Harold_V wrote:Keep in mind, when cutting threads, especially coarse pitch threads, the helix angle is a problem, so the leading edge of the tool may require clearance (relief) that looks excessive. That makes sense because you have to overcome the angle of the helix, plus have clearance.
The Aloris threading tool actually has adjustment screws to tilt the tool for helix angle:
GlennW wrote:Also look at the tool bit closely and make sure it isn't rubbing below the cutting edge from not enough relief.
An easy way to check is to color the tool with Sharpie marker. Anywhere the tool is rubbing, it will take off the Sharpie.