Mechanical/Mechatronics Engineer – Tablet Grinder & Dryer Feasibility

I am looking for an experienced Mechanical / Mechatronics / Product Development Engineer to perform an independent engineering feasibility audit of a compact device that combines controlled low-temperature drying and subsequent fine grinding of tablets or similar safe test materials.

This is not simply a CAD, rendering, or industrial-design project.

I already have several preliminary concept designs, but I do not want an engineer to simply convert them into CAD or confirm that they “look possible.”

I need someone who can critically evaluate the physics, mechanics, airflow, heating, grinding, powder handling, cleanability, safety, manufacturability, and cost.

If my current concept is too complicated, expensive, unreliable, difficult to clean, or mechanically incorrect, I want you to say so clearly and propose a better solution.

If one of my existing concepts is already the best option, that is also acceptable — please explain why.

Basic Intended Workflow

The device should approximately work as follows:

load tablets → controlled drying → cooling → grinding → direct downward powder discharge

Drying and grinding must happen sequentially, not simultaneously.

The device should ideally be compact and hand-held, somewhat similar in use to a large electric spice grinder.

The powder should fall directly onto an ordinary flat plate, laboratory tray, glass surface, or another clean flat surface. A proprietary receiving cup should not be mandatory.

The product-contact path should retain as little powder as possible and should be removable, washable, visually inspectable, and easy to clean.

Existing Mechanical Concepts

I currently want to compare at least three architectures:

A — Separate drying cassette + burr grinder

Material is dried in a removable cassette and then transferred into a compact burr-grinding mechanism.

B — One cassette with rotor + classification screen

The same cassette is used for drying and later grinding. A rotor breaks and moves the material across a screen, while acceptable powder falls directly downward.

C — Engineer’s own alternative

If both concepts are unnecessarily complicated or mechanically weak, propose a simpler architecture from first principles.

Possible alternatives may include a miniature cone mill, rotor-impact mechanism, friction grinder, burr system, or another compact solution.

I specifically want these alternatives compared rather than selecting one without analysis.

Main Engineering Questions

The audit should determine:

* Is controlled drying at approximately 30–40°C practical for such a small load?
* Can low-cost temperature/humidity sensors meaningfully detect the drying endpoint?
* What airflow direction, airflow rate, blower pressure, and heater power are required?
* Could small fragments be carried away by the airflow?
* Will fine meshes/screens create excessive airflow resistance or clogging?
* Which grinding mechanism is best for approximately 1–15 tablets?
* Can the same mechanism grind both one tablet and a larger load reliably?
* What motor speed, torque, gearbox, and power are required?
* What screen size is practical?
* What particle-size distribution is realistically achievable?
* How can large unground fragments be prevented from exiting?
* Where will powder remain inside the mechanism?
* Can hidden powder retention around shafts, bearings, screens, or joints be minimized?
* How should the motor and bearings be isolated from the powder path?
* Can all product-contact parts be removed and cleaned without tools?
* How can powder scatter and dust be minimized during direct discharge onto a plate?
* Is a soft silicone outlet skirt useful?
* Can one motor perform multiple functions, or would this make the system more complicated and expensive?
* Which sensors, actuators, or mechanisms can be eliminated?
* Which standard mass-produced components can replace custom parts?
* How can the BOM and manufacturing cost be reduced?

Cost Reduction Is Important

Please treat value engineering / cost reduction as a major part of the project.

For expensive components or subsystems, please identify:

1. What function the component performs.
2. Whether that function is truly necessary.
3. Whether it can be eliminated.
4. Whether it can be combined with another component.
5. Whether a standard off-the-shelf alternative exists.
6. Approximate cost impact.
7. Any reliability, safety, cleaning, or performance trade-off.

The first MVP should preferably avoid unnecessary features such as:

* touchscreen;
* large display;
* Wi-Fi/Bluetooth;
* mobile app;
* load cell;
* large internal battery;
* separate vibration motor;
* complicated automatic scraper;
* auger;
* pump;
* long powder tube;
* complex dosing system;
* mandatory proprietary receiving cup.

