I would like to cut a T8*2 2mm lead (single-start) ladder tap from a piece of matching lead screw. It only needs to cut plastic, so cutting it from lead screw should be fine. (That would work to cut aluminum or brass too if I want, but it's not what I need to do for now; in any case, I wouldn't be cutting steel with it.) I want to make something with very little play, because I want to use it for the Z block for a CNC router.
I tried making a 2-flute tap with a 2⁰ angle on the compound setting the taper, but it was too aggressive and took a lot of pressure, and it had small but perceptible play. I milled out the flutes by holding the tap in a v-block on the mill, and put the edge of the mill slightly past the center, to add some rake to the cutting angle. I turned a section at the tip to the minor diameter to align the initial cut.
The T8 lands are 1mm deep, so naively if I set the compound to 1⁰ I'll have to make the tapered section of the tap almost 60mm long. That seems excessive.
Questions:
I tried making a 2-flute tap with a 2⁰ angle on the compound setting the taper, but it was too aggressive and took a lot of pressure, and it had small but perceptible play. I milled out the flutes by holding the tap in a v-block on the mill, and put the edge of the mill slightly past the center, to add some rake to the cutting angle. I turned a section at the tip to the minor diameter to align the initial cut.
The T8 lands are 1mm deep, so naively if I set the compound to 1⁰ I'll have to make the tapered section of the tap almost 60mm long. That seems excessive.
Questions:
- Cut the taper first or the flutes first?
- How many flutes would you use for cutting plastic with a ladder tap like this?
- Thoughts on taper angle on the compound for the ladder step?