FAQ's & Help related to RP industry

Please check frequently asked questions related to CAD, CAM, RP & CNC Machining
What is preferred 3D Cad file format for cnc machining?
We prefer cad files in one of these formats:
  • STP or STEP (.stp or .step)
  • IGS or IGES (.igs or .iges)
  • PARASOLID (.x_t or .x_b)
What is STL format, and how can I export from CAD package?
STL file is simply a mesh of triangles wrapped around a CAD model was defined by 3D systems in the 1980s. STL, name is derived from rapid prototyping process, StereoLithography, also known as abbreviation of Standard Triangulation Language. This very simple format has become an industry standard for the Rapid Prototyping sector. Virtually all modern CAD systems now include STL or Rapid Prototyping output as a standard feature.

N.B. Sometimes we receive very low resolution STL files so nowadays we recommend our clients to send us 3d cad files in one of these formats: IGES (IGS), STEP (STP), Parasolid (.x_t or .x_b)

What to consider while creating STL file:

Generating STL files is usually a fairly simple process. But every CAD system uses different terms and parameters for defining the STL file resolution. It's not necessary to understand all those parameters to produce a useful STL file. The Following is a brief checklist which can help to produce a good quality STL file:
1) As a typical example mesh with triangles approximately the size between 0.02mm (.001") to 0.05 mm (.002") will produce a good quality STL file. Please keep in mind if you reduce mesh tolerance further down doesn't mean prototype accuracy will be improved. As a thumb rule parts with many contoured or curved surfaces need to have fine tolerance than straight geometric parts.
2) STL files are always preferred to be saved in Binary format than Ascii mode.
3) If you are using Solid CAD modeling package to create 3D model, there are fewer chances of having any error in STL file. For surface model please stitch/sew all surfaces together to make a single water tight model before exporting STL file. You may be still able to produce STL file from untrimmed or corrupt surfaces but will never get a clean STL file and much harder to fix STL file than native CAD file.
4) Generally STL file has no UNITS attached to it so its always good practice to send overall part sizes along with your STL file otherwise we wouldn't know your part dimensions. Most common units are MM or Inches.
5) Some CAD systems will generate error messages during STL conversion showing that some part of geometry is outside the positive X, Y, Z quadrant or is in negative space. These warning messages can be ignored.
6) Make sure to join all the solid model pieces to a single entity which you want to see in a single prototype. Otherwise, all those bits and pieces will end up separately in STL file, and we'll have to spend time to join them together, unless you want them to be separately made.

STL export guidelines from some of the common CAD systems:

Unigraphics
1) File > Export > Rapid Prototyping
2) Output type : Binary
3) Triangle & Adjacency Tolerance: .05mm
4) Set Auto normal Gen to ON
5) Set Normal Display to OFF or ON
6) Set Triangle Display to ON (good idea to leave ON so that you can see mesh pattern on your model)
7) File Header Information: Press OK
8) Sometimes it shows error messages "Negative coordinates found" which can be ignored
Pro/Engineer
1) File > Save a copy
2) Add 'New Name' or copy and paste from 'Model name' and choose STL from type drop down menu. > Hit ok
3) Accept 'binary' and 'negative value' defaults. Enter '0' in chord height box and system will set to minimum available.
4) Set angle control to 1
5) Check file name change if desired hit ok. File will be saved to your working directory.
SDRC I-DEAS
1) File > Export > Rapid Prototype File
2) Select the part to be exported
3) Select Prototype Device to SLA500.dat
4) Set Absolute Facet Deviation to 0.01 mm/(0.000395")
5) Select File type Binary and Save
SolidWorks
1) Open File > Save As
2) Set file type as STL
3) Select Options > Output as Binary
4) Select the units mm or inches
5) Select Quality > Fine
6) Save
SolidEdge
1) Open Model & select File > Save As
2) Select File type as STL
3) Options > conversion tolerance to 0.0254 mm (0.001")
4) Surface Plane Angle > 45°
5) Select Binary type and OK
6) Name & Save STL file
CATIA
1) Select STL command
2) Maximum Seg to 0.0125mm
3) Select the model and > select Yes
4) Select Export > type File name > OK
AutoCad
Note: STL can only be generated from 3D model not from 2D drawings or wireframe.
1) Type "STLOUT" at the command prompt
2) Select the objects to be exported
3) Select "Y" for Binary format
4) Type File name
If you get error message "No Solids selected" try to move your model in positive octant.
3D Studio Max
1) Open Document and save as a new file.
2) Select a few items of your object at one time.
3) Go to Modifiers ⇒ More ⇒ Select Mesh smooth ⇒ OK.
4) Under parameters increase iterations by 2 or 3.
5) If your part geometry is complex you may add more polygons.
6) Now your wire frame model is defined with polygons.
7) Once finished select all and export as an STL file.
IronCad
1) In the Graphics window Right-click on the part
2) Pick the Part Properties and Rendering
3) Select Facet Surface smoothing to 160
4) File and Export to an STL file
Rhinoceros
1) File > Save As
2) Select File Type to STL
3) Select File Name > Save
4) Select Binary
5) Select Detail Controls from Mesh Options
6) Max Angle = 20, Max aspect ratio = 6, Min edge Length = 0.0001
7) OK

