Intro: Making 5-Axis Cuts on an OMAX Waterjet
Given a machine that blasts water and garnet pellets with 50000 pounds of pressure, you'd think most people would be like "I'm gonna take over the world!"
Instead, the majority seem to agree on something closer to "I want to take this clip art and make a metal version of it!"
You can't just stop there. You need more than 3 translational degrees of freedom, only 2 of which are used unless you're getting into the terrain follower which is another instructable entirely.
You require 2 additional axes of rotation, and the OMAX Waterjet is ready and willing. All you have to do is learn how to harness that power.
Now for the low price of "clicking on the next step" button, that power can be yours.
Step 1: Preparations and the Example Model
First off, I'll be assuming some basic waterjet usage knowledge. You should have at least know how to find/set zeros on the machine, have done multiple two axis cuts, and basically be used to operating the waterjet before tackling 5-axis cuts.
Note to Autodesk P9 Users: You will need to have taken the Basic OMAX Waterjet course before trying this Instructable.
For this instructable, I'll be using a model similar to the one shown above. This is created from a script that approximates a curve using boxes, applies random rotations to the boxes, then cuts slits into each box so they seat into each other. Due to the randomness of the angles, this puts the waterjet through all sorts of movement. For this project, I'm also cutting small versions of the boxes (1" x 1" on 3/16th mild steel), which means we have to take special precautions not to lose the pieces in the waterjet bath or let them jump out and possibly collide with the nozzle. I'll cover more on this later.
I'll be using 3 different pieces of software here:
- OMAX IntelliCAM: This generates the cut angles for our 5-axis cuts. In OMAX parlance, angle information is referred to as "XData". Usually, generating this by hand was a nightmare. IntelliMAX makes this part easier.
- OMAX Layout: I'll use this to set up tabs and clean up the path information. You should already be familiar with this from doing 2-axis cuts.
- OMAX Make: The software that actually controls the machine and makes the cuts. You should already be familiar with this from doing 2-axis cuts, though I'll be covering some features you may not be familiar with.
Step 2: Importing Into IntelliCAM
Importing into IntelliCAM is pretty easy. Simply click on the OMAX Button in the upper left hand corner. This will allow you to open your model file. IntelliCAM has support for many different formats, including CAD specific formats like Inventor or SolidWorks, or exchange formats like IGES and STEP.
Alternatively, if IntelliCAM is installed on your system, it comes with importers that allow you to directly send models from Inventor, SolidWorks, or Rhino to IntelliCAM (Note to Autodesk P9 Users: You cannot have this nice thing, as IntelliCAM licenses cost money. You will just have to deal with doing this on the Waterjet machine itself, but it's not a huge deal).
Step 3: Telling IntelliCAM What to Cut, and Fixing Your Model When IntelliCAM Doesn't Like It
So, now your model is in IntelliCAM. Neat!
The next thing you'll want to do is click on the "3D Pather" tab at the top of the window. This brings up the tools for creating 5-axis paths in your model.
After this, you'll need to tell IntelliCAM which faces on the model you want to cut. This is done by clicking on the "Set Top Face" tool in the toolbar. If you scroll over your model with this tool on, valid faces to cut will turn yellow. To add a face to cut, click on the face.
Now for the fun part: FACE NORMALS MUST MATCH TO BE IN A SELECTION GROUP.
This means thatall selected faces must have normals that match to an extremely small tolerance. Selecting any face with a non-matching normal will nullify the current selection group and restart the selection from scratch. No error message will warn you of this.
In the first model in the pictures above, only one face can ever be selected since none of the face normals match. This means I have to go through an extra layout step in my modeler. I have to go back and layout all of the pieces in a way where their face normals match. After this, we'll be ready to set top faces.
Step 4: What to Do When Selecting Faces Continues to Fail
Ok, so I went back and laid out the model with matching faces, and can start selecting things. For some reason, a single face won't select.
As far as I can tell, this is a bug in IntelliCAM. I've tried taking the file back into Inventor and checking normal angles, and everything is fine there. But due to the absolute lack of information IntelliCAM gives you, I don't know what its problem with the model is. So, I improvise.
In this case, I flipped the model over and used the underside of the boxes as the top faces, as orientation doesn't specifically matter for this model. All faces selected fine, so I could continue on with path generation.
However, if this doesn't work for you, there are other steps that could be taken. For instance, exporting the offending piece as a separate file, seeing if IntelliCAM likes that better, and combining paths at a later step in OMAX Layout.
Step 5: Generating Paths and Wondering Exactly What IntelliCAM Is Thinking
Once you've got all your faces selected, it's time to generate paths for the waterjet.
Hit the "Autopath" button, and IntelliCAM will start to grind away on path creation.
If your path looks sane, you can skip to the last paragraph of this step. For the case of this tutorial, however, things weren't so easy.
In our case, there are 17 pieces, so you'd figure that IntelliCAM would generate paths through either the rows, or columns. Right?
Well, sort of. It goes up the columns, but bounces between pieces within the columns. These traverses, especially done as heads up traverses, will take forever.
Obviously, IntelliCAM is drunk (Or at least, buggy, or just has odd ideas about model traversal). While it's correct about our cut angles and will save us a ton of time in entering them, it should not be allow to drive the nozzle path. This can be fixed in the next OMAX Layout.
For all I know, this may be something that's specific to this odd multi-piece model. That said, even if your path looks OK in IntelliCAM, we'll be repathing anyways when creating tabs in Layout, so don't get too attached to it.
So, save to DXF if you want to have a backup or want to use OMAX Layout on another machine. Otherwise, hit "Send to Layout" and let's continue on our adventure.
Step 6: But What If I Just Want to Make a 2 Axis Cut With IntelliCAM?
