Shenzhen Alu Rapid Prototype Precision Co., Ltd.
Industry News
3D Printing Tolerance and Dimensional Accuracy Guide: SLA, SLS, MJF, FDM, DMLS, Holes, Fits and Inspection
3D printing can reproduce complex geometry without conventional tooling, but a digital model is not transferred to the physical part with perfect numerical identity. Layers have finite thickness, material shrinks or curls, supports pull on surfaces, holes close, thin walls move, and finishing removes or adds material. A part may look highly detailed yet fail at a bearing seat, connector opening or mating face.
Dimensional accuracy also differs among processes. SLA and DLP cure liquid photopolymer. SLS and MJF fuse polymer powder. FDM extrudes roads of thermoplastic. DMLS and SLM melt metal powder and require stress relief plus support removal. Each process has different sources of error, feature limitations, build-orientation effects and inspection needs.
This guide explains how to specify and achieve realistic 3D printing tolerances for prototypes and production parts. It compares SLA, DLP, SLS, MJF, FDM and metal powder-bed fusion, then covers holes, pins, slots, threads, clearances, wall thickness, support surfaces, scaling, post-processing, machining, measurement, capability and RFQ preparation.
Quick Answer: What Tolerance Can 3D Printing Hold?
There is no single tolerance that applies to all 3D-printed parts. Achievable accuracy depends on process, machine, material, part size, feature size, build orientation, location in the build, support strategy, thermal history, post-processing and inspection method.
For an RFQ, identify a small number of critical dimensions and ask the supplier to confirm capability for the exact process and geometry. Use general tolerances for noncritical printed features. Add machining, reaming, tapping, grinding or inserts when a fit requires accuracy or surface quality beyond reliable as-printed capability.
Do not copy one linear tolerance across every dimension. A 100 mm outer length, a 3 mm hole, a thin slot and a flat sealing face behave differently even when they are on the same part.
Accuracy, Precision, Resolution and Tolerance
These terms are often confused.
Accuracy is how close a measured result is to the intended value.
Precision is how closely repeated parts agree with each other.
Resolution is the smallest machine movement, pixel, voxel or layer increment the system can address.
Tolerance is the acceptable variation stated by design.
Repeatability describes variation under the same defined conditions.
Reproducibility describes variation across machines, operators, builds or sites.
A printer can have a fine advertised resolution and still produce a dimensionally inaccurate part. A tiny laser spot or pixel does not eliminate shrinkage, light bleed, thermal stress, powder adhesion or finishing variation.
Why 3D-Printed Parts Deviate from CAD
The geometry moves through several transformations:
CAD model export or tessellation.
File repair and orientation.
Slicing into layers.
Exposure, extrusion or melting.
Material consolidation and thermal contraction.
Support or powder removal.
Cleaning, curing or heat treatment.
Surface finishing and machining.
Conditioning and inspection.
Each step can change the result. The relevant question is not whether the printer is “accurate,” but whether the complete controlled manufacturing route can repeatedly meet the specified feature.
Build Envelope Error Is Not Uniform
A machine is calibrated over a build volume, but accuracy can vary by location and geometry. Optical distortion may change near an SLA platform edge. Thermal gradients affect powder-bed parts. FDM gantry alignment and bed temperature influence long dimensions. Metal builds can experience local stress near supports or high heat accumulation.
Suppliers use calibration artifacts, compensation maps, preventive maintenance and build-layout rules to control these effects. For demanding production, ask whether critical parts are restricted to qualified zones or orientations.
Scale Error vs Local Feature Error
Dimensional deviation can be separated into broad categories.
Global scale error
The entire part is consistently too large or too small in an axis. Machine calibration, material shrink compensation, cure and thermal contraction may contribute. Controlled scaling can sometimes correct this after correlation.
Local systematic error
Holes print undersize, outside corners grow, downward-facing surfaces sag or support contact adds stock. Feature-specific compensation may help.
Shape distortion
The part bows, twists, cups or becomes oval. This is not solved reliably by one scale factor. Orientation, support, heat, geometry and residual stress must be addressed.
Random variation
Powder condition, resin state, nozzle flow, machine drift, support removal and operator finishing produce part-to-part scatter. Process control and capability evidence are required.
Diagnose the error type before modifying CAD.
SLA and DLP Dimensional Accuracy
Stereolithography and digital light processing cure photopolymer resin layer by layer. They can produce fine detail, smooth surfaces and sharp cosmetic models, but accuracy depends on exposure, support, resin behavior and post-cure.
