[ Services · Mechanical engineering ]
Mechanical engineering
for hardware products.
From the architecture to the drawings and parts list a factory builds from.
Our mechanical engineers decide how your product holds together, moves, carries its loads and goes through the factory. They place every part in the architecture, model each one in 3D CAD, prove the critical ones by calculation or finite element analysis, set the tolerances where parts meet, then release the drawings and the bill of materials a workshop or a factory builds from.
Since 2017: 150+ projects and 50+ products shipped. The practice started on aerospace and heavy vehicle programs.
What does it have to do?
Tick everything it must do. The page below becomes your engineering plan.
Your plan, below: a product that moves and holds what is inside. Six phases, most of them inside about 16 weeks of development.Read it ↓
[ Your plan ]
What does your
engineering plan cover?
Your engineering plan turns each thing your product has to do into a requirement in numbers, the engineering that meets it and a project where we did it. For a product that moves and holds what is inside, it starts from the requirements marked below; the others stay one click away.
A good brief turns wishes into numbers a designer and an engineer can work to: "light enough to carry up the stairs" becomes a weight, "affordable" becomes a retail price and a cost per unit the factory has to meet. Engineering then proves each number, phase by phase, and each phase ends with a decision point where you approve the result.
- R1
It has to move
A mechanism, a hinge, a driveIn the briefThe travel, the force and how often it moves, written as numbers before anything is drawn.
We engineerThe mechanism laid out and drawn through its whole travel, its actuator or drive sized, a fit chosen at every pivot.
As on PhotonixOne button sets a cutting height of 0.5 to 3 inches, through a servo, a turnbuckle and two axle arms. The case study →
- R2
It has to carry a load
A frame, a chassis, a structureIn the briefThe loads it must carry, where they enter, and how much the product may weigh.
We engineerThe load paths and the structure, a material chosen for each part, the critical parts proven by calculation or FEA.
As on eXalt SOLOSized before any surface was drawn, then built on a chromoly spaceframe, an aluminum spar and carbon caissons. The case study →
- R3
It has to go together
Assembled in a factory, or by its ownerIn the briefWho assembles it, with which tools, in what order, and how it opens for service.
We engineerModules and their interfaces, ordinary fasteners, the assembly sequence, and the tolerances where parts meet.
As on eXalt SOLOModules that bolt together: 40 hours to full assembly, no specialized tools. The case study →
- R4
It has to hold what is inside
Boards, a battery, water, airIn the briefWhat goes inside, how it is reached for service, the heat it gives off, the water or air that moves through it.
We engineerThe architecture in section, walls, ribs, bosses and snap fits, the way in for service, each part shaped for molding.
As on MangoA sealed tub of two shells, the O-ring pinched flat in a groove of its rim, and three membranes whose forces cancel at 120 degrees. The case study →
- R5
It has to come in versions
Sizes, models, configurationsIn the briefWhich sizes or configurations it comes in, and what every one of them shares.
We engineerOne architecture with shared parts, standard drawings and one numbering scheme, so each version is a variant, not a new project.
As on HiRailOne drawing set per truck, four log loader configurations, weight and balance checked for each. The case study →
[ TIME AND COST ]
How long does it take,
and what does it cost?
Mechanical engineering for a molded consumer product takes about 16 weeks of development, at $5,000 to $25,000 as an order of magnitude, then continues through prototyping, about 16 weeks at $7,500 to $30,000 with our workshops. It joins earlier, in the brief and the concept, and finishes with the DFM pass before production.
Orders of magnitude, not a quote: you get a fixed price once the brief is written.
A water bottle and a jet ski are not the same project. From one product to another, the effort can range from one to fifty times.
The DFM pass and detail design before production, and a small batch of 10 to 200 cast units, are quoted per project. Production molds are paid to the factory, separately.
Proof of concept, when the product needs it. Some products depend on something not done in that form before: a new mechanism, a sensor in an unusual place, heat in a small volume. That one function is tested on its own, scoped with development, before the final design is engineered around it.
