Time to don those 3D glasses

We are moving into a new dimension.

CNC machines are not restricted to 2D patterns and simply cutting in to produce a raised (or recessed) pattern.  Nor are they restricted to 2.5D, which is how patterns that are cut in 2D then built up to produce a 3D image are classified.

True 3D means the cutter is moving through all 3 dimensions as it is cutting.  This can still produce something like a bas relief image, but irrespective of how complicated, or simple the result, the motion of the cutter throughout the cut is the defining parameter.

Finding 3D patterns to send to the CNC machine are not as easy to find as I expected.  The 3D printing community openly creates and exchanges their creations, including the required files, and open source development programs, whereas the 3D CNC community charges significant fees for each and every pattern, and the software to develop your own costs $thousands.

I did download a sample file from VectorArt3D.com who also provide the code generator program (for free, but it only works with their files) called Vector Art 3D Machinist.  Bit of an experiment-was not sure if it would work on the CNC Shark, but it was fine.

The program produces the required G-Code for the CNC machine control program, but has an interesting additional output, that of a roughing out pass.

Given how much material the can be removed to create a 3D object, it is good being able to first run a heavier cutter to take a few quick passes to remove the bulk of material before the fine, final cutter moves in to refine the design.

Rather than just use any router bit to attempt to machine a design, I turned to the precision Amana Tool bits that are specifically developed for 3D CNC routing.  These come from Toolstoday.com, and are Zirconium Nitride (ZrN) coated router bits.  I know it says coated, (which to the layman suggests painted or dipped) but I suspect they may be produced using one of the physical vapour deposition techniques.  This is an important distinction.  A coating can rub off over time.  A vapour deposition has characteristics somewhat akin to welding, where the coated layer fully penetrates into the surface of the base material, effectively creating an alloy at the surface.  Localised, controllable, surface alloying is a particularly effective modern technique for producing exceptional products.

The bits are all up-spiral, pulling material up and out of the cut, while the cut itself is not a chipping action, but a slicing one.  They are particularly sharp, and smooth.

The first pass was a roughing pass, using the largest bit seen to the left here.  It quickly scallops away the bulk of material, leaving the finer router bits to produce the detail, without having to push through tonnes of material.

Once that pass was done (4 minutes), the bit was swapped over for the one making the final passes for detail.

The final result looks a bit rough – more refinement by me I think.  It is definitely not the router bit – the ZrN bits performed superbly.

Final pass, which was about 16 minutes for this size pattern.

The additional benefit of these router bits, is their ability to handle other materials, such as aluminum, brass, copper, graphite, phenolic composites, plastic, sign board, & wood.  The ZrN surface is particularly useful in preventing buildup of the material being cut, such as plastic and other gummy materials.

The benefit of having a set of bits is having the right ones available when you need them (and less costly than purchasing individually).

The set of 4 covers a good range.  If you are heavily into 3D CNC woodworking (and as a business), consider the 8 piece set.

Progress Report

It seems like days of preparing components for the cot – lots of machining.  And that is pretty much exactly what it has been.  We have been working primarily with 190 x 45 Tassie Oak (kiln dried hardwood), although there has now been some pine thrown into the mix.  Each piece has been resawn, planed, thicknessed.  It really gives a sense of ownership of a project where every dimension is controlled by you, and not relying on standard timber sizes provided.

Clamping up the end-boards

The panels at the end of the cot are made from solid pine, so were reduced in thickness to 12mm, then joined with the Frontline Panel clamps.  With their unique action to cause the work to be held down, as well as together, they yield excellent results. More on these end panels later – we will leave them now while the glue dries.

Sorting out the components part 1

After machining so many components, it was useful to lay them out according to the parts they are made for.

Sorting out the components part 2

Lots of individual parts in one of these things!

Mortising for the slats

Cutting the mortises for the slats is made incredibly simple with the Festool Domino, and with the extension wings added on either side to get exactly the desired clearance between the slats (and in accordance with Australian Standards).  A job that could otherwise take hours completed in a matter of minutes.

Assembling the mattress section

The mattress section was assembled and glued, and there was a slight problem with the MDF sheet – it was not 6mm thick as it should have been, being up to 0.5mm out, which made it bind in the slot that was cut.  So the power of the Frontline clamps was bought into play – this time by converting to a standard panel clamp layout, then the Frontlines were closed up.  It took no where the full 4 tonne these clamps are capable of, and nothing can resist!

Now the observant among you will notice I have opened my Bessey account.  I decided to go with a brand that was readily available, so started my new collection with 2x 1000mm and 2x 600mm Bessey clamps.  Now I just need more (and more clamp sizes)

Assembling the sides

So once the sides were routered, it was time for it to go together.  The slats were not glued – easy to remove if they ever break (presumably not – we have already torture tested them).

Starting to really look the part

It is really looking like a cot now!

Routed end detail

Once the end panels were dry, it was time to add some details, so I chose to go with the 3D router carver from Carbitool.  One panel got a classic treatment. The other found something a lot more appropriate.

Adding 3d Routed Detail

So assembly has begun in earnest.  Hard to stop once the finish line is in sight!