Metric - 0.3 mm under, Inch - 1/64 under.If you want a 6.5 mm reamed hole, drill 6.2, if you drill 6.48 ??- 6.4 you will most likely loose it. Don't forget to cut your speed way down and lubricate. This is gen. shop practice for use in drill press or vertical mill. In a belt driven Bridgebort for reaming speed just switch to "low speed" without changing the belt from the speed you used for drilling
Blind holes, flat bottom can not be done with a regular reamer. You need an End-reamer like for jigbore use. You will still have a small radius on the bottom. If you cut off a standard reamer you will have to stone a radius on the bottom. Do it in a vise using a triangular oilstone and tooth after tooth stone a light radius with a back up. Do not try to stone a radius on the end while the reamer is turning in a chuck. |