A logical conclusion

Using the same steps discussed in the last entry, I have taken a vector drawing of a Celtic Cross (created by “CarveOne” on the Vectric Forum), and produced a 3d rendering of the design.

This is the first time I have really tried using multiple paths on the same object.

The first pass was a roughing pass – used to remove as much of the unwanted timber as possible with a strong router bit, and higher feed rates to perform the task quickly.

DSC05816For this I used the 46294 3D carving bit from Toolstoday.com  It has a Zirconium Nitride (ZrN) ceramic coating, so this bit is also appropriate for routing in aluminium, brass, copper, cast iron and titanium alloy.  It makes very short work of the camphor laurel!

DSC05818There wasn’t a lot of material that needed to be removed, but it is still a worthwhile step to minimise any unnecessary load on the finishing step (and router bit).

DSC05820The final design was then carved using the 46282 3D carving bit.  This has a 1/16″ diameter tip, so can really get into the details.  Even so, there is a bit that is even finer, if even more detail is required (with a 1/32″ round nose tip).

I was using these at around 80mm/sec.

Once the design was cut, I swapped over to a solid carbide 1/8″ upcut bit to first cut around where the gaps were meant to be inside the design, and then to cut around the outside, down to about 12mm deep.

DSC05822For a sense of scale, the cross is about 300mm high, and 200mm wide.  Straight off the router bits, there is no need for sanding where the carving bits have been.  There is a bit of feathering on the outside of the cut out, but that is both a function of the timber, and insufficient router bit speed.

I deliberately didn’t cut all the way through the timber, so there was no need for tabs to hold the cut pieces in place.

To release the cross from the surrounding material, I turned the whole thing over, then ran a basic flattening profile on the back, taking off 2mm at a time with a surfacing cutter – using the RC2248 replaceable tip cutter.


Once this cut down to the required depth, the cross was released.

Each project presents different challenges, so I get to know more and more about how to use the CNC router effectively, and how to incorporate it as another workshop tool.

I had a look back at some tests I did on the CNC Shark using 3D carving bits – the finish I am achieving here is chalk and cheese compared to my early experiments.  I don’t know if I can attribute it all to the platform, but having such a solid, heavy duty CNC router certainly is not harming the finish that I can now produce!


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