Common sources of deviation include:
Overcure or light bleed around small features.
Resin trapped in holes and cavities.
Peel or separation force during building.
Support pull and support-removal damage.
Curling of large thin panels.
Cleaning-induced swelling or incomplete cleaning.
Post-cure shrinkage and thermal distortion.
Continued aging or moisture response.
Small holes often print undersize because cured material encroaches on the opening and uncured resin is difficult to remove. Support surfaces may need sanding, which changes local dimensions.
For precise interfaces, orient the part to protect the feature, add finishing allowance and machine or ream after full cure.
SLS Dimensional Accuracy
Selective laser sintering fuses polymer powder, often nylon, without attached support structures. The surrounding powder supports the part, enabling complex geometry and nested builds.
Dimensional behavior is influenced by:
Powder refresh ratio and thermal history.
Bed-temperature uniformity.
Laser energy and scan strategy.
Part packing density and build location.
Curl from thermal gradients.
Powder adhered to surfaces.
Cooling schedule and breakout timing.
Moisture conditioning.
Media blasting or tumbling.
SLS holes and channels can retain powder, especially when they are small, long or curved. Surface texture affects measurement and fit. Nylon dimensions can change with humidity, so inspection condition should be defined.
The absence of support marks is valuable, but it does not make every orientation equivalent. Long flat parts and thin walls remain sensitive to thermal distortion.
MJF Dimensional Accuracy
Multi Jet Fusion uses agents and heat to fuse polymer powder. It supports complex batches and can provide useful repeatability for nylon production parts. Accuracy still depends on thermal management, agent behavior, orientation, nesting and cooling.
Typical issues include:
Local heat accumulation.
Edge growth or feature bias.
Warpage in long thin geometry.
Surface texture and adhered powder.
Differences among build locations.
Color or finishing effects.
Moisture-related dimensional change.
MJF suppliers often apply calibrated compensation based on machine and material history. For repeat production, keep the approved orientation, material route, post-process and inspection condition under change control.
FDM Dimensional Accuracy
Fused deposition modeling extrudes thermoplastic roads through a nozzle. It is economical and can use production-like thermoplastics, but layer paths, bead width and thermal contraction create distinctive limitations.
Accuracy depends on:
Nozzle diameter and extrusion width.
Layer height.
Flow calibration.
Material moisture.
Bed adhesion.
Chamber temperature.
Raster direction and infill.
Support gap.
Seam and start-stop behavior.
Cooling and residual stress.
Holes may be polygonal or undersize. Outside dimensions can grow because of extrusion calibration. Long ABS or high-temperature thermoplastic parts may warp at corners. Thin walls that are not compatible with an integer number of extrusion paths can be overfilled, underfilled or omitted.
For a functional FDM part, design wall and feature sizes with the chosen nozzle and toolpath strategy in mind.
DMLS and SLM Metal Accuracy
Metal powder-bed fusion melts metal powder with a laser. DMLS, SLM and related systems can produce complex metal geometry, but high thermal gradients create residual stress and distortion. Supports anchor the part, conduct heat and resist movement.
Dimensional influences include:
Build orientation.
Support geometry and contact.
Scan strategy.
Heat accumulation.
Part-to-plate attachment.
Stress relief.
Plate removal method.
Hot isostatic pressing when used.
Support removal and grinding.
Machining and heat-treatment distortion.
Critical bores, datums, sealing faces, threaded holes and precision fits are normally printed with stock for machining. The drawing should distinguish as-printed surfaces from machined surfaces and define the datum-transfer strategy.
Orientation Is a Dimensional Decision
Orientation affects layer stepping, support contact, flow of heat, anisotropy, trapped material and finishing access. The cheapest orientation may not be the most accurate orientation.
Review orientation for:
Critical dimension direction.
Flatness and straightness.
Circularity of holes.
Support access.
Downward-facing surfaces.
Cosmetic faces.
Load direction.
Powder or resin drainage.
Build height and production time.
Machining setup.
Keep the approved orientation controlled for repeat orders. Rotating a part to increase machine utilization can alter fit and strength even when the file is unchanged.
Layer Thickness Does Not Equal Part Tolerance
A 0.05 mm layer height does not mean the part holds plus or minus 0.05 mm. Layer height controls vertical sampling and affects surface stepping. In-plane accuracy depends on spot, pixel or bead behavior, calibration and material response. Global shape depends on thermal and mechanical effects.