Can you use STL file for machining?
Sorry, we can't use STL file for machining. We can use STL file for viewing or quotation purpose but need 3d CAD file in Parasolid or STEP or IGES format for machining.
Can you use 2D file for machining?
Occasionally we may accept 2D files like Autocad .dwg or .dxf formats for 2D machining, routing or wire-cutting jobs but prefer to have 3d file.
Do you work in Millimetres or Inches?
MM (Millimetres).
What is Rapid Prototyping?
Rapid Prototyping is an initial stage of product development process whereby it enables designers to evaluate the design intent. Rapid prototyping plays a pivotal role in an engineering product design context, helping designers to find an optimum design solution by iterative design methodology. Most of RP technologies are based on additive layering process to build a physical model.
What is 3d Printing?
3d Printing is a generic term primarily used for an additive manufacturing process, whereby an object is created layer by layer. There are a number of 3D Printing technologies borrowed from large RP systems, the major difference amongst them is material choice, build speed and accuracy of parts. 3D printing process starts with a 3d CAD model, designed on CAD software, which is sliced into layers. These layering data is passed on to 3d printer to build 3d physical model layer by layer.
What is FDM?
FDM also known as Fused Deposition Modeling is a layered manufacturing process. FDM offers functional prototypes with PLA, ABS and other materials. A thin bead of molten plastic is extruded through the computer controlled nozzle, which is deposited on a layer-by-layer basis to construct a prototype directly from 3D CAD data. The technology is commonly applied to form, fit and function analysis and concept visualisation. In addition, FDM can be used for pattern generation and rapid manufacturing.
What is SLA? How SLA Process works?
SLA also known as "Stereolithography", provides the greatest accuracy with an excellent surface finish. SLA parts are durable and these functional parts are suitable for wide variety of applications e.g. preproduction, Product verification, Form/Fit/function testing, thin walled parts. Please check our SLA specification page for detailed information.
How SLA Process works?
Stereolithography process produces plastic parts directly from 3D CAD model; by solidifying the surface of a liquid photo polymer layer by layer with the help of a laser beam. When the laser beam hits the liquid, it solidifies the resin. When a layer is fully traced, the elevator is then lowered in the vat. The self-adhesive property of the material causes the layer to stick with each other and in this way a 3d part is formed in multi-layers.
What is SLS? How SLS Process works?
SLS also known as "Selective Laser Sintering", primarily used to quickly produce three-dimensional prototypes, parts, direct mould inserts, tools, and lost wax casting patterns. SLS process provides durable, metal, plastic or rubber like prototypes directly from CAD models. These prototypes can be used as test parts for form, fit and function. SLS technology provides a broad range of materials e.g. rigid thermoplastics, stainless steel, polystyrene, thermoplastic elastomers, cast form plastic for investment castings. Please check our SLS specification page for detailed information.
How SLS Process works?
SLS process produces parts directly from 3D CAD model; layer by layer similar to SLA but rather than liquid resin powder is used. The CO2 Laser provides a concentrated heating beam which is traced over the tightly compacted layer of fine heat-fusible powder. The temperature in the entire chamber is maintained little below the melting point of the powder. So the laser slightly raises the temperature to cause sintering, means welding without melting. For the next level, the piston moves down along with the formed object and powder is spread with a roller for the next layer. Process repeats until the full object is formed.
What are the main applications of Rapid Prototyping?

Although there is a big listing of prototyping applications. This technology is maturing rapidly specially in automotive, medical, toys building, packaging, aerospace, electrical, scientific applications and so on.
Few examples of prototyping applications:
a) Imagine there is a major exhibition next week and your new product is still in development stage, How to get the part urgently? Just send us your CAD file rest is up to us to meet your deadline.
b) Why to take a risk of getting unrealistic quotes from your suppliers by sending 2d drawings, when you can send an inexpensive 3d physical part which will not only help to save money at the end but also helps to open new options to manufacture the part or tooling.
c) Manufacturers who need parts in small quantities where tooling or production cost is not justified.
d) Sometimes it is difficult for the designers or toolmakers to visualise or find out the problems in the drawings, by having the 3d part in their hands, helps them to figure out the problem and redesign it if required before investing on actual tooling.
e) Helps the medical field in different ways specially for re-constructive surgery by making 3d models created from CT scan of the patient's body parts.
f) Quickly making master model for vacuum casting to produce small quantity of Poly Urethane parts.
g) If you are a student, scientist, teacher, and you need to make a part for your next project or class demonstration, what to do? Rapid prototyping is the quick answer for you.
h) Building my new home but like to see how the design will look like in real life.
i) To make some Artistic or unique design for example statue, jewellery, special type of toy even some part is broken of your home appliance which is not easily available in the market.
j) Any spare parts or auto parts hard to find in the market.
k) Tooling inserts for plastic injection moulding direct in steel able to produce thousands of parts.
l) For further applications and material details please feel free to contact us

