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What to do when a torque driver fails calibration after use on a clinical build

Thu, 30 Apr 2026 12:02:44 GMT

When a calibrated torque driver fails an in-house check after it's already been used on a clinical trial build, the question worth investigating isn't whether the tool is broken now. It clearly is. The question is whether the units built before the failure are still within spec, and whether you can defend that conclusion with evidence rather than assumption.

A few weeks ago my Director of Quality came to tell me one of our torque drivers had been dropped. We tested it in-house right away and it was reading out of spec. Torque drivers get dropped, you replace them, you move on. The complication was that this particular wrench had been used the week before to build five units for a client's clinical trial.

The wrench had a clean recent record. It came back from a full external calibration six months ago, with another six months of useful life ahead of it. About a month before the clinical build we'd spot-checked it on our in-house calibrated torque checker, and it was in spec then too. So when it failed yesterday's test, the obvious story was that the drop had broken it, and the obvious story was probably right. The problem with stopping there is that "probably right" doesn't survive contact with a regulator, and it doesn't really survive contact with a thoughtful client either. We were either going to show that the five clinical units were still good, or we were going to tell the client they weren't. Splitting the difference wasn't an option.

Did the drop cause the calibration failure, or did the tool drift earlier?

Honestly, we don't know for certain. The drop is the obvious cause and probably the real one, but we can't rule out earlier drift, and it turns out we don't need to. Whether the drop did it or whether the tool had been creeping out of spec for weeks, the only question with practical consequences is whether the screws on the clinical units were torqued to a value that puts them at risk. So we worked backwards from that. What was the nominal torque setting, how far out was the wrench reading, in which direction, and where in the assembly was it being used.

How do you check a torque wrench when your checker doesn't reach the working range?

The wrench is an adjustable torque driver set to 5 Nm for a single joint in the build. It was going out for full external calibration regardless — that's not optional after a known impact event — but we wanted a data point quickly. Our in-house checker only goes up to 3.5 Nm, so we set the wrench to 3 Nm and ran it. It read 3.4 Nm, about 13% high.

Direction matters as much as magnitude here. A wrench reading high means the operator hits the click later than they should, which means the screws received more torque than spec, not less. That is a meaningfully different failure mode than a wrench reading low.

Is over-torque on a screw a risk to the assembly?

This was where my Director of Quality and I started disagreeing, which is exactly what's supposed to happen. My read was that over-torque on this joint isn't a loosening risk. The screws are tighter than intended, not looser, and a tighter screw doesn't fall out.

Quality pushed back that you can over-torque a screw to the point of stripping the threads, at which point it doesn't matter how high the tool was reading because the screw isn't holding anything. Fair point, and one I had a counter for. A stripped screw doesn't torque. The wrench never reaches the click, the assembler notices the joint isn't behaving the way it usually does, and the unit gets flagged. Our senior techs didn't flag anything on those five builds. Quality still wasn't satisfied. Even short of stripping, sustained over-torque can fatigue a joint and let it back off in service. That one I didn't have a clean answer for.

Why a chemical thread-locker resolved the question

What got us unstuck was a detail neither of us had on the tip of our tongue. Our manufacturing engineer, who has been close to this project from the start, mentioned that the joint in question also gets Loctite. That changed the picture. The over-torque was bounded at 13% above spec, not double. The screws weren't stripped. And the chemical thread-locker provides retention that doesn't depend on preload at all. Between those three facts the joint is fine, the units are fine, and we can defend that conclusion with evidence instead of assumption.

What goes into a Non-Conforming Material Report (NCMR) for an out-of-cal tool?

The rest was process. We opened a non-conforming material report on the torque driver with the full timeline, the measurement data, the failure mode reasoning, and the conclusion about the clinical units. Then we told the client. They'll have questions, and they should, that's part of why they hired us, but the rationale holds together and the records are auditable.

The broader takeaway

I don't think we over-complicated it. The temptation in this kind of situation is to take the convenient explanation, write a short report, and move on, because the convenient explanation is probably right. You don't get credit for being right by accident in a regulated environment. You get credit for being able to show your work.

