At TopoThings we pride ourselves on accuracy. Precise carvings and value are what we strive for in our carvings. We offer Standard Definition (SD) and Ultra High Definition (UHD) carvings.
We decided to demonstrate the importance of programming and selecting cutter sizes appropriately for our projects.
We cut samples with different cutter sizes to show real life results and logged the cutting times.
Stepover and Scallop height calculation
In order to reduce post-machine finishing we keep our Scallop Height at or below 0.001 in. When the carving comes out of the machine we do some slight fuzz removal and seal the surface. Because our parts come out so clean we don’t have to sand the carved surface keeping the topography intact.
We selected a slice of the Grand Canyon 10m data set for this demo
This will be cut into light Poplar using 4 different cutter sizes. Every cutter is a MicroGrain Carbide ball nose.
0.250in. Dia.
0.125in. Dia.
1.5mm/0.059in Dia.
0.5mm/0.019in. Dia.
Each cutter was run with a 0.001in. chip thickness at 24,000RPM.
As part of this exercise we manually analyzed data.
This is the original data set. We selected a cross section to visually show a variety of contours. The cross section used is shown in red.
Cross section and Cutter detail depth
It becomes clear that a drastic contour like the Grand Canyon requires small cutters to get definition. Keep in mind this is a 2D cross section the cutter offsets are calculated in 3D making things a lot more complex. This shows all 4 cutters used in our demo.
Demo strips Machined from the same data using different cutter diameters
The demo strips are 14.8 X 2.15in. machined from the same piece of poplar. Finished in lacquer with no sanding of the surface. The top strip is 0.25in. Diameter cutter. Progressing through the 0.125, 0.059, and 0.019 diameter cutters top to bottom. It becomes very clear as the small details come out as the cutters get smaller.
Standard Definition, Top. Ultra High Definition, Middle. Original Data, Bottom
In conclusion
This demonstration clearly shows the differences in detail and quality with a variety of cutter sizes. We use the 0.250 cutter for our roughing routines. The .059 cutter is used for our Standard Definition (SD) carvings and the 0.019 is used for our Ultra High Definition (UHD) carvings. The cost difference is a reflection of machining time.
Machining times
As cutters get smaller the stepover gets smaller to maintain the less than 0.001in. scallop height. The machining times for the demo strips are as follows and does not include roughing.
0.250 – 55m
0.125 – 1h 44m
0.059 – 2h 18m
0.019 – 3h 31m
Selecting a definition level
Selecting a definition level affects the value and definition of the final carving. Some areas have a high level of detail and would benefit from Ultra High Definition (UHD) carving. Other areas would not benefit from UHD carving and we would recommend Standard Definition. Thicker pieces naturally show more definition. Allow us to assist you in selecting the best definition level for your project.