Use layer thickness to evaluate surface and small vertical detail, not as a shortcut for a tolerance statement.
CAD Tessellation and File Preparation
STL represents curved surfaces with triangles. A coarse mesh creates faceted holes and arcs even if the printer is capable of smoother geometry. An excessively fine file increases size without adding meaningful accuracy.
Prefer a format that preserves units and geometry when the supplier supports it, such as STEP for engineering exchange or 3MF for additive workflow metadata. If STL is required:
Confirm units.
Use suitable chord height and angular tolerance.
Check manifold condition.
Remove duplicate shells and internal faces.
Verify wall thickness and normals.
Compare the exported mesh with source CAD.
File repair should not silently close intentional gaps or remove small features. Record the approved production file and revision.
Overall Part Size
Absolute dimensional error often grows with part size. A tolerance that is realistic over 20 mm may not be realistic over 500 mm. Long parts also accumulate thermal distortion and measurement uncertainty.
Use a tolerance framework with a fixed component and a size-dependent component when appropriate. For very large prototypes, segmenting and joining may reduce build risk but creates seam and alignment error.
Identify the dimensions that must remain continuous. A cosmetic mockup may tolerate seam finishing; a long optical or sealing interface may require machining or another process.
Minimum Wall Thickness
Minimum printable wall and dimensionally stable wall are not the same. A demonstration coupon may contain a very thin wall that is fragile, distorted or inconsistent in a full part.
Wall capability depends on:
Process and material.
Wall height and unsupported length.
Orientation.
Connection to the main body.
Post-processing.
Handling and service load.
Use thicker walls for tall fins, large panels and production parts. Avoid sudden transitions that concentrate heat or support stress. Ask the supplier to review aspect ratio, not only thickness.
Holes Usually Need Special Treatment
Holes are among the most common additive tolerance problems. They may print undersize, out of round, tapered or blocked.
Causes include:
Stair stepping.
Overcure or melt-pool growth.
Extrusion path geometry.
Powder or resin retention.
Support inside the opening.
Thermal distortion.
Surface roughness.
Measurement contact with peaks.
For clearance holes, add process-specific compensation after supplier review. For precision dowels, bearings, seals and threads, print pilot geometry and machine, drill or ream after building.
Do not compensate a hole based on one uncorrelated sample. The required offset depends on process, orientation and diameter.
Horizontal vs Vertical Holes
Hole orientation changes shape. A vertical-axis hole may be defined mainly in the layer plane. A horizontal hole contains strong stair stepping at the top and bottom and may need support or self-supporting geometry.
Horizontal circular holes in FDM or metal printing can sag at the upper surface. Teardrop or diamond forms can be useful for non-precision channels when circularity is not required. Powder-bed polymer processes avoid attached support but still have thermal and powder-removal limits.
Specify function. A cable route can use a self-supporting shape; a bearing seat cannot.
Pins, Bosses and Small Positive Features
Small pins can become oversized from exposure or extrusion, or undersized after blasting and sanding. Tall slender pins can bend during building or handling.
Improve reliability by:
Increasing diameter.
Reducing unsupported height.
Adding root fillets.
Orienting for strength and shape.
Protecting during depowdering.
Replacing delicate printed pins with metal dowels.
If a pin locates an assembly, a separately installed precision dowel often provides better repeatability than an as-printed feature.
Slots, Gaps and Internal Channels
Thin slots can close because of overcure, fused powder, bead width or finishing debris. Deep narrow channels are hard to clean and inspect.
Review:
Minimum opening relative to depth.
Drain and escape paths.
Line of sight for cleaning.
Support-removal access.
Internal surface roughness.
Inspection method.
Whether a sacrificial opening can be sealed later.
For fluid channels, dimensional accuracy is only one concern. Surface roughness, trapped powder, porosity and contamination may control performance.
Clearances for Moving and Mating Parts
Assemblies printed in place require clearance between bodies. The necessary gap depends on process, orientation, size, surface texture and cleaning. A clearance that frees easily in one process can fuse in another.
For separate printed parts, consider:
Dimensional variation of both parts.
Surface peaks.
Alignment over the engagement length.
Paint, dye or plating thickness.
Humidity and temperature.
Desired sliding or snap behavior.
Use tolerance stack-up, not a nominal gap alone. Prototype a clearance ladder in the real process when motion is important.
Press Fits and Slip Fits
As-printed press fits are sensitive to hole bias, roughness and material compliance. They can work for low-risk prototypes but need experimental correlation.
