CNC FAQ SHEET

This page should help explain some frequently asked questions regarding general information about CNC milling, our size capabilities, how to best prepare files, and our policies.

CNC (Computer Numerically Controlled) milling is used to produce precise objects.

Our machines work with router bits in a spindle, which cut or carve objects in a subtractive process. These objects we produce are created using CAD (Computer Aided Design). Next, G-code (toolpath data) is created using CAM (Computer Aided Machining) software. Finally the G-code is ported to the CNC machine directing the motions and cutting paths.

There are two basic types of CNC milling we do: 2D and 3D.

2D Milling is for shapes that are cut out like a cookie-cutter. This type of cutting is referred to profiling, other 2d operations include: pocketing, drilling, chamfering, and engraving. Files for 2D cutting are vectors files, common formats are DXF (AutoCAD), AI(Illustrator), and 3DM(Rhinoceros).

3D Milling is for shapes that are in the round or have topographical or relief-type features. 3D objects created in CAD programs are either nurbs or meshes. Common formats are 3DM(Rhinoceros), IGES, STL(Sterolithograpgy), and DWG(AutoCAD). If possible try to supply a solid 3D form without any holes. Holes or gaps within an object can cause problems with toolpath generation and milling. Holes can be acceptable in some cases- if the cutting bit will not ‘fall-through’ the hole.

Our machines operate in 3 and 4th axis.

3-axis: 3-axis milling is defined when the machine can move in 3 axes simultaneously. These axes are referred to as X, Y, and Z.

4-axis: 4-axis milling is similar to 3-axis (x,y,z axes) however an additional axis is used. The 4th axis is located parallel to one of the other axes and rotates 360 degrees, acting like a lathe under the spindle. Generally this axis is refered to the A-axis.

SIZING

The capacities of our machines are as follows:

3 Axis: 10 feet (x-axis) x 5 feet (y-axis) x 40 inches (z-axis)
4 Axis: 40 inches diameter x 10 feet long

These dimensions show the largest part we can cut, however much larger objects can be fabricated by assembling with multiples parts.

MATERIALS

We are capable of cutting a variety of materials including: all non-ferrous metals (aluminum, brass, copper), plastics (Renshape, acrylic, Corian, ABS, foams (urethane, EPS), wood (solid, engineered).

FILE FORMATS

We take a variety of vector formats. Vectors graphics are created from mathematical creations (curves, points, surfaces) and are necessary for CAM output.

We work natively with Rhinoceros 3D software and prefer .3DM files, however other acceptable formats are: .DXF, .DWG (AutoCAD), .AI (Illustrator), .STL (Stereolithography), .3DS (3D StudioMax), .OBJ (Alias Wavefront), .IGES, among others.

We can also use bitmaps files. Bitmaps are images created through the use of pixels. However these images must be converted into vectors, which can be done upon request.

FILE PREPARATION

Please make all files as clear as possible to avoid confusion, this includes:

-If multiple sheets are drawn in one file, label each sheet individually within that file.

-If multiple processes are being executed (i.e. drilling, pocketing, engraving, and cutting) please put each process on a different layer labeled with the desired depth of cut. Example: To cut a dado with a depth of 3/8” label the layer: DADO-3-8IN-DEPTH.

-If cutting a 3D file, try to supply a file without any holes. Holes can be acceptable in some cases if the cutting bit is larger in diameter than the hole.

-If you are exporting your file we recommend that you import that file back into your program to make sure that it is precise. When exporting to a .DXF or .DWG file, smooth arcs may become segmented based on the export settings; this may change the shape dramatically.

Please make sure your file contains no:
-Loops.
-Identical parts copied on top of parts.
-Identical points on top of points.
-Identical lines on top of lines.

JOB PRICING

Cutting prices are based on several factors.

Our minimum job order is for $150.

2D cutting prices are based on the number of sheets of material, the number of parts per sheet, the number of operations, and the total linear inches of cutting.

Discounts are added as the job size increases.

3D cutting prices are based on the material being cut, the size of the piece, the complexity of the object, and most importantly the resolution of the final finish. This finish is referred to as stepover. Stepover is the amount of material that the bit will take off with each pass, the small the amount the bit takes off, or the finer the finish, the more machining time and cost.

Discounts are added as the job size increases.

MATERIAL PRICING

Clients may opt to supply their own materials. If the client does supply their material, we ask that he/she agrees to supply extra material in the case that there is a machining error. Generally, we will ask clients to supply extra sheets of material in larger jobs at the rate of 1 extra sheet per 20 sheets cut. These issues only apply if the client opts to supply materials.

ADVANCES AND FINAL PAYMENTS

We ask a 30% advance payment for all jobs over $1000.
We expect payment in full upon completion of any job. We will charge a finance charge for late payments, please see estimate or invoice for specific terms concerning payments and advances.

RUSH FEES

You may ask us to quote you for a rush turn-around. Our rush fees are: 30%, 50% or 100% added to base cost. The percentage given is based on the size of the job versus the extremity of the rush.