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Starting April 18, 2022, quoting and ordering will begin moving from Big Blue Saw to the Xometry website. You'll continue to be able to get fast service and instant quotes, in addition addition to a whole host of new materials and manufacturing processes!

Big Blue Saw Blog

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When you order custom waterjet cut cold rolled steel on the Big Blue Saw website, you've got a choice of several different thicknesses for your parts. We offer the following thicknesses, from 0.0239 inch all the way up to 0.135 inch:

0.0239, 0.0299, 0.0359, 0.048, 0.0598, 0.075, 0.09, 0.105, 0.12, 0.135

But why these sizes in particular? Why not nice round numbers like 0.04 inches or at least useful fractions like 1/16 (0.0625)? These values aren't round numbers when converted to metric, either.

The answer lies in the gauge system of standard sheet metal thicknesses. In the US, standards for sheet metal come from the American Iron and Steel Institute (AISI). AISI standards tell manufacturers how thick to make steel sheets (the gauge) as well as what tolerances are allowed.

Many of our customers are used to the gauge system when ordering parts cut from steel sheet. So a customer might e-mail us to ask about getting a set of parts waterjet cut from 14 gauge steel, rather than asking for parts 0.075 inches thick.

Confusingly, as the gauge gets higher, the thickness gets lower. So 10 gauge steel is a stout 0.135 inches thick (about as thick as a stack of 2 quarters), whereas 24 gauge is a puny 0.0239 inches thick (thinner than a credit card).

In the chart below, you can see the thickness we sell, its corresponding gauge, and its metric equivalent. In the chart, inch and millimeter measurements are only for cold rolled steel sheet, not aluminum, not stainless steel, nor any other material. Other materials have their own gauge system. That's an article for another time.

Big Blue Saw's Nominal 
Thickness,
Inches 		Gauge Minimum
Thickness,
Inches		 Maximum
Thickness,
Inches		 Nominal 
Thickness,
mm 		Minimum
Thickness,
mm		 Maximum
Thickness,
mm
 0.135 10 0.1285 0.1405 3.429 3.264 3.569
 0.12 11 0.1136 0.1256 3.048 2.885 3.190
 0.105 12 0.0986 0.1106 2.667 2.504 2.809
 0.09 13 0.0847 0.0947 2.286 2.151 2.405
 0.075 14 0.0697 0.0797 1.905 1.770 2.024
 0.0589 16 0.0548 0.0648 1.524 1.392 1.646
 0.048 18 0.0438 0.0518 1.219 1.113 1.316
 0.0359 20 0.0329 0.0389 0.912 0.836 0.988
 0.0299 22 0.0269 0.0329 0.759 0.683 0.836
 0.0239 24 0.0209 0.0269 0.607 0.531 0.683

 

For example, when Big Blue Saw gets an order for a part from 0.12 inch thick Cold Rolled Steel A366/1008, we'll use the gauge size sheet provided to us by our suppliers. Based on the standard tolerances,  the parts the customer receives may be as thin as 0.1136 inches or as thick as 0.1256 inches. Be sure to design your assemblies to tolerate this kind of variation in thickness.

If you're wondering how these sizes relate to various real world objects, read our article on deciding on a material thickness.

 

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It's time to start planning for the next sale on custom waterjet cut parts. The sale starts Monday, February 13 and runs through Wednesday, February 15, 2017. The sale material this time around will be aluminum 6061 in 0.125 inch thickness. Get your designs ready now and upload them to the online quoting and ordering system.

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In our last article, we talked about two different branches of image files you may have for your parts. I said that you can also convert EPS, PDF, SVG and PNG files to DXF for cutting, with some caveats. Each file extension has its own quirks, so lets go through these one at a time.

EPS

Is a format most commonly used in graphic design. It converts over to DXF very nicely, but not every design software suite can open and alter them. I also haven’t found an online converter that is easy for a layperson to use. If you have an EPS that you can’t convert, send it to us by uploading it to our online quoting and ordering system, and we will get it converted for you.
 
 
Generally speaking, the vectors in EPS files are really clean and allow them to convert to DXF with relatively few issues. The trick is to make sure that you are starting with a black and white file that has defined outlines, and no grays or gradiated borders.
 
 

PDF 

I can convert PDF files that have a vector image in them to DXFs. The difficulty here is that you can also get a PDF that is a bitmap image embedded in it. PDFs with embedded vectors do not do so well when I try to trace it. An easy way to test if your PDF has vector or bitmap is to open it in Inkscape and in the menu bar change the Display Mode to the Outline view.
 
