Laser and Water Jet Cutting for DIY

When thinking about DIY, we normally don’t envision big or expensive machinery to do the job.  There are times, however, when it’s really nice to have.  There are some really good reasons for Water Jet cutting (or laser cutting), instead of the normal DIY methods.

In our article, DIY – 7 Ways to Cut Steel we cover many of the normal cutting methods for Do-It-Yourself projects.  While they all work well in their sphere, there are times when taking it up a notch has big benefits.  Perhaps the most common is CNC plasma cutting.  The next level up, IMHO, is water jet cutting.  Then, if you want one more, move up to laser cutting.  All of these bring computer control to making parts.

In this article, we will talk most about water because it is reasonably accessible, quite accurate, and (usually) not horribly expensive.  The 5 big benefits are highlight below with the (#)‘s.

I should point out also, that much of the discussion below can apply to plasma cutting, and laser cutting.  They all have a place.

What is Water Jet Cutting?

Tiny PartsWe cut steel with water?  Yes, and aluminum, and foam, and plastics, and . . . well, you name it.  There’s not much a good waterjet won’t touch.

But, cutting with water?  Yes.  A very high pressure, small stream of water will cut nearly anything.  From personal experience, I’ve cut thick, heavy, heat treated, super strong steel, plastic and a bunch of other materials.  I say “I’ve cut”, but really I take the parts and CAD files to my local water cutting shop, and he cuts them for me.

The image here shows some tiny parts cut with water.  See below for some much larger pieces.

Basically, water jet cutting is a way of cutting sheet material.  It can do more than sheet, but sheet material of some sort is the norm.

So what is it?  I’ll leave the long description to Wikipedia – Water Jet.

Quick Parts, Accurate Cutting

If you want to add a little style, or maybe make “fancy” parts, water cutting makes contours easy.  Or, maybe you want accurate cuts to remove guesswork from your assembly.  (1) Water cutting is a fairly cheap way to get complex parts, fast.  And, (2) the cutting process is pretty accurate.  When you need parts to fit, or to make alignments that are right, CNC is about the best way to go.  Water jet cutting is just one good CNC process to know.

Box CornerYes, you can do similar things with a CNC Plasma cutter, but not as tidy, and not as accurate.  It’s the nature of the technologies.  Choose what you need.  For even more accuracy, laser cutting is awesome.  Though, laser is often more expensive.

The green arrow in the image points to a small relief cut allowing the sharp corner of the mating piece to fit.  (3)  No problem with cutting tiny features using water jet cutting, even in large parts.  Laser will do it also, but small features like this are not something for plasma.

(4)  Another benefit is Repeatability.  Yeah, I make all kinds of complicated parts in the shop just with a saw and grinder.  However, I find it tedious to be accurate making a second one to match.  Or, making a bunch.  I also find duplicating parts is not as fun.  So, when I need a few of something accurate, hiring a CNC is worth it to me.

Some Project Examples

Box by Water Jet CuttingThe photos in this article are all project examples of things we build using water jet cutting, or laser cutting.  Some of the examples also have CNC mill machining, but start with water.

As one example of intricate cutting in a project, these 2 near photos show a machine base created like a 3D puzzle.   The pieces fit close so it will go together with everything aligned — without measuring or complicated setup.  This is 1/4″ steel, all with water jet cutting.  The box goes together with a few bolts to force perpendicularity.

The photo is after a first simple assembly.  Then, we weld the box complete.  Welding at all the puzzle connection points for a super solid specialized machine base.  This is a good example for taking advantage of accuracy in water jet cutting.  Yeah, it’s more complicated than most DIY projects, but it is DIY.  Call it DIY with a little help from CNC water cutting.

The main top plates (2 square plates) are from CNC machining.  They are the machine mounting plates which are set parallel within 0.002″ using thin shims and a large CMM.

Almost Any Material

(5)  Water jet cutting truly allows more choices of material.  Water does not care if the material is hard or soft.  It also does not add any heat to the parts, so it does not change the temper — like plasma cutting does, for instance.

Choose aluminum or steel or plastic or foam or just about anything.  Hey, if you’re building a small camper, there are a lot of ways water jet cutting can enhance (and speed up) your build!

A few years ago we were making some super high strength parts out of Stainless 17-4 (half hard).  It’s tough to machine, and you have to go slow.  Material is also not easy to get, so we cut the blanks out of 6″ diameter tempered bar stock.  Cutting it with a saw would have taken days.  Cutting it with water took more time to set it up (CAD programming and such) than to actually cut it.

The photo below shows the final CNC machined parts, from the raw stock 17-4 half-hard material.