For a reliable production fit:
Machine or ream the hole.
Use a controlled metal insert.
Define the mating component.
Specify insertion force and retention.
Consider creep in polymer.
Control humidity for nylon.
Test repeated assembly if required.
A rough bore may create high insertion force while providing poor long-term contact. Fit terminology alone does not define performance in additive surfaces.
Threads
Large coarse threads can be printed, particularly for low-load prototypes. Small or frequently used threads are more reliable when tapped, thread milled or fitted with inserts.
Printed thread accuracy depends on:
Orientation.
Pitch and profile size.
Support or powder removal.
Layer stepping.
Material brittleness.
Post-cure and finishing.
Use heat-set, helical, press-fit or bonded inserts as appropriate to the material. Specify installation, torque, pull-out and assembly-cycle requirements.
For metal powder-bed fusion, print a pilot hole with machining allowance and tap after heat treatment and stress relief.
Snap Fits
Snap fits combine dimensional accuracy with modulus, elongation, notch sensitivity and build orientation. A geometrically accurate brittle resin snap can still fail immediately.
Validate:
Engagement and undercut.
Lead-in geometry.
Root radius.
Strain direction relative to layers.
Material conditioning.
Repeated cycles.
Assembly temperature.
Use separate dimensional and material coupons when useful. Final production behavior may require testing in the intended molded material.
Text, Logos and Engraving
Embossed and recessed details have different minimum sizes. Fine recessed text can trap powder or resin. Fine raised text can be lost during blasting or sanding.
Increase stroke width, depth and spacing for reliable readability. Consider orientation and paint fill. A logo that renders on a flat upward face may blur on a curved downward surface.
Inspect against intended viewing distance and lighting, not only under magnification.
Support Surfaces and Downskin
Support contact is a local manufacturing allowance. SLA nubs, FDM support interfaces and metal support scars require removal. Downward-facing metal and polymer surfaces may be rougher and less accurate even without attached supports.
Keep critical fits and cosmetic areas away from supports when possible. If support is unavoidable:
Add stock for finishing.
Define the allowed witness area.
Provide tool access.
Protect adjacent datums.
Specify final roughness and dimension.
Support removal is part of the controlled process, not an informal cleanup step.
Surface Finish Changes Dimensions
Bead blasting, tumbling and sanding remove high points and soften edges. Primers and paint add thickness. Vapor smoothing redistributes the polymer surface. Dye changes little dimensionally but can alter conditioning. Plating adds a controlled but nonzero layer.
State whether dimensions apply before or after finish. Mask critical interfaces or machine them after cosmetic processing. For coated holes and slots, account for thickness on both sides of the opening.
Aggressive finishing can make a prototype attractive while destroying small text, edges and fit features.
Heat Treatment and Post-Cure
SLA parts usually need post-cure to reach intended properties. Metal parts often need stress relief and may need solution treatment, aging or hot isostatic pressing. Polymer powder parts cool for a controlled time in the build.
These steps can change dimensions. Inspecting before the final thermal route gives incomplete evidence. The production traveler should define process order:
Build.
Stress relief or primary cure.
Plate or support removal.
Heat treatment.
Machining.
Surface finish.
Final inspection.
The exact route varies, but dimensional approval should reflect the delivered condition.
Machining Allowance
Hybrid additive and machining is often the most economical way to combine geometric freedom with precision. Add stock only where machining is required.
Allow for:
Build variation.
Support removal.
Distortion after stress relief.
Datum creation.
Workholding.
Tool runout and surface cleanup.
Too little allowance risks an uncleaned surface. Too much adds build time, material, residual stress and machining cost.
Create robust datum pads and clamping features. A complex lattice part cannot be machined accurately if it cannot be located and held.
Inserts and Secondary Components
Precision interfaces can be added after printing:
Threaded inserts.
Dowel pins.
Bushings.
Bearings.
Sealing sleeves.
Electrical contacts.
Machined plates.
Design enough surrounding material and access for installation. Define adhesive, heat, press or mechanical retention. Account for the variation in the printed receiving feature and verify pull-out or torque when functional.
Compensation and Scaling
Suppliers may compensate known process bias through machine calibration, material profiles, global scale or local geometry offsets. Compensation should be based on controlled data.
Avoid permanently altering master CAD for one supplier's offset unless the change is clearly documented. Prefer a manufacturing derivative or supplier-controlled build preparation with revision traceability.
