Hallo,
oh yeah, D-Bits are a fine thing and sometimes a great alternative to the multiple cutting edge type cutters. Especially if you are in need of some tools which are hard to get from the ordinary suppliers, for instance special shapes and small dimensions, it really makes sense to grind your own cutters.
In former times I also made them from hardenable Carbon Steel (like 115CrV3 / 1.2210 or 45S20 / 1.0727), but since I have my Tool and Cutter Grinder I manufacture them more often directly from HSS or even carbide blanks.
Particularly if it comes to very small cutting faces and a little more durability for machining steel instead of brass or aluminium HSS or carbide is simply the better choice.
Here are two examples of a medium size and a very small dove tail cutter I made over the year. The “big” one has an effective diameter of 8.5mm, the small one cuts a 4mm diameter over the tips.


For very small diameters I normally use cylindrical blanks and will half the tip myself, but grinding this half away from a 10 or 12mm blank is a real ugly job without the opportunity of flooding the work with coolant. So I prefer pre-divided blanks for the bigger D-Bits as you can see on the photo.

And here at last one of the workpieces I needed the bigger one for, okay its only brass this time, but believe me, they will work fine in steel too.

There was no way to do the job on the table stops of the Mini Bonelle with my smallest commercial cutter (diameter 16mm). I simply had not enough room for a guiding bar wider than 11mm in front of the t-nut table, and the self made D-Bit does it very well.

And by the way, it can really make a lot of fun to realize your special jobs with, in principle, such simple home made tools.
By from Achim