The draw-bar hole in my (MT3) ER32 collet chuck goes right through. If your chuck is the same, you could always screw up, through the chuck, into the spindle (with a smaller bolt). I find I don't need to tighten the draw bar on my morse taper quill quite as tight as on most R8 devices, since the taper is fairly secure on its own. I'd have thought that a long M6/M8 allen bolt would hold the chuck in place perfectly well for light use.