ericcsforge wrote: ↑Mon Jun 21, 2021 4:42 pm
Hi Gene. This result looks great, thanks. I guess that I still think about this from the point of view of a manual machinist.
A solid start, CNC just gives more options.
I would not do this job with an end mill less than 6 mm.
The same applies with 3D surface, Use the largest tool that will fit. A larger ball endmill or bullnose endmill ( with larger radius) will produce fewer surface ripples due to step over for the same percentage stepover, and process faster.
Using surface you are not constrained by borders or edges. (Turn off Boundary Enforcement) You can fiddle with these with the relevant parameters as well.
I guess I could always do some fiddling.
The best way to learn something like FreeCAD, as per Gene's example; not everything has or can be documented (like manual machining again)
You can use various machining strategies depending on tooling and job shape or material .
For 3D surface your best friends are the properties in the DATA TAB for the Operation.
Create a 3D Surface Operation with Boundary Enforcement deselected
With the Surface Operation selected in the job tree, go to the Data Tab and right mouse click on any of the Property lines and check Show All box, this should give you a much bigger list; mostly in highlight yellow.
The main ones of use in handling surface are in "
Clearing Options " and "
Selected Geometry Settings "
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Cut Mode choice of Conventional or Climb
Cut Pattern list of patterns, I prefer line or zig-zag, zig-zag reduces the repositioning rapids and introduces alternating conventional climb cuts
Cur Pattern Angle very handy- sets the angle of the tool path . Usually 0.0 by default which gives X-axis travel. Change the angle to suit preferred travel orientation . 0.0 along the face , 90.0 across the face , or anything else, say 45.0 to travel down a face truncated off the corner of a cube.
Cut Pattern Reversed reverse the travel direction of the path. From top down to bottom up ; or left to right to right to left
Depth Offset offset the path vertically to leave material, finish allowance, but there are better ways to do roughing
Layer Mode single pass, multi pass ; single pass is what I use as the step over is creating small material removal
Pattern Center At list, have only used center of mass
Pattern Center Custom list of options
Profile Edges none ( there is a list of options
Sample Interval Smaller gives finer detail at the cost of calculation time. Smaller preferred
Step Over percentage of cutter size, small as practical to minimise surface roughness ( ripples left from step over )
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Most useful here are:
Boundary Enforcement false, to allow cutter to go to the extremities of the shape
Boundary Adjustment , by default the path will wrap over the edge of the shape by the tool radius, not a problem, but by giving this a negative value of up to the tool RADIUS this overlap can be reduced or eliminated. The overlap is not really needed as the center of the tool will cut up to the edge anyway. ( more negative values can be used to leave a rim for example )
Fiddle away, it will teach you the most about Freecad if you apply it to all aspects. The default settings are usually just the starting point