The seven steps from idea to launch, each one timed and priced, in our guide ↗
What moves the budget
- Number of parts
Each part is designed, drawn, prototyped and later tooled.
- Electronics and a battery
A board, firmware and heat to manage add a discipline to every step.
- Certification
FCC, CE or UL testing adds preparation, samples and lab time.
[ WHAT YOU GET ]
What does each phase
of engineering deliver?
Each phase of mechanical engineering delivers something you can check: an architecture, the 3D CAD of every part, mechanisms proven through their travel, the analysis of the parts that carry loads, a tolerance study, then the drawings and the bill of materials. Each phase ends with a decision point, where you approve the result before the next one starts.
Most of this work sits inside development, about 16 weeks on a molded consumer product, and carries on through the prototypes, whose tests send changes back to the CAD. The architecture often starts earlier, during the concept, because the shape has to hold what goes inside.
The drawing follows one real mechanism through the six phases: the cutting-height adjustment of the Photonix solar mower, traced from our prototype CAD. One button on the handlebar drives a servo; a 60 mm arm and a 70 mm turnbuckle swing the front axle arm on its pivot, so the wheel moves on a 38 mm arc and the deck rises or settles with the blade. Beside each phase, what it means for a product that moves and holds what is inside.
Starts with the conceptDecides yours
Product architecture
Every major part placed in 3D before any of them is detailed: the volumes, the loads, the way in for service.
The architecture decides where everything goes and how the product holds together: walls, ribs, screw bosses and snap fits, how it opens for service, how heat leaves it. For Photonix, an integration model placed the shell, the wheels, the drive and blade motors, the blade, the battery rack and the fertilizer tank in CAD, and a 12-page architecture study set it out before the body was drawn around it. KORU was drawn whole in section first: the root cavity, the fan and filter stack, the reservoirs in the base, a slot between shell and base for the air.
For a product that movesThe architecture leaves room for the whole travel of the mechanism, not only its rest position.
For a product that carries a loadIt decides where the loads enter and which parts take them to the ground.
For a product that goes togetherIt splits the product into modules whose joints can be made with ordinary tools, as on the eXalt SOLO.
For a product that holds what is insideIt is drawn in section first, as KORU was: what sits where, and how air, water or heat moves through the body.
For a product that comes in versionsIt separates what every version shares from what changes, as Glow's frame, door and benches stayed while the width went from 1300 to 2500 mm.
You getAn architecture: the main components placed in 3D, the modules and how they join.
Development · About 16 weeks in all
3D CAD of every part
Each part modeled in 3D, in its material, and assembled with the others in one model.
Every part is drawn in its material and joined to its neighbors in one assembly, so a part that does not fit shows up on screen, not in the workshop. The eXalt SOLO sits in one digital mock-up, from the chromoly spaceframe and the aluminum central spar to the six carbon caissons of each wing, where the interfaces between modules were worked out together rather than part by part. On Photonix we laid out the chassis part by part, down to the servo, its mount and the horn that set the cutting height.
For a product that movesMoving parts are modeled with their pivots and stops, so the motion can be checked in the same model.
For a product that carries a loadEach part is modeled in the material that carries its load, so the analysis runs on the real geometry.
For a product that goes togetherInterfaces are modeled on both sides at once, as the eXalt modules were, in one mock-up.
For a product that holds what is insideWhat goes inside is modeled too, so the enclosure is drawn around it, as KORU's shell was merged with the client's own parts in one systems CAD.
For a product that comes in versionsEach version is assembled from the same set of models, as each HiRail truck was, instead of being drawn again.
You getThe 3D CAD model of every part and of the assembly, with the material of each part.
DevelopmentDecides yours
Mechanisms and motion
Every moving part checked through its whole travel in the model, before anything is cut.
