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- Written by Simon Arthur
- Parent Category: Big Blue Saw Blog
How close can a hole be to the edge of a waterjet cut part?
We know that there are limits to hole size and narrow areas are a bad idea but how close can you place the cutting line of a hole and another feature? In some cases placing the holes too close to the outer cutting line can cause problems. We can make some assumptions based on the known accuracy of the waterjet cutter, but it's best to test it out.
In this design for our test, the 6 holes are 0.12 inches in diameter, and are placed progressively closer to the edge as you go further to the right. The holes are situated 0.09", 0.06", 0.04", 0.025", 0.01", and 0.001" from the edge. To see how the stock thickness affects the resulting parts, we waterjet cut this part from aluminum 6061 in three thicknesses: 0.063", 0.125", and 0.25".
First up is the 0.063 inch thick material. Here's the result:
Notice that the hole closest to the edge (0.001 inch) is starting to wear through to the outer cutting line. Keep in mind that holes are only guaranteed to be within 0.01 inches of the specified diameter due to nozzle wear and other factors. Also, the thin section between the hole and the outer cutting line can vibrate during cutting, again leading to this kind of blowout.
In the photos above, you can just barely see that the hole spaced 0.01 inches from the edge is starting to cut through to the edge as well.
The effect is more pronounced in the 0.125 inch thick material:
And it's even more visible on the 0.25 inch thick material shown in the two pictures below.
Remember that due to taper, the hole is wider on the top face, and narrower on the bottom face. (Low-taper waterjet cutting wouldn't help in this case. The taper-compensation process needs a certain amount of space to work correctly, so you will still end up with taper on small holes even when cutting using the low-taper option.)
If this kind of defect doesn't matter for your design, we can still cut the holes close to the outer cut line. Just keep in mind that your holes might end up connecting to the outside if there's not 0.025 inches or more between the hole and the outside of the part.
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- Written by Simon Arthur
- Parent Category: Big Blue Saw Blog
As it's time to bid farewell to 2017 and ring in 2018, and it's time to say goodbye to some of our stock materials and say hello to a few new ones.
Certain sizes of stock material have getting harder to obtain from our suppliers. So we've dropped them from our online quoting system (they may be available as a special order, just contact us and we will see what we can do).
Other materials, like aluminum 5052 and cold rolled steel A366/1008, have been increasing in popularity. So we're adding new sizes of those for instant ordering.
Here are the materials which have newly updated thicknesses:
| Material | Available thickness in inches |
|---|---|
| Aluminum 5052 | 0.02, 0.025, 0.032, 0.04, 0.05, 0.063, 0.08, 0.09, 0.1, 0.125, 0.1875, 0.249, 0.375 |
| Aluminum 6061 | 0.016, 0.02, 0.025, 0.032, 0.04, 0.05, 0.063, 0.08, 0.09, 0.1, 0.125, 0.16, 0.19, 0.25, 0.3125, 0.375, 0.5, 0.625, 0.75, 0.875, 1 |
| Stainless Steel T-304 | 0.018, 0.024, 0.03, 0.036, 0.048, 0.06, 0.075, 0.105, 0.12, 0.1875, 0.25, 0.3125, 0.375, 0.5, 0.625, 0.75, 1 |
| Stainless Steel 316 | 0.018, 0.024, 0.03, 0.036, 0.048, 0.06, 0.075, 0.105, 0.12, 0.135, 0.1875, 0.25, 0.3125, 0.375, 0.5, 0.625, 0.75, 1 |
| Cold Rolled Steel A366/1008 | 0.0239, 0.0299, 0.0359, 0.048, 0.0598, 0.075, 0.0897, 0.105, 0.125 |
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- Written by Super User
- Parent Category: Big Blue Saw Blog
Our last sale of 2017 lets you save on our most popular material: aluminum 6061 in 0.25 inch (1/4" or 6.35 mm) thickness.
During the sale, parts using this stock material and ordered online will automatically receive a quantity discount, no matter the size of the order! If you've never ordered from us before, a sale is the best time to try our services. And aluminum 6061 can be used in a tremendous variety of applications. It's lightweight, strong, and weldable, with good thermal and electrical conductivity. We've had customers use aluminum 6061 in literally hundreds of applications including bearing blocks, baseplates, jigs, fixtures, extruder dies, and much more.
Read more about customers who love Big Blue Saw.
