Thread: climb vs conventional

im boring/threading a 4" npt hole in a production job outta 60/61 aluminum