ONE-CNC Machining Tolerance Standards

ECOREPRAP provides two categories of tolerances: “GENERAL TOLERANCE” and “TIGHTER TOLERANCES”.

General Tolerance

General tolerance is the tolerance across the part if nothing is indicated on a technical drawing.DIN ISO 2768-mk (medium) is the general standard for ECOREPRAP CNC machining standard.

Tighter Tolerances

If tolerances tighter than ISO-2768MK are needed, it can be requested when building a quote. It also needs to be specified in a technical drawing in order to indicate exactly which features are concerned.

ECOREPRAP CNC Machining General/Standard Tolerance

CNC machining tolerance

TWO-Sheet Metal Fabrication Tolerances Standards

ECOREPRAP provides two categories of tolerances: “GENERAL TOLERANCE” and “TIGHTER TOLERANCES”.

General Tolerance
General tolerance is the tolerance across the part if nothing is indicated on a technical drawing.

Tighter Tolerances
If tolerances tighter is requested,it also needs to be specified in a technical drawing in order to indicate exactly which features are concerned.

ECOREPRAP Sheet Metal Fabrication General/Standard Tolerance

THREE-CNC Machinging and Sheet Metal Fabrication Parts Edge Breaking and Deburring Standards


1. Deburring comes as a standard with all finishes.
2. Standard is deburring plus break sharp edges (chamfer).
3. No secondary burrs allowed.
4. Chamfer size rang is 0.25mm ±0.15mm.
5. Internal threads, bores and blind holes will also be deburred with the aid of deburring brushes when need be.
6. Chamfers will be done during the machining steps as much as possible, to ensure a consistent look.When not possible, these can be done by hand with a regular hand deburring tool.


Other non standards options for deburring can be indicated on the 2d drawing as aditionnal requirements.

FOUR-CNC Machinging Cosmetic Standards

Cosmetic Definition

Finishes are differentiated into two categories, cosmetic and non-cosmetic. Cosmetic is the best option when visual consistency across batches is required and parts cannot have cosmetic defects on their “primary” side. Non-cosmetic is the less expensive option. Parts can present slight visual differences and cosmetic surface imperfections.


When you select a cosmetic finish, we commit to producing high-end, customer facing products. We guarantee that you will receive “beautiful-looking” parts according to our cosmetic standards described below.

FIVE-Threads Standards

Threads Types




Thread tolerances

Metric Threads Tolerances

Unless specified on the drawing, metric threads tolerances should follow the ISO 965-1 standard. The standard thread tolerances are used for external and internal threads: 6H for internal threads and 6g for external threads.

UN Threads Tolerances

Unless specified on the drawing, UN threads tolerances should follow the ASME B1.1-2003 standard. The standard thread tolerances are used as for external and internal threads: 2A for external threads and 2B for internal threads.

Important Note:

If your parts need to pass through GO-NO-GO gauge, please indicate it when placing the order or on the 2D drawing.

SIX-Cosmetic Standards-Visually Consistent For The Same Batch

1. Brush marks will be in the same direction.
2. Same grit will be used across parts for sanding or brushing.
3. Color will be consistent to the same hue when parts are placed next to each other.
4. Gloss units will be consistent across the batch.
5. Only minor defects are allowed on the hidden B side.
6. Surface quality on our side upon receiving will be visually inspected at a distance about 50cm in a pproximately 45 degrees in all directions. Lighting conditions are 500-1000 Lux.

DefectsPrimary side (A side)Secondary side (B side)
Scratches, dents, stains, blemishesNoneNone
Hanging marksNoneMinor hanging marks
Minor defectsNoneUp to two minor defects
* When required, primary (A) side and secondary (B) side need to be indicated on the technical drawing.

SEVEN-Inspection Standards

A defect is considered as a discrepancy to ECOREPRAP technical requirements and/or customer specifications.

Our QC will carry visual and dimensional inspections prior to order shipping. We use standard defect books and inspection criteria that help us to get a consistent level of control, wherever and whenever the order is produced. For an order with multiple units of the same line item, our partners and inspection teams use ISO2859 – General Level 2 sampling.

For example, a batch of 20 units will be inspected on a sample of 5 units.

Defects are described with pictures, as well as level of defect (which are linked to AQL levels for inspection purposes).

The defects are described with 5 properties:

1. Category: Surface finishes, Tolerances & dimensions, Threads, Materials, Parts finishing & Cleaning, Packaging.
2. Name: description of the defect
3. Level: criticality of the defect
4. Bad photo: example of the defect
5. Good photo: example of an acceptable part

Categorisation of defects levels

1. Minor defect
Minor defects usually slightly affect parts appearance but usually do not affect parts usability.
2. Major defect
Major defects are more serious defects that can affect parts usability.
3. Critical defect
Critical defects are defects that affect part usability, and that could lead to harmful or hazardous situations if the part is used as it is.

In case parts are non conforming to Customer specification and/or ECOREPRAP technical requirements, the inspection results are passed along to the customer for a potential disposition. (The customer owns the part design and its intended usage)

EIGHT-Non Standard Features Requirements Standards

Non Standard Features Requirements – Sharp Corners

Internal sharp corners necessitate EDM (Electrical Discharge Machining) operations, resulting in a substantial increase in machining expenses. Consequently, it is advisable to minimize the presence of such sharp corners whenever feasible. In the majority of cases, if there is a request for sharp corners, the supplier will propose alterations to enhance the part’s machinability.