How much can you save with our quantity discounts? Check out these examples:
This 21x21 inch robot baseplate normally goes for $172.20 when waterjet cut from 0.25 inch thick aluminum 6061. During the sale, you can get the quantity 10 price even when ordering as little as 1 piece. That brings the price down to $125.20, or 27% off.
For smaller parts, the deal is even better. This gearbox plate at 4.7x4.4 inches would normally be $92.10 when ordering 1 waterjet cut from aluminum 6061 in 0.25 inch thickness. But during the sale, you can get it for $12.60, the same price as if you had ordered 10. That's 86% off the regular price.
This is Big Blue Saw's last sale of the year, so act now byuploading your design to our online quoting and ordering system. The sale starts Monday, December 11 and ends Tuesday, December 12, 2017.
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- Written by Super User
- Parent Category: Big Blue Saw Blog
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- Written by Simon Arthur
- Parent Category: Big Blue Saw Blog
At Big Blue Saw, we get a lot of DXF files from our customers, and some of the file sizes are just too big. Sometimes even simple designs can result in huge file sizes, making them inconvenient to store, e-mail, load into CAD programs or use to get a quote in our online quoting and ordering system. Let's look at problems that bloat file size and how we can slim down the files so that they're more managable.
First, keep in mind that there is a certain amount of overhead associated with the DXF file format. This overhead varies based on the DXF version used. The DXF format originated with AutoCAD, the granddaddy of all 2D CAD software. As AutoCAD added more features with each release, the file format changed. Versions of the DXF format are named based on the AutoCAD version where they were first introduced. Some popular versions include R12 (AutoCAD version 12), R15 (AutoCAD 2000, the 15th relase of AutoCAD), and R32, from the 32nd release of AutoCAD, AutoCAD 2018, the latest as of this writing. (All of this also applies to the DWG file format as well.) In general, the newer DXF formats have more overhead, meaning that the files eat up more storage.
Consider this simple 8 inch square, drawn in QCad. Let's see how the various DXF versions affect the size of the file when it's saved.
When saving as an R12 DXF in QCad, the file size is 17,392 bytes. Saving as an R27 DXF, though, balloons file file size up to 101,172 bytes, a 5.8x increase.
We have some custom tools that we use internally at Big Blue Saw to manipulate DXF files, and using those, we can strip the file down to a puny 469 bytes!
But that's not always the whole story. Take a look at the design below, again made with QCad. The internal holes are made using the spline tool.
QCad lets us save as both an R12 DXF and an R27 DXF. Here are the file sizes for both versions:
| Version | Size |
| R12 | 176,226 bytes |
| R27 | 136,518 bytes |
Unlike in the previous example, the R12 file is actually much larger.
Let's take a closer look at what's going on. If you zoom in on one of the irregularly shaped holes you can see that the spline has been turned into a series of small lines.
This is because R12 and earlier DXF versions do not support splines directly. So QCad, like many CAD tools, converts these splines into tiny lines in order to approximate the true shape. With all of these lines, the file size increased dramatically.
Again, at Big Blue Saw we have a tool we use internally which can turn both splines and curves made of many segments into smooth circular arcs which are compatible with the R12 DXF format. You can do this manually by drawing arcs on top of the shape in a new layer. After running this tool, the file size is only 61,851 bytes, less than half size of the R27 version with the splines. The image below gives you an idea of what the arc segments look in the updated file.
Another common source of file bloat comes from tracing bitmap (AKA raster) images to vector format. If we use an automatic tracing tool on the raster image below, we can produce a DXF file.
The DXF file that results from the trace is 15,752 bytes.
Again, if we zoom on the details in the design, we can see that it's made from hundreds of tiny segments.
Replacing those segments with smooth circular arcs brings the file size down by half.
The resulting file is just 7600 bytes.
There's one final source of file bloat I want to show you: unused blocks. Here's a file sent to us by a customer (slightly modified to protect the customer's design).
This simple design clocks in at a whopping 7.3 megabytes. It's not made up of a zillion tiny lines like in the previous examples, either, just a simple curve at the top and 3 line segments. So why is the file size so huge? Opening the file in QCad gives us the answer.
There are hundreds of unused blocks in this design. Fixing the file size is a matter of deleting the unused blocks or copying the visible design and pasting it into a new file. (A similar problem can occur with unused or invisible layers as well.)
This reduces our 7.3 megabyte behemoth to a much more managable 16,042 bytes.