When Ops and Quality disagree, the disagreement is doing useful work, and you should let it run a little longer than feels comfortable before reaching for the answer. The other thing is that whoever is closest to the actual build usually knows something the people running the meeting don't. Neither I nor my Director of Quality remembered the Loctite. The engineer on the floor did, and that detail closed the case.

Written by Jordan, Director of Operations at Engineering CPR — a Toronto-based ISO 13485-certified medical device contract manufacturer specializing in high-mix, low-volume elect ro-mechanical assemblies, cleanroom manufacturing, and box builds.

How to Actually Break Into Medical Device Engineering

Tue, 28 Apr 2026 20:04:15 GMT

Why smaller service organizations beat the giants — and the gamble of an underfunded startup

You don't really need to chase certifications to break into medical devices. What you do need is to target the right companies.

A lot of people starting out think they need to apply to big names like Boston Scientific, Medtronic, or Siemens. Applying isn't a bad move — it can't hurt — but you have a high chance of being 1 of hundreds or thousands of applications that aren't shared across business units. Your resume stalls, and you end up continually re-applying to every new opening on a rolling basis.

And if you do get in, you will almost certainly limit your learning potential. You become one cog in a massive machine where you only do X, Y, or Z — but never all three.

What about startups?

Some people go the startup route instead, but there are two problems with that.

1. Most serious startups can't afford to hire new grads for development work.

Startups are cost-conscious and need their investment to deliver a definite return on a reliable timeline (i.e., they need you to design the prototype and get it working in three months). Serious founders who don't have the technical know-how themselves are pushed to hire people with very transferable experience designing a similar product before, or to hire a product development firm to do it for them. No matter how good your final-year design project was, you don't fit these criteria yet.

2. The startups that do hire new grads often can't mentor them properly.

Some startups hire new grads specifically to save money. If you end up at one of these, make sure you're supported by a technical supervisor. Without someone to mentor you, you'll pick up bad habits that you'll spend a career having to unlearn. The standards (ISO 13485, MDSAP, etc.), if read without any acceptance of gray space, can lead junior teams to spend too much time on the wrong problems — ultimately producing a design that is less safe than it ought to be. Senior engineers are absolutely necessary to guide you to do the right amount of work on the right things.

So how do you actually get started?

Apply to the smaller service organizations in your area that support medical device development and manufacturing.

Start in manufacturing or operations at one of these companies, prove your worth, and then move into development. Send your resume to their general inquiries email. If they're nearby, stop by in person and drop off a copy. These smaller organizations with manufacturing operations still operate the old-fashioned way — a visit can genuinely push your resume to the top of the pile.

They might not have something for you right now. But when they land a new client and scramble to hire, they'll call you.

Hope this helps.

How do I get a Prototype made in Canada?

Fri, 01 Sep 2023 16:53:38 GMT

How to make a Prototype?

If you are reading this you likely have a product idea in mind, maybe some sketches, drawings, or models. You now want to take the design work to the next step and create a prototype. The prototype can be used for many things, here are a few examples:

validating the product idea for yourself (i.e., testing if it works)
showing the product idea to potential investors (e.g., giving them something to hold during your investment pitch)
safety testing (e.g., electrical safety)
preproduction validation for regulatory submissions for Health Canada and the FDA (e.g., for medical devices)

How much does a Prototype cost?

Depending on the intended use of the prototype, the cost can vary dramatically. Prototypes can range from:

Craft-like (e.g., using pipe cleaners, cardboard, and hot glue)
Functional yet rough (e.g., using plywood and screws)
Non-functional but aesthetically representative of a finished product
Preproduction quality (functional and representative of a finished product)

They also vary widely depending on the type of product you are prototyping. For example, prototypes for electromechanical products are generally going to cost more than prototypes for purely mechanical products.

We suggest that before spending a lot of money and time on a prototype, you first perform your due diligence on your product idea. One of the most important due diligences you must perform is to confirm your idea does not infringe on anyone else’s patents. If it doesn’t, then you can continue your product strategy due diligence (market research, etc.) and then file a patent application.

