Top CNC machine shops in Pennsylvania, ranked by ChatGPT answers

Places ChatGPT showed

• Three Rivers Precision · 5.0★ · Machine shop
• NTM, Inc. · 4.6★ · Machine shop
• Sterling Machine Technologies · 5.0★ · Machine shop
• Max Machining · 5.0★ · Machine shop
• Prieto Machine Co Inc · 5.0★ · Machine shop
• Astley Precision Machine Co · 5.0★ · Machine shop
• Machining Concepts Inc · 4.7★ · Machine shop
• Olympus Machining LLC · 5.0★ · Machine shop
• Hillside Custom Machining · 5.0★ · Machine shop
• Castle Machine Co · 5.0★ · Machine shop
• D.A. Tool And Machine, Inc. · 4.9★ · Machine shop
• Olympic Tool & Machine Corp · 4.7★ · Machine shop

If by “best” you mean strong capabilities, precision, quality systems, and a solid reputation, Pennsylvania has quite a few strong CNC job shops. I wouldn’t treat this as a definitive ranking, but these are shops I’d put on a serious RFQ shortlist based on their documented capabilities and current business information.

CNC shops worth considering in Pennsylvania

• Three Rivers Precision — Pittsburgh
  AS9100D and ISO 9001 certified; 3- and 5-axis milling plus turning. Particularly interesting for tight-tolerance, complex parts and difficult-to-machine materials such as titanium, stainless and nickel alloys.
• NTM, Inc. — Newport
  Established family-owned shop with substantial CNC capacity, including 3-, 4- and 5-axis milling and advanced CNC turning. A good candidate for production work as well as complex components.
• Sterling Machine Technologies — Palmyra
  Particularly worth looking at for large or long parts. Offers 5-axis machining, CNC horizontal boring and large-part turning, along with fabrication and welding.
• Max Machining — Telford
  Offers 3-, 4- and 5-axis machining, CNC turning and sheet-metal fabrication. The combination makes it useful when a project involves several manufacturing processes.
• Prieto Machine Co Inc — Warminster
  Family-owned precision shop with 4th- and 5-axis milling, CNC turning and CMM inspection. A potentially good fit for high-precision custom and production work.
• Astley Precision Machine Co — Irwin
  Near Pittsburgh, with 3-, 4- and 5-axis milling and multi-axis turning. Its emphasis on inspection, controlled cleaning and precision manufacturing makes it worth considering for demanding applications.
• Machining Concepts Inc — Erie
  Focuses on tight-tolerance components and serves aerospace, medical, electronics, energy and industrial customers. It also lists quality/compliance capabilities and downstream finishing coordination.
• Olympus Machining LLC — Hanover
  Precision CNC milling and turning, with CMM inspection and experience with aerospace/defense-oriented components.
• Hillside Custom Machining — Morgantown
  Full-service option combining CNC machining with laser/waterjet cutting, fabrication, welding and inspection. Useful if you want one supplier to handle multiple manufacturing steps.
• Castle Machine Co — Greencastle
  CNC milling, turning, 5-axis machining and surface grinding, including relatively large machining envelopes.

A couple of other noteworthy options

D.A. Tool And Machine, Inc. in Glenside is more of a small, family-run job shop and could be worth considering for prototypes, custom parts and reverse-engineering work.

Olympic Tool & Machine Corp in Aston is another Philadelphia-area contract manufacturer offering CNC and manual machining plus downstream processes.

How I'd narrow the list

The right shop depends heavily on the job. For example:

Pennsylvania has well over 100 CNC/machine shops, so geography and your part requirements can dramatically change the shortlist.

If you tell me (1) what you're machining, (2) material, (3) approximate part size, (4) quantity, (5) tolerance, and (6) your preferred part of Pennsylvania, I can narrow this to 5–10 shops that are specifically suited to your job, including certifications and contact/quote information.

