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Big Blue Saw Blog

General Updates

Valentine's Day Sale on Custom Waterjet Cut Parts

We love our customers, and starting Monday, February 13, you'll be able to save with sweetheart deals on custom aluminum parts. During our Valentine's Day sale, Big Blue Saw is offering savings on waterjet cutting your designs from 0.125 inch (1/8 inch) thick aluminum 6061. 

Gather your loved ones together and place your orders online to automatically receive quantity discounts.

Here are some examples of how you can save:

This lovable 21 x 21 inch robot baseplate design is normally $114.40 when ordered in quantity 1. That's with waterjet cut from aluminum 6061 1/8 inch thick. During  the sale, this same part would be just $56 in quantity 1. That's a savings of $58.40, a savings even the most emotionless robot couldn't ignore.

 

Normally, our cherished "Butterfly" example piece is $92.10 in quantity 1. During the sale, it will be only $9.20. That's a honeybunch of savings of $82.90 or 90%.

This nameplate design (perfect if your paramour happens to be named "Gavin Chan") when waterjet cut from aluminum 6061 alloy in  0.125" is typically $92.10 when you're getting just 1 piece. But during the sale, you can get it in quantity 1 for just $10.60, or $81.50 off!

Remember that the sale is only on custom waterjet cut aluminum 6061 parts in 0.125 inch thickness ordered through the website during the sale. And the sale ends on February 15. So upload your designs to our online quoting and ordering system now.

 

 
 
 

How Thick is a Steel Gauge? And Why is My Part 0.002 Inches Too Thin?

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.

 

Early details on upcoming sale

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.

EPS, PDF, and SVG files

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