When I was selling mandrels the problem I had with MT mandrels is that there are too many people that are not that experienced with using a wood lathe. They would not always use the tailstock and the mandrel would come loose and go flying. And the emails indicated "it was my fault" that they did not use the tailstock. The liability issue can become a nightmare.
Next issue with the 1/4" mandrels are they are easily bent. Once they are bent it will result in out of round calls. So they need to be cheap and easily replaced on the MT shaft/arbor.
Marvin