How do I patent an idea in Canada?

There are two main patents we care about when it comes to product development:

Design Patents and Utility Patents .

Design Patents are useful in protecting your implementation of an object. Nike might have design patents that cover each one of their shoe designs, and so would Adidas. Usually, these patents have lots of diagrams describing the design aspects that are being patented. If another person copies this patent 90% and only differs from the design aspects specified in the patent, they would not be infringing on the patent. Therefore, design patents are easy to get around by just changing a few inconsequential design characteristics.

Utility Patents describe the function of a product. I.e., if someone has a utility patent for a shoe it might be described as “An object that wraps around a foot” If Nike has a patent for this – nobody else would be allowed to profit from such an object. It would be a very lucrative patent to have since it would be hard to design a shoe that doesn’t wrap around a foot.

For this reason, utility patents are usually much more valuable than design patents.

Keep these core concepts in mind when searching to see if your product idea is patent protected and when considering patenting your product ideas for yourself.

To learn more about patenting product ideas and searching for patents already issued, we suggest you consult “File a Canadian patent application: Before you start”

How do I create a product prototype?

You have identified that your product idea is new, not patented by someone else, and you have started down the path of patenting it for yourself. Now is the time to start making and testing more serious prototypes.

As described in the introduction, prototype development costs and effort can vary widely. Depending on the intended use of the prototype, you may be able to save a lot of money by doing it yourself with the materials you have around.

Once you start needing to produce prototypes for investors, preproduction validation, or safety testing, you’ll have to get some more rigorous design work in order.

Investor prototypes are usually geared toward showing that the product can work, and that the product can be pretty.

Oft en early on, you can show these two aspects using two different prototypes, a functional ugly prototype, and a non-functional pretty prototype .

Safety test and preproduction validation prototypes should be representative of what you are intending to sell.

To make these prototypes, you will need to create some design files:

CAD files – 3D part files for custom metal work and rapid prototyping of plastic parts.
Drawings – most metal shops will require drawings in addition to the CAD files, these drawings call out important dimensions, materials, coatings to use, and other part-specific requirements.
Gerbers – electronic circuit board files if you have a custom circuit board in your prototype.
Bill of Materials (BOMs) – If you want a manufacturer to build anything out of a bunch of items, you must provide a list of those items in a BOM. You may have many BOMs that describe how to make each one of your assemblies. E.g., one for your custom circuit boards, one for a mechanical sub-assembly, and another for the completed product.
Assembly and Test Instructions – If you want someone else to assemble and test your prototype or parts, you will need to communicate how to do so. Assembly and test instructions can be simple to start (a word document listing the steps) and become more detailed as you get closer to production .

Industrial Prototyping

Next, you will need industrial suppliers for the various parts of your prototype or a turnkey supplier that will make your whole prototype for you. You will send them your design files listed above and they will provide a quote to do the work. Some things to consider:

Building low quantities of parts often have a high unit cost. Prototype costs are therefore not a good indicator of production costs.

Depending on your application, it may be okay to just find anyone with a metal bender, rapid prototyping abilities, or a workshop to make your parts for you.

For higher-risk parts (electronics) or for medical device applications you should properly source reputable vendors. Common certifications to look for are ISO 9001 for general industrial prototyping and ISO 13485 for medical device prototyping.

When working with reputable suppliers, the “quality” of your parts will depend heavily on your part specifications. For example, if you want a supplier to take sharp edges off your parts, you must tell them to deburr the edges in your drawings. Do not leave anything up to assumptions.

Larger, more reputable suppliers don’t like making small quantities of parts for someone they don’t know. They are often interested in what is in it for them in the long run, so try to paint a picture of your intended production volumes for them. E.g., “we expect to make 100 per month once we get into production”.

If you are still not getting anywhere with part suppliers, they may be too big for you, or you may need to partner with a turnkey prototype manufacturer that will build the whole thing for you. Turnkey manufacturers already have relationships with part suppliers that they can leverage.

