Design Guidelines for Composite, Wood and Plastic

Specifications, tips, and best practices for designing your CNC machined composite, plastic, and wood materials.

Best File Formats for CNC Machine Routing

Files Accepted by Our Instant Quote System:

Adobe Illustrator	.ai
AutoCAD	.dxf
CorelDraw	.eps
Fusion360	.dxf
Inkscape	.eps
Solidworks	.dxf

For laser cutting, we only accept vector files. We currently accept DXF (Preferred), AI (Adobe Illustrator), EPS, and DWG (more coming soon) in our automatic online quoter.

If you design your parts in non-CAD software (Adobe Illustrator, Inkscape, CorelDraw) please send us the original (native) .ai or .eps file. We’ll take care of the conversion on our end.

Please note that we cannot accept or process STL (mesh) files or raster-type (JPEG, TIFF, PNG, BMP) files.

Stuck with only a raster file (JPEG, GIF, PNG)?

We have tutorials to help you convert your art to vector in Adobe Illustrator and Inkscape.

Tooling Diameter and Radius

For composite materials, we use a CNC, chip-subtractive method (2-dimensional CNC flatbed machining) to cut your parts. We’ll use a 0.125″ bit, so allow for a radius of .063” on all internal geometry and minimum hole size of .125”.

Simple, 2-Dimensional, Perpendicular Cuts

No V-groves
No Threads
No 3D Contours
No Partial Depth Cuts
No Double-Sided Cuts
No Counter Bores

Minimum and Maximum Part Sizes

For composite materials, we are limiting the minimum and maximum part sizes in order to provide you with the quickest and most efficient CNC machining possible.

Minimum part size:

1” x 2”

Maximum part size:

44” x 23” (Delrin)
44” x 30” (ABS, ACM, HDPE, MDF, Plywood, and UHMW)

Overall size limitations for cutting by material can also be found in our part sizing chart.

CNC Router Tabs

All parts machined using the CNC router will have small fixturing tabs leftover on the edges. We use these tabs to ensure your parts remain in place and secure during the manufacturing process.

Tabs will be approximately .1875″ wide, and the depth will be equal to half of your chosen material thickness. These tabs can be easily sanded down and will not affect your final design in any way.

Check out our information on using fixture tabs in CNC machining if you have further questions.

Internal Geometry Considerations

Inside angles (acute angles) will have a slight radius due to the use of a round cutting tool. The radius will be .063″ due to the tool’s .125″ diameter.

Outside corners are unaffected, but tooling limitations make it impractical for us to produce perfectly square or sharp inside corners.

Material Removal and Design Density Considerations

Parts with large amounts of material removal may be impractical for us to produce. Grills, grates, and perforated patterns are not recommended and may be rejected.

We recommend no more than 50% material removed from a given part. The more material that you remove, the greater the risk that your part will move during the cutting process and become damaged.

Using Dogbone Fillets for Square Corners

If you have been designing in CAD for any length of time, you will be familiar with standard fillets. You may be less familiar with another type of fillet commonly used with CNC milling: The “Dogbone” fillet.

A standard fillet is used to reduce the sharpness of corners. You can modify corners with either a chamfer or curve.

The solution: Dogbone fillets!

However, for materials that are CNC machined, the inner corners can never be sharper than the diameter of the cutting tool. This is because the tooling is round, and it’s not possible to get perfectly square corners on interior geometry. Instead, these corners will be slightly rounded inwards (approximately .063″ radius). This can cause problems when joining parts, as a part with square edges might not fit in a hole or slot with rounded corners.

Ready, set go!

Now that you have the knowledge you are ready to start designing your parts for the CNC mill. Questions? Email us anytime: support@sendcutsend.com

Pre-flight Checklist

File is a two-dimensional vector format file.
All holes and cutouts are at least 50% material thickness for laser cut parts
All holes and cutouts are no less than 0.070” for most waterjet cut parts
All holes and cutouts are no less than 0.125” for all CNC routed parts
File is built at a 1:1 scale, preferably in inch or mm units
All objects are on the same layer
All stray points, duplicate lines, empty objects and text areas have been removed
No shapes have open contours
All shapes have been united, combined or merged
All text has been converted to outlines or paths
Cut-out text (reversed text) has bridges or has been stencilized

Materials available for CNC Routing

ABS

The perfect material for prototypes & instrument panels.

ACM Panel

Lightweight material for panels & simple parts.

Baltic Birch Plywood

Inexpensive, stable, and is made with waterproof glue.

HDPE

Easily moldable material used in medical & nautical applications.

MDF

An inexpensive alternative to plywood.

Polycarbonate

An incredibly versatile clear material used in robotics projects.

UHMW

Abrasion, impact, & chemical resistant.

Start your first SendCutSend project today!

Upload your CAD design or use our parts builder and get a free instant quote on your custom laser cut parts, all delivered to your door in a matter of days.

SKU	FH-M8-12
Thread Size	M8 x 1.25
Hole size in sheet (+0.003/-.0.000)	.315″
Minimum sheet thickness	0.94″
Maximum sheet thickness	.347″
Fastener material	Steel
Minimum distance hole C/L to edge	0.378″
When determining the distance between two or more fasteners, you can calculate the distance by the formula, C/L to edge + 1/2 the diameter of the second mounting hole.	.535″
Recommended panel material	Steel/Aluminum
Coating type	Zinc
Length	.472″
Aluminum material ranges (5052, 6061, 7075)	0.100″-0.250″
Steel material ranges (CRS, HRPO, HR)	0.104″-0.250″

SKU	SO-440-8
Thread Size	4-40 x .250″
Hole size in sheet (+0.003/-.0.000)	.168″
Minimum sheet thickness	0.040″
Maximum sheet thickness	.125″
Fastener material	Steel
Minimum distance hole C/L to edge	0.230″
When determining the distance between two or more fasteners, you can calculate the distance by the formula, C/L to edge + 1/2 the diameter of the second mounting hole.	.314″
Recommended panel material	Steel/Aluminum
Coating type	Zinc
Length	.250″
Aluminum material ranges (5052, 6061, 7075)	0.040″-0.125″
Steel material ranges (CRS, HRPO, HR)	0.048″-0.119″