Global scale is appropriate only for approximately uniform systematic error. It can worsen holes, wall thickness and local features if used to correct a shape-distortion problem.
Designing a Calibration Coupon
A project-specific coupon can reduce uncertainty before a large build. Include representative:
Hole diameters and orientations.
Pins.
Slots and gaps.
Wall thicknesses.
Text.
Fit pairs.
Support surfaces.
Surface-finish zones.
Build the coupon with the intended machine, material, orientation and post-process. Use it to agree compensation and acceptance, but remember that a small coupon does not reproduce all thermal behavior of a large part.
General Tolerances on Drawings
A drawing should distinguish critical features from ordinary printed geometry. Apply a practical general tolerance appropriate to the process and size, then use specific tolerances only where function requires them.
Avoid applying precision-machining tolerances to every dimension. It increases inspection cost and may force unnecessary machining.
Include notes for:
Process and material.
Orientation if controlled.
Delivered post-process condition.
As-printed versus machined surfaces.
Surface roughness zones.
Inspection temperature and conditioning.
Removal of supports and loose powder.
Allowed build lines and witness marks.
Use GD&T to communicate function when size alone is insufficient.
Datums and GD&T
Datums should reflect how the part assembles and how it can be inspected. A rough organic surface is a poor primary datum unless functional contact truly occurs there.
Consider printed or machined datum pads. Profile can control a complex surface relative to functional datums more clearly than dozens of linear dimensions. Position controls holes after reaming or machining.
For flexible polymer parts, state whether tolerances apply in the free state or under restraint. Define datum targets and fixture force where needed.
Measurement of Rough Surfaces
Surface texture creates uncertainty. Contact calipers may touch peaks. A CMM probe can bridge valleys. Optical scanning may respond to color, translucency or reflectivity. CT can reveal internal geometry but has voxel and reconstruction limitations.
Choose the method according to feature function and tolerance. Control:
Probe size and force.
Scan density.
Filtering and fitting rules.
Part temperature.
Moisture condition.
Fixture support.
Alignment and datum simulation.
The measurement method should be agreed before production, not debated after a result fails.
CT Scanning
Computed tomography is useful for internal channels, lattices, wall thickness and inaccessible features. It can compare the full volume with CAD and identify porosity in some materials.
Accuracy depends on part size, material density, scan energy, voxel size, artifacts, threshold selection and reconstruction. A CT color map is not automatically a calibrated dimensional report.
Define the required feature, uncertainty, analysis method and acceptance. Use traceable artifacts or correlation when CT supports a critical decision.
3D Scanning
Optical scanning captures external shape rapidly and is valuable for warpage and profile comparison. Shiny, dark or transparent surfaces may require preparation, which can affect the measured surface.
Set the alignment method carefully. Best-fit alignment can make an overall color map look favorable while hiding functional datum error. Use drawing datums for acceptance and best fit only for diagnostic analysis unless otherwise agreed.
First Article and Build Reports
For a new part, request a first-article package proportional to risk. It can include:
Build ID, machine and material lot.
File and revision.
Orientation and layout.
Layer or process settings.
Post-processing route.
Dimensional report.
Material certificate.
Heat-treatment record.
Surface-finish record.
Nonconformance and repair disclosure.
For repeat production, retain traceability so a dimensional change can be linked to machine, powder, resin, build and finishing.
Process Capability
One accurate part does not prove repeatability. Production additive parts need evidence across builds, locations, material lots and post-processing batches.
Study critical features with an acceptable measurement system. Separate within-build and build-to-build variation. If several machines are approved, compare them rather than pooling data immediately.
Capability depends on a frozen manufacturing route. An orientation, machine, layer setting or finishing change can invalidate previous evidence.
Cost of Tight Tolerances
Tighter tolerance increases cost through:
Restricted orientation and build layout.
Calibration coupons.
Lower nesting density.
Supports and finishing.
Machining setups.
Inspection programming.
CT or scanning.
Scrap and rework risk.
Documentation and traceability.
Apply tight limits to features that control fit, sealing, alignment or performance. Allow the rest of the part to follow process-appropriate tolerances.
A machined insert may cost less than forcing an entire printed housing into a narrow tolerance.
Common 3D Printing Tolerance Mistakes
Treating layer height as dimensional tolerance.
Applying one tolerance to every feature and size.
Ignoring build orientation.
Expecting small holes to print at nominal size.
Using global scaling to correct local warpage.
Releasing coarse STL files for curved precision features.
Forgetting finish thickness and support-removal stock.
