| Richards Machining Co Inc Milling, Turning | Santa Clara, CA | MillingTurning | - |
| RivCut Milling, Turning, Bending, Metal AM · ISO 9001, AS9100, ITAR | Union City, CA | MillingTurningBendingMetal AM | ISO 9001, AS9100, ITAR |
| Rivera Solutions Inc Milling, Turning, Assembly | Gilroy, CA | MillingTurningAssembly | - |
| RJ Enterprises Milling, Turning, EDM · ISO 9001, AS9100, ITAR | Gardena, CA | MillingTurningEDM | ISO 9001, AS9100, ITAR |
| Ronlo Engineering Ltd Turning | Camarillo, CA | Turning | - |
| S & B Precision Manufacturing LLC Milling | Vista, CA | Milling | - |
| S R Machining, Inc Milling, Turning, Swiss, Welding, Casting · ISO 9001, AS9100 | Norco, CA | MillingTurningSwissWeldingCasting | ISO 9001, AS9100 |
| Sabrin Turning, Welding, EDM, Assembly · AS9100 | Pasadena, CA | TurningWeldingEDMAssembly | AS9100 |
| Salsa Prototype Specialties Milling, Turning, Waterjet · ISO 9001 | Ventura, CA | MillingTurningWaterjet | ISO 9001 |
| San Jose Die Casting & Machining Corp Casting | Lincoln, CA | Casting | - |
| Santa Lucia Manufacturing, Inc Milling, Turning, Grinding | Atascadero, CA | MillingTurningGrinding | - |
| Savage Machining Inc Milling, Turning, EDM, Finishing, Assembly · ISO 9001 | Simi Valley, CA | MillingTurningEDMFinishingAssembly | ISO 9001 |
| Schulte Corporation Milling, Turning, Welding, Finishing · NADCAP | San Clemente, CA | MillingTurningWeldingFinishing | NADCAP |
| SDS Engineering Milling, Turning, Grinding · ISO 9001 | Sun Valley, CA | MillingTurningGrinding | ISO 9001 |
| Sharp Dimension Inc Milling, Turning, Bending, Welding, Grinding, Finishing, Assembly · ISO 9001, ITAR | Fremont, CA | MillingTurningBendingWeldingGrindingFinishingAssembly | ISO 9001, ITAR |
| Sheet Metal Specialists (SMS Fabrications, Inc.) Bending, Laser, Welding, Waterjet · ISO 9001 | Riverside, CA | BendingLaserWeldingWaterjet | ISO 9001 |
| Si Aerospace Inc Milling · ISO 9001, AS9100, ITAR | Van Nuys, CA | Milling | ISO 9001, AS9100, ITAR |
| Snowline Engineering Laser, Waterjet, Welding, Finishing · ISO 9001, AS9100, NADCAP | Cameron Park, CA | LaserWaterjetWeldingFinishing | ISO 9001, AS9100, NADCAP |
| Sonoma Industries Inc Milling, Turning, Swiss · ISO 9001, AS9100, ITAR | Bell Gardens, CA | MillingTurningSwiss | ISO 9001, AS9100, ITAR |
| SP Manufacturing Inc Milling, Turning, Welding, Finishing · ISO 9001, AS9100 | Livermore, CA | MillingTurningWeldingFinishing | ISO 9001, AS9100 |
| Specialty Precision Machining Milling, Turning, Laser · ISO 9001 | Stockton, CA | MillingTurningLaser | ISO 9001 |
| Superior Jig Inc Milling, EDM · ISO 9001, ITAR | Anaheim, CA | MillingEDM | ISO 9001, ITAR |
| Superior Thread Rolling Co, LLC Milling, Turning, Grinding · ISO 9001, AS9100, NADCAP | Arleta, CA | MillingTurningGrinding | ISO 9001, AS9100, NADCAP |
| Surfacemode, Inc Milling · ISO 9001, AS9100, ITAR | San Diego, CA | Milling | ISO 9001, AS9100, ITAR |
| Swiss Screw Products Inc Milling, Turning, Swiss, Grinding, Assembly · ISO 9001 | Santa Clara, CA | MillingTurningSwissGrindingAssembly | ISO 9001 |