Blank from Water Jet Cutting

So, materials are not usually a limit.  I even had them cut some rare-earth magnets for me.  (If you’ve ever tried to cut those, or drill them, they usually crumble.)

Why Use Water Jet Cutting in DIY

OK, so the examples above are not the typical DIY scenario.  What about the ‘normal’ DIY projects?

Here is a CAD image showing the back end of our 8×20 Deck-Over Trailer plans.  Notice the shape of the plate?  Look a little closer at all the holes in it.

There is a shape for the outside, the oval holes for the tail lights, the large rectangle holes for the ramps (and doors).  Then, there are 3 holes for the center running lights (screws and wires), and more holes for assembly (of the light protection ribs), alignment (to the trailer frame), and for plug welding.  2 of the alignment holes are a D shape to show alignment during setup, then act for plug weld holes in final assembly.  There are even holes for mounting a license plate.

That’s a lot of holes to get right if doing it by hand.  For a part like this, it is much better to use water jet cutting (or other CNC process) to be accurate for the best trailer build.

Tail Plate Assembly

In the plans we provide a .DXF file so you can have the part made.  Take the file to a local supplier, and they will cut it out.  Yes, this works with a plasma cutter as well as for laser or water jet cutting.  However, some features, like the little bolt holes, are more accurate with water or laser.

Another place we recommend water cutting is in the frame fabrication for our Tiny House Trailers.  It allows much faster construction, with more accuracy and less welding than traditional methods.  Even if there is a cost in having the cuts made, it more than makes up in labor saving and easy accurate building.

More Water Jet Cutting In Our Plans

At Mechanical Elements, we find the advantages of water jet cutting very appealing for the right circumstances.  The above example for the tailplate, for sure.  And, there are more examples.

The Twin Torsion Walking Beam suspension is another really good example.  Axle alignment is super important, so using CNC methods like Water Jet makes this much easier.  You can see the horizontal bars with the square notches for the axle beams in this image below.  They weld to the main walking beam, and are cut with water so alignment is fixed.  See the linked article for more detail.

Tandem Torsion Walking Beam

Trailer Tongue HingeThe Tongue Hinge is another good example.  (Follow the link to see the actual water cut parts.)  The parts making up the hinge itself are all from water jet cutting so they can interact and align easily.

Of course, there are many uses for such CNC parts.  The above project example parts are material specifically cut to fabricate into assemblies.  The technique provides both location or the alignment where it is critical for function.

Disadvantages

The three big downsides for water jet cutting are:

A)  Water jet cutting (as with most CNC processes) requires a large, expensive, special machine.  Not something in the typical DIY garage.  So, to get parts, we must hire a cutting company to do it.

Companies that can do water jet cutting are in most larger towns and cities.  There are also online sources like “Big Blue Saw”.  Either way, it can be a bit of hassle to send things out, but it is worth it.

B)  It requires CAD files to tell the machine what to cut.  We provide those files with our plans, like the Deck-Over tail plate above, but if you want something different, you’ll need to sketch it out and have the water cutting shop make the files.  That may make it more expensive.

C)  Every cutting method has its characteristic edge.  That is also true with Plasma, Water Cutting, and Laser.  Plasma leaves a flame style edge.  Water has a light “sandpaperish” edge.  Laser is smoothest.  No matter what choice you make, if the edge is important, you may have to handle burrs or something.

I suppose cost is a fourth disadvantage, but I don’t like thinking that way because you get value.  The value is in nice accurate parts, that are better than I could build myself.  There is also value in time saving if the parts are big, complicated, or if I need a lot of them.  So, there is a cost, which is a disadvantage, but it comes with value.  I’ll let you decide.

Water Cutting Conclusions

Laser Cut Parts
Laser Cut parts for a nicer edge finish, and even more accuracy in the cuts.

With everything, there are both advantages and disadvantages.  We’ve highlighted a few of each and the reasoning behind them.  Use water jet cutting as another tool in your pocket, and one more way to achieve cool parts for your projects.  It’s not for everything, but it sure comes in handy at the right times.

I personally love the expanded thinking it allows.  Make decorative parts, or functional ones.  Make sheets to bolt parts on, or make several pieces to weld together to make something totally different.  It’s all an option.

Oh, and if water is not accurate enough, try the laser.  The image here shows a simple assembly from 2 pieces of laser cut steel.  We had to make several of these and they had to be accurate.  This is the shell, then electronics go inside.  The laser parts fit perfect, with capture by a single screw.

The choice for technology should match the needs of the project.  If water or laser or plasma cutting can help, go for it.

Good Luck with your DIY Projects.

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