Contract deep hole drilling is buying the hole instead of the machine. Dedicated job shops run gundrilling and BTA work for hundreds of customers, so for a handful of parts a year — or a material you have never drilled — outsourcing beats a major machine purchase. The skill is not finding a shop; it is knowing which specifications to send and which answers to check.
The make-vs-buy decision is about volume, material mix and who controls the risk. If you already have the volume, the machine pays for itself; if you do not, the service provider carries the machine cost and the learning curve for you.
Not all deep hole shops are equal. The specs below separate a shop that can do your part from one that cannot — compare them before you compare price.
| Capability | What to ask | Why it matters |
|---|---|---|
| Bore diameter | Minimum & maximum diameter | Micro gundrilling and large BTA are different shops |
| Depth / L/D | Maximum drilling depth, max L/D | A 1 m gundrill and a 15 m BTA bore are different machines |
| Methods | Gundrill / BTA / ejector / trepanning | Method must match diameter and depth |
| Materials | Steels, stainless, titanium, Inconel, hardened | Material experience drives yield on hard alloys |
| Quality | Straightness, tolerance, finish achievable | Match your print, not their brochure |
| Inspection | CMM, bore gauges, straightness measurement | They must be able to prove the hole they made |
| Certifications | ISO 9001, AS9100, ISO 13485, NADCAP, ITAR, N-stamp | Industry & customer requirements |
The better your RFQ, the better and faster the quote. A complete deep hole drilling RFQ includes:
With the hole called out as a feature — not just a line on the part. Show entry conditions and any boss or chamfer.
Grade, hardness, heat-treatment state. Hardness spread across bars is a real yield risk.
Diameter + tolerance, depth, L/D, straightness (mm/m), surface finish (Ra), blind or through.
Quantity now, annual volume, batch size. Volume drives method and price.
Cleanliness, plating, pressure test, burr control, traceability, packaging & shipping.
Contract pricing is usually structured as tooling (one-off) + per-hole or per-part cost. Tooling includes the gundrill or BTA head sized to your hole; per-part cost scales with diameter, depth, material and quantity.