Last Updated: 2026-10-05
Quick Answer: A power supply mounting drawing should be reviewed before the OEM releases a backplate for fabrication. Match the complete model and drawing revision, define the viewing direction and datums, separate the outer envelope from the mounting-hole pattern, and obtain the applicable hole and fastener details. Record the drawing-to-CAD comparison and first fabricated plate inspection. A supply that sits within the available rectangle is not necessarily a supply that can be mounted correctly.
An enclosure can have enough space for a component and still arrive with the wrong holes. That is a manufacturing problem distinct from choosing output power or commissioning an electrical circuit. A power supply mounting drawing connects the supplier’s mechanical interface with the OEM’s controlled fabrication file. Losing that connection can turn a straightforward sheet-metal order into rework, an improvised bracket or an undocumented assembly deviation.
This guide concerns the release of a chassis-mounting layout, not electrical installation instructions. The photographed example is WEHO LRS-150-12: its actual source label identifies 12 V and 12.5 A, while the current mechanical specification documents a 159 mm long, 97 mm wide and 30 mm high enclosure. The two application illustrations show disconnected mechanical preparation for a packaging-machine OEM and an industrial marking-equipment build. They do not establish either machine’s load requirements, compatibility, mounting approval or electrical acceptance.
Start with the interface question, not a convenient rectangle
Before comparing drawings, describe what the fabricator needs to produce. Is the order a drilled backplate, a formed support or a replaceable subassembly? Which face will carry the supply, and which direction must provide access to its terminal end? Identify the equipment layout revision, the available mounting surface and the owner who can approve a change.
Keep the full supplier model in this record. A family name, photograph caption or nominal wattage is not a controlled mounting interface. Two products can have similar outlines but different hole patterns, terminal projections or access requirements. Conversely, the same family can include more than one size. Do not use the photograph of one variant to define the holes for another unless the supplier explicitly confirms that the same drawing applies.
For this example, the official WEHO LRS-150 product page supplies series context and the 12 V/12.5 A model column. The exact enterprise-drive source photograph and its mechanical sheet are retained together for the local editorial review. A purchasing team should request the controlled drawing applicable to the actual ordered revision; a web illustration is not a manufacturing release.
Keep three different spaces separate
The outer envelope, the mounting interface and the installation working space answer different questions.
| Space | Question answered | What it does not establish |
|---|---|---|
| Component envelope | Will the documented body fit in the proposed region? | Hole coordinates, fastener suitability or cooling clearance |
| Mounting interface | Where and how does the supported fixing attach? | The surrounding equipment’s structural acceptance |
| Working and service space | Can the prescribed assembly and maintenance tasks be performed? | A universal clearance based solely on case dimensions |
On the current LRS-150 drawing, 159 mm is the long body axis, 97 mm the short body axis and 30 mm the case height normal to the broad perforated face. These are not interchangeable labels for cabinet width, upright height and rail depth. Define how the part is oriented in the OEM layout before copying any dimension.
The 30 mm case height does not authorize a 30 mm closed cavity. Terminal access, conductor routing, permitted ventilation conditions and any servicing requirement must come from the applicable installation information and the equipment design. This article supplies no universal spacing or torque value.
Establish the viewing direction and datums
A mirrored pattern can look reasonable until the assembler tries to use it. Record whether the supplier view looks toward the terminal end, from the broad cover or from another documented face. Identify the terminal end in the CAD model. Keep the input and output markings as identification references, not as a wiring procedure derived from the picture.
Choose and document the datums used to locate the component and the holes on the plate. A designer may work from a plate edge, a centre line or a controlled locating feature. The important point is that the drawing-to-CAD comparison uses the same defined coordinate system. Do not quietly mix dimensions from a side elevation with dimensions from the plan view.
When a dimension has to be converted to the OEM coordinate system, retain the calculation and its source. A second reviewer should be able to reproduce the result without tracing pixels. A printed or screen-displayed drawing may have been scaled; measuring its picture with a ruler does not recover an unlabelled engineering dimension reliably.
Read hole notes as part of the drawing
A small circle in a drawing does not, by itself, tell the fabricator to make a clearance hole. Review the associated callouts, the face to which they apply and the supplier’s fixing instructions. Distinguish a hole in the OEM plate from a threaded feature in the supply case. An outline drawing can show several features that are not all alternate fixing options.
The current LRS-150 sheet contains M3 fixing annotations with depth or length notes. Preserve those original annotations in the controlled request; do not translate a short note into a guessed maximum screw penetration or assume that every visible opening accepts the same fastener. Obtain clarification where the ordered-unit instruction does not establish the intended fixing face, engagement and permitted fastener arrangement.
The OEM must also specify its own plate material, thickness, hole treatment and manufacturing tolerances through the appropriate design process. The supplier’s component drawing is not a substitute for that plate specification. Do not add extra product holes, use ventilation openings as attachment points, or select adhesive mounting merely because it avoids drilling.
Compare the release file with the source, one feature at a time
A practical review sheet can contain one row for each controlled feature: full model, applicable document revision, terminal-end orientation, overall length, overall width, body height, intended fixing face, mounting coordinates and relevant hole notes. For every row, name the source, the value entered in CAD, the comparison result and the reviewer.
