Big  Blue Saw


General Updates

We often see parts come out slightly smaller than the designer expected when they're designed in a vector based drawing tool like Inkscape, Illustrator or Corel Draw. These parts show up smaller in the online quoting tool than they do in the drawing software. This is due to the stroke width of the part. Let's take a look at how this can happen.

In Inkscape, we'll resize a square with rounded corners to be 5 inches by 5 inches and export the design to a DXF format file.

When uploaded to our online quoting system, the size is only 4.902 x 4.902 inches!

What's going on here?

The secret is that Inkscape counts the stroke width as part of the object's size. So if your line is 0.098 inches wide, this increases the overall width and height of the part beyond the center of the line by 0.098 inches (0.049 inches on each side). Our online quoting tool (and most CAD programs) measure from the center of the line, rather than the edge of the stroke.

The solution is to set a very small or 0 line width before resizing. Let's set the line width to be 0, then resize to 5 x 5 inches, and export again.

Now when the part is uploaded, the dimensions are correct.


You have seen parts from Big Blue Saw being used for robots, lighting fixtures, signs, car parts, electric vehicles, and more robots. But you may be having trouble deciding which material to order. During our Tough and Transparent Sale from Monday, October 17 though Wednesday, October 19, you have two great materials to choose from. And you can save on both of them.



All of Big Blue Saw's polycarbonate and aluminum parts are made using waterjet cutting, which allows us to turn flat sheets of solid mateiral into real parts based on the designs you upload to our online quoting system.

Polycarbonate is a plastic with a high tensile strength of 8000 to 16,000 psi. 

Being a polymer, it is lightweight. And it's transparent to boot.




Polycarbonate happens to be one of the tougher plastics around.  Impact toughness is the ability of a material to absorb energy and plastically deform without fracturing. To put some numbers behind it, polycarbonate has a notched Izod impact strength of  5.71 ft-lb/in² or 12.0 kJ/m². That's over 7 times tougher than acrylic (Plexiglas®) plastic. So polycarbonate can take a beating without shattering or cracking.





Meanwhile, if you need something much tougher, you could try aluminum alloy 6061. It has a fracture toughness (ability to resist breaking completely after cracking) of 29.0 MPa-m½ or 26.4 ksi-in½.

Aluminum 6061 also provides fantastic stiffness for its weight, making it an ideal material for frame parts, trusses, bearing blocks, and the like. It also is corrosion resistant, weldable, and looks good too, which makes it a great choice for a variety of other applications.

If you're looking for stiffness of aluminum or the transparency and light weight of polycarbonate, Big Blue Saw makes the custom parts you need.




During the Tough and Transparent Sale, waterjet cut parts ordered online made from aluminum 6061 in 0.25 inch thickness and polycarbonate in 0.125 inch thickness will automatically receive a quantity discount. This means that when ordering as few as 1 part,  you'll get the same discount as if you had ordered 10 pieces. Depending upon the design, you will save as much as 70% off your order.

Upload your design now to our online quoting system to get started.

"You have areas inside the part which cross each other."

You may have seen this error when uploading a design to Big Blue Saw's online quoting system. Let's take a closer look at what this error means and how we can correct the problem.

This message indicates that the online quoting system is able to find the outside outline of the part, but you have holes or other features within that outline that cross over each other.

If you're just beginning with Big Blue Saw, it's important to understand two things:

1.  What kinds of parts you can make with Big Blue Saw. We can make parts using waterjet cutting or laser cutting. This means that all parts are cut from flat stock. The flat stock is cut completely through on every pass of the laser or waterjet.

2. Your uploaded design should contain only the outline of the part to be made, scaled 1:1. Read our guide to formatting CAD files.

With those 2 basics in mind, read on for help diagnosing and correcting common mistakes.

Where to click to get a diagnostic view.

When you get an error when uploading a design, you should begin diagnosing the problem by clicking the link for the Diagnostic View of the part. This will show incomplete lines and highlight problem areas.

Diagnostic View

If you haven't already, review the DXF or DWG file in software which is specifically intended for working with these files, like DraftSight, LibreCAD or QCAD. We have a list of free and low cost software for working with DXF files. Sometimes when you export from an application which is not specifically designed for DXF files, the export won't be completely clean. Zoom in on the areas where the online quoting system finds a problem. Sometimes you will need to zoom in quite closely to find the mistake.

Here are 5 common causes of the error "You have areas inside the part which cross each other."

1.  The line in the drawing was intended as a cut line, not the outline of a part.

Drawing of a puzzle with common cut lines.

Box for laser cutting with common cut lines.

This is often the case for jigsaw puzzles and designs with pieces intended to fit together after laser cutting. Every part should be outlined individually to work with the online quoting system.

It can sometimes be practical for us to do this type of cut. Contact us if you really need this type of waterjet or laser cutting.

2. You have duplicate overlapping lines due to a 3D projection error.

3D part incorrectly projected into 2D

If you have created the original drawing with a 3D drawing tool (SolidWorks, Sketchup, OnShape, etc.), make sure that your export to a 2D drawing does not include any hidden lines. The drawing used with Big Blue Saw should be a single outline of the face to be cut.

Often lines from a 3D projection will be closely overlapped and may be hard to see without zooming in closely. You may have to try selecting lines and deleting them to find closely overlapped lines.

3. You have duplicate overlapping lines due to a stroke path.

Outline from a doubled stroke path.

When using a vector based illustration tool like Illustrator, Corel Draw, or Inkscape, make sure that the export procedure you used exports a single line for the outline of your part. These tools can sometimes export a stroked path as two separate lines: the inside of the stroked shape, and the outside of the stroked shape.

View the drawing in outline mode (View | Display Mode | Outline  in Inkscape or View | Outline in Illustrator) to see the outlines which make up the shape.

Normal view on left in Inkscape of a shape with a complex stroke path, outline view on right.

Delete any outlines other than the ones which show the exact outside outline of your parts. Remove any lines or paths which cross over other lines or paths.

4. You have visible objects in the drawing which were not merged correctly.

Outline view of a part with incorrectly merged holes.

Like #4, this problem is also commonly seen when using drawing applications like Illustrator, Corel Draw, or Inkscape. You have multiple objects in your drawing which appear to be the a single object because they overlap and are the same color.

Again, view the drawing in outline mode (View | Display Mode | Outline  in Inkscape or View | Outline in Illustrator) to see the outlines of the shapes in the drawing. Merging the shapes before exporting should fix this problem.

Normal view (left) and outline view (right) of a part with incorrectly merged holes.

5. Your drawing includes a sheet format or information other than the outline of the part to be cut.

Some CAD software will create a grid for you to enter information about the creator of the file, date, material, and so forth. The solution here is to delete everything in the drawing other than the outline of the part to be cut.

If you have gone through all of these steps and still can't find the problem with your file, please contact us and we'll do what we can to get your design working.





CAD without CAD? No, it's not a Zen koan, it's maker.js, an open source project from Microsoft Garage that lets you create CAD designs by just tweaking a few settings. For example, the ring designer shown above lets you make rings or washers of any size by just entering an inner and outer diameter. Best of all, it outputs DXF files compatible with Big Blue Saw's online quoting system.

Here's another useful tool from maker.js: a sign creator with support for stencil fonts, rounded corners, and mounting holes.

There's also double pipe clamp builder. I'm told that this was inspired by the custom clamp from our articles on designing for waterjet.

Check out more things you can design on the maker.js demo page.

If you're ready to join two waterjet or laser cut parts together at 90 degrees to each other, you have a few good options.

Welding will work, but comes with its own difficulties, including the fact that it requires a welding machine and the skill to use it.

To join flat parts at right angles using only fasteners like nuts and bolts, read on.

The first technique is the t-nut techique, optionally using tab-and-slot for additional strength. Read more about it in our article on corner braces and the t-nut technique.

This technique can be done with common hardware store nuts and bolts. It occupies little space, except where the nut protrudes from the plate. The hardware is partially exposed, which can make assembly easier, but is less elegant looking than using nutstrip (described below) and leaves the hardware vulnerable to being bumped out of place.

Another popular option for joining plates at 90 degrees is to use nutstrip. This handy hardware is a square bar of aluminum with tapped holes at 90 degrees to make it easy to stick two parts together. You can cut it to length with a hacksaw to get just the right amount of hold.

One disadvantage of nutstrip is that it does occupy some space in the corners where your plates come together. On the other hand, it is very handy for lids and access panels, as you don't have to worry about the nutstrip falling out while you screw it in from the outside as it's held in place to the other panel. Read more about using nutstrip.

Got any other ideas for joining flat parts together at 90 degrees? Let us know!