Another penturner, another opinion: I have always found inlace acrylester to be brittle and difficult. I have found that presenting a rigid tool to any squared resin blank (and especially inlace) is always asking for trouble. I skip the roughing gouge, and go straight to 50 or 80 grit sandpaper until the blank is cylindrical or nearly so.
Not only does this get rid of the corners, but it gets the blank good and warm, which makes it softer, easier to turn, and much less prone to chipping. I have carbide tools, but I have not had the best of luck when using them with resin. The tools are essentially scrapers, but the carbide holds no burr, and so you tend to use more lateral pressure to get the cut started. That's when it digs in, and when your blank explodes.
I use a round nose scraper for all of my rough shaping on resin. You can probably interchange any steel tool there and have similar results. The round nose only contacts a small part of the blank, so virtually no lateral pressure is needed for the cut to start. A flat nosed scraper contacts a lot of the blank, so there is more tendency for the blank to chip instead of start to cut nicely. I have still had better results with flat scrapers than with carbide, though. That's been my experience, and yours may be different.
I turn resin at pretty high speeds. I start with the blank warm, as mentioned, and the scraper will get warm as I work, which makes things easier. At too high a speed, the surface of the blank will melt and smear a bit. This is skin-deep, so not to worry: just back the speed off a bit and go at it again.
For finishing, you want slow speeds. There is no danger of chipping here, so just keep the speed down and the pressure light to avoid overheating and melting the surface. I wet sand with MicroMesh, and I typically skip the two coarsest grades, depending on how good a job I did with my tools. I typically don't buff my pens, but I should. Regardless, the MM does a good enough job that I can't tell much difference.
I hope this was helpful!