Mark unanswered points as open. A rendering that looks attractive is not a measurement record, and a supplier’s statement that a model is “slim” is not a tolerance. If different sources disagree, record the conflicting statements and ask for an applicable ordered-revision clarification. Do not choose the most convenient value for the fabrication file.
The LRS-150 example illustrates this boundary. The mechanical envelope and pictured 12 V/12.5 A identity agree with the selected source set. The source nameplate prints 100–240 VAC, 3.0 A and 50/60 Hz, while available website and specification text describe other input-range statements. This guide does not reconcile those electrical statements or authorize energizing the sample. Electrical selection and release remain separate work that requires confirmation for the ordered unit.
Inspect the first plate before multiplying the order
Use the OEM’s authorised mechanical inspection method for the first fabricated plate. Compare its identified revision and features with the released drawing, and record the actual results. An unconnected sample can help assess physical access and supported alignment, but its presence on a plate is not proof that a fixing arrangement is approved.
The packaging illustration uses a separate, loose nominal 35 mm rail as a contextual scale anchor; the marking-equipment illustration uses a generic nominal 100 mm mechanical reference bar on the same work surface. Neither item is attached to the LRS-150-12, which remains a chassis supply. The bar’s long axis is parallel to the supply’s 97 mm short axis so their nearly equal spans can be compared in context. The supply’s documented body remains 159 mm long, 97 mm wide and 30 mm high. These illustrations are not calibrated measurements, prescribed clearance or inspection certificates, and neither scene claims completed mounting, isolation or commissioning.
If the first plate does not match, stop the affected fabrication release and identify whether the source revision, CAD transfer, manufacturing file or actual plate differs. Record the disposition. Avoid turning enlarged holes, field drilling or a new bracket into an invisible correction that future builds cannot reproduce.
Control the next change, not just the first build
Link the approved fabrication file to the supply identity and drawing revision used for its release. Put a revision change or proposed substitute through a defined impact review. The review should ask specifically whether the envelope, fixing interface, terminal-end orientation or working access has changed; matching output voltage does not answer those questions.
Keep withdrawn files out of the normal production route and make the current release clear to the fabricator. A useful handover includes the applicable supplier drawing, the OEM plate drawing, the comparison sheet, first-plate evidence and any accepted deviation. This focused mechanical record complements a broader first-article approval process but does not replace electrical, thermal, safety or system qualification.
Key Takeaways
- Review the power supply mounting drawing before releasing a plate for fabrication.
- Match the full model, document revision, viewing direction and coordinate datums.
- Keep the body envelope, fixing interface and working space separate.
- Preserve hole callouts; never infer fastener limits from a photograph.
- Inspect and record the first plate, then control changes to the released file.
- The LRS-150-12 example and disconnected illustrations are not installation or electrical acceptance evidence.
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A clean mounting layout is a controlled translation from an applicable supplier drawing to an OEM fabrication file. It depends on identifiable revisions, unambiguous views, traceable dimensions and a recorded first-plate result—not on whether a product appears to fit a rectangle. For a WEHO chassis supply, send the full ordered model, proposed mounting face and layout constraints when you contact WEHO for the applicable drawing and any unresolved interface details. Keep electrical release and machine acceptance separate from the mechanical fabrication decision.
Product and specification sources
- WEHO LRS-150 product page — model-column and envelope context; mixed input statements are not used as an electrical release.
- WEHO public LRS-150 specification — public comparison; the applicable ordered revision must be confirmed before manufacture.
- Approved enterprise-drive LRS-150 source photograph and current mechanical specification — retained in this local package with original file/revision identifiers and hashes; not altered or used as finished article images.
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Do the 159 × 97 × 30 mm body dimensions define the mounting-hole pattern?
No. Those dimensions describe the current LRS-150 body envelope. The intended fixing face, coordinates, hole callouts and applicable mounting instructions must be reviewed separately for the ordered revision.
Can a designer measure an unlabelled hole position from a PDF picture?
Do not use a scaled screen or printed image to invent an engineering dimension. Request the controlled dimension or clarification, identify the viewing direction and retain a traceable source for the CAD coordinate.
Are all visible circles in a mechanical drawing clearance holes for the OEM plate?
No such assumption is supported. Read the relevant callout and view, distinguish the component’s features from the OEM plate features and confirm the intended fixing arrangement. Threaded features and clearance holes have different roles.
What should happen when the first fabricated plate does not align?
Hold the affected fabrication release, record the actual result and determine which source revision, CAD transfer, manufacturing file or plate differs. Let the responsible owner disposition the deviation rather than silently enlarging holes or adding an unrecorded bracket.
Do the application pictures show commissioned packaging or marking equipment?
No. They show disconnected mechanical-layout preparation with an exact source-controlled LRS-150-12. The scenes do not establish equipment compatibility, completed fixing, electrical isolation or commissioning.
Does a passing mechanical review authorise energizing LRS-150-12?
No. Mechanical fabrication approval does not resolve electrical source differences or approve the equipment. Confirm the ordered model’s input, loads, installation instructions and project acceptance requirements through a separate authorised process.
