When I lent my services to a collegue who was working on a film about 12 years ago, I was introduced to the world of cnc. I remember watching this huge machining centre milling out a slab of mdf and turning it into a fantastic set of gears. I knew that it would have taken me hours to achieve the same thing with traditional power tools. I decided then that I would invest in a cnc router for my own business Oxenham Design. At that time I could turn on a computer, but even to check email seemed like a crazy set of operations. I persevered and learned every piece of relevant software I could get my hands on. I am now fortunate enough to be using Vectric's ASPIRE software, and Techno cnc routers, which has helped us to create some amazing projects, both in part, or in full. I thought that this blog would be a great place to share "behind the scenes" adventures with the software, materials and equipment we use, as well as the projects we build.

Tuesday, 25 February 2014

Machining The Second Layer!

With the second layer component now visible, and selected in the working window,
I used the create vector boundary tool, then offset the vector outwards by the same .300" offset.
In cases like this, I would toolpath this vector before-hand, and have our Techno cut the flat shape, having it on standby for gluing on. Or, you could just cut a rough block of  1" at this point on the saw.

We're going to assume I've now glued the second layer of material to the first layer that has already been machined.

The next step is to draw a box around the entire object. We'll use this to create a "false bottom"
Using the new box vectors, I set the height of this new component to 1.7" inches. This is approximately .250" below the actual surface of our real world material block on the cnc.
Make sure to set it to "MERGE"
The reason I do this, is to completely remove the danger of the cutter wanting to plunge all the way to the table surface, where the geometry of the model permits. Largely between the leg area. Without this block, I would crash the collet into the model, due to the shorter tool length were using.
You can see in this image where the seam is, and that the tool will completely machine over it, but just down to the block component.
Now we can turn on the second layer slice, and get ready to toolpath!
We now have to adjust our material setting. The first layer block was 2", we then glued a 1" block to our first slice, so the new material thickness becomes 3" total. Make sure you leave the Z zero at the bottom still.

With our 2nd layer offset vectors selected, I simply calculate a new roughing and finishing pass.
This machines the second layer, and removes any of the glue that may have oozed out during laminating the 2 layers. Keep in mind, the glue has to be dry. Usually we use a CA clue with HDU, so the dry time is pretty fast!

You can do this indefinitely,  adding layer by layer. Without having to buy longer and longer cutters, or machine separate slices, and glue them up, trying your best to line them up together.
I do this all the time, and it certainly saves a lot of post finishing. Just be sure to adjust your material block height in the setup window for each layer.

Not rocket science, and I'm sure I'm not the only one doing it this way,
but hopefully it might help someone who hasn't done it before!

Monday, 24 February 2014

Slicing Made Easy!

Since we finished the butterflies, we have been busy making a couple of video game characters for an exciting new game! These guys are full size at 78" tall and made almost entirely from HDU! I can't post anything else about it until the NDA is up in March, but I have been documenting it as I go.
We also have some pretty cool film props that also have an NDA, so I'll post them later as well.

In the mean time, I thought I would do a helpful post on slicing 3d models, and getting the cnc to clean up the glue joints.

There are a million reasons why you would want to slice some model parts on the router.
One of the biggest for us, is that we are sometimes limited by available cutter lengths or material thicknesses.
For example, when were cutting a model over 3.5" thick, but the available material only comes in 2".

One way is to have Aspire slice the model, machine the parts separately, then glue them up. But then the seams require work to clean-up after. I much prefer letting our Techno do as much work as possible, because it does it faster and better than I ever could!

So here's a 3d model replica I made of the Excel gum's bad breath coffee guy like in their commercials.
As you can see, the front half of the model come in at 2.4998" thick on the Z axis. The problem is my
HDU material is exactly 2" thick. I also have a piece of 1" material I can use as well. I could glue them together into a 3" thick slab, but the other problem I have is that my 1/4" ballnose cutter is only 2.5" long. So after it's slid into the collet, I only have a total of 2" of cutter length available! I certainly can't do it all in one shot...........or can I? (dun, dun, dun) That was cliffhanger music you just hummed..............

First thing up is to slice the model into layers I can use.
In order to overcome any material variances, I slice my model just a hair under the material thickness. In this case 1.95". This will let the cnc plane off .05" creating a dead flat surface to glue the 2nd layer of the model to.
Here's our model, sliced at 1.95" thick, and the second layer turned off in Aspire.

I had Aspire create a vector boundary around the whole 3d model slice, then offset it outwards just over the .250" ballnose diameter we'll be cutting this with. In this case, .300" This will limit the toolpath so we don't machine the whole 12" material block.