What is CNC machining?
CNC, stands for Computer Numerical Control, applies to machine control system but erroneously used as a replacement term for NC. CNC is a generic term for a vast field of numerical controllers. Our application is related to CNC Milling; used for machining complex parts and shapes hard to machine with conventional machines. Firstly cutter path is generated direct from the CAD model, which is transferred to machine controller in the form of numerical data. This data is used to move the machine table and tool to create the high precision jobs.
What are the Advantages of CNC machining?
  • No need to compromise with raw material because parts can be machined directly out of engineering plastics, ferrous or non-ferrous metals.
  • Suitable for accurate and highly finished parts.
  • Economical for small to short run of production parts that require wide range of operations to be performed.
  • Generally large and bulky parts are economical by CNC machining compared to Rapid Prototyping processes because most of RP proprietary materials are expensive.
What are the Disadvantages of CNC machining?
  • Need to spend considerable time for programming before actual machining.
  • Sometime sharp corners are difficult to machined due to cutter radius which need to be sharpened by secondary operation.
  • Undercuts are difficult to machine therefore sometimes parts need to be made in sections and glued to accommodate undercut features.
  • Deep and narrow pockets/slots could be difficult to machine due to cutter size constrains.
What is your most common plastic material used for general purpose components?
ABS, (Acrylonitrite Butadine Styrene) is a general purpose rigid Thermoplastic with a combination of properties that make it ideal for the widest range of applications.
What is suitable material for living-hinge featured components?
We normally use PP(Polypropylene) for living hinge parts. Check more detail on our Material related pages.
What is suitable material for clear transparent lens like parts?
  • Acrylic, also known as PMMA (PolyMethyl-MetaAcrylate) is an amorphous thermoplastic material with very good optical clarity.
  • PC (PolyCarbonate) can also be used for clear parts however clarity is a bit lower than Acrylic. If you need a combination of clarity and strength then Polycarbonate could be a better choice.
  • Follow more detail on our Material related web pages.
What are the other materials do you use for machining?
PLASTICS: ABS, Polycarbonate(PC), Acrylic(PMMA), Acetal(POM), Nylon(PA6), GF Nylon, PP(Polypropylene), HDPE (High Density PolyEthylene), Teflon.
METALS: Aluminium 6061, Aluminium 5083, Brass, Mild Steel, Stainless Steel 304, SSteel 316, Tool Steel, Zinc, Copper.
Can we supply our own material for machining?
Sorry we are unable to use third party materials due to company policy.
What type of finishing available?
  • By default, parts are supplied with smooth finish i.e. outer visible faces lightly sanded to remove all machining marks but inner non-visual faces are left as a machined finish.
  • Following type of finishes available:
  • Standard finish: Also comes under the category of Smooth finish, suitable for visual presentation
  • Polish finish: Good for clear parts
  • Highly Polished finish: Good for master models
  • Primer Finish: Parts are Grey primed making them ready for painting
  • Painted Finish: We can match to your Pantone PMS colour code in Matt, Satin or Gloss finish.
  • Metallic Finish: Can paint in metallic finish in most common colours.
  • Tinting: We can tint on Clear or translucent parts
  • Chrome Plating: Yes we can Chrome plate on ABS plastic parts, works well for Tapware and other metallic look parts
  • Anodising Finish: We can anodise Aluminium parts in most common colours.
  • Bead Blast: We generally use Bead Blast (Sand Blast) finish on metallic or translucent parts.
Do you have photos of different type of available finishes?
Do you have Pantone(PMS) colour chart available?
Yes, we have PMS chart available online but use with caution because colour matching may not be accurate due to monitor settings. Here's link Pantone PMS Chart
Do you take credit card payment?
Yes we do.
Do you ship Internationally?
Absolutely, we are serving worldwide clients for more than two decades. We use FedEx, DHL, TNT for overseas shipments depends upon your preference.

Are you looking to get your parts CNC Machined out of Plastic or Metal?

Please feel free to fill up our online quotation form for obligation free quote.