If the sharp corners are not absolutely indispensable, we would suggest two solutions.

Solution 1: Increasing the radii
A radius of at least 1/4 of the pocket depth can be suggested
For example, this pocket is 10mm deep, at least 2.5mm radius will be suggested.

Solution 2: Use corner compensation fillet
“Dog bones” fillet can be suggested
Corner compensation fillet is a technique used to add small rounded corners or fillets to the inside corners of a design. These fillets are applied to compensate for the diameter of the cutting tool used in the machining process. The purpose of adding these fillets is to ensure that the machined part accurately fits the intended dimensions.
Corner compensation fillet is often called as “dog bones”, because it looks like a dog bone shape.

EDM (sinking EDM or wire-EDM): EDM should only be reserved for the cases where the sharp corners are absolutely indispensable. It will significantly increase machining costs.
Non Standard Features Requirements – Knurling
Knurling is a machining process that adds textured patterns to cylindrical surfaces for grip or aesthetics. Specify knurling on drawings and default to standards like DIN 82 or ISO 13444:2012 if no standard is mentioned. If an alternative standard is specified, it must be feasible within us; otherwise, we’ll suggest suitable known standards for consistency and quality.
Non Standard Features Requirements – Part Marking

1. CNC engraving, laser engraving and silk screening are provided on demand.
2. Vector file (AI, CorelDRAW, Autocad, DXF) PDF with exact positioning of marking shall be provided.
3. By laser engraving, the depth is about 0.08mm to 0.5mm, usually grey color.

For any other no standard features requirement, please contact us

NINE-Quality Documentation Standards

To ensure orders meet our quality standards and provide certifications and reports upon request, we provide the following quality documentations.
 DefinitionAdditional CostTechnologyMinimum Order ValueRequired
Certificate of ConformanceA Certificate of Conformance certifies that a particular order has been delivered with the required order specifications. Certificates of Conformance are available for CNC and SM only.YesCNC
 Sheet metal fabrication
NoneThrough your project manager
RoHS Certificates of ComplianceRoHS stands for Risk of Hazardous Substances. It is a legal requirement in EU. It is typically required to ensure that parts have been manufactured responsibly.YesCNC
 Sheet metal fabrication
NoneThrough your project manager
REACH CertificateA REACH Certificate declares that the materials used to manufacture the products, including packaging, do not contain more than 0.1% of hazardous substances as per the ones listed in the European REACH regulation. It is similar to RoHS, but does not require additional testing per order to certify it.YesCNC
 Sheet metal fabrication
NoneThrough your project manager
Material CertificatesMaterial Certificates are typically requested by customers to ensure the material provided meets their standards. Material Certificates are available for all materials. For metals, a material test report is encouraged instead.NOCNC
 Sheet metal fabrication
NoneThrough your project manager
Material Test ReportA Material Test Report certifies that the chemical analysis and mechanical properties are in conformance with the specified material specification. It’s also known as a mill-test report. Material testing is carried out by a third party quality lab. Material test reports are only available for metals.  Chemistry testing, tensile test and hardness test are on a sample from the production batch.NOCNCNoneThrough your project manager
Dimensional Inspection Report (CMM)A Dimensional Inspection Report assesses key measurements in a small batch or full order against acceptable tolerances. Dimensional Inspection Reports can be done manually or automated with a CMM machine. In cases where CMM is impractical, manual tools are used, and the specific tool is documented in the report.YesCNC
 Sheet metal fabrication
Depends on critical dimensions, batch size and number of different parts. $100 minimum, free for orders above $10,000USD.1. Critical dimensions specified on technical drawings.
2. Batch size, typically following industry standards.
3. Parts to undergo inspection.
First Article Inspection (FAI)
“First Article Inspection” (FAI) is a service to ensure that parts meet specifications before mass production begins. It involves thoroughly measuring and documenting all features of a part or assembly. Typically, we conducts the FAI, and the customer reviews or approves the report to ensure compliance with specifications, such as those outlined in the technical drawings. The inspected article may not necessarily be the very first produced but a representative sample from the initial production lot.

FAI documentation includes:

1. Material compliance certificates, which vary for metals and plastics:
· Metals: Material Test Report
· Plastics: Material Certificates
2. A comprehensive Dimensional Report
3. A Production Flowchart
4. A Production Control Plan
5. A Parts Acceptance Letter

Approval Procedure:

Upon sample part delivery, the customer has 1 week for approval. Approval involves signing the parts acceptance letter.

1. If Approved: Mass Production proceeds, and the entire order is fulfilled as usual.
2. If Disputed for Quality Reasons: A standard dispute process is followed, and the customer can choose to cancel the order or request a remake.
3. If Declined for Design Reasons: The customer can cancel the entire order and will be responsible for the cost of the sample sets.
YesCNCNone1. Critical dimensions specified on technical drawings.
2. Batch size, typically following industry standards.
3. Parts to undergo inspection.