Your Next Steps

Now you’re ready to build your prototype and show how great your idea is! Whether you are designing and building by yourself or working with a Product Development company. The key steps you have just learned about can help you commercialize your product quickly and on budget.

Why a Use-Case Analysis should be your first step in identifying your product requirements

Tue, 30 Aug 2022 15:16:24 GMT

When considering product requirements, startup founders and investors will often consider the questions:

What features are essential,

what features are nice to have,

and what features are distractions?

You may have a good idea with a clear customer value, but if you implement the wrong features, your product could still flop. Understanding the Use-Cases in which your product will be used is the essential precursor to answering these formative questions above.

Use-Case Analyses are effective at identifying product requirements because they let you step into your customer's shoes. They allow you to experience the frustrations of your product firsthand before you even start designing it.

Doing a Use-Case Analysis early in product development will help you:

Develop a comprehensive product requirements list that considers your customer's needs
Focus your engineering talent on features/problems that matter
Go to market sooner by reducing late-stage redesign

What is a Use-Case Analysis?

A Use-Case Analysis is a three-part activity.

First , you identify how a user interacts with your future product or existing products on the market. These user interactions are called Use-Cases.

Second , you analyze the Use-Cases for complexity.

E.g., Are there any unnecessarily tricky steps? Are there too many steps? Or does the user have to make difficult or unnecessary decisions?

Lastly , you eliminate the complexity from your Use-Cases wherever possible and important.

Eliminating complexity will improve your customer experience by saving them time and headaches; and helping them avoid use errors.

Always consider the three main aspects of Human Factor Design: the Users, the User Interface, and the Use Environments, when determining the importance of removing a step/decision.

What are some successful Products that have employed a Use-Case Analysis?

The products in the examples below have distinguished themselves by removing steps or decisions customers would otherwise have made.

They were successful in removing the right steps because they considered the three main aspects of Human Factors Design:

the Users,
the User Interface,
and the Use Environments.

1. Gmail Smart Compose

In 2018, Gmail launched a new feature so Users can write emails faster.

Gmail now performs the first step of entering a recipient's name (e.g., "Hi Jacqueline") and will also propose phrases matching your typical structure and tone.

While typing “Hi Jacqueline” takes seconds, this feature saves Gmail users more than a few simple keystrokes. It allows users to jump quickly into the meat of their email—no more moments of hesitation or pleasantry considerations.

Image: Google

This example shows the importance of considering the User when doing a Use-Case Analysis. In this example, the critical User characteristic is their mental state of being in a hurry . This mental state may feel like a universal User condition, but depending on your product, it may differ. If Google were making software for writing personal journal entries for self-reflection, this feature would likely be more annoying than helpful. In that scenario, the User’s mental state would be very different.

By considering the Use-Case and the User, Google honed its Machine Learning tech on a problem that matters to its Users: writing emails quickly.

2. Breville "A Bit More" Toaster

In 2017, Breville unveiled a toaster with a new feature, the "A Bit More" button.

Image: Breville

The button aimed to fix the problem that we all know too well:

You put bread in the toaster.
It comes up too light.
You put your toast back down, intending to stop the toaster shortly.
You forget.
Your toast is burnt.

Breville solved the Burnt Toast problem by analyzing this Use-Case and considering their User Interface's limitations. They added an "A Bit More" button to remove the impact of User forgetfulness. This User-Interface addition changed the Use-Case to:

You put bread in the toaster.
It comes up too light.
You press the "A Bit More" button.
Your toast is perfectly cooked.

Breville's solution to an age-old problem did not require significant technological advancements or a genius designer. All it needed was a comprehensive Use-Case Analysis with particular attention to the User Interface to identify the problem that needed solving. Once we know the problem, fixing it is rarely all that difficult. Sometimes it is as simple as adding a button.

Once we know the problem,

fixing it is rarely all that difficult.

Sometimes it is as simple as adding a button.

P.S. The Atlantic thought this product was worth a full write-up: Why a Toaster Is a Design Triumph

3. Japanese Ketchup & Mustard packet

Japan, the country that brought us The Toyota Way, brings another leap forward: single-hand operated Ketchup and Mustard packets.

