Commercial
Replacing a discontinued acrylic part without a drawing
The original drawing is gone, the supplier has closed, and the part is in your hand. That is enough to work from, if the right things get measured.
Commercial
The original drawing is gone, the supplier has closed, and the part is in your hand. That is enough to work from, if the right things get measured.
A great many acrylic parts we make are replacements for parts whose drawing no longer exists. The process is not complicated, but it depends on measuring the right things and identifying the material, because a replacement that is dimensionally correct in the wrong material will fail in the same way as the original.
| Measurement | Method | What it decides |
|---|---|---|
| Outline and hole centres | CMM or a measured overlay | The geometry of the replacement |
| Thickness at several points | Micrometer | Whether the original was nominal or selected sheet |
| Flatness | Surface plate and dial indicator | Whether flatness was ever a requirement |
| Edge condition | Magnification | Whether the edge was polished, flame polished or as cut |
| Colour | Comparison against the sheet range in daylight | The nearest available sheet, or a printed match |
| Material identification | Burn or fracture behaviour, marking, density | Acrylic, polycarbonate, PETG or polystyrene |
It matters, and it is not always obvious. Acrylic and polycarbonate look similar and behave completely differently on impact. Three practical indicators:
If the original was polycarbonate and we make the replacement in acrylic, it will crack at the first impact. Identifying the material is not a formality.
The finish is what the customer notices, and it is often the hardest thing to reproduce from a worn part. A polished edge that has been cleaned for years has lost some of its original clarity, and matching it exactly may not be desirable.
We compare the worn part against a fresh sample of each candidate finish and agree which one the replacement should be. In most cases the answer is "as it was when new", not "as it is now".
A replacement is the cheapest moment to fix the detail that caused the failure, and the most common failure we see is a fixing that did not allow movement. If the original cracked at a hole, the replacement should have a larger hole and a washer.
We will always tell you what we would change and why, and we will quote both the exact replacement and the improved one. The decision stays with the customer, because sometimes an exact match is what the other thirty machines need.
Sampling a replacement is 3 to 7 business days from receipt of the part or a complete measurement, and production is 7 to 15 business days. A single urgent replacement can sometimes be cut in 3 to 5 business days if the material is in stock, and we will say honestly whether that is achievable rather than promising it.
For a machine that is down, tell us that at the first email. It changes the priority and sometimes the process, for example cutting from stock rather than ordering the exact original thickness.
Yes, that is a common request. Send the part or the pieces, and we measure, model and quote against a marked-up drawing for approval.
Send all the pieces. The break tells us where the stress was and whether the failure was in service or at installation, which changes what the replacement should be.
We can get close with the nearest sheet colour, or exact with a printed back on clear acrylic. We will show both and say how each will look at the edges.
Send it and we will identify it from the fracture behaviour and a burn test. It matters, because a polycarbonate guard replaced with acrylic will crack on the first impact.
Yes, and it is common. We keep the measured model on file, so a second replacement does not need the part again.
When a drawing does not exist, the sample is the specification. The process below is the order that produces a usable part rather than a copy of the original's defects.
| Step | What happens | What it catches |
|---|---|---|
| 1. Identify the material | Cast or extruded, tinted or clear, coated or not | An extruded original that was bonded — the copy will craze where the original did |
| 2. Measure the features that matter | Mounting holes, locating edges, and any mating face | A part that measures right and does not fit |
| 3. Check for movement | Whether the original had slotted holes or a clearance | Repeating a failure by copying a rigid fixing |
| 4. Photograph the failure | Where it broke, in situ | A design fault that would be reproduced faithfully |
| 5. Decide what to improve | Anneal, radius a corner, slot a hole, thicken one dimension | A replacement that fails the same way in six months |
| 6. Record it | A drawing is produced for the new part | A second replacement having to start from scratch |
Step five is the one that separates a good supplier from a copying service. A replacement part is the only moment when a design problem can be fixed for free, because the tooling is being made anyway. If the original cracked from a hole 6 mm from an edge, the replacement should have 12 mm; nobody will ever pay less to make that change than right now.
The output of this process is a drawing, not just a part. That drawing is what makes the third replacement a catalogue item rather than a project, and it costs nothing beyond the time to produce it during the first remake.
The measured model becomes the record, so the next replacement does not need the original at all.