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The information below comes from Carl Olsen's website waterjets.org. Whenever a customer comes to me with a very technical question about waterjets or waterjet cutting that I can't answer, I refer them to waterjets.org and Carl. If he doesn't know the answer, he knows who does.
With Carl's permission, I thought I'd post some of the great information he's written concerning the advantages of waterjet cutting.
- Simon Arthur
There is a reason that waterjet machining has rapidly grown in popularity since the mid-1990's. Actually there are a number of reasons, listed below, but they mostly come down to "versatility." A waterjet is a versatile and flexible machining tool. You can cut a wide variety of material efficiently and cost-effectively and can create a wide variety of parts.
Machine any two-dimensional shape with one tool
Cut virtually any material
Because waterjets cut using water and abrasive, they can work with a wide variety of materials. These materials include:
- Copper, brass, aluminum:
- Pre-hardened steel
- Mild steel
- Exotic materialss such as titanium, Inconel and Hastalloy
- 304 stainless steel
- Brittle materials such as glass, ceramic, quartz, stone.
- Laminated material
- Flammable materials
One of the few materials that cannot be cut with a waterjet is tempered glass. Because tempered glass is under stress, as soon as you begin to cut it, it will shatter into small fragments—as it is designed to do.
![[picture dragon artwork machined with an abrasive waterjet]](/images/stories/waterjets_org/dragon.jpg)
Pictured here is a dragon machined from 1" (2.5 cm) thick bulletproof glass, and inlay of marble and granite
Fast setup and programming
With waterjet machining, a flat piece of material is placed on a table and a cutting head moves across the material (although in some custom systems, the material moves past a fixed head). This simplicity means that it's fast and easy to change materials and that no tool changes are required. All materials use the same cutting head, so there is no need to program tool changes or physically qualify multiple tools.
The movement of the machining head is controlled by a computer, which greatly simplifies control of the waterjet. In most cases, "programming" a part means using a CAD program to draw the part. When you "push print," the part is made by the waterjet machine. This approach also means that customers can create their own drawings and bring them to a waterjet machine for creation.
Little fixturing for most parts
There are very low sideway forces with waterjet machining--cutting the material doesn't push it. The downward forces are also small, in the range of a few pounds. Typically, the largest force is from the water in the tank pushing back up against the material.
Fixturing is generally a matter of weighing down the material by placing weights on it. Small parts might require tabs to prevent them from falling into the tank.
The low side forces, means you can machine a part with walls as thin as 0.01" (0.25 mm). This is one of the factors that make fixturing is so easy. Also, low side forces allow for close nesting of parts, and maximum material usage.
Almost no heat generated on your part
What little heat is generated by the waterjet is absorbed by the water and carried into the catch tank. The material itself experiences almost no change in temperature during machining. During piercing 2" (5 cm) thick steel, temperatures may get as high as 120° F (50° C), but otherwise machining is done at room temperature.
The result is that there is no heat affected zone (HAZ) on the material. The absence of a HAZ means you can machine without hardening the material, generating poisonous fumes, recasting, or warping. You can also machine parts that have already been heat treated.
No mechanical stresses
Waterjet machining does not introduce any stresses into the material.
Machine thick material
While most money will probably be made in thicknesses under 1" (2.5 cm) for steel, it is common to machine up to 4" (10 cm). The thicker the material, the longer it will take to cut. A part made from material twice as thick will take more than twice as long. Some companies make low tolerance parts out of metal that is up to 5" to 10" thick (12.5 cm-25 cm), but it takes a long time and tends to be an occasional operation. Typically, most waterjet parts are made from metal that is 2" (5 cm) or thinner.
![[picture of 2in ss304 machined with an abrasive waterjet]](/images/stories/waterjets_org/part2.jpg)
Pictured here is a part made from 2" (5 cm) thick 304 stainless steel
Are very safe
Obviously, you don't put any body parts in front of a waterjet machining head while it is on. Anything that can cut through 2" steel will make short work of flesh and bone. Aside from this, however, waterjets are very safe. A leak in a high-pressure water system tends to result in a rapid drop in pressure to safe levels. Water itself is safe and non-explosive and the garnet abrasive is also inert and non-toxic. One of the largest hazards is cuts from the sharp edges of material created by the waterjet.
Modern systems are now very easy to learn
Control of the waterjet head is complicated and requires careful calculation to get the proper speed that will give the best result. This means that the system needs to be controlled by a computer, which means that the user-interface for the system can be simplified and made friendlier. Modern systems are designed the same way as many other computerized CAD systems and are quickly learned.