 
If you see a box with a red X in it, you have a bitmap PDF. 
 
Using bitmap editor Gimp’s contrast and color indexing tools you can probably get a sharp enough black and white image for the Bitmap Tracing tool in Inkscape to trace this. But it is going to come out blobby, organic, and if there is any pixel resolution issues the edges will be all craggy and there may be tiny holes showing up in your part. If you get craggy edges, the quoting system is going to charge you for cutting out those plus all the tiny holes, which means your part will quote much more expensive than it would cost if we ran a clean version through the quoting software. We have cut some decorative parts that were organic in nature from a traced bitmap that came out nicely, but this process can be dodgy in getting you the parts you want. 
 
If you have a scanned copy of a mechanical drawing in your PDF the chances of it not working is extremely high. The resolution and amount of background digital noise on the average scanner is pretty high. Given the tolerances that usually need to be maintained with the parts in mechanical drawings, there are only one realistic way to resolve this. To have a designer (yours or mine) redraw the part completely in CAD software. 
 
If you see your part outlined in a thin black line, then you have a vector file. Yay! First thing you need to do is to check to see if it is the right size, so click on it with the pointer tool. Just below the title bar in Inkscape there is a toolbar that should show you the size of the part. You may need to change the unit of measurement to inches in the pull down box to the right of the height measurement.
 
Is that the size you intended? If not, select the part profile and any holes. Don’t select any measurements if this is a mechanical drawing, especially if they are laying on top of the part’s edges. Then click the little lock button between the Width and Height boxes so it is closed.
 
Now if you know the width of your part is supposed to be 3”, type 3 in the width window and hit the Enter key. Now your part is sized proportionally to the correct size. That said, this only works if your part is drawn to scale. So if your designer wasn’t paying attention to the measurements when he or she drew the part or if there are jogs in the part profile, then this isn’t going to fix the sizing. In that instance they need to get you a proportionally drawn part. (Also note that the line width affects the size.)
 
If it is a mechanical drawing and has a bunch of measurements and sheet notes in it, go ahead and select and delete those now. Their presence in the DXF is only going confuse the quoting software as to what is the inside and what is outside of the part profile.
 
Save As a DXF. Try uploading it to our main page. If there are errors in the part, click on the diagnostic link to see where they are. Use LibreCAD to connect any endpoints that came unglued and delete any extra lines. You can get LibreCAD for free from the LibreCAD website.
 
So that covers EPS, PDF, and SVG files. What about PNGs you say? PNGs can also be converted to DXF format, but they take a little doing. So in my next article we will be talking about how to convert PNGs and what that entails.
 
 
 

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I was interviewed late last year by Courtland of Indie Hackers. Read the interview for a little background on how I built the Big Blue Saw starting from a side project.

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Our customer Tessa Gerwing was expecting a baby and wanted something special for her nursery. The little one was going to be named "Mollie Sue" and Tessa felt that she needed a sign to hang above her crib that was as unique as her little one.

Tessa e-mailed us with the handwritten design in the image below. The handwriting belongs to her grandma and namesake, Lonna Sue. It was then up to our designer to turn it into a design that could be waterjet cut.

The final CAD design is shown below. Note that the lines needed to be fattened for strength and the dot above the "i" bridged. As shown, the whole design is about 56 x 14 inches.

 

Long time Big Blue Saw followers will note that this is somewhere between the type 3 and type 4 signs. The words are separate like in a type 4 sign (this is easy because of the cursive writing). But the dot above the "i" is connected to the rest of the letters as in a type 3 sign in order to avoid having to install that tiny piece separately.

Big Blue Saw waterjet cut the design from 1/2 inch thick polycarbonate plastic. This material is light, but strong enough to support the sign's weight even in the narrow areas. Tessa spraypainted the sign glittery purple before hanging it on the wall.

Here's the waterjet cut and painted pieces installed in the new baby's room. 

Mollie is doing great in her new nursery and enjoying the sign.

If you're interested in making a sign, read more about how to turn a logo into a custom metal sign, the different ways to turn a logo into a sign,  and take a look at our gallery of signs and stencils. Then upload your design to our online quoting and ordering system or contact us for help with your design.

 
  1. Piretti Shows Its Putters With Made-To-Order Parts From Big Blue Saw
  2. Sale On Aluminum and ABS Plastic January 16-18
  3. The Difference Between Vectors and Bitmaps
  4. Forging New Signs with Ben Matthews of Moonlight Forge