At this point, it is important to add some small tabs to hold the model in place for the second layer machining. I simply drew some rectangles, and made the .250" thick. Make sure to set the tabs to "MERGE" or they'll pop out the model, looking weird. This should hold it while it cuts.

When we set-up our material block in Aspire, we want to set the Z zero to the machine bed/ bottom of the material block. It get's to be too much of a math game for me to set it to the top of the block :)

So this is the roughing pass done with a .250" ballnose cutter. I'm a little lazy, so I usually rough and finish with the same size cutter to eliminate a manual toolchange.
And the finishing path as well! As long as you don't do a cutter change between the roughing and finishing pass, you can use the same vector boundary for the finish machining. Aspire calculates differently between an endmill or a ballnose, A ballnose gets calculated to the centre of the cutter, while an endmill calculates to the edge of the cutter. So if you plan on using different cutters, you'll have to adjust the vector boundary accordingly.

Tomorrow I'll cover the rest of the process...........

Tuesday, 4 February 2014

Last of the Butterflies!

The last portion of the "Bullets to Butterflies" exhibit were necklaces!
Saba, the artist, wanted us to fabricate butterflies from empty shell casings.
The empty casings were picked up from a local shooting range.
I drew up a butterfly set of wings in Aspire, and nested and toolpathed them out on the sheet.
We cut them from a sheet of .040 brass, using a tapered 1/16" ball nose cutter. I originally started with a 1/8" endmill, but it didn't quite get all the detail. I didn't want to chance my 1/16" endmill, so the tapered ballnose did the trick!
The last thing to do was punch the hole for the chain in the bullet, and solder on the wings. Saba actually did the soldering, which was pretty funny on the first 2, but she quickly got the hang of it!

We attended the local showing at the art gallery on Saturday, and the work by all three artists, Saba Syed, Huma Durrani, and Unaiza Karim was fabulous!
It was a great afternoon for both Jody and I!

Monday, 3 February 2014

Hot Weather, Sign Magazines, and 3d routing!

What a week! Jody and I booked off for a super last minute vacation to Panama, which was killer HOT! Woo-Hoo!
While we were away, a couple of things came up that were kinda cool.
The first was finding out that our work is on the cover of both the 2013 and 2014 Sign Media Canada's Buyers guide! This is a great honor for us for sure!

Special thanks to Peter Saunders for supplying the covers images to us!
The second cool thing is that we'll be back in Bridgeton, Indiana on June 1st through the 3rd. teaching 3D modelling and routering.
Unlike years past, this year will be just Jody and myself teaching. I will be covering the 3D end of things, and Jody will be teaching color theory and paint techniques. This will be pretty intense, depending on peoples skillset, but no-one will leave without a great handle on things!
Here is the course outline:

                                3D MODELING COURSE FOR CNC
We'll cover the basics of sub-division surface modelling. Understanding how the
software calculates surface smoothing, and how to control it in your favour.
I'll be teaching this with the 3D software package 'Hexagon' which is available for less
than $20 through the DAZ 3D website. This will be a hands on learning, and everyone
should come equipped with a laptop, and the software installed. This process can then
be carried over to any other SDS modelling package, as they mostly all behave the same.
We will then create a small scene, and you'll learn the proper workflow for carrying your
scene over into your CAM package. We'll also focus on optimizing your geometry for
relief carving. Due to the different Skill-sets of everyone, we'll allow ample time for
everyone to work on their projects, and ask for quick one-on-one help.
We'll be teaching using ASPIRE, but the workflow will also pertain to other “art-based”
CAM packages as well. Being that this will be taught in ASPIRE, it would make sense
to also have ASPIRE installed on your laptop as well. You can download a trial from the
Vectric website.
The trial versions will not allow you to save a toolpath for your CNC other than the
special sample files that are included. However any files that are created and saved with
the trial versions of ASPIRE can be opened and made fully operational once you
purchase and install the full version of the software as long as it is installed on the same
PC as the trial version software.
We'll bring our day 1 scene into ASPIRE, and use the powerful toolset to add more
detail to the scene.
We'll then cover toolpathing of the scene, optimizing the cutting strategies for the best
finish and machining time! We'll have an actual piece on the CNC, so we can see the
real-world results as we pick the different strategies.
This will be devoted to color theory. Understanding why colors work, and don't work
together. Alot of people can be intimidated by this portion, and we'll aim to make it
easy! We'll also cover a few painting styles, from glazing, to dry-brushing and washes.
This will be a pretty intense 3 days, but this will remove some of the mystery out of 3D
CNC routing. This will be good for both the newcomer, and the experienced, looking to
move into the 3D world, or learn some new techniques.

If anyone is interested in signing up, this can be done through the event organizer Robert Jones

Hopefully we'll get to see you there!