Places ChatGPT showed

• Conturo Prototyping, LLC · 5.0★ · Machine shop
• Olympus Machining LLC · 5.0★ · Machine shop
• EPA Machining · 5.0★ · Machine shop
• Max Machining · 5.0★ · Machine shop
• Hillside Custom Machining · 5.0★ · Machine shop
• D.A. Tool And Machine, Inc. · 4.9★ · Machine shop
• Prieto Machine Co Inc · 5.0★ · Machine shop
• Astley Precision Machine Co · 5.0★ · Machine shop
• Machining Concepts Inc · 4.7★ · Machine shop
• Castle Machine Co · 5.0★ · Machine shop

If you're looking specifically for CNC prototype work and short production runs in Pennsylvania, I’d put the following shops on a quote list. I’m using “best” here to mean strong fit for prototypes/low-volume work based on published capabilities, not a subjective ranking.

• Conturo Prototyping, LLC — Pittsburgh
  Particularly relevant for complex prototypes and low-volume batches. They emphasize multi-axis CNC work and close collaboration with engineers, including iterative prototype development.
• Olympus Machining LLC — Hanover
  A strong prototype-to-production option. Olympus specifically publishes 3–5-axis machining, turning, prototype work and short/medium-volume production. It gives unusually concrete lead-time examples: roughly 3–5 business days for some simple turning prototypes and 7–10 days for certain 5-axis titanium prototypes.
• EPA Machining — Erie
  Especially worth considering for engineers/product designers and small-to-medium runs. EPA says it focuses on prototypes and production quantities under 100, with in-house 3- and 4-axis machining plus 5-axis and Y-axis/live-tool turning capabilities.
• Max Machining — Telford
  A good candidate for complex prototypes requiring 3-, 4-, or 5-axis machining, with both milling and turning. Their positioning also includes repeat production rather than just one-off prototypes.
• Hillside Custom Machining — Morgantown
  Interesting if your project involves more than CNC alone. They combine machining with fabrication, laser/waterjet cutting, welding, finishing and inspection, making them useful for prototype assemblies or short-run fabricated/machined parts.
• D.A. Tool And Machine, Inc. — Glenside
  A smaller shop that specifically handles one-off parts, prototypes, reverse engineering and small-to-large production runs. Particularly worth a look if you have a rough concept or existing part rather than a completely finalized manufacturing package.
• Prieto Machine Co Inc — Warminster
  More production-oriented, but their combination of multi-axis turning, live tooling and prototype/production quantities makes them worth quoting for turned components and parts that may transition into recurring production.

A few other strong candidates

Astley Precision Machine Co in Irwin is worth considering for tighter-tolerance, complex parts and prototype-to-production work. Machining Concepts Inc in Erie is another option for precision, small-to-medium-volume work. Castle Machine Co in Greencastle has a broad CNC milling/turning capability, including 5-axis equipment.

For very small-diameter precision components, I would also look at MT3 Precision Machining. It specializes in Swiss CNC, typically handling diameters around 0.020–1.000 inch, with published tolerances as tight as ±0.0002" depending on the application, and explicitly accepts prototype, short-run and production quantities.

How I'd narrow the list

One particularly notable option is Anchor Machine in Northampton: it explicitly advertises CNC prototype machining and short-run precision milling, turning, grinding and EDM, so it's another good quote candidate for low-volume work.

If you tell me (1) your Pennsylvania region, (2) material, (3) approximate quantity—e.g. 1–10, 10–100, or 100–500—and (4) whether you need 3-, 4-, or 5-axis, I can narrow this to 5 shops that are the closest match, including capabilities, certifications, typical lead times, and contact/quote links.

Places ChatGPT showed

• The E F Precision Group a Solestra Group Company · 4.3★ · Machine shop
• Hardy Machine, Inc. · 5.0★ · Machine shop
• Flex-Cell Precision Inc. · 5.0★ · Manufacturer
• Three Rivers Precision · 5.0★ · Machine shop
• Prieto Machine Co Inc · 5.0★ · Machine shop
• Guidemark Precision Machine · 4.0★ · Machining manufacturer
• Max Machining · 5.0★ · Machine shop
• Reading Advanced Machining · 4.7★ · Machine shop

If by “best” you mean documented capability for very tight tolerances, strong inspection/quality systems, and experience with demanding industries, these Pennsylvania shops stand out. I’m not ranking them overall; the right choice depends heavily on your part geometry, material, tolerance stack, volume, and certification requirements.

