I agree with the Joel, John & Hockenberry .. I think too much is invested in having the tool really securely fitting the handle.. but I think the handle is more for comfort and ease of control - not meant to be structural (like a screwdriver handle needs to withstand torque) tools with tangs can just as easily be used without handles at all (or typically should be able to be) - if they are being subject to a lot of leverage forces, - especially those with flat tangs (other than maybe scrapers and hollowing tools?), then the real issue is with the user, and not with the tool or its handle.. so for most tanged tools (most that I can think of outside of box scrapers and the like.) they typically don't ever see much in the way of overhang , and thus little to no leverage, so the tool handle would be more just for the comfort of the user.
I recently got a new D-Way skew and have yet to make a handle for it, but even without the handle, have been using it and it works beautifully.... At some point I'll make a handle more just for comfort of my hands, but plan to just drill a hole for the tang just bit smaller than tang width and just drive it in , with a ferrule in place to keep handle from splitting. I would not expect it to need anything more secure than that. Of course, for hollowing tools and bowl gouges and scrapers, I deal with that differently as the handle also adds to leverage control when the tool has to extend further out over the tool rest... so those are treated differently...