Environmentally friendly
As long as you are not machining a material that is hazardous, the spent abrasive and waste material become suitable for land fill. The garnet abrasive is inert and can be disposed of with your other trash.
If you are machining lots of lead or other hazardous materials, you will still need to dispose of your waste appropriately, and recycle your water. Keep in mind, however, that very little metal is actually removed in the cutting process. This keeps the environmental impact relatively low, even if you do machine the occasional hazardous material.
In most areas, excess water is simply drained to the sewer. In some areas, water treatment may be necessary prior to draining to sewer. In a few areas, a "closed loop" system that recycles the water may be required.
The pumps do use a considerable amount of electricity, though, so there is some additional environmental (and cost) impact due to this.
No start hole required
Start holes are only required for materials that are difficult or impossible to pierce. A few poorly bonded laminates can fall into this category, in which case pre-drilling or other special methods may be used.
Narrow kerf removes only a small amount of material
The amount of material removed by the waterjet stream is typically about 0.02" (0.5 mm) wide, meaning that very little material is removed. When you are working with expensive material (such as titanium) or hazardous material (such as lead), this can be a significant benefit. It also means that you can get more parts from a given sheet of material.
When machining or roughing out expensive materials such as titanium, your scrap still has value. This is because you get chunks, not chips.
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- Written by Simon Arthur
- Parent Category: Big Blue Saw Blog
Many of our customers' applications demand lightweight thin material such as the popular 1/8 inch (~3mm) thick aluminum 6061.
What do you do if you need to attach something with a screw to a plate of that thickness? You could just use a nut, but what do you do when the nut needs to be on the INSIDE of the thing you're screwing onto?
How about tapping threads? At 1/8 inch thickness, it can be difficult to tap threads: it yields only 3 threads when using a standard #10-24 machine screw. This isn't a lot of meat for screw to hold onto and could lead to the screw stripping the threads.and assortment of thread sizes.Using nutstrip can solve this. Another possibility to use rivet nuts. Rivet nuts are threaded inserts designed to be crimped in place in thin material. Rivet nuts come in an assortment of thread sizesand variety of styles to work with a range of material thicknesses, from 0.02 inches to 0.3 inches.
Two plated steel rivet nuts. The left one has a 1/4-20 thread, and the right one a #10-24 thread.
I happened to get a good deal on a bunch of steel rivet nuts a few years ago. I keep them in a gallon container.
Rivet nuts do require a special tool to seat them properly. I bought one made by Marson that came with accessories for riveting several sizes of nuts in place.
Here's a rivet nut installed into the chassis of my fighting robot Jaws. You can see that on the inside, the thread starts a little way down inside the rivet nut.
Note that when correctly installed with the crimping tool, the ribbed section expands to bite into the sheet material and hold it to prevent it from falling out or rotating in place. When they're subjected to extreme loads or shock, as can happen in robot combat, rivet nuts do tend to come loose. That's why if I'm installing a rivet nut in that kind of situation, I'll put a little retaining compound around the head of the rivet nut before crimping it.
Note that the waterjet was used to make the hole in which the rivet nut sits. This is faster than drilling them by hand and allows you to position the hole more accurately relative to the other holes and to the overall part. I would suggest making the hole 0.01" oversize in diameter to make sure that the rivet nut can fit.
Rivet nuts are available in a variety of thread sizes and materials from the major industrial suppliers: McMaster-Carr, MSC, Grainger, and the like.
Let us know: have you used rivet nuts with waterjet or laser cut parts?
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- Written by Simon Arthur
- Parent Category: Big Blue Saw Blog
Regularly I get emailed by individuals, groups, teams, and events seeking sponsorship for their project. Typically Big Blue Saw's sponsorship comes in the form of free waterjet cutting or laser cutting services or as gift certificates.
Big Blue Saw has sponsored or is currently sponsoring a number of things:
- Bite Force from BattleBots
- Maker Faire Atlanta
- The Dallas Personal Robotics Group
- Robot Battles
- Atlanta Hobby Robot Club's Robot Rally
Plus we've done a number of stealthier sponsorships: Big Blue Saw has helped people with their projects with the knowledge that they would give us a shout out in social media or on their web sites.
Given the amount of sponsorship we've done, I thought I'd let people know what we're looking for when we sponsor. We're looking for the same things as many other businesses, so these tips will also help you when searching elsewhere for sponsorship.