A mechanism is drawn at both ends of its travel and everywhere between, so nothing binds, collides or runs out of reach. On Photonix one button on the handlebar sets a cutting height of 0.5 to 3 inches. A servo turns a 60 mm arm; a 70 mm turnbuckle swings the front axle arm on its pivot, and the wheel moves on a 38 mm arc. The rear axle follows in a curved slot, on an arm of the same radius and its own servo, so the deck rises or settles parallel to the lawn. The front arm also carries the drive motor, which keeps its gears in mesh at every height.
For a product that movesThis is the phase that decides your product: the mechanism drawn at both ends of its travel and at every point between.
For a product that goes togetherParts that go in one after another are moved into place in the model, to check there is room for the hand and the tool.
For a product that holds what is insideDoors, lids and covers are opened in the model, so the way in for service is checked before anything is molded.
You getMechanisms checked through their travel: positions, clearances and the motion of each moving part.
Development
Loads and analysis (FEA)
The loads followed from where they enter to the parts that carry them, and the critical parts proven by calculation or FEA.
Every load enters somewhere and has to reach the ground through a chain of parts; the weakest link sets the design. Finite element analysis (FEA) splits a part into small elements in software and computes its stress and deflection under the loads you give it, before the part is made. We run it, static, dynamic, thermal or fatigue as the part needs, on the parts that carry the loads that matter. The eXalt SOLO was sized before any surface was drawn, wing loading setting its take-off weight and wing area. Each HiRail configuration went out with its weight distribution analysis, so its weight and balance were known before the truck was built.
For a product that movesThe forces in the mechanism size its actuator and its pivots: the servo, motor or spring has to win at every position of the travel.
For a product that carries a loadThis is the phase that decides your product: the load cases written down, and the parts that carry them proven by calculation or FEA.
For a product that holds what is insideHeat is a load too: where it is made, and how it leaves the enclosure.
For a product that comes in versionsEach configuration has its own weights, so its balance is checked on its own, as each HiRail truck's was.
You getThe load cases, the calculations or FEA that prove the critical parts, and the changes they call for.
Development
Tolerances, fits and GD&T
How much each dimension may vary, set where parts meet, so the product works with real parts, not perfect ones.
A tolerance is the amount a dimension may vary and the part still work. Where parts meet, the variations add up along the chain, and a tolerance stack-up checks that the worst case still assembles and works. GD&T, geometric dimensioning and tolerancing, puts it on the drawing: the symbols that control form, orientation and position, not only size. On Photonix, the gears stay in mesh because the drive motor rides on the axle arm: the distance between the gears is held by one part. On the eXalt SOLO, three materials meant three processes and three sets of tolerances meeting at the same joints.
For a product that movesPivots, slots and gear meshes get the fits that let them move freely without play.
For a product that goes togetherThis is the phase that decides your product: the joints where modules meet carry the stack-ups that let it go together every time.
For a product that holds what is insideThe seams between shell parts get the tolerances that keep them closed and even.
You getA tolerance study of the critical chains, and the fits and GD&T that go on the drawings.
Development, then before the factory
DFM, drawings and BOM
Each part shaped for the process that makes it, then the drawings and the bill of materials a workshop or a factory builds from.
Design for manufacturing (DFM) shapes each part for the process that will make it: draft so it leaves the mold, even walls so it does not warp, fewer parts and screws so it assembles fast. The Photonix chassis was cut on a CNC, light and made in small runs, because the prototype had to exist and be filmed before anyone ordered one; its choices went into a first prototype bill of materials in December 2021. KORU's prototype files left on 23 December 2020, every part in CAD and STEP with the assembly, followed by its bill of materials; its casing was developed for injection molding, with parting lines, assembly points and fastenings defined.
For a product that movesBought parts, such as the servo, go into the bill of materials beside the parts that are made.
For a product that carries a loadThe material and the process are named on each drawing, so the part that is made is the part that was analyzed.
For a product that goes togetherThe assembly sequence goes onto the drawings and, on HiRail, into an assembly manual and inspection plans.
For a product that holds what is insideMolded parts get their draft, parting lines and even walls here, and undercuts, recesses that would lock a part in its mold, are removed, as on KORU.
