On Thu, 11 Mar 2021 at 06:31, Chris Albertson <albertson.ch...@gmail.com> wrote:
> What's the best kind of steel to buy that gives a > combination of machinability on a small mill and strength. I will concur with Marcus, when making starter gears for the Ner-a-Car I used EN8. EN8 is the old name (ie, before 1970) name for 080M40 In turn 080M40 is similar to US 1039, 1040, 1042, 1043, 1045 > Given my setup, a HF mill and manual (non-CNC) HF mini lathe which would > have the best result, a hob or an involute cutter? You can only hob if you can set the hob spindle at an angle to the gear axis. Hobbing should give a perfect profile at any tooth count, but it more difficult to arrange. You definitely can hob on a mini-mill, though. https://youtu.be/ZhICrb0Tbn4 > The really hard part that I don't know how to do is a ring gear. I can't > figure out how to cut internal teeth. Cutting internal teeth isn't something that can be done with a hob _or_ an involute cutter. You need a Fellows gear shaper, or at least to find a way to set up the equivalent on your CNC mill. https://youtu.be/72YgpVF4O7g I don't think it is impossible, with the cutting tool in the rotary axis, circularly interpolating around the blank. It might be simpler to order one wire-spark eroded for a one-off or a stock part from HPC or similar. -- atp "A motorcycle is a bicycle with a pandemonium attachment and is designed for the especial use of mechanical geniuses, daredevils and lunatics." — George Fitch, Atlanta Constitution Newspaper, 1912 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
