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Big Blue Saw Blog General Updates

Useful new materials in white

We're happy to announce 3 great new options for white plastic. Many loyal Big Blue Saw customers have been searching for better options for white keyboard plates, enclosures, control panels and the like.

First up: we are now offering white acetal plastic in 0.03 and 0.062 inch thicknesses. Acetal is a tough, durable material for machine parts, bearings, washers, and the like. We also offer acetal in black and in a variety of other thicknesses.

Next, we are pleased to offer white ABS plastic in 0.06 inch thickness. ABS is also tough, but less suited for wearing applications than acetal. It's also easier to glue, form and shape, and has better chemical resistance than acetal.

All of these new options come in white. But is white really white? Listen to the sonorous voice of poet Ken Nordine answer these questions far better than I ever could.

As always, if you don't see the material you need for your project in our online quoting system, please contact us and let us know what you're looking for!

Tips for Fixing Problems with CAD Files

We are often asked to diagnose problems with CAD files that don't work with our online quoting system. There are a couple basic rules for formatting CAD files: enter only the outline of the design you want us to cut, and make sure that the endpoints of all segments meet.

But some problems with CAD files can be tough to diagnose.  Let's take a look at a few common problems and their solutions.

Hidden overlapping lines

The CAD file shown below seems simple enough: a rectangle with two round holes.

But when we upload the design to the online quoting system, the system shows the circles as positive space. The rectangle is nowhere to be seen!

 

 

To diagnose this problem, we'll need to take a look at the diagnostic view. On designs with unclosed lines or other problems, there will be a link to the diagnostic view.

 

The diagnostic view shows something unusual: an endpoint on the upper segment of the rectangle. This indicates that we may have an extra segment in the outline.

Selection 245

To find the extra segment, we will open the design in our CAD program, QCad. We'll  use a selection box to select the entire corner area.

 


 

QCad highlights any selected segments by showing blue squares as its endpoints.  You can see in the image below an extra segment that overlaps the line at the top. We'll delete this and try the online quoting system again.

 

Success! The online quoting system now shows the correct outline of our file.

 Selection 248

 

Endpoints not meeting correctly

  Occasionally, you will see a message like the one below.

Selection 249

This message can be due to a variety of problems, but typically this is due to the outline not being complete. Let's take a closer look using the diagnostic view as mentioned above.

Selection 250

The green circles indicate endpoints of segments. Where a green circle appears, the quoting system was unable to match the endpoints of two segments together. So it makes sense to zoom in to check each of these areas for problems.

Opening the file in QCad and zooming in on the area in the upper center shows a section that doesn't look like a smooth outline. We can correct this by deleting any extra segments, and making sure that segments meet at their endpoints.

Selection 251

 

After deleting the unnecessary lines and making sure the remaining segments meet at their endpoints, the online quoting system can now correctly deterimine the shape of the piece to be cut.

Selection 252

Self-crossing contours in thin areas

Let's take a look at another kind of problem: self-crossing enclosures. These show up as orange areas in the online quoting system. The image below is typical of a certain kind of design we see from customers.

Selection 253

From experience, I know that the long thin cutouts at the bottom can be a problem. Remember that the kerf width of the waterjet is about 0.04 inches (1 mm) in diameter. So the narrowest areas in the cutouts likely won't be able to be cut. So I would guess that the these areas have not been reviewed correctly by the original designer.

Opening the file in QCad and zooming in shows that this is indeed the case. You can see in the image below that rather than meeting at a point, the lines making up the edges of the slots are crossing over each other.

Selection 255

 With some use of the "Trim" tool in QCad, the design can be cleaned up as shown below.

Selection 256

And now the design is ready for the online quoting system, as seen here.

Selection 257

 

Now that you've seen how to fix some of the more common problems, why not try uploading your design to our online quoting system?

