Deep Bored Features: Quote the Usable Depth, Not Just the Hole Diameter

Give machine shops the entry, exit and inspection detail they need to quote a deep bored feature.

Separate the usable feature from the transitions

Show the length that must meet the finished diameter and identify whether the bore is through or blind. A lead-in, bottom radius or tool relief is not part of the usable cylindrical length unless the drawing defines it that way. Add a section showing the mating part’s stop location if the fit depends on reaching a shoulder.

Review reach and chip clearance in the quote

A long tool reach can limit rigidity, while a narrow entry or blind end makes tool and chip access more consequential. Ask the supplier to flag the features driving tooling selection rather than prescribing one bar geometry for every material and setup. For acceptance, agree how the deepest controlled section will actually be measured.

What to put in the RFQ

• Provide a section and entry clearance
• identify dimensions near the bottom separately
• request the proposed inspection method at the deepest controlled location.

Technical reference: Sandvik Coromant’s boring application guide.