You may be familiar with the problem; you have a hotdog in one hand and your sealed ketchup and mustard packets in the other. How do you open the packets?

Some use their teeth; others try to use a few fingers from their hotdog hand; others search for a clean resting spot for their hotdog.

Each option presents risks, whether to the hotdog or our clothing.

7-11s in Japan have dealt with this problem by creating a ketchup and mustard packet that can be opened and dispensed with one hand.

Image: Imgur

This example shows the importance of considering the Use Environment alongside the Use-Case. By recognizing that a clean, sturdy surface isn’t always around when dressing your hot dog, these designers could identify the problem to be solved; single-hand condiment dispensing.

With this problem definition, they could develop a novel, low-tech solution.

Conclusion

As you can see, a Use-Case Analysis is an effective means of turning your product idea into a product that truly stands out.

By considering the User, the User Interface, and the Use Environments alongside your Use-Case, you can quickly identify the critical problems to be solved for your customers.

Once you do that, it is simple to create thoughtful and unique features that fulfill your customer's needs before they even know it is something they need.

How to perform a Use-Case Analysis?

So now that you have a bit of an idea of how a Use-Case Analysis can help take your product from average to extraordinary, you probably want to try it yourself.

If you would like a Use-Case Template, sign up below , and we'll send you ours, along with some explanations and examples on how to use it.

By joining our community, you will also gain access to periodic deep dives like this one, plus other content.

4 Questions To Ask Before Choosing A Part Numbering System

Tue, 09 Aug 2022 20:34:27 GMT

Considerations for a great Part Numbering System

Hey, Congrats! You've got an idea for a product and maybe some design files, neatly organized (or not), and you feel it's time for part numbering.

But what part numbers (P/Ns) should you pick?

It seems simple enough, but here are some of the less obvious things you should consider now to avoid headaches later:

1. Do you want to assign classes to your Part Numbers?

Sometimes companies will create part numbering classes. I.e., if your base P/N is four digits long (YYYY), you may add a few digits as a prefix (XX) to categorize the parts.

An example of categorizing parts based on type:

Cables begin with 10; Custom metal parts begin with 20; packaging begins with 30, and so on.

P/Ns in this system might look like XX-YYYY (e.g., 10-YYYY, 20- YYYY, 30- YYYY)

Benefits:

Quickly identify what you are looking at from the P/N prefix
Improve ability to recall or find a part by filtering for the prefix

Drawbacks:

Defining the classification criteria becomes a question in itself
Adherence to the classes may be a challenge when new designers join the development team
Overlapping classes of parts can cause confusion
Multiple different P/N tracking logs might be necessary to track each class
MRP/ERP systems might not be able to give you the next P/N for a given class easily

If you plan on using a class-style Part Numbering system, we suggest you:

Take the time to define your classes well
Ensure there is minimal overlap between classes
Generate some guideline documentation to help explain the classification criteria to new staff
Create an easy way (log or otherwise) to assign new part numbers for each class

2. Do you want an Alpha, Alpha-Numeric, or a Numeric Part Numbering system?

For this, I will define Alpha as A-Z (case insensitive) and Numeric as (0-9).

Alpha or Alpha-Numeric Systems:

Benefits:

With fewer digits, you get more P/Ns (e.g., three alpha-numeric digits will get you 46,656 P/Ns, vs. three numeric digits will only get you 999 P/Ns)

Drawbacks:

Characters can get confused ("O" and "0", "I" and "1", etc.)
Some people may use lowercase vs. uppercase digits
The next available P/N is not always straightforward (e.g., if you are at A39 in alpha-numeric, then your next number is likely A3A)
MRP/ERP systems might not be able to give you the next P/N easily
Blocking P/Ns for a specific designer or group may get confusing:

e.g., Imagine telling someone:

"Ok, design me this widget; you can use this block of P/Ns A39 to AF9".

If I were that designer, I would be unable to quickly tell how many P/Ns I have, nor how to increment them.

