Question
Download Solution PDFA Ø 6H7 hole is to be reamed in a steel work piece. What size of drill will be required?
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFConcept:
A reamer is a multipoint cutting tool used for enlarging by finishing previously drilled holes to accurate sizes.
For reaming with a hand or a machine reamer, the hole drilled should be smaller than the reamer size.
Calculating drill size for reamer
A method generally practised in workshop is by applying the following formula:
Drill size = Reamed size - (Undersize + Oversize)
- Finished size is the diameter of the reamer.
- Undersize is the recommended reduction in size for different ranges of drill diameter.
|
Diameter of ready reamed hole (mm) |
Undersize of rough bored hole (mm) |
|
Under 5 |
0.1 – 0.2 |
|
5 – 20 |
0.2 – 0.3 |
|
21 – 50 |
0.3 – 0.5 |
|
Over 50 |
0.5 - 1 |
- Oversize is generally considered that a twist drill will make a hole larger than its diameter. The oversize for calculation purposes is taken as 0.05 mm - for all diameters of drills.
Given: Ø 6H7 hole
Calculation:
Finished size = 6 mm
Under size as per table = 0.2 mm
Over size = 0.05 mm
Drill Size = 6 – (0.2 + 0.05) = 5.75 mmLast updated on May 28, 2025
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