External low-voltage or USB-C power is acceptable for the first prototype if this significantly reduces cost, size, and complexity.

Cleaning and Product Recovery

Cleanability is one of the highest priorities.

All parts contacting the material should ideally:

* be removable without tools;
* be visually inspectable;
* avoid hidden cavities;
* avoid exposed threads and screw heads;
* avoid inaccessible narrow grooves;
* avoid lubricant or bearings in the powder path;
* be washable and easy to dry;
* allow the user to manually recover remaining powder with a soft brush or spatula.

The design should minimize both dose loss and cross-contamination.

Preliminary Prototype Targets

These are test targets, not guaranteed medical claims:

* more than 95% of starting mass automatically reaches the receiving surface;
* approximately 99% or more total recovery after optional manual collection;
* no obvious individual fragments larger than approximately 0.8 mm;
* preliminary D90 target approximately 300–600 µm;
* minimal visible powder cloud;
* no significant overheating;
* repeatable operation with approximately 1, 5, and 15 tablets.

Higher performance such as 97–98% automatic recovery may be investigated later if technically realistic.

First Paid Stage

The first paid stage is an engineering feasibility audit, not full production CAD.

I want the engineer to provide:

* feasibility verdict;
* list of major technical problems and contradictions;
* comparison of at least 2–3 architectures;
* recommended architecture;
* preliminary airflow and heating calculations;
* preliminary motor / torque / RPM estimates;
* assessment of screens and clogging risk;
* assessment of powder recovery and cleanability;
* preliminary dimensions and weight;
* preliminary BOM;
* cost-reduction recommendations;
* proposal for the cheapest possible grinding test bench;
* proposal for the cheapest possible drying test bench;
* preliminary FMEA / risk analysis;
* clear separation between:
* what is supported by calculations;
* what is based on analogous systems;
* what remains a hypothesis;
* what requires experimental validation.

Full production CAD is not required during this first stage.

If the concept proves feasible, later stages may include:

* test rigs;
* physical prototypes;
* 3D CAD;
* STEP/STL/DXF;
* engineering drawings;
* electronics requirements;
* testing;
* design iterations;
* final BOM;
* DFM/DFA;
* preparation for mass production.

Concept Images

I have detailed concept images showing the current internal layout and mechanisms.

Concept images will be shared privately with shortlisted candidates.

They are conceptual visualizations, not validated engineering drawings. I want them critically reviewed rather than assumed to be correct.

A much more detailed technical brief is also available to shortlisted candidates.

Preferred Experience

Strong preference for engineers with experience in one or more of:

* small grinders / mills;
* coffee or spice grinding mechanisms;
* powder-handling equipment;
* food-processing equipment;
* laboratory devices;
* compact consumer appliances;
* rotors and screens;
* small gearmotors;
* blowers / PTC heaters / airflow systems;
* removable washable mechanisms;
* prototyping;
* DFM / DFA;
* mass-production cost optimization.

Medical, pharmaceutical, or laboratory-device experience is a strong advantage, but pharmaceutical compatibility should not be independently certified by a mechanical engineer alone.

IMPORTANT — Please Do Not Send a Generic Bid

Please begin your proposal with:

DRY-GRIND

Then answer these five questions:

1. What are the three biggest engineering risks you see from this description?
2. Which would you test first: drying or grinding, and why?
3. Have you previously designed any grinder, mill, powder-handling device, food-processing mechanism, laboratory device, or similar electromechanical product? Please show the closest examples.
4. What would you physically test before spending money on final CAD and enclosure design?
5. What fixed price would you charge specifically for the first engineering audit stage?

I am looking for practical engineering judgment, not just CAD modelling.

If the first audit is successful, the same engineer may continue with prototyping, testing, CAD, BOM optimization, DFM, and preparation for manufacturing.