To make a discontinued machine part you need three things: the original part (or what is left of it), a survey that separates functional dimensions from free dimensions, and a reasonable identification of the material. With that, a laser cutting, bending and welding shop can reproduce it from a drawing so you no longer depend on the original manufacturer.
In maintenance, few situations create as much pressure as a machine stopped by a part nobody supplies anymore. The manufacturer discontinued the model, the distributor has no stock and the line is waiting.
At that point the question is not only where to get the part, but how to reproduce it right the first time. For the big picture of how a plant keeps running, see our article on industrial maintenance. Here we go into detail: what to measure, what to decide and what to hand over.
Which parts can be reverse engineered in sheet and plate
Not everything is solved with laser cutting and bending. A gear with a fine tooth profile or a shaft with bearing fits is machining work.
But a good share of the spare parts that stop a line are sheet or plate parts: brackets, bases, covers, guards and adjustment plates. These are the most common cases:
- Motor mount. Laser cutting and welding, usually in A36 steel. What matters is the position and diameter of the holes, which follow the motor frame dimensions (NEMA MG 1 for American motors or IEC 60072-1 for metric motors).
- Industrial pump base. Cutting and heavy bending in thick steel. Flatness and the shaft alignment required by the pump manufacturer are what count.
- Gear plate. Precision laser cutting. If the tooth profile is functional, it is checked against AGMA and may require machining.
- Hinged access cover. Cutting, bending and welding, often in galvanized sheet. It has to fit the existing frame and the original hinge.
- Machine support bracket. Laser cutting and bending, usually at 90°. Its holes have to match anchors already set in the floor.
As a size reference, at Versotech in Metepec, State of Mexico, we cut A36 steel with an ideal thickness of 20 mm and a maximum of 26 mm, and we bend carbon steel up to 10 mm in lengths of up to 3,200 mm.
How to survey a discontinued part
The most common mistake is not measuring wrong. It is measuring everything with the same importance.
A part has dimensions that decide whether it fits (the distance between mounting holes, the diameter of a hole for a fitted bolt, the height of a shaft) and dimensions that only define the shape (a cosmetic chamfer, a cutout to save weight). If twenty measurements are sent without telling them apart, the shop has to guess which ones matter.
What is worth gathering, in order of value:
- The physical part, even if it is broken or worn. Measuring the real part settles doubts a photo will never settle.
- The neighboring part or the mounting point. If the bracket bolts to a machine bed, measuring the bed is worth more than measuring the worn bracket, because the bed is the reference that did not change.
- Photos with scale, with a tape measure or a ruler in view, from the front and from the edge.
- What it does and what load it carries, in one or two sentences. "It holds a motor and it vibrates" changes the thickness decision.
- Old drawings, even incomplete ones. An original drawing with a single reliable dimension serves as an anchor for everything else.
When the part is worn, you measure where there is no wear and rebuild the original geometry. In a hole that vibration has made oval, the right measurement is not the oval: it is the diameter of the bolt that goes in there.
Which material to ask for when nobody knows what the original was
Without a drawing or a certificate, the material is inferred. A magnet helps separate carbon steel or ferritic stainless, which stick strongly, from an austenitic stainless such as 304, which barely sticks (although it can attract a little in bent or cold-worked areas). Color and weight separate aluminum from steel. Galvanized steel shows on the edge and on the surface.
For parts where the exact composition matters (wear resistance, weldability, food contact), the right move is to send a sample for laboratory analysis before making a batch.
A practical rule: if the original part lasted years and failed from normal wear, it is reproduced in the same type of material. If it failed early, it is worth reviewing with maintenance whether it is better to increase the thickness, change the material or add a reinforcement. Making an exact copy of a part that breaks every six months is making the next failure.
From survey to drawing
A reverse-engineered spare part needs to be documented, because the second time it is ordered it should not start from zero. The output of the survey is a 3D model and a drawing with the functional dimensions toleranced and the rest under a general tolerance.
For dimensions without an individual tolerance, the usual practice is to state a class of ISO 2768-1, the standard for general tolerances on linear and angular dimensions. For critical dimensions, such as the position of a hole pattern, it is best to use geometric tolerances per ASME Y14.5, the reference for geometric dimensioning and tolerancing (GD&T) in North America.
A good practice before making the batch is to make a single test part and fit it on the machine. It is the fastest way to find the dimension nobody measured: the hole that was actually 3 mm from where it seemed, or the bend that had a different radius on the original. A test part costs less than a batch that does not fit.
What can be done to solve it
When a spare part can no longer be found, the path is usually the same:
- Analyze the part: its function, the load it carries and the cause of failure.
- Separate the dimensions that define the fit from those that only define the shape.
- Choose the material and thickness, with the option to improve the part if it was failing early.
- Turn the survey into a drawing that maintenance can validate before cutting.
- Make a test part, validate it on the machine and then produce the batch.
The last step is the one with the most value in the medium term. Once the spare part has a drawing, it stops being an emergency: it can be made in batches and kept in stock before it fails again.
Frequently asked questions
Can a spare part be made if the original drawing does not exist?
Yes. With the physical part, photos with scale and the function it serves, a survey is made and a new drawing is created. The test part confirms the functional dimensions are right before the batch is made.
Is it legal to reproduce a discontinued part?
Making a spare part to maintain your own equipment is something done often in maintenance. If the part is protected by a patent or a registered industrial design that is still in force, or if the equipment is still under warranty, it is worth checking first with your legal team or with the manufacturer.
What if the original part failed often?
That is the moment to improve it. With the cause of failure identified (wear, fatigue or corrosion), you decide whether more thickness, another material or a reinforcement is better, and the new drawing records that change.
A spare part with a drawing stops being an emergency
A machine stopped by a part that no longer exists on the market does not have to become a recurring crisis. With a good survey, the right material and a validated drawing, the spare part goes from being a problem to being a file ready to be made whenever it is needed.
Because in maintenance, the best spare part is not the one you get fast, but the one that never stops the line again.