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Big Blue Saw Blog General Updates

Custom laser cut acrylic lighting diffuser

At Big Blue Saw galactic headquarters, we have a number of recessed ceiling lights that have sprouted high efficiency CFL bulbs. They produce plenty of bright light, helpful in the dark winter months. The downside is that they look kind of ugly. See for yourself in the photo below.

I had the idea to make these a bit prettier by making a cover.  But why make a plain lighting diffuser when I could use the laser cutter to make them Big Blue Saw themed! I designed a 10 inch diameter diffuser with a series of 5 mounting holes the at the same diameter as the recessed lighting fixture ring.

 

 

For the material, I chose our stock P95 acrylic, which is ideal for a lighting fixture as it transmits 95% of light and diffuses light in a soft pattern. After laser cutting and removing the protective paper coating, we had the piece shown below.

To install these, I used some clips made from copper wire. The diffusers were installed frosted side up. Here are the results.

Much better. I especially like the way the edges catch the light. What do you think? Let us know in the comments.

 

 

Sale February 9-10 on Custom Waterjet Cut Parts

Big Blue Saw is having a sale on custom waterjet cut parts! On Tuesday, February 9, and Wednesday, February 10, all orders of waterjet cut aluminum 6061 in 1/4 inch thickness will automatically receive a quantity discount. When ordering as few as 1 part, you're getting the same price as if you ordered 10.

Let's see a couple examples of how this works.

Our 36x22 inch salon sign from our list of examples, waterjet cut from 1/4 inch thick aluminum 6061 normally costs $248.70 in quantity 1. But during the sale, you'll be able to get it for just $211. That's a savings of 15%.

Here's another piece from our example page: the gearbox side plate at 4.7x4.4 inches. When cut from 1/4 inch aluminum 6061, this piece would normally cost you $92.10 in quantity 1. During the sale, you'll save $79.50 on this, or 86%!

Get started by uploading your design to our online quoting and ordering system.

 

Jewlery and Other Small Parts with Waterjet Cutting

Big Blue Saw has done quite a bit of waterjet cutting of small parts. Small parts are often jewelry made with special materials like silver and bronze.

Let's take a look at how this can work out for a simple trefoil design cut from 1/8" thick aluminum plate. As you can see below, we made the design in several different sizes, from about 2 inches (50 mm) across down to 1/4 inch (6.4 mm) across.

The parts all had a rectangle at the top 0.125 inches wide. On the smallest two pieces, the lobes were 0.262 (6.7 mm) and 0.131 inches (3.3 mm) in diameter.

You can see how they turned out in the closeup photo below. Note that our limiting factor here is the cutting stream size (kerf width) of the waterjet: about 0.04 inches or 1 mm in diameter. That's slightly thinner than a CD or DVD. You will notice that the sharp inside corners of the original design become visibly rounded off at this scale. Designs at this scale and smaller are quite limited in the amount of detail they can have.

Below is an even closer look at the smallest piece. The top lobe is slightly asymmetrical, possibly due to the waterjet cutting path or vibration during cutting.

Small parts are typically tabbed to the sheet from which they're cut to prevent them from falling into the water catch tank. Here we can see that the tab is about 1/64 inch (0.4 mm) wide. This is almost too small for this particular design and material.  The larger pieces actually broke loose from their tabs during the simple handling needed to take these photos. The tab is designed to be thin enough that we can remove the part from the sheet easily. (Thin areas tend to break.) Thinner and weaker materials (remember that we're using 1/8" aluminum here) will likely require a wider tab, which could interfere with a small part's design.

 

Thin features on waterjet cut parts

It's true that waterjet cutting doesn't put much stress on the sides of the material that it's cutting compared to, say, milling. But vibrations from the cutting process can cause problems, especially near thin features. We created a couple sample pieces from aluminum 6061 to show just how thin you can make waterjet cut features. The photo above shows on the left a piece made from 1/4 inch (6.35 mm) thick material, and on the right you can see the same design cut from 1/16 inch (1.6 mm) stock.

You'll notice that the thinner material has one fewer bar. That's because the beefier material can hold thin features better than its skinnier counterpart. Thinner material is weaker for a given area and so it's more likely to vibrate when cut. You can see in the closeup below where the bar broke off. This bar was drawn to be 0.018 inches (0.46 mm) thick.

Even the thicker material had some trouble with a bar this thin. You can see that on the top face (the side where the waterjet stream first enters the material), the bar is missing some of its thickness and is just barely attached.

Below is a CAD drawing with the thinnest 3 bars. They are 0.0566, 0.0372 and 0.018 inches thick, respectively.


 

Keep in mind that these bars are only suspended from one side to the main body of the part. Connecting them to a bigger piece on both ends would help keep them stable when cutting. Also, different materials will behave differently when waterjet cut.

To summarize: narrow areas in  your design under 0.018 inches (0.046 mm) will probably not work out. Keep feature thickness to 0.037 inches (0.95 mm) and above. If absolutely must have thin features, use thicker material.

 

 

Load Holding Fixtures Using Waterjet Cutting

Fresh out of my e-mail inbox comes this fixture from a customer who wishes to remain anonymous. 

(Of course, at Big Blue Saw we keep your designs confidential. We also keep the fact that you're even a customer confidential as well. Many of the things we make end up in finished products, and our customers see Big Blue Saw's service as a competitive advantage. [Many are happy to provide testimonials, thankfully.] )

The structural pieces  were waterjet cut by Big Blue Saw from 1/4 inch thick aluminum 6061 and assembled by the customer using off the shelf hardware. The design uses tab-and-slot with the pieces held together with through bolts as in tensioned plate construction.

The customer says:


These are medium-load holding fixtures.  Using BBS for these type of fixtures saves us 50%+ on traditional tooling and also allows us to build instrument & medium load machines in a clean office!  (No welding, milling, sawing, etc - -just a few fasteners and counter-sinks.)  These fixtures are doing the job of machined 1/4" Al C-channel assemblies.


Got any parts you would like to show off or want to tell us how we are doing? Let us know!

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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