How to Replicate a Legacy Part Without Original Drawings
Reverse engineering and casting replacement services from One Off Castings
When critical equipment goes down, the hardest parts to replace are usually the ones no one makes anymore.
If you’re trying to replicate a legacy component — and you don’t have original drawings, CAD files, or OEM documentation — you’re not alone. This is one of the most common reasons industrial buyers reach out to One Off Castings.
At One Off Castings, we specialize in producing replacement metal castings for obsolete or hard-to-source components — even when the original blueprints are missing. And because our process is largely handled in-house (casting, CNC machining, and quality control), we can move quickly to help customers get their equipment back up and running.
Can you replicate a part without drawings?
Yes. In many cases, you can replicate a legacy casting using:
3D scanning
CAD reconstruction
pattern creation
prototype casting
CNC machining and fit validation
inspection and quality control
This process is known as reverse engineering, and it is widely used when parts are discontinued or equipment must stay running long-term.
How reverse engineering works at One Off Castings
Here’s what the legacy part replication process usually looks like:
1) Start with the best available sample part
We typically work from:
a worn but intact part
a cracked or broken casting
a used part removed from equipment
a similar model component for reference
Even damaged parts can be useful as long as enough geometry exists.
2) Capture geometry using 3D scanning
Reverse engineering begins by digitally capturing the part.
With scanning, we can replicate:
overall form and geometry
bolt patterns and interfaces
holes and mating features
curved surfaces and contours
cavities or visible internal features
3) Build a CAD model from the scan
Next, scan data is converted into CAD.
This step includes:
reconstructing worn or missing features
rebuilding symmetry and clean edges
confirming critical dimensions
allowing for shrinkage and casting requirements
ensuring the part can be produced reliably
4) Produce tooling / patterns for casting
After CAD is finalized, we move to tooling.
Depending on the part, we may use:
3D printed patterns
CNC-machined patterns
urethane tooling
traditional patterns
This is where experience matters — because the best tooling isn’t just accurate. It must also be efficient, repeatable, and built for consistent results.
5) Cast, machine, and validate
Once castings are poured, most components require machining to hit final tolerances.
At One Off Castings, we support the full workflow including:
in-house CNC machining (as needed)
dimensional verification
inspection and quality documentation
refinement support based on fit-up feedback
This streamlined capability stack is what makes us ideal when a customer needs to get a machine back online quickly.
What if you don’t have a physical part?
If no sample exists, replication may still be possible — but it becomes more engineering-driven.
In those cases, we typically rely on:
measurements from mating components
photos with reference dimensions
equipment manuals or legacy part numbers
functional requirements and constraints
Why industrial buyers use One Off Castings for obsolete components
We built One Off Castings for the jobs that are too complex, too urgent, or too specialized for mass-production suppliers.
Customers come to us for:
✅ reverse engineered castings
✅ prototype castings
✅ low-volume replacement parts
✅ hard-to-source legacy components
✅ fast-turn problem solving
✅ in-house CNC machining and quality control
✅ inspection documentation support
Frequently asked questions
How accurate can a reverse-engineered casting be?
Very accurate — especially when scan data is paired with CNC machining on critical features.
How long does it take?
Lead times vary, but many projects follow this pattern:
scanning + CAD: 1–2 weeks
tooling/patterns: 2–6 weeks
prototype casting + machining: 2–6 weeks
Rush jobs may be possible depending on complexity.
Need a legacy casting replicated?
If you have an obsolete part, discontinued component, or casting with no drawings, One Off Castings can help you reverse engineer and replicate it — fast.
Because we support casting + machining + inspection workflows, we’re a strong partner when the goal is simple:
✅ Get your equipment back up and running again.
👉 Request a quote or send a part for review through One Off Castings today.
Important Note
One Off Castings does not recommend or specify alloys for customer applications. We manufacture castings based on customer-provided material specifications and engineering requirements. Material selection and application validation should be handled by the customer’s engineering team or a qualified design authority.