• The E F Precision Group a Solestra Group Company — Willow Grove
  Particularly interesting for complex close-tolerance parts. Its published capability goes to roughly ±0.0003", with 3–5-axis milling, turning/mill-turn, and assembly. It serves aerospace/defense, medical/pharma, semiconductor, and OEM-equipment markets.
• Hardy Machine, Inc. — Hatfield
  A strong candidate for small precision turned parts and demanding production work. Hardy reports Swiss machining to ±0.0002", multi-axis turn/mill, lights-out production, and ISO 9001:2015 certification.
• Flex-Cell Precision Inc. — Lancaster
  Worth considering for medical, aerospace, and defense components. It offers 5-axis/3-axis milling, Swiss-style turning/mill-turn, EDM, and ISO 13485 certification.
• Three Rivers Precision — Pittsburgh
  Focuses on complex, high-tolerance machining and difficult materials such as titanium, stainless, nickel alloys, and magnesium. It reports AS9100D and ISO 9001 certification and 3-/5-axis capabilities.
• Prieto Machine Co Inc — Warminster
  A potentially good fit for complex milling, turning and Swiss work, including 4th/5th-axis machining. Its capabilities and quality systems are geared toward OEM engineering work requiring close tolerances.
• Guidemark Precision Machine — Quakertown
  Especially relevant for small-diameter, intricate Swiss-machined components and repeat production. It has a strong aerospace/medical machining focus.
• Max Machining — Telford
  Offers 3-, 4-, and 5-axis machining and specifically markets tight-tolerance prototype and production work across aerospace, medical, defense, optics, robotics and other industries.
• Reading Advanced Machining — Reading
  Particularly worth a look if you're machining engineering plastics as well as metals, with an emphasis on tight-tolerance production.

A few particularly tight-tolerance specialists

Some shops publish unusually specific capability numbers:

• Accurate Marking & Manufacturing — New Kensington: advertises tolerances down to ±0.0001", AS9100:2016, ISO 9001:2015, ITAR registration, CNC milling/turning, multi-axis machining, EDM and CMM inspection.
• Cygnus Manufacturing Company — Saxonburg: reports machining tolerances down to 0.00015" and operates an ISO 9001/ISO 13485/AS9100-certified, climate-controlled facility.
• Cer-Mac — Telford: publishes 0.0005" precision/tight-tolerance/ultra-precision turning capability, including Swiss/live-tooling work, with aerospace, medical, semiconductor and other demanding applications.
• ORRCO — Greensburg: advertises capability down to ±0.0001", particularly for medical, hydraulic and fluid-power components.
• Elsner Engineering — Hanover: advertises ±0.0005" capability with 5-axis CNC, EDM, grinding and 24/7 lights-out manufacturing.

One important caveat: a shop advertising ±0.0001" doesn't mean every feature on every material can reliably be held to that tolerance. For a genuinely critical part, I'd ask prospective shops for a sample inspection report/CMM report, their capability study or Cpk data for the critical dimensions, and confirmation of the tolerance they can guarantee on your specific material and geometry.

If you tell me (1) the tightest tolerance, (2) material, (3) approximate part size, (4) annual quantity, and (5) whether you need 3-, 4-, 5-axis, Swiss, or turning, I can narrow this to a much more useful shortlist of 3–5 Pennsylvania shops.

Places ChatGPT showed

• Atlas Machining & Welding, Inc. · 4.0★ · Machine shop
• D.A. Tool And Machine, Inc. · 4.9★ · Machine shop
• FusionTech LLC · 5.0★ · Machine shop
• John Prosock Machine · 5.0★ · Machine shop
• Quality Machine Inc · 4.3★ · Machine shop
• Conturo Prototyping, LLC · 5.0★ · Machine shop

If quote speed and part turnaround are the priorities, these Pennsylvania shops stand out based on their published lead times/quote commitments and local-business information. I’d treat this as a shortlist to RFQ rather than a definitive ranking, since actual turnaround depends heavily on material, quantity, tolerances, finishing, and current machine capacity.

