Old School Machinist Trick for Reaming Oversized Holes The paper towel causes the reamer to remove more material than it normally would. This can be observed by switching from coolant to more viscous fluid, which might remove a small amount of material. The addition of a paper towel allowed this 0.5000" dowel pin to fit what was a 0.4990" reamed hole. If this seems impossible, try it for yourself. This experiment is easy to repeat. 👍 | Octane Workholding