You Have the Part. You Do Not Have the Drawing.
The machine is old, the supplier is gone, the engineer who designed it retired, or the file was never yours in the first place. A physical part can be turned back into a drawing — but only some of it. Measuring gives us the geometry. It does not give us the intent, and pretending otherwise is how reverse-engineered parts fail six months later. Here is exactly what we can recover, what we have to ask you, and where we stop.
A part tells us its shape. It does not tell us why.
Every dimension on a finished part is the result of a decision somebody made, and the part carries the result without the reason. This is the whole difficulty of working without a drawing, and it is the part that most quotations quietly skip.
| What we can recover from the part | What we cannot, and have to ask you |
|---|---|
| Every dimension, to the accuracy of our measuring equipment | Which of those dimensions actually matter, and which were whatever the cutter happened to leave |
| Surface roughness, measured by an independent test house rather than guessed | Whether that roughness was specified or was simply the finish the last process produced |
| Thread sizes and fits, verified with gauges | The class of fit intended — a worn thread and a loose thread measure the same |
| Hardness, tested by an independent laboratory, and a reasonable opinion on the material family | The exact alloy and heat treatment. If the grade matters, it needs a material analysis before we cut — we will tell you when we think it does |
| The geometry as the part is today | The geometry as the part was when it was new. A worn part measured faithfully produces a worn drawing |
| Where the part is damaged or deformed | What it mates with, what loads it sees, and which face is doing the work |
None of these are reasons not to do it. They are the questions we will send you after we measure, and the answers are usually in your head rather than in any file.
Where reverse engineering goes wrong, every time it goes wrong
1. Copying the wear
A shaft that has run for eight years is smaller than the shaft that was fitted. Copy it to three decimal places and you have faithfully reproduced the failure. Send us an unused part if one exists anywhere — a spare on the shelf, the one from the machine that was never commissioned. If only a worn part exists, tell us which surfaces ran against something, and we will treat those dimensions as questions rather than facts.
2. Inventing datums
A part without a drawing has no datums, and every dimension has to be measured from somewhere. We choose a datum scheme from how the part is mounted and what it locates against, then send it to you for approval before anything is cut. We do not want to discover on the first article that we measured from the wrong face — and neither do you.
3. Inventing tolerances
The lazy version of this work puts a tight tolerance on everything, because that is safe for the shop and expensive for you. We propose a scheme instead: general ISO 2768-m, with tight tolerances only on the features that locate, seal or fit — and we write down why for each one. You approve it, and it becomes your drawing.
From a part in a box to a part on your machine
Photos and rough dimensions first
Before anything is shipped, send photographs from several angles with a ruler in frame, and whatever dimensions you can take with a caliper. That is usually enough for us to say whether it is a job for us, roughly what it will cost, and whether we need the physical part at all.
Tell us what the part does
What it mounts to, what it seals against, what turns inside it, and what failed. Five sentences from you are worth more than five hours of measuring.
We measure and build the model
Dimensions on the CMM and threads with GO / NO-GO gauges, here in our own measuring room. Surface roughness and hardness go to an independent test house — we would rather send it out and give you a report from a laboratory than guess in-house. The result is a 3D model and a dimensioned drawing.
You approve the drawing before we cut
With the datum scheme and the proposed tolerances marked, and our questions listed on it. This is the point where your knowledge of the application corrects our measurements. The drawing is yours to keep either way.
One piece first
For anything that has to fit an existing assembly, we make one and you try it before we run the batch. It is slower on paper and faster in practice.
First article report against your new drawing
Measured values, not a pass stamp — so that from now on the part has a documented standard, which is the thing you were missing at the start.
Two things we will not do
Copy a part you do not have the right to copy
We reverse-engineer parts our customers own, parts from machines they own, and parts whose original supplier no longer exists. We do not copy a competitor’s patented or proprietary component for resale, and we will ask the question before we quote rather than after. If you are unsure, tell us what the part is and where it came from — it is a short conversation.
Guess a material and call it a specification
We can tell you the material family from hardness, weight, magnetism and how it cuts, and for a bracket that is usually enough. For a part that carries load, seals pressure or sees heat, an opinion is not a specification. In those cases we will say that the grade needs to be confirmed by analysis before we commit — and the honest version of that sentence costs us work sometimes.
Your part, your photographs and your drawing stay in the shop. An NDA is available on request before you send anything, and we will sign yours rather than insisting on ours.
Send photos before you send the part
A few pictures with a ruler in frame and any dimensions you can reach with a caliper. We will tell you whether it is worth doing, roughly what it costs, and what we will need to ask you — within 16 hours, at no charge.