May the Fourth (of an Inch) Be With You in Our Sale on Aluminum and Steel

Big Blue Saw sale on 1/4" thick aluminum 6061 and hot roll steel 1045 runs May 4-6.

On May the Fourth, Big Blue Saw strikes back with the revenge of low prices: a sale on custom CNC waterjet cut parts! This is not your ordinary holiday special: we're offering discounts on both 6061 aluminum and 1045 hot roll steel through Wednesday, May the 6th.

Every order placed online for these 3 days with waterjet cutting will automatically receive a quantity discount. Here's a trilogy of examples:

  • Our control panel example part waterjet cut from aluminum 6061 normally costs $103.30 in quantity 1. During the sale, the price will be just $46.00, a savings of over 44%.


  • The baseplate example waterjet cut from 1045 hot rolled steel has a regular price of $121.90 in quantity 1, but the sale price is just $32.40, saving you 73%.


  • Our butterfly example part waterjet cut from aluminum 6061 is regularly priced at $92.10 in quantity 1, but during the sale will be just $11.30, a savings of almost 88% off the original price!

If you've never used Big Blue Saw before and have a new project you're hoping to start, this is a great time to start without spending a lot of money. Those of you who need to clone an earlier project should attack the online quoting system now.

Use the share buttons below to tell your friends all about Big Blue Saw's latest sale!


Spring Design Contest: the Winners

We're proud to announce the winners today of Big Blue Saw's Spring Design Contest. The contest was close because all of the entries had their strengths, but in the end our judges were abe to pick the winners.

 

First up, the Honorable Mentions, in no particular order:

 

2nd Place and winner of $150 in services from Big Blue Saw waterjet or laser cutting:

Spring Flowers by Ian M.

Ian designed this lovely vase and flowers so that nearly all the pieces could be made using Big Blue Saw. Says Ian:

In honor of the spring design contest, I decided to create a centerpiece which shows spring in two ways. The first is thematically with a fresh bouquet of flowers with butterflies flying around. The weather turns warmer, and the flowers start to bloom. The second is by construction technique for the vase. The vase is cut from three sheets of copper which are then stretched upwards to form the vase, one large spring.

Read more about it and download the CAD files from Ian's GrabCAD page.

 

Grand Prize Winner $300 in services from Big Blue Saw waterjet or laser cutting

Luma Scissors by Jeff K.

Barely edging out Spring Flowers to win the grand prize by a hair is Luma Scissors, by Jeff K. Luma Scissors are a moving sign for hair salons. His cause was no doubt helped by his detailed video explaining exactly how he puts together the Luma Scissors signs from parts made by Big Blue Saw.

Jeff is a big fan of waterjet cutting. He writes:

By taking advantage of the water jet process’s ability to make precise and intricate designs, I am able to reduce the cost of my parts and reduce the cost of assembly.

Read more about the Luma Scissors on their website.

A big thanks to everyone who entered and our esteemed judges!

 

Nesting Files for Optimum Pricing With Big Blue Saw

Rufous hummingbird (female nesting)

"Nesting" refers to packing multiple shapes together.

As many of you know,  you can get a much better per-part price if you put multiple parts of the same design in to a single file to upload to our instant quoting system.

I'm often asked by customers looking to order multiple parts in a single file how to correctly arrange the files together in order to get the best possible price. In the majority of cases, the answer is "don't bother". Sometimes it does make sense, though. We'll take a closer look at when you might want to pack your parts closely together and when you shouldn't worry about it.

Note that this information is current as of the date of this article, and we may update or improve our instant quotes in the future.

When nesting doesn't matter at all

Let's first take a look at a case where it does not matter how you nest the parts.

In this design, four rectangles are spread out over an area about 31.4 inches by 15 inches. If we pick one of Big Blue Saw's most expensive stock materials, Stainless Steel 304 at 0.75 inches thick, we get a single set price of $247.90.

So we pack them closer together. Now the rectangles are squished into 18x7.1 inches. The single set price with the same material as above is now... $247.90.