For a product that comes in versionsThis is the phase that decides your product: one drawing set and one numbering scheme for every version, as on HiRail.
You getDrawings, a bill of materials, STEP and native CAD; before production, the DFM pass a factory can quote from.
01/Where each part lives
Front axle module of the Photonix prototype, traced from our CAD as published in the case study. The load path and the fits drawn on it show the principle, not a computed result.
[ THE SHORT ANSWER ]
What is
mechanical engineering?
Mechanical engineering decides how a physical product works inside: how it holds together, how its mechanisms move, how it carries its loads and lets its heat out, which material each part is made of, and how every part is made and assembled. It turns a concept into parts a factory can build.
At ONMOTIO it starts with the architecture, often during the concept, and runs through development: every part modeled in 3D CAD, the mechanisms checked through their travel, the loads followed to the parts that carry them, the tolerances set where parts meet. It ends with the drawings, the bill of materials and the files a workshop or a factory quotes from.
Our engineers work on the same 3D model as our industrial designers, from the first week. The engineering serves the design: the form a product was imagined with is kept, and made to work, hold up and go through the factory. Industrial design decides what you see and touch; mechanical engineering decides what holds it up.
Since 2017 that work adds up to 150+ projects and 50+ products shipped. The steps around it, from the brief to the launch, are laid out in our guide, how to develop a physical product.
[ THE RIGHT STEP ]
When is mechanical engineering
the right next step?
Mechanical engineering is the right next step when your product has a form or a sketch and now has to hold together, move, carry its loads and be made, or when a prototype that works on the bench has to become parts a factory can build. When something else has to be settled first, start there.
Start with mechanical engineering when
- The form is set or sketched, and the product now has to hold together, move and be made.
- Your prototype works on the bench and has to become parts a workshop or a factory can make.
- A mechanism or a structure carries the product, and it has to be proven before money goes into tooling.
- You build the same product in several sizes or configurations, and each one is engineered from scratch.
- You need drawings, a bill of materials and a release a factory can quote from.
Start with another service when
- The product has no form yet, and its appearance is what will sell it.
Industrial Design → - The open question is the circuit board, the firmware or the radio.
Electronics & Firmware → - One function has to be proven to work before anything is engineered around it.
Which prototype do you need first? → - You are still deciding what to build, for whom and at what price.
Product Strategy →
[ WHAT IT COVERS ]
What does our mechanical
engineering cover?
Our mechanical engineering services cover product architecture, 3D CAD and assemblies, mechanisms, structure and FEA, weight and balance, tolerances and GD&T, DFM and assembly, drawings and bills of materials, hydraulic and electrical routing, and product platforms. Each skill says what it decides and links to a project where you can see it. The ones that weigh most for a product that moves and holds what is inside come first.
01Product architecture
Key for yours
Where every major part sits, how the modules join, how the product opens for service and how its heat leaves. It is decided first, because every later part has to fit inside it.
Photonix: a 12-page architecture study before the body →03Mechanisms and kinematics
Key for yours
Hinges, linkages, drives and adjustments, drawn through their whole travel and sized for the force and the motion they have to give.
Photonix: one button sets the cutting height on two axles →06Tolerances, fits and GD&T
Key for yours
How much each dimension may vary, chosen where parts meet and checked along the chain, then written on the drawings in GD&T so a workshop can make and inspect them.
eXalt SOLO: three materials meeting at the same joints →07DFM and design for assembly
Key for yours
Each part shaped for the process that makes it, injection molding, CNC machining or casting, and the assembly kept to ordinary tools and as few steps as the product allows.
eXalt SOLO: a kit that bolts together in 40 hours →023D CAD and assemblies
Every part modeled in its material and assembled with its neighbors in one model, so interfaces are worked out together and a part that does not fit shows up on screen.
eXalt SOLO: every assembly in one digital mock-up →04Structure, load paths and FEA
Frames, chassis and housings that carry their loads, followed from where each load enters to where it leaves, with finite element analysis on the parts that matter.
eXalt SOLO: chromoly spaceframe, aluminum spar, carbon caissons →05Weight and balance
The mass of every part added up and the center of gravity placed, loaded and empty, so a vehicle or a machine stays stable in every configuration it is sold in.
