I thought you were using your antique turning heel tool upside down.
I treat all these old articles, and especially illustrations, with extreme caution. Many of them, if not all, were written and drawn by professional writers and illustrators, not professional tradesmen, turners, in this case.
Likewise people drawing 'de-facto' conclusions of how things were done, or how a tool was used from old paintings, where much artistic licence or simply ignorance of what was being done could be in evidence.
I enclose an article I have extracted from 'The Amateur Mechanic' which I think was published shortly after WWl. although I fancy it was in fact written before the war. In which Fig.71 shows what they consider to be a heel-tool, and fig.91 shows it in use.
{gallery}TTArticles/Heel_tools/turning_tools.jpg{/gallery}
{gallery}TTArticles/Heel_tools/turning_tools_fig_91.jpg{/gallery}
(Note that the drawing shows the wrong position and the faint dotted line shows what the text says is the correct position Refer this back to your article and Figs. 415 & 417 from Holtzapffel.)
{gallery}TTArticles/Heel_tools/holtzapffel_heel_tools.png{/gallery}
If we consider your tool as if it is a leg with the foot on the end. I note that the angle of the 'sole' of your tool is the reverse of the ones in many of the old illustrations. However this only means that the toolrest has to be set at a different height, in your case well below centre, to allow the cutting edge to be tangential to the workpiece.
At this point we have to realise that modern slide-rest lathe tools are designed to work clamped, in the same position, and at a designed angle to the centre height of the lathe. Hence everyone's tool for a specific job is very much the same. The hand held tool however, so long as it has a good cutting edge can usually be positioned in some way to make it work. I believe this has a lot to do with the apparent difference of these heel-too1s from one worker to another, or from area to area. The tool in Fig.71 appears to be bullnosed, and is intended to be used pressed flat on the tool-rest, in use exactly as a modern roughing tool, except that it is hand-controlled. Some of the old illustrations appear to be 'double toed' forms of the above. Some illustrations, eg. Holtzapffel fig 420 seem to be showing how to get the tool jammed in between the tool-post and the workpiece, damaging all of them. Add to this fig 419 showing a wood turner's hook-tool which I cannot imagine anybody trying to use in metal turning.
If next we consider the use of a graver as a turning tool, I can speak about this with some experience. I use a Swiss style watchmaker's lathe and have managed to make a replacement balance staff for a platform escapement, which is turned in ready hardened and tempered spring steel.
Looking at fig.93 I can quite categorically state that I do not use a graver like that, and, I am pretty sure nobody else does.
{gallery}TTArticles/Heel_tools/graver_fig_93.png{/gallery}
The graver is used utilising one or the other of the front edges of the tool, depending on which way you are working. The point of the tool never quite coming in contact with the job. Just as in wood turning you use the skew chisel. Bringing the tool to bear on the job so that it is just rubbing then changing the angle until the tool starts to cut.
Now. Keeping the principle of the skew chisel and the graver in mind. Using your tool, resist the first thought that the point is of use. With the point upward, press the sole of the tool on the job, then keeping the ankle pressed firmly flat on the rest, angle the tool, to one side or the other, until it begins to cut, then slide it along the tool-rest, keeping it flat on its back so that the cutting geometry does not change as you move along the workpiece, See sketch (I'll continue to practise my drawing.)
It would be much more helpful if these tools were classified as 'heel' or 'toe' cutting edge tools dependent on which way up they are supposed to be used. And they should be engraved 'OVER SHARPENED' or 'RE-FORGED'
or 'ADAPTED FROM --*-', etc. etc.
Mike Kimpton