How to Source Replacement Machinery Parts
Getting a worn or obsolete machine part made without a drawing: what to send, what to measure, how to identify the material, and what to ask the shop.
53 shops tagged Industrial Equipment among 5,104 CNC machining companies in the Noramark directory
Replacement parts are the RFQ with the least information. The machine builder is gone or quotes weeks and a high price, the drawing never existed or is lost, and the part in hand is worn, broken or both. A machine shop can still make it, but somebody has to decide what the original dimensions, material and heat treatment were, and that is where most of the time and risk sit.
A good replacement-part RFQ sends the part (or clear photos and measurements), its mating parts, what the machine does and how the old part failed. Say how quickly the machine must run again, and whether you want an exact copy or an improved part. Ask the shop to produce a drawing as part of the job: it costs a little more now and turns the next failure into a normal reorder instead of another reverse-engineering project.
RFQ checklist
15 things to settle on the drawing or in the request before you ask for replacement part quotes. Print it and tick it off against the print, or copy it into the RFQ.
The old part and the machine
The part itself, or a worn part and an unused spare if you have both
A physical sample beats any photo, and a worn part next to an unused one shows which dimensions are original.
Machine make, model and serial number, the builder's part number, and the part's position in the assembly
A shop that knows the machine may have made the part before, and the builder part number sometimes still leads to a drawing or a parts manual page.
How the part failed: wear, fracture, fatigue, corrosion or crash damage, and how long it lasted
The failure tells the shop whether to copy the original or upgrade material or heat treatment. A copy of a part that wore out in a year will wear out in a year.
Mating parts, or their part numbers and dimensions: bearings, seals, shafts, bores, gears and keys
Fits and gear mesh are set by the mating parts. A worn size can be rebuilt from the unworn size of its mate.
Dimensions and fits
Which dimensions are critical and which areas are worn
The shop measures everything but must decide which sizes to restore to nominal. Marking the worn areas avoids copying the wear.
Measured sizes of fits, with the bearing or seal part numbers they carry
A bearing seat that measures 39.99 mm on a worn shaft is a 40 mm k5 or k6 fit on the new drawing. Part numbers let the shop use the standard fit instead of the worn size.
Threads checked with thread gauges: inch, metric or special form, hand and class
Older machines use Acme, Whitworth, left-hand and special threads. Guessing a thread from calipers is a common cause of scrap.
Gear data for any teeth: tooth count, outside diameter, and the mate's tooth count and center distance
From these a gear shop can work out module or pitch, pressure angle and profile shift.
Material and treatment
Known or suspected material, with any evidence: magnetic or not, hardness readings, spark test, XRF or lab analysis
A hardness test and an XRF reading cost little compared with guessing wrong. XRF identifies stainless and alloy grades in seconds.
Surface hardness on wear faces, and whether the part was case hardened or through hardened
A hard skin over a soft core means carburizing or induction hardening. Copying it in through-hardened steel changes how the part wears and how it breaks.
Coating, plating or paint on the original
The finish may be part of the function (wear, corrosion, sliding), and it affects fit sizes.
Urgency and deliverables
Urgency: machine down (days) or planned replacement (weeks)
Many shops can turn a simple part in a day or two for a premium. Knowing the machine is down changes how they schedule and what they quote.
Quantity: one now, spares, and expected future needs
Reverse engineering and programming cost the same for one part or five, and spares are cheap once the setup exists.
Deliverables: a drawing and STEP model of the new part, and inspection results
Paying for a drawing turns the next order into a standard RFQ any shop can quote.
An approval step for the derived drawing before metal is cut
A day spent reviewing the drawing catches misread features before the part is made.
What to send with the RFQ
- The part, shipped to the shop, or several clear photos with a scale and measurements of every feature.
- Machine make, model and serial number, and where the part sits in the machine.
- Any partial drawing, sketch, parts manual page or exploded view.
- Mating part numbers (bearings, seals, fasteners) and measurements of the mating parts.
- How the part failed and how long it lasted.
- How fast you need it and how many you want.
Lead times
| Prototype or first parts | Simple turned or milled parts from a sample: 1-5 business days expedited, 1-3 weeks at normal priority. |
|---|---|
| Production or repeat orders | Parts with gears, heat treatment or grinding: 2-6 weeks. Repeat orders from the drawing and program made the first time are faster than the first piece. |
Typical of U.S. job shops, from order or approved drawing to shipment; confirm with the shop for your part.
What drives the cost
- Reverse engineering: measuring, modeling and drawing the part, usually billed as hours.
- Material identification and hardness testing when the original is unknown.
- Expedite premiums for machine-down work that jumps the queue.
- Complex features on old parts: gears, splines, special threads and cams.
- Heat treatment and grinding, often done outside with their own lead times.
- Quantity: one part carries the whole setup; spares lower the cost per part.
Common mistakes
- Copying worn dimensions instead of restoring them to the original fits.
- Guessing the material from its appearance, then watching the new part wear or break faster.
- Measuring threads with calipers only.
- Not asking for a drawing, so the next failure starts from zero.
- Photos without a scale, or without the mating parts.
Questions to ask the shop
- Do you reverse engineer parts, and will you deliver a drawing and a model?
- How do you identify material: hardness tester, spark test, XRF?
- Can you turn a machine-down part in days, and what does the expedite cost?
- Do you have gear cutting, heat treatment and grinding in-house or nearby?
- Will you keep the program and drawing on file for repeat orders?
Typical processes
Typical materials
Charts and calculators
Frequently asked questions
- Can a shop make a part without a drawing?
- Yes. Most job shops reverse engineer parts from samples routinely: they measure the part, model it and cut it, and many will deliver the drawing too. Worn features, unknown material and special threads are the hard parts, so send the mating parts and whatever history you have.
- Can I legally have a replacement part copied?
- Making a replacement for equipment you own is routine work for machine shops. Patents, registered designs or contract terms can restrict copying some current OEM parts, so check whether the part is still under patent or covered by an agreement with the builder before ordering copies in quantity.
- How do I find out what material the old part is?
- Start with a magnet and a hardness test. A handheld XRF analyzer identifies most alloys, including stainless and alloy steel grades, in seconds without damaging the part, and many shops and metal service centers have one. XRF cannot measure carbon, so for carbon content or a failure analysis a lab can run spark spectrometry and check the microstructure.
Build the RFQ: attach the print and this checklist
Attach the drawing (PDF) and the model (STEP), and put your answers to the checklist in the description. A Noramark sourcing specialist matches the request with U.S. shops that make replacement parts and contacts you within 1 business day.