If for some reason you've decided to ignore the whole 5-axis part of this tutorial and just want to use IntelliCAM to path your 2-axis cut, click on the 3D to 2D Conversion tab. This will allow you to select faces or slices to cut, and then export to either Layout or directly into Make, with paths prebuilt. All cuts are assumed to be 90 degrees. Doing this can sometimes allow you to skip model export/import steps in Layout when doing 2-axis cuts, though the paths that IntelliCAM builds should still be checked and simulated to make sure they're sane before actually running a cut.
Step 7: Importing Cuts Into OMAX Layout, and Scrubbing Away the Insanity
Now in OMAX Layout, it's time to clean up our paths and get ready to add more features. I'm going to have to add some tabs in the next step, so these current paths won't be valid anyways. Right click on the Lead I/O button, and select "Erase Leads & Traverses (Remove Path)". This should cause all of the greens lines to go away, while still leaving the XData, which is represented by the little arrows around the cut paths.
Step 8: Tabs in OMAX Layout, Because That Matters Now
For 2-axis cuts, you can usually live without tabs if you know your material won't fall through the metal slats in the waterjet pool, and that your workpiece is heavy enough that it won't kick back into the nozzle when disconnected from the stock.
I'm hitting two reasons to need tabs here. Not only is the final product 1" x 1", meaning it'll possibly fall into the pool if it cuts completely out of our stock, 5-axis cuts make it much more likely pieces could jump when disconnected and hit the nozzle, possibly destroying it.
However, the tradeoff with tabs on a 5-axis cut come when extracting the cuts from the sheet. If there are steep conflicting angles on opposite sides of a cut AND a tab, it can be VERY tricky to remove the piece from the sheet after the cut. I'll cover strategies for this in a later step, but these are all things to weigh when deciding whether to tab on 5-axis cuts. I err on the side of caution and instruction here.
Before making our tabs, right click on "Lead I/O" button again and hit "Autopath (Quick)". This generates a far more sane traversal path for the cut. Then we can add our tabs.
The tab options screen in shown in the image. The tab specified here is ridiculously huge for 3/16" metal, I ended up going with a .030 gap on a .15 length, which worked well enough.
I'll need to create an extra line out of one of the tabs for our path start point, then click on the "Path" button, choose the start point, and make sure everything looks good. Save the path as an OMX file in order to keep the XData in there. If XData is lost, only a 2-axis version of the 5-axis cut will happen. Ain't nobody got time for that.
Now we're ready to almost start thinking about maybe cutting something!
Step 9: Importing Paths Into OMAX Make, and Setting Up for a 5-axis Cut
After saving the OMX file, open it in Make. This works just like it would with a 2-axis cut, except now I need to pay attention to the "Enable A-Jet" toggle. The A-Jet is the piece of hardware that adds the rotational DOFs to the waterjet nozzle. Make sure this is on.
The nice thing about this is, if we forget to turn this on, Make will actually warn us that we need to turn it on or else will lose angle data.
Also make sure to do the usual checking of the tool offset to make sure it's 1/2 the kerf of the current nozzle (or possibly slightly smaller if you want a VERY tight fit, but this is risky when doing 5-axis cuts unless you really know your material and how it'll cut).
After this, we can continue on to setting up our zeros like normal. In addition, the A-Jet may need to be squared, which is basically similar to zeroing the axes, except for rotation instead of translation. Unlike moving to zeros though, there is no user settable "zero" point for A-Jet squaring, so there's nothing to set up for the cut. It's just best to make sure it's squared before moving the nozzle and setting zeros for the translational axes.
Step 10: Securing the Stock
When securing for 2-axis cuts, I need to make sure that the piece is held down. However, for 5-axis cuts, the waterjet will be exerting some lateral forces on the stock. All clamping should be checked to make sure the piece cannot shift laterally when force is applied.
Step 11: Simulate Twice, Cut Once, or Cost Yourself a Nozzle (if You're Lucky)
With 2-axis cuts, it's a good idea to run a simulation and make sure the nozzle doesn't smack into the stock/clamps/siderails. With 5-axis cuts, depending on the steepness of the cut, all sorts of fun stuff can happen, like getting the abrasives tubes curled around clamps or colliding the A-Jet with solid, immovable objects.
ALWAYS run a dry run before doing a 5-axis cut. As seen in the video, the XData is actually quite complicated and almost impossible to visualize in Layout/Make alone. This gives an idea of what to expect when the actual run is happening, especially when running a submerged cut.
Step 12: Cutting
After simulation succeeds, it's time to run a cut. Note that this will most likely take significantly longer than a 2-axis cut of the same length, due to all of the dancing the A-Jet has to do to get to the angles.
I've included a video of a submerged cut run to demonstrate what I was referring to in the last step.
Step 13: Extracting Pieces With Tabs
The stock is out of the waterjet, but all of the pieces are still stuck in it due to those pesky tabs. What to do?
First off, LABEL PIECES BEFORE EXTRACTION IF THEY ALL LOOK THE SAME SINCE THEY'RE STILL IN MODEL ORDER. Sure, it sounds like common sense, but while writing this tutorial, I remembered this step about halfway through extracting things and ended up having to figure out which piece was which by which hole they fit in. Oops.
I had a few strategies for removing my pieces. First was just lots of wiggling. For pieces without nasty conflicting angles on each side, this worked pretty quick. For anything that would come out partially and that I could pry up, I took a rubber mallet to it to try and get it out, but that sometimes caused corners on angled slits to become slightly bent.
A cold chisel and a hammer was good to taking directly to tabs. A combination of that and wiggling took out the hardest to extract pieces.
Finally, I sanded the remainder of the tabs off.
Step 14: Admiring Your Work
Yup. That sure is a 5-axis cut.