| Systomatic Milling, Turning, EDM | Union City, CA | MillingTurningEDM | - |
| T & T Metals Milling, Laser, Punching, Bending, Welding, Finishing · ISO 9001 | Covina, CA | MillingLaserPunchingBendingWeldingFinishing | ISO 9001 |
| T&K Machine Milling, Turning, Welding, EDM, Grinding | Livermore, CA | MillingTurningWeldingEDMGrinding | - |
| TDC Manufacturing Inc Milling, Turning, Laser | Redlands, CA | MillingTurningLaser | - |
| Tecma Milling, Turning, Welding, Waterjet, EDM, Stamping, Casting · ISO 9001, AS9100, ITAR, NADCAP | Sacramento, CA | MillingTurningWeldingWaterjetEDMStampingCasting | ISO 9001, AS9100, ITAR, NADCAP |
| ThermoAir Grinding | Burbank, CA | Grinding | - |
| TL Machine, LLC Milling, Turning · ISO 9001, AS9100 | Garden Grove, CA | MillingTurning | ISO 9001, AS9100 |
| Top Precision Milling, Turning, Assembly · ISO 9001, ITAR | San Luis Obispo, CA | MillingTurningAssembly | ISO 9001, ITAR |
| Topnotch Quality Works Milling, Turning · ISO 9001, ITAR | Pacoima, CA | MillingTurning | ISO 9001, ITAR |
| Tridecs Corp Milling, Swiss, EDM, Grinding, Finishing, Assembly · ISO 9001 | Hayward, CA | MillingSwissEDMGrindingFinishingAssembly | ISO 9001 |
| Trinity Machining, LLC Milling, Turning, Bending, EDM, Grinding, Finishing · ISO 9001 | Grass Valley, CA | MillingTurningBendingEDMGrindingFinishing | ISO 9001 |
| TTN Machining, Inc Milling, Turning | Spring Valley, CA | MillingTurning | - |
| Upland Fab Inc Milling, Turning · ISO 9001, AS9100, ITAR | Ontario, CA | MillingTurning | ISO 9001, AS9100, ITAR |
| V&S Engineering Milling, Turning, EDM, Grinding · ISO 9001, AS9100, ITAR | Huntington Beach, CA | MillingTurningEDMGrinding | ISO 9001, AS9100, ITAR |
| Van's Manufacturing, Inc Milling, Turning | Simi Valley, CA | MillingTurning | - |
| Veco Technologies, Inc. Milling, Turning, Welding, EDM | Fresno, CA | MillingTurningWeldingEDM | - |
| Verdugo Tool & Engineering Co Inc Laser, Punching, Bending, Stamping, EDM, Grinding, Finishing · ISO 9001, ITAR | Chatsworth, CA | LaserPunchingBendingStampingEDMGrindingFinishing | ISO 9001, ITAR |
| Vinaco Precision Machining, LLC Milling, Turning, Grinding, Finishing · ISO 9001, AS9100, NADCAP | Chatsworth, CA | MillingTurningGrindingFinishing | ISO 9001, AS9100, NADCAP |
| Vision Aerospace LLC Milling, Turning, EDM · AS9100 | Northridge, CA | MillingTurningEDM | AS9100 |
| W Machine Works Inc Milling, Turning, Assembly · ISO 9001, AS9100, ITAR | San Fernando, CA | MillingTurningAssembly | ISO 9001, AS9100, ITAR |
| Walker West LLC Bending, Welding, Stamping, Assembly | Ontario, CA | BendingWeldingStampingAssembly | - |
| Wildfactory Milling, Turning, Waterjet | Camarillo, CA | MillingTurningWaterjet | - |
| Will-Mann Inc Turning, Laser, Punching, Bending, Welding · ISO 9001, AS9100 | Fullerton, CA | TurningLaserPunchingBendingWelding | ISO 9001, AS9100 |
| Wire Works EDM Inc Milling, Turning, Welding, EDM, Assembly · CMMC | Santa Ana, CA | MillingTurningWeldingEDMAssembly | CMMC |