The #1 most important thing we're looking for is an existing following or fan base. This could be via social media like Twitter or Facebook, through online forums, a YouTube channel, mailing lists, or through your own website. Nearly all of our business comes through our website, so getting an online audience is absolutely critical.
For you, as a potential sponsored party, the great thing about this is that none of this costs you money. Social media profiles are free to create and so are blogs. Use those to build a following with people in your community. Similarly, if you're the one in a community forum who's the go-to person for getting help, we'd love to hear from you.
The #2 thing we look for is exposure in traditional media like television, magazines and newspapers. This type of exposure can be valuable if the audience is right: getting the name Big Blue Saw in front of people who are likely to need our services.
Sponsoring the winning robot on ABC TV's BattleBots brought us a little bit of national exposure, but it was really the social media work of the Aptyx Designs team that brought people to the website. Keep in mind that traditional media can be hard to count on as you're at the mercy of TV producers, editors, and so on. With social media YOU are in control. Also it doesn't bring the immediacy that most web exposure or social media bring; people are typically watching TV or reading magazines in a passive mode, not ready to jump on the Big Blue Saw website.
#3 is exclusivity. We'd rather NOT have our logo drown among a sea of other sponsors logos. Offer us something that no other sponsor gets.
Factor #4 is having something interesting for us to sponsor. Overemphasizing this factor is the top mistake that most people make when looking for sponsors. If you're passionate about your project, it's only natural that you would want to talk about it.
But there's a whole world of cool stuff out there, so why would we want to sponsor you in particular? Let us know what you can do for Big Blue Saw.
If your project makes good use of waterjet and/or laser cutting, that's something we can show off to potential customers via our own social media and website. If your event is dedicated to a popular meme, great!
Finally, #5 is live event exposure. Like traditional media exposure (#2, above), people who see Big Blue Saw's logo at the event aren't necessarily in a mindset to come to our website and get an immediate quote. Also, if you only control a small portion of the overall event, e.g. your own robot, putting our stickers where people in the audience or passersby may be able to see them doesn't do much for us. Putting a giant banner across the top of the stage where everyone will be looking is much better. Talking to hundreds of people and getting them to sign up for our mailing list is also very nice. Having the right audience at the event is also critical here: people with a need for custom machined parts.
Now, working on some of the factors above might not overlap with your skills. If you're visiting the Big Blue Saw website, chances are that you like building things a lot, and there's a good chance you don't care so much about having Twitter followers or documenting your build process with slick YouTube videos. And that's perfectly understandable. So if you don't yet have a solid online or media presence, you should consider adding to your team someone to be your media director.
Finally, when reaching out to us for sponsorship, make sure you're clear about what exactly you need. If you need waterjet machining and have DXF files ready for us to cut, it makes our decision much easier than if you don't have a design ready. Similarly, if you want gift certificates for prizes, let us know the exact amounts and quantity you require.
We're always on the lookout for great events, teams and even individuals to sponsor. Now that you know what we're looking for, you can e-mail us and let us know how we can work together to help each other: info@bigbluesaw.com .
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- Written by Simon Arthur
- Parent Category: Big Blue Saw Blog
I wanted a steel multitool to show off to customers and potentially use as a giveaway. I found this clever design by seanmichaelragan on Thingiverse. The original design "incorporates 21 distinct wrenches for metric and SAE nuts, 3 flat screwdrivers, a serrated cutting edge, a can opener, a wire breaker, a centerfinding tool, and a lanyard loop hole." The design, available on the download page, included a DXF version, which made it much easier to work with for waterjet cutting.
I did have to clean up a few typical problems with the file: unclosed contours, overlapping lines, and the like. If you're familiar with Big Blue Saw, you probably already know what the final DXF should look like and how to clean up a problematic DXF for waterjet cutting.
After a little scrubbing in QCad, the design was ready for waterjet cutting.
There were a couple issues with this design, however. One was that the smallest wrench holes were too small to be useful after cut on the waterjet due to the waterjet's kerf of 0.04 inches (1 mm). The other was that there needed to be a place to put the Big Blue Saw logo. So, with some reluctance, I eliminated a few of the features.
The final piece, cut from 1/4 inch thick 1018 cold rolled steel, came out great, and has a nice spot for a Big Blue Saw sticker.
Using carbon steel instead of stainless gives it a sort of steampunk look. I can imagine Captain Nemo using one of these to repair the Nautilus.
If you have a multitool design you'd like us to waterjet cut, read our FAQ on CAD files, then upload your design to get an immediate quote and order online.