Creating a Step-off Chart for Turning Radii

[petertha]

Further to my post about the option to dimension a series of tool position coordinates, however the drawing/display can get a bit unwieldly if the density is high. Just happened to be thumbing through a website & this (slightly redacted by me) screen grab made me chuckle.

[john mills]

looking at this i spent years working out tool paths for programming cnc and nc machines  in those days no cad cam to use the computer was only am
an editing function.so it was a pencil and calculator and programming using G codes.the older machines the cutter compensation was not possible in lots of cases.i usually made charts of positions for shaping .usually the centre of the radius of the tool similar to the tool parts as for profiling
a shape using a end mill.turning is the same only the radius is smaller so the figures worked out for the party of the centre of the radius..I used calculators till they wore out i think it is the fourth one i still have now.
John
       

[gbritnell]

This entire transmission case was done using the radius step-off method. It required the use of a CAD program to generate the arcs, tangencies and surfaces but the only other way would have been to make a computer models and cut it with a CNC machine. It takes time but if you are trying to duplicate cast parts it's the only way to achieve them. As I stated all of my work is done this way and once you do the charts it goes quicker than you would think.

[Kim]

That's some incredible work there, George!  Especially knowing I was done by hand!     

Kim

[cnr6400]

 

[crueby]

Thats a ringing endorsement for the step off chart method George! 

When doing curves like that on the mill, do you use an end mill with a rounded corner to help blend the steps?

[gbritnell]

All ball end mills down to 3/32 diameter.

[crueby]

All ball end mills down to 3/32 diameter.

Good to know - thanks!