HiRail: weight distribution for each truck configuration →08Drawings, BOM and release
Drawings a workshop can build from, a bill of materials, the bill of every part and component of one unit, and one numbering scheme with a release workflow, so the right revision reaches the right hands.
HiRail: one numbering scheme and a release workflow →09Hydraulic and electrical routing
Lines, hoses and harnesses routed in the 3D model with everything else, so they fit, reach each function and can be serviced, then drawn as schematics for the workshop.
HiRail: every hydraulic line routed in 3D →10Product platforms and configurations
One architecture built to produce many products: shared parts, standard drawings and rules, so each new size or configuration is a variant, not a new project.
Glow Saunas: one frame, door and bench layout across four widths →[ THE WORK ]
Which products
have we engineered?
Our mechanical engineering is behind the eXalt SOLO light aircraft, the Photonix solar mower, the HiRail road and rail trucks, KORU ONE, an air purifier and planter, and Mango, our own floating speaker. Each case study shows the architecture, the decisions and where the product went.
Light sport aircraft, sold as a kit
eXalt SOLO
A single-seat aircraft split into modules that bolt together: a chromoly spaceframe, a carry-through and an aluminum central spar, six carbon caissons per wing, the empennages, the gear and the engine mount, all worked out together in one digital mock-up. The difficult work moves back to the factory, and the builder joins finished assemblies with ordinary tools.
40 hours to full assembly, no specialized tools. About US$1.2M in government funding secured.
Read the case study
Solar-powered mowerClosest
Photonix
An architecture study, then the chassis laid out part by part, the cutting height set by one button through a servo, a turnbuckle and two axle arms, and a chassis cut on a CNC.
A working prototype, tested on real grass for traction, blade performance and efficiency.
Floating 360 degree Bluetooth speaker, our own brandClosest
Mango
A sealed tub of two shells, the O-ring pinched flat in a groove of the rim and an ePTFE vent, three coaxial modules at 120 degrees whose forces cancel, so it does not walk on a table or drift on water, all in a STEP CAD written in code, v01 to v14.
About 600 g, it floats with almost half of it above the water.
Road and rail maintenance trucks
HiRail
A configuration system for every chassis: one drawing set per truck, a numbering scheme and release workflow, weight distribution per configuration, hydraulics and wiring routed in 3D, then the assembly manual and a day of training.
Weight and balance validated for each configuration, and the process handed over to HiRail's own team.
Air purifier and self-watering planter
KORU ONE
Two machines in one body, drawn in section first, merged with the client's parts in one systems CAD, then the prototype files and bill of materials, and a casing developed for injection molding.
Funded at over 1000% of its goal on Indiegogo, raising $110,000+, then sold for four years.
[ WHY ONMOTIO ]
Why work with ONMOTIO
on mechanical engineering?
ONMOTIO puts mechanical engineers and industrial designers on one model, comes from aerospace and heavy vehicle programs, and builds and tests prototypes in its own workshops. Since 2017: 150+ projects delivered and 50+ products shipped.
Eduardo Leardini, our head of product development, leads engineering execution, with over ten years of R&D in aerospace design, structural testing and prototyping. Our two co-founders, Izek Therrien and Clément Simon, come from aerospace, automotive, rail and composites. About us →
Engineers and designers on one model
Three engineering and prototyping specialists work beside three industrial designers, on the same 3D model from the first week. The engineering serves the design: the form is kept, and made to work.
Roots in aerospace and heavy vehicles
The practice started in Canada, on aerospace and heavy vehicle programs: a kit aircraft that bolts together, trucks that run on road and rail. The same discipline goes into a mower or a planter.
Built and tested in our own workshops
Besides the studio, we run two workshops of our own, in Brazil and in North America, where prototypes are built and tested. A part that rubs costs a revision there, not a mold.
