As a pen turner I have found all of those commercially made circuit board blanks to be challenging to turn. They are cast in poly-resin and are either mixed pretty hot or stored afterwards in a hot climate because they can be very chippy and do not turn as easily as other resin casts. That wouldn't make them a bad blank- just challenging to turn, like inlace acrylester. I only reference that because I know when I turn it I have to approach it differently than other casts. I know there are several materials out there I stay clear of because they present challenges in turning that I don't appreciate, but I know others who successfully turn them. I've damaged blanks while turning, sanding, assembling, and any other way possible. I continue to learn by adjusting my techniques so not to repeat these disasters. Most of them were my fault.
On the other side...and this is just another way to think about it... as a blank maker, I have had people come back and say the blank I made was a defect - after they turned it. The problem is, I don't know their turning abilities, experience or approach on turning the blanks, so it's hard to say if it's the blanks fault or the turners fault. I just know I wouldn't be in business long if I accepted the blame every time someone complained, after they turned the blank. Most sellers don't have a problem with returns as long as they receive a product they can recover their expense from, but if it's already turned, how do you prove what caused the problem. At least prior to turning would show any visible defects. After turned... it's anybody's guess. I wish you luck. Those blanks can be challenging.