Specifying precision fits on rough as-printed surfaces.
Measuring before cure, heat treatment or conditioning.
Best-fitting a scan when functional datums should control.
Approving one part without build-to-build evidence.
Changing machine or orientation without revalidation.
Designing trapped channels that cannot be cleaned or inspected.
Applying machining tolerances without adding machinable stock and datums.
3D Printing Tolerance Review Checklist
Before ordering, confirm:
The process and exact material are selected.
Functional dimensions are separated from cosmetic geometry.
Orientation requirements are understood.
Holes, fits and threads have a finishing plan.
Walls and small features are robust for the full geometry.
Supports avoid critical and cosmetic surfaces where possible.
Powder, resin and support removal have access.
Post-cure, heat treatment and finishing occur before final inspection.
Machining stock and datums are designed in.
Drawing tolerances match process capability.
Measurement methods and conditioning are defined.
Multiple builds are considered for production approval.
Packaging protects thin and delicate features.
Any geometric compensation is revision controlled.
Supplier changes require appropriate revalidation.
RFQ Information for Dimensionally Accurate 3D-Printed Parts
Send the supplier:
Native CAD or STEP plus any required mesh.
Revision-controlled 2D drawing.
Exact material or required properties.
Quantity now and expected repeat demand.
Intended process if fixed.
Critical dimensions and GD&T.
Mating parts and fit requirements.
Threads, inserts and assembly loads.
Surface finish, color and cosmetic zones.
Controlled orientation or prohibited support areas.
Internal-channel cleaning requirements.
Heat treatment, cure and conditioning.
Machined features and surface roughness.
Inspection report and traceability requirements.
Packaging for thin or delicate geometry.
Ask the supplier to identify the proposed process, machine family, orientation, post-processing, general tolerance, machining allowance and inspection method in the quotation. This prevents a low price based on assumptions that cannot meet the functional interfaces.
Frequently Asked Questions
Which 3D printing process is most accurate?
It depends on part size, geometry and feature type. SLA can provide fine detail, polymer powder processes can provide good batch repeatability, and metal printing combined with machining can achieve precision interfaces. No process is best for every feature.
Why do 3D-printed holes come out undersize?
Exposure growth, extrusion paths, stair stepping, powder adhesion, resin retention and surface roughness reduce the effective opening. Precision holes should usually be drilled, reamed or machined.
Does smaller layer height improve tolerance?
It can improve vertical detail and surface stepping, but it does not automatically correct scale, shrinkage, warpage or in-plane feature bias.
How much clearance should printed moving parts have?
The needed clearance depends on process, orientation, size, finish and cleaning. Use supplier guidance and a test ladder in the actual production route rather than a universal value.
Can threads be printed accurately?
Large coarse low-load threads can be printed. Small, high-load or frequently used threads are more reliable when tapped or fitted with an insert.
Should I compensate hole size in CAD?
Only after correlating the exact process and orientation. Keep compensation documented in a manufacturing derivative so the master engineering geometry remains clear.
Can an STL file cause dimensional error?
Yes. Coarse tessellation makes curves faceted, incorrect units change scale, and repair can alter geometry. Verify the mesh against native CAD before release.
When is machining necessary after 3D printing?
Use machining for bearing seats, sealing faces, precision datums, dowel holes, tight threads and other interfaces beyond reliable as-printed capability.
How should a flexible printed part be inspected?
Define free-state or restrained-state requirements, datum supports, fixture force, temperature and moisture condition. An uncontrolled fixture can create the result it is supposed to measure.
Can one approved build prove production capability?
No. It proves only that the sampled build produced acceptable parts. Repeat production should evaluate build-to-build, machine, material and finishing variation according to risk.
Conclusion
3D printing tolerance is the capability of a complete manufacturing route, not a number taken from layer height or machine resolution. SLA, SLS, MJF, FDM and DMLS each create different feature biases and distortion mechanisms. Orientation, supports, thermal history, post-processing and measurement can influence the result as much as the printing step.
The best design strategy separates ordinary printed geometry from precision functional interfaces. Use realistic general tolerances, protect critical surfaces, provide cleaning access and plan machining or inserts where they create a more reliable fit. Control the approved orientation and post-process for repeat orders.
For an accurate quotation, send AluPrototype the CAD model, drawing, material, quantity, mating parts, critical dimensions, surface requirements and inspection expectations. A process-specific review can then identify which features can remain as printed, which need compensation and which should be machined for dependable assembly.