How much smaller should a hole be before reaming?
Material Issues A rule of thumb is 0.010 ” to 0.015 ” should remain after drilling for reaming, except for small diameters, such as 1⁄32 “, which should have 0.003 ” to 0.006 ” of material for reaming, Lynberg noted.
Table of Contents
How is reamer size calculated?

The following formula is used to calculate Reamer drill size….Undersize.
Sr. No | Diameter of Reaming Hole | Under Size of Rough Bore Holes |
---|---|---|
1 | Up to 5 mm | 0.1 mm to 0.2 mm |
2 | 5 mm to 20 mm | 0.2 mm to 0.3 mm |
3 | 21 mm to 50 mm | 0.3 mm to 0.5 mm |
4 | Above 50 mm | 0.5 mm to 1.0 mm |
How much can you remove with a reamer?
A reamer will not make the original hole; it will only enlarge a previously drilled or bored hole. It will cut to within +0.0005 inches of tool size and give finishes to 32 micro inches. Reamers are usually made of High Speed Steel, although solid carbide and carbide tipped reamers are made in many sizes and styles.
What is the size of drilled hole for reaming 10mm?
Reamer to Hole Size Chart

FINAL HOLE REAMER SIZE | Reduce Drill Hole Size By (inch) | |
---|---|---|
mm | inch | MAX |
10.00mm | .39370″ | -0.00787″ |
15.00mm | .59055″ | -0.01575″ |
20.00mm | .78740″ | -0.01575″ |
What is reaming allowance?
The planned difference between the drill diameter and the reamer diameter is called an allowance. (It allows for the removal of a certain small amount of material.)
How do you reduce the size of a bolt hole?
1. Using Matches or Toothpicks. The most common – albeit not professional – way to fill screw holes when you need to make them smaller is by using matches or toothpicks as shims. This method has been used for a long time, but should only be used for holes that won’t hold any great weight.
What is the drill size for ø15 mm reaming hole?
Square end (a)h12= 11.00mm. Number of cutting edges (Z) = 6. Recommended pre-drill size = 14.80mm.
How much material should a reamer remove?
Typically, the rule of thumb is to keep 0.010″ to 0.015″ material after drilling for the reamer to remove. Very small diameters, say 1/32″ or less, should have 0.003″ to 0.006″ of material to remove by reaming.