Numeric Systems:

Benefits:

The next available P/N is clear as day (this benefit is not to be understated)
MRP/ERP systems can easily give you the next available P/N
No confounding characters
No lowercase/uppercase issues
Easily to block P/Ns for designers

Drawbacks:

Less P/N permutations are available

3. What happens to a Part Number when you update the part?

Consider a Part Numbering system wherein the base format is four digits (YYYY).

Now imagine you have a released cable of P/N 1638, and the next part number available in your system is P/N 2394. If you change the cable (P/N 1683) and your Part Number Change Rules* dictate that the P/N should change, you might end up with the cable changing to P/N 2394.

This P/N jump is fine, but it can become a headache for design and operations staff who grow accustomed to the specific numbers they deal with daily. Also, if you ever want to see the old drawing for this cable, you might have to do a lot of digging before finding out that P/N 1638 was the last design iteration of P/N 2394.

One way to get around this issue is to add a suffix to all your P/Ns (YYYY-ZZ).

E.g., rather than changing P/Ns from 1638 to 2394, you would change from P/N 1638 to P/N 1638-01. Or rather, if you started with the suffix, P/N 1638-00 would change to P/N 1638-01.

Important Distinction:

This suffix is not to be confused with revisions.

The P/Ns 1638-00 and 1638-01 are as different as P/Ns 1638 and 2394.

This suffix system just helps us mortals navigate our way around part folders and specs by providing a bit of continuity between updated part numbers.

Further Work Instruction Benefit:

The other added benefit of having P/Ns change like this is that you can write your Work Instructions to reference parts like this:

"Connect cable 1638-xx to the flux capacitor."

And let the BOM for the work order tell the assembler the specific cable to use (1638-01, 1638-02, etc.).

This suffix system lets you change the cable P/N without needing to respin your Work instructions.

*Part Number Change Rules to be discussed in a subsequent blog post.

4. What Part Numbers do we use at Engineering CPR ?

Since we are a contract manufacturer, we have used various Part Numbering Systems set out by our customers.

None are objectively good or bad; however, each does need different maintenance levels to make them sing. You can make most systems work as long as you develop and follow a process to mitigate any drawbacks of the Part Numbering System you choose.

If you're interested in knowing exactly how we do our Part Numbers and some more lessons-learned,

we invite you to join our Keener community, and we'll send you a breakdown!

By joining our community, you will also gain access to periodic deep dives like this one, plus other content.

mysite167

What to do when a torque driver fails calibration after use on a clinical build

Did the drop cause the calibration failure, or did the tool drift earlier?

How do you check a torque wrench when your checker doesn't reach the working range?

Is over-torque on a screw a risk to the assembly?

Why a chemical thread-locker resolved the question

What goes into a Non-Conforming Material Report (NCMR) for an out-of-cal tool?

The broader takeaway

How to Actually Break Into Medical Device Engineering

Why smaller service organizations beat the giants — and the gamble of an underfunded startup

What about startups?

So how do you actually get started?

How do I get a Prototype made in Canada?

How to make a Prototype?

How much does a Prototype cost?

How do I patent an idea in Canada?

How do I create a product prototype?

Industrial Prototyping

Your Next Steps

Why a Use-Case Analysis should be your first step in identifying your product requirements

What is a Use-Case Analysis?

What are some successful Products that have employed a Use-Case Analysis?

﻿ Conclusion

How to perform a Use-Case Analysis?

4 Questions To Ask Before Choosing A Part Numbering System

Considerations for a great Part Numbering System

1. Do you want to assign classes to your Part Numbers?

An example of categorizing parts based on type:

Benefits:

Drawbacks:

If you plan on using a class-style Part Numbering system, we suggest you:

Alpha or Alpha-Numeric Systems:

Benefits:

Drawbacks:

Numeric Systems:

Benefits:

Drawbacks:

3. What happens to a Part Number when you update the part?

Important Distinction:

Further Work Instruction Benefit:

4. What Part Numbers do we use at Engineering CPR ?

Conclusion