Arduino UNO R3 enclosures: mounting dimensions and connector access

Which board exactly: the UNO R3, SKU A000066

Before drawing a single dimension, identify the board. The Arduino datasheet covers the UNO R3, SKU A000066, built around an ATmega328P and an ATmega16U2. The Arduino product page lists other boards in the same family: UNO R3 SMD, UNO R4 Minima, UNO R4 WiFi and the UNO Mini Limited Edition. The dimensions used in this guide apply to the classic UNO R3 and do not silently transfer to those variants, to clones, or to a board with altered headers.

According to the Arduino page, the UNO R3 carries 14 digital I/O pins, 6 analog inputs, a USB connection, a power jack, an ICSP header and a reset button. Every item in that list is either an access point or a raised feature the enclosure must respect. The page adds that the ATmega328P is socketed rather than soldered, so it can be replaced: a box that blocks access to the chip gives up that benefit.

The Arduino product page provides the UNO R3 datasheet, schematics and CAD files. To prepare a case for this board, consult those resources against SKU A000066 and check the components on your actual unit. The guide to editable STEP models describes another way to work from an editable model; it does not replace checking the physical board.

Mounting dimensions the Arduino datasheet actually gives

The datasheet section titled “Board Outline & Mounting Holes” includes a drawing of the outline and mounting holes. In the figure, four holes are labeled Ø3.20 mm. That dimension describes the holes in the board; it does not specify clearance for a printed boss or the opening for a screw. Choose those dimensions for the fasteners you actually select, and check the fit with a small sample before finishing the enclosure. The dimensional accuracy page gives ways to check a particular print.

Two dimensions on the drawing can be mistaken for overall size. The 66.04 mm line runs from the left PCB edge to the vertical centerline of the right-hand hole pair, before the PCB notch. The 50.80 mm line runs from the top edge to the centerline of the lower-left hole, above the bottom edge of the PCB. Neither gives the board’s overall width or height; do not use either by itself to set the enclosure’s inside envelope.

The figure shows the outline and hole locations; Arduino’s product page also provides CAD files. For hole placement, refer to the complete drawing or CAD geometry associated with the UNO R3, then check your physical board. Do not infer a full rectangular hole pattern from only the 66.04 mm and 50.80 mm lines. Calipers can measure accessible distances, but a single edge or hole-diameter measurement does not reconstruct every coordinate in the drawing.

Clearances to plan: connectors, headers and the reset button

The bare-board drawing does not dimension clearance around a plugged-in cable. The datasheet identifies the X1 2.1 × 5.5 mm power jack, X2 USB-B connector, ICSP headers, reset button, and JANALOG and JDIGITAL rows. These names help inventory access points; the datasheet does not give the envelope of your plugs, cables, wires or attached shields.

For each access point, check the exact cable or adapter you intend to use with a clearance gauge or an early print. Record its height above the board, side projection and the room needed to operate the button. A shield or added headers change the envelope; check those configurations separately rather than assuming one lid fits all of them.

Model the box in a parametric tool so clearances can be adjusted without redrawing everything. The FreeCAD guide shows how to tie cutouts to a few variables, which pays off if you later move to another board revision.

For the intended use, allow access to the reset button and visibility of the indicators you need. Locate them on the actual board to size the model’s openings; this mechanical check is not electrical diagnosis.

Securing the board: screws, inserts and printed standoffs

The UNO R3 A000066 figure shows four Ø3.20 mm holes. Several enclosure fastening approaches can be considered, such as bosses, standoffs or threaded hardware, but the figure specifies no screw, tolerance or strength for a printed assembly. Select components for your design and check clearance and alignment on a sample before the final print.

The datasheet and board view do not replace inspecting the underside of the actual board. Check where components and soldered leads sit on the unit you intend to fit, then provide clearance from the printed part. Required height depends on the installed parts and chosen fastening design; no universal height is specified here.

Check the board outline and hole alignment before tightening it into the enclosure; correct a constrained fit in the design rather than forcing assembly. The choice between a screwed lid, clips or another closure depends on the intended use and parts. It does not establish the electrical characteristics of the assembly.

Keep mechanical design separate from power questions

The A000066 datasheet includes electrical characteristics for the board, including input values on VIN and USB. They describe the board in that document; they do not determine enclosure clearances or the safety of an integrated supply. This page is not a guide to choosing a power source, wiring or electrical design.

For the case, focus on the locations and heights that affect mechanical fit. The sources here do not validate integrating a mains supply, battery or charger into a printed part, and they are not enough to qualify such an assembly. Power and electrical-compliance decisions are outside this enclosure tutorial.

The datasheet pinout lists +3V3 and +5V separately as power rails, and IOREF as a logic-voltage reference. Those labels are distinct from the VIN and USB input ratings; this page does not infer any input/output tolerance or give wiring instructions. Its scope remains board geometry, mounting holes and connector access.

Temperature, venting and filament choice

The datasheet lists recommended operating conditions for the whole board from −40 °C to 85 °C and warns that some components may not operate as expected at temperature extremes. Those values concern the UNO R3 board; they do not give the air temperature inside an enclosure or the thermal performance of a printed part.

If enclosure temperature matters for your application, define a check for your board, workload, material and openings, then record the setup and ambient conditions. That would be a measurement of your unit, not a result provided by the Arduino datasheet. The cited documents do not prescribe vent geometry or a thermal result for a custom case.

The Arduino datasheet does not recommend a filament for this case. Consult the maker’s data for the exact material you are considering and check fit and intended use for your part. The PETG and ABS/ASA pages can help compare material families; they do not qualify this enclosure for a critical application.

Sources and limits

• Arduino UNO R3 A000066 — Datasheet
• Arduino — UNO R3 hardware resources

We organize manufacturer and community documentation; we have not measured these products ourselves. The manual for your exact model takes precedence over general guidance.