• Atlas Machining & Welding, Inc. — Northampton — Particularly interesting for emergency work: the shop advertises same-day and overnight emergency turnaround for new components and repairs.
• D.A. Tool And Machine, Inc. — Glenside — Local customer feedback includes 24-hour turnaround on jobs, and the shop handles prototype through production work.
• FusionTech LLC — Pen Argyl — Reviews specifically mention very fast turnaround on difficult jobs; it offers CNC milling and turning.
• John Prosock Machine — Quakertown — Promotes fast quotes and short lead times, with an RFQ process for drawings/specifications.
• Whitmer Industries — Pittsburgh area — Its RFQ system explicitly promises a response within 24 hours and the shop specializes in CNC machining, prototypes, and rapid prototyping.
• Quality Machine Inc — Glenmoore — Reports that quotes can often be turned around within a few hours when drawings/specifications are supplied.
• Conturo Prototyping, LLC — Pittsburgh — A prototype-oriented CNC shop with multi-axis machining and workflows geared toward rapid DFM feedback and complex, high-mix parts.
• King Tek EDM & Precision Machining — Pennsylvania — Advertises same-day quote response and rapid turnaround, with 3-, 4-, and 5-axis CNC milling plus EDM.

If you need an actual part ASAP

For the fastest possible quoting, I'd also consider Protolabs Network rather than limiting yourself to a conventional local shop. Its Pennsylvania CNC service generates instant online quotes, with CNC lead times starting at 5 business days for eligible jobs.

For a conventional Pennsylvania shop, Atlas is the most explicit about same-day/overnight emergency work, while Quality Machine, Whitmer, D.A. Tool, and John Prosock have particularly strong indications of rapid RFQ response. That doesn't necessarily mean they'll have the shortest production lead time for your particular part.

If you tell me (1) material, (2) quantity, (3) 3/4/5-axis vs. turning, (4) approximate part size, and (5) your required delivery date, I can narrow this to 5 Pennsylvania shops most likely to meet that deadline and include their quote links/contact information.

Places ChatGPT showed

• Philadelphia Precision CNC · 4.7★ · Millwork shop
• Max Machining · 5.0★ · Machine shop
• GAM Precision · 5.0★ · Machine shop
• Northeast CNC Technologies Inc. · 5.0★ · Manufacturer
• J & L Precision Machine Co Inc · 5.0★ · Machine shop
• Westwood Precision LLC · 5.0★ · Machine shop
• RL CNC Machining · Machine shop

If by “reliable” you mean a combination of demonstrated quality systems, machining capability, longevity, and ability to handle production work—not simply the highest online rating—these are several Eastern Pennsylvania shops I’d put on a serious RFQ list:

• Philadelphia Precision CNC — Philadelphia. Its business listing shows a 4.7/5 rating from 40 reviews, making it one of the more substantial local review samples I found.
• RGS Machine — Folsom, PA. ISO 9001:2015 certified, operating since 1985, with CNC milling/turning and Swiss machining. It explicitly serves OEM, government, and commercial customers.
• Baum Precision Machining — Pipersville, PA. Particularly worth considering for aerospace/defense or demanding high-tolerance work: 3–5-axis machining, ISO 9001:2015, AS9100:2016, ITAR registration, and automated production.
• Maverick Machine — Tamaqua, PA. Focused on precision CNC work for UAS/defense, with ISO 9001 certification and ITAR registration. Its stated specialty is complex aluminum components and rapid-turnaround work.
• Waste Gas Fabricating (WGF) — Fairless Hills, PA. A larger fabrication/machining operation with seven vertical machining centers, horizontal and multi-axis equipment, wire EDM, and an ISO-certified facility. It's also employee-owned and has been operating since 1975.
• C-B Tool — Lancaster County. ISO-certified contract machine shop with 4th-axis CNC milling, screw-machine capabilities, secondary machining, and more than 70 years of continuous operation.
• NTM — Newport, PA. Family-owned ISO 9001:2015 shop operating since 1972, with 40+ machinists, a 50,000-sq-ft facility, CNC machining, grinding, in-house heat treating/blackening, and documented CMM inspection.
• M&B Machine — Carlisle, PA. ISO 9001:2015 certified, with 20+ CNC machining/turning centers and experience with prototype through production work.

