One tooth gear hobber
Posted: Sun Nov 07, 2010 10:41 am
Years ago I wrote a DOS program to calculate the dividing head settings and Y offset to simulate a HOB.
I am stuck inside with a bad cold on a WONDERFUL fall day and spent the last 2 hours converting the old DOS program into a G code generating 4 axis CNC windows based program.
The program uses a hand ground fly cutter shaped like a rack tooth or a rack formed milling cutter.
It starts by slicing the center of each tooth cut to the full depth then works it way up each side of each tooth by simulating the rolling involute action of a rack running against the gear.
You will need to make or buy a rack tooth cutter for each pitch but it should mill any number of teeth.
Please let me know what you think of this. It worked well with a manual dividing head years ago. Counting turns and holes really got interesting!
The big advantage of this over the endmill 2.5D cutting is it can do very fine pitch gears.
Chuck
Feel free to download the program below. And please let me know what you think!
Update: I made some changes and have posed an updated version 0.01
Update: I added Horizontal/Vertical Milling machine selection and rack tooth formed endmills
version 0.02. It is still needs work to remove some air cuts but looks like it is working.
Update: Added tooth tip clearance control with a "Whole depth" calculation and a variable to widen
the cut for a formed cutter too narrow for standard tooth. Version 0.03
I am stuck inside with a bad cold on a WONDERFUL fall day and spent the last 2 hours converting the old DOS program into a G code generating 4 axis CNC windows based program.
The program uses a hand ground fly cutter shaped like a rack tooth or a rack formed milling cutter.
It starts by slicing the center of each tooth cut to the full depth then works it way up each side of each tooth by simulating the rolling involute action of a rack running against the gear.
You will need to make or buy a rack tooth cutter for each pitch but it should mill any number of teeth.
Please let me know what you think of this. It worked well with a manual dividing head years ago. Counting turns and holes really got interesting!
The big advantage of this over the endmill 2.5D cutting is it can do very fine pitch gears.
Chuck
Feel free to download the program below. And please let me know what you think!
Update: I made some changes and have posed an updated version 0.01
Update: I added Horizontal/Vertical Milling machine selection and rack tooth formed endmills
version 0.02. It is still needs work to remove some air cuts but looks like it is working.
Update: Added tooth tip clearance control with a "Whole depth" calculation and a variable to widen
the cut for a formed cutter too narrow for standard tooth. Version 0.03