpening now non-hardened A2 now. Looks to us like 260-275 is going to be the number. Lower numbers can be squeezed out but not on a consistent level throughout the edge. Don't know what the 30° chisels are going to turn out to be yet because we haven't tried them yet. To the right is a micro pic of a sharpened and deburred edge. We've done the minimum amount of grinding here. The bevel is 15° and all we've done is created a 19° micro-bevel on the edge.

                                               

We did run another test prior to shipping these off. We ran a roll test on this now sharpened but non-hardened A2 steel. As you may recall we did something similar with a piece of cold rolled sheet goods that was .050 thick a few weeks ago. That non-hardened material was sharpened to 275 and then placed in the SET for rolling...and roll it did, all the way to 818 (one series of five back and forths). This as compared to hardened steels that roll in the 200 - 250 point range (ending sharpness level minus beginning sharpness level). The non-hardened A2 began at 259 and ended at 720 so it seems that hardening must have some considerable and beneficial effect with regard to rolling of edges. We're sure that this revelation comes as quite a surprise to Mark Reich but as we said in an earlier post (remark) about Mark. Even an old dog can learn new tricks.

Of course we have just presented strong evidence of something we had all suspected was true so "why do it?" We are about to harden A2 steel at different levels and then measure the effect of these various hardness levels on edge rolling. Now we have established the far end of the hardening spectrum as well... no hardening at all.  Our conclusion is that "non-hardened steels roll a lot and now we know, fairly precisely, how much "a lot" is. "

Annealed A2 steel may have hardness some 20 HRC only.

Jan