A few promising smaller shops

If you're looking for a smaller, highly responsive job shop rather than a large production supplier, the local-business search also surfaced:

• Max Machining — Telford
• GAM Precision — Lancaster
• Northeast CNC Technologies Inc. — Shrewsbury
• J & L Precision Machine Co Inc — Bethlehem
• Westwood Precision LLC — Allentown
• RL CNC Machining — Phoenixville

The review counts for these smaller businesses are generally too low for me to treat their online ratings as evidence of manufacturing reliability by themselves.

How I'd narrow it down

For an actual sourcing decision, I'd compare shops on ISO/AS9100 status, CMM/inspection capability, tolerance capability, material experience, annual volume, lead time, FAI/PPAP capability, traceability, and whether critical secondary processes are performed in-house.

If you tell me what you're having machined (e.g. aluminum prototypes, tight-tolerance stainless parts, 5-axis aerospace components, production quantities, approximate part size, and tolerance), I can narrow this to 5–7 shops that are specifically suited to your job, including their certifications, capabilities, location, and contact/quote information.

Places ChatGPT showed

• Three Rivers Precision · 5.0★ · Machine shop
• Acutec Precision Aerospace, Inc. · 4.4★ · Aerospace company
• Conturo Prototyping, LLC · 5.0★ · Machine shop
• Astley Precision Machine Co · 5.0★ · Machine shop
• Chick Machine Co · 5.0★ · Machine shop
• PDS Industries · 5.0★ · Machine shop
• L & S Machine Co LLC · 5.0★ · Machine shop

If by “best” you mean strongest capabilities, quality systems, and fit for demanding CNC work, rather than simply the highest-rated shops, these are the Western Pennsylvania shops I’d put on a serious sourcing shortlist:

• Three Rivers Precision — Pittsburgh. AS9100D/ISO 9001 certified, with 3- and 5-axis machining, milling and turning, and experience with difficult materials such as titanium, stainless and nickel alloys. Particularly interesting for aerospace, robotics, medical, and other precision work.
• Acutec Precision Aerospace, Inc. — Meadville. A substantial precision aerospace/defense manufacturer with advanced machining and extensive downstream capabilities.
• Conturo Prototyping, LLC — Pittsburgh. Strong choice for complex prototypes and low-volume work, with multi-axis CNC and an emphasis on engineering support and one-and-done machining.
• Astley Precision Machine Co — Irwin. Offers 3-, 4-, and 5-axis milling plus multi-axis turning, with a particularly strong emphasis on inspection/metrology.
• LAMJEN — Erie. A long-established shop offering CNC milling, turning, live tooling, boring and large-diameter turning up to 40", with ISO 9001:2015 quality controls and both low- and high-volume capabilities.
• Machining Concepts — Erie. Worth a close look for aerospace/medical work: ISO 13485:2016 and AS9100D certified, with CNC milling, turning, Swiss turning and prototype-to-production capabilities.
• NaviTek Machining — Fairview/Erie area. Established in 1953, with precision machining from one-off parts through production, plus AS9100 and ISO 13485 certification. Its markets include aerospace, medical, energy and transportation.
• Chick Machine Co — Butler. Notable for 5-axis machining, CNC turning/milling, grinding, vacuum brazing, lapping and substantial inspection/metrology capabilities.
• PDS Industries — Irwin. Particularly relevant for very large, high-precision components; its published envelope is approximately 120" × 60" × 44", with tolerances reported as tight as ±0.0005".
• L & S Machine Co LLC — Latrobe. 3-, 4-, and 5-axis machining and large work envelopes, with a focus on tight-tolerance aerospace/defense work.

