SAECO Tester Reads MINUS 4????

[Grump]

Hauled out the old, old Minie balls I cast when I still had hair, and on the nice big flat meplat the SAECO tester doesn't even get to zero before the witness mark lines up.

Reading "10" as -1, two samples both read "7" which is four marks below "zero".

Do I have a serious calibration problem here or is something else afoot? FWIW, what reads SAECO 5/BHN 8 or whatever, I can groove lightly with my fingernail. What reads 8 or about BHN 14-ish (IIRC), I can leave a mark on the lead but barely.

Thanks!

[detox]

When reading Rotometal pure soft lead i get a reading of Saeco 0 or slightly lower. So my Saeco tester appears to be doing as instructed. Miinie balls are usually pure soft lead? When reading minie ball is the top vernier scale to the left of the lower vernier scale as shown in figure 7 of instructions? If so material could be a tad softer than 5 bhn. If top vernier scale is to the right of lower vernier scale, alloy is harder than Saeco 0 or 5 bhn

If after the witness and index marks are aligned, the left-most mark on the lower vernier is on the right side of the "0" mark on the upper vernier, we have material with the hardness of less than Saeco '0' or 5 bhn

Your Saeco 5 and Saeco 8 readings sound correct if you were testing other cast boolits of different harder alloy.

What size minie ball are you testing? Is it resting securely in stepped holder?

[Mk42gunner]

I think it really takes a delicate touch to use the Saeco hardness tester. I had one that read negative numbers with ACWW, with me using it.

I passed it along to another member here, and so far as I know, he is happy with it.

Robert

[Grump]

Detox:

They're big hollow-base .5X something or others cast from the first Lee aluminum mould I ever tried. Since I did almost 600 of them, you can guess that it worked pretty well.

These boolits sit better in the tester than most, go up very straight, and the cone-pushed half of the scale does compress quite nicely for the first few turns--it just never gets "up" to zero.

I have noticed with many other smaller caliber boolits that the scale often drops by one number before reaching the witness mark. I have always chalked that up to a little bullet tipping resulting in the outer ring portion contacting before the cone finishes driving in, then stabilizing to a more true reading with the ring settling into a proper relationship with the spring pressure on the cone. I can visualize it but can't explain it well.

The way that line curves on the graph, it makes me wonder if the methodology falls apart below about SAECO 1/ BHN 5 or so.

Anyone notice that the chart says 0 = BHN 4 but the legend says 0 = BHN 5?

[detox]

I used the RCBS .357 158 grain Flat Nose boolit to get my reading. I casted a few of these just to check hardness of my Rotometals pure lead. This lead reads just a tick under Saeco zero.

Atleast you know your minie balls are soft lead if reading below Saeco 0.