Files your team can run with
Drawings, a bill of materials, a numbering scheme and, when it helps, the manuals and the training. On HiRail the process was handed over so the capability stayed inside the company.
What it buys is a twentieth conversion as good as the first.
[ Questions ]
Questions founders ask
about mechanical engineering.
Ordered for your plan: the 4 marked first are the closest to a product that moves and holds what is inside. Open a question to read its answer; something else? Ask us on a call.
What is a tolerance stack-up, and what is GD&T?For your plan
A tolerance is the amount a dimension may vary and the part still work. A tolerance stack-up adds those variations along a chain of parts to check that the worst case still assembles and works. GD&T, geometric dimensioning and tolerancing, writes it on the drawing with symbols that control form, orientation and position, not only size.
How long does mechanical engineering take?For your plan
For a molded consumer product, mechanical engineering takes about 16 weeks of development, then continues through about 16 weeks of prototyping, as the tests send changes back to the CAD. It joins earlier, in the brief and the concept. A simple accessory takes less; a product with many parts, electronics or certification takes more.
What is DFM, and when does it happen?For your plan
Design for manufacturing (DFM) shapes each part for the process that will make it: draft so it leaves the mold, even walls so it does not warp, fewer parts and screws so it assembles fast. It starts in development, where it costs least, and is finished in a DFM pass before production, once the works-like prototype is settled. Injection molding optimization for startups →
What is the difference between industrial design and mechanical engineering?For your plan
Industrial design decides what the product looks like, how it feels and how its visible parts are shaped. Mechanical engineering decides how it works inside: structure, mechanisms, tolerances, heat and how each part is made. At ONMOTIO both work on the same 3D CAD model from the first week, so neither hands the other a surprise. Industrial design →
What does a mechanical engineer do on a product?
A mechanical engineer decides how a product holds together, moves, carries its loads and is made: the architecture, the 3D CAD of every part, the mechanisms, the analysis of the parts that carry loads, the tolerances, then the drawings and bill of materials. At ONMOTIO that work runs on the same model as the industrial design.
How much does mechanical engineering cost?
As orders of magnitude for a molded consumer product, development costs $5,000 to $25,000 and prototyping $7,500 to $30,000, both shared with industrial design and our workshops. The effort can vary fifty times from one product to another, so we give a fixed price once the brief is written. Production molds are paid to the factory, separately.
What is FEA, and does my product need it?
Finite element analysis (FEA) splits a part into small elements in software and computes its stress and deflection under the loads you give it, before the part is made. A product needs it where a part carries a load that matters, a frame, a hinge, a mount, and a failure would be costly. Simple parts are checked by calculation instead.
What do I receive at the end?
You receive the 3D CAD of every part and of the assembly, as STEP files and native CAD, the drawings, the bill of materials, the analysis and tolerance studies of the critical parts, and the test results of the prototypes. Before production, the DFM pass gives a factory what it needs to quote and cut the molds.
Can you engineer from our existing prototype, sketches or CAD?
Yes. Many projects start from a sketch, a working prototype or CAD that has to become parts a factory can make. We work from what you have, alongside your engineers, your factory or both, and deliver STEP files or the native format your team uses. A prototype that already proves the principle can skip the proof of concept.
Can you work with our factory?
Yes. We work with your own manufacturer, or help you find one, in North America, Europe or Asia. Factories quote best once the works-like prototype is settled and the DFM pass is done; before that, every revision changes the quote. On Glow Saunas, the manufacturers worked directly from our 3D models.
Who owns the engineering, and will you sign an NDA?
You do: under our standard contract, the intellectual property is transferred to you once all invoices are paid, and we sign an NDA from the first exchange if you want one. If you plan a patent, speak with a patent attorney before you show the product in public, a crowdfunding page included.
[ NEXT STEP ]
Have a product
to engineer?
Send us what you have: a sketch, CAD, a prototype that works on the bench. A first call takes thirty minutes and costs nothing. You leave it with a view on feasibility, a rough order of cost and the next steps worth taking.