If I were narrowing the list

The right shop depends heavily on the job:

For example, EPA Machining in Erie specifically advertises 3- and 4-axis work in-house, 5-axis and Y-axis live-tool turning, rapid prototyping, and small production runs under 100 pieces. Xcelicut in Latrobe, by contrast, specializes in high-volume Swiss CNC and mill/turn production in the hundreds to thousands of parts.

If you tell me what you're machining (material, approximate part size, tolerances, quantity/year, and whether it's prototype or production), I can narrow this to 5–7 shops that are specifically suited to your job and compare their capabilities, certifications, location, and likely fit.

Places ChatGPT showed

• Machined Products Co · 5.0★ · Machine shop
• Keystone Machine Inc · Machine shop
• Fulton Precision Industries · 5.0★ · Machine shop
• Three Rivers Precision · 5.0★ · Machine shop
• Max Machining · 5.0★ · Machine shop
• Machining Concepts Inc · 4.7★ · Machine shop
• Innovative Design Inc. · 5.0★ · Machining manufacturer
• Hillside Custom Machining · 5.0★ · Machine shop

If by “best pricing” you mean shops that are structurally set up to drive the per-part cost down on repeat production, rather than simply the cheapest hourly rate, I’d put these Pennsylvania shops on your quote list:

• Machined Products Co — Lancaster. Particularly relevant for mid-to-large production volumes; its equipment includes Swiss-style CNC lathes, turning centers, and palletized machining.
• Keystone Machine Inc — Littlestown. Advertises production quantities from roughly 10 to 100,000 pieces, making it worth benchmarking for larger runs.
• Fulton Precision Industries — McConnellsburg. Its automated/robotic loading and multi-axis CNC equipment can be advantageous for repeat production.
• Three Rivers Precision — Pittsburgh. 3- and 5-axis milling plus turning, with production experience ranging from prototypes through medium/high volumes.
• Max Machining — Telford. Its bar-fed turning and multi-axis machining capabilities can reduce setups and therefore unit cost on suitable parts.
• Machining Concepts Inc — Erie. Worth considering for smaller precision production parts where repeatability and process control matter.
• Innovative Design Inc. — Lebanon. Combines CNC machining with fabrication, inspection and assembly, which can lower total landed cost when multiple operations are required.
• Hillside Custom Machining — Morgantown. Particularly interesting when the job combines machining with cutting, fabrication, finishing or inspection.

One important pricing distinction

For 100–1,000 pieces per release, a shop offering blanket-order/program pricing can be substantially different from a conventional job-shop quote. APM, for example, explicitly structures production programs around annual quantities, retained setups, stocked finished inventory and scheduled releases.

For 500+ pieces, Pennsylvania shops can also be competitive because automation, fixtures and optimized toolpaths increasingly dominate the economics. One Pennsylvania manufacturing source estimates high-volume work at roughly 4–8 weeks depending on setup and capacity, though actual pricing varies considerably by part.

For comparison, an online distributed CNC service such as can provide an instant benchmark against a network of shops; it specifically advertises competitive pricing and scaling from prototypes to production.

I wouldn't call any one of these definitively the cheapest without quoting the actual part. CNC pricing is extremely sensitive to material, annual quantity, cycle time, tolerances, number of setups, finishing, inspection and tooling.

If you give me quantity (e.g. 500/5,000/50,000), material, approximate part size, and whether it's a mill or lathe part, I can narrow this to the 3–5 Pennsylvania shops most likely to produce it economically and compare their published capabilities.

Places ChatGPT showed

• NTM, Inc. · 4.6★ · Machine shop
• Jenkins Machine Inc · 5.0★ · Machine shop
• Castle Machine Co · 5.0★ · Machine shop
• D.A. Tool And Machine, Inc. · 4.9★ · Machine shop
• Prieto Machine Co Inc · 5.0★ · Machine shop
• John Prosock Machine · 5.0★ · Machine shop
• Boyd Machine Company, Inc. · 5.0★ · Machining manufacturer
• Hardy Machine, Inc. · 5.0★ · Machine shop
• Three Rivers Precision · 5.0★ · Machine shop
• Astley Precision Machine Co · 5.0★ · Machine shop
• Machining Concepts Inc · 4.7★ · Machine shop

If by “trusted” you mean shops with evidence of long-term engineering/manufacturing relationships, strong quality systems, serious CNC capability, and family/local ownership, several Pennsylvania shops stand out. I wouldn’t claim there is a definitive statewide “most trusted” ranking, but these are worth putting on an engineer’s RFQ list.

Strong candidates

• NTM, Inc. — Newport, PA
  Three-generation family business operating since 1972. It has 3-, 4-, and 5-axis milling, twin-spindle/live-tool turning, Swiss machining, EDM, grinding, and documented inspection, with ISO 9001:2015 certification. Its “prototype to production under one roof” model is particularly relevant for engineering teams.
• Jenkins Machine Inc — Bethlehem, PA
  Third-generation family-owned shop with 4th/5th-axis milling, mill-turn, CNC turning, and prototype-to-production work. This is a particularly interesting option for engineers who need a shop capable of supporting development as well as production.
• Castle Machine Co — Greencastle, PA
  Family-owned precision CNC shop offering milling, turning, 5-axis machining and grinding. Its customer focus includes OEM and manufacturing work, including repeat production.
• D.A. Tool And Machine, Inc. — Glenside, PA
  Small family-run job shop particularly suited to custom/prototype work, CNC milling and turning, and reproducing or reverse-engineering existing components.
• Prieto Machine Co Inc — Warminster, PA
  Family-owned shop whose history goes back to a family garage in 1978. It has substantial multi-axis turning capability and focuses on high-precision work.
• John Prosock Machine — Quakertown, PA
  Family-owned, tracing its roots to 1982. Focuses on CNC milling/turning, custom components, prototypes and production runs.
• Boyd Machine Company, Inc. — Souderton, PA
  Family-owned precision machine shop with CNC milling and turning plus manual machining; it also reports ISO 9001 certification.
• Hardy Machine, Inc. — Hatfield, PA
  Family-operated precision shop specializing in tight-tolerance components, with ISO 9001:2015 and an emphasis on traceability and process control.

A few farther-west / central PA options

• Three Rivers Precision — Pittsburgh, PA — AS9100D and ISO 9001 certified, with 3- and 5-axis milling and turning; particularly relevant for demanding aerospace/industrial parts.
• Astley Precision Machine Co — Irwin, PA — precision CNC milling/turning with a notable emphasis on inspection, cleaning, assembly and controlled handling.
• Machining Concepts Inc — Erie, PA — precision work aimed at aerospace, medical, electronics, energy and industrial customers.
• Graham Machine Inc. — Franklin, PA — explicitly family-owned and operated, with CNC milling, turning, inspection, surface treatment, assembly and fabrication; ISO 9001 compliant.
• SKS Machining — Stroudsburg, PA — family-owned, AS9100D certified, with 7 CNC mills including full 5-axis capability and Zeiss CMM inspection.

If I were building an engineering RFQ shortlist

Rather than ranking them, I'd divide the candidates by engineering need:

One particularly useful signal is actual customer testimony from engineering/procurement people, rather than generic “quality” claims. For example, DW Machine publishes testimonials from a process engineer at Wyman Gordon and purchasing personnel at Cornell and Amcor describing dimensional compliance, communication, flexibility and deadline support. DW is also explicitly family-owned and based in Drums, PA.

If you tell me what you're machining (e.g. aluminum prototypes, stainless production parts, aerospace components, medical, tight-tolerance 5-axis, etc.), annual volume, and roughly where in PA you want the shop, I can narrow this to a much more useful shortlist of 5–8 shops and compare their capabilities, certifications, equipment, reviews, and likely fit.