Yes, I had this problem repeatedly with Delrin. It is so flexible that it resists the reamer. On one memorable occasion I was reaming a longish body section (one-piece body on a Pratten) and it stuck fast on the reamer! I mean really stuck. I thought I'd never get my reamer back without somehow cutting the Delrin flute body off of it. My reamer is powered by a heavy-duty gear motor that is bolted to a workbench at the back of my shop. I was unable to pull the damn thing off the reamer using my own strength. In the end I had to take a fence-stretching winch (the cable type that have the ratchet lever on them) and use it to pull the flute off the reamer! This involved a LOT of fuss and bother, figuring out how to get hold of the flute body on the one hand, and where to secure the other end of the cable so that I could winch it tight enough to pull the thing off. It took a shocking amount of force to get that thing off the reamer. A never-to-be-forgotten lesson .Terry McGee wrote: ↑Mon Jan 10, 2022 5:18 am But here's an interesting observation. I have marks on my reamers that tell me: stop when you get to this mark. So I naturally stopped at that mark when reaming the Delrin. But later, I noticed the bore was a smidge smaller.
Part of the problem stemmed from using rod stock that was too narrow. If I have a 30mm diameter piece of Delrin that I'm using for a D flute, the narrower girth makes it more flexible. If I hold it with my hands when reaming (which I cannot do for any sustained period of time) I can feel the material ovaling and distorting as the reamer turns. Instead of making a cut, it merely pushes the material around. Using a thicker Delrin rod solves the problem, but increases the waste. The added material gives stiffness to resist the reamer (so it cuts instead of bends). But bigger Delrin means more expense and more plastic shavings.