Finally, we'll really pack them in and get rid of almost all the space between parts so that they're now 17.5x7.1 inches. The price then becomes... $247.90 yet again. So for all of our effort to get a good nesting on these parts, we've saved no money.

When nesting matters a little

But nesting DOES matter in some cases. Take a look at these two parts within a single file. They are approxmately 11x17 inches and 1.4x8.4 inches. When you get a quote for these with aluminum 6061 in 0.125 inch thickness (one of our most popular materials),  you get a price of $97.60 for quantity 1 set or  $23.34 each set in quantity 10.

Now let's fit the two pieces together as shown here. The  price comes down to $96.80 for each set of 2 or  $22.49 in quantity 10. So you'd be saving 80 cents off of your total price in quanitity 1 or $8.50 in quantity 10.

Why did this nesting change the price when we saw earlier that packing the shapes closer together didn't affect the price? The online quoting system looks the rectangles measured horizontally and vertically which enclose the parts and uses those to calculate the amount of material needed to make your parts. If the rectangles don't overlap, you have the case we saw earlier, where the nesting did not affect the price. However, if the bounding rectangles overlap, we can probably use less material to make your parts, and thus you will save money.

Note that if nesting two parts together gives an enclosing rectangle with an area larger than the area used by the parts separately, the quoting system will add the two bounding rectangles together in order to give you a lower price.

When nesting matters a lot


With that in mind, let's take a look at an extreme example. In this case, the parts are 10.9 x 17 and 12 x 8.6 inches. When we choose an expensive stock, like 0.75 inch thick stainless steel 304, the price for 1 set is $479.10 for the separate pieces and $366.80 when the pieces are closely nested. Here, the difference is between two enclosing rectangles 10.9 x 17 and 12 x 8.6 inches  or 288.5 square inches vs. a single enclosing rectangle 11.5 x 17 inches or 195.5 square inches.

Part orientation

Here's another case where how you position the parts in your design can have an impact on your final quote. The pieces on the left and right have the same dimensions, but the one on the right has been tilted almost 45 degrees. The piece on the left has a measurement of 0.9 inches X 15.9 inches. On the right, it measures 12.5 inches horizontally by 11.1 inches vertically. When made with stainless steel 304 0.75 inches thick, the price goes from $96.90 for the piece on the left to $250.10 for the piece on the right. This is because the enclosing rectangle for the tilted piece is significantly larger, so the quoting system thinks that it will take a lot more material to make the part.

Making things easy for us

We often get e-mails from customers wanting to change their nesting in order to "make things easy" when the parts are cut, wanting to fit into a whole sheet, and the like. This usually doesn't make sense, as we cut most of our parts from very large sheets and charge you strictly for the material used. Often, the sheets we're using have already had a few previous parts cut from them, so your nesting may not fit into the stock we have available.

If you happen to make the parts too close together on an order with stock material, this isn't a problem for us, as we typically end up re-nesting anyway.

The one case where having a nesting from a customer may make a difference is if we are cutting a custom material supplied by that customer. When you're ordering this way, should know the dimensions of the material you're providing. Keep in mind that for waterjet cutting, we need a 0.25 inch margin around all edges and a 0.125 inch space between each part. For laser cutting, we need an 0.25 inch margin, and 0.03 inch spacing between each part.

Summary

  • For designs with a mostly rectangular outline, changing the nesting won't change the price at all.
  • If you can fit one part inside another, it may help the price, especially on more expensive stock materials.
  • Rotate your parts to minimize the enclosing rectangle.
  • After you order, when it's time for us to cut your parts, we often re-nest parts on stock materials.

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Big Blue Saw
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Waterjet and Laser Cut Custom Parts.
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3522 Ashford Dunwoody Rd NE #145
Atlanta, GA 30319
Phone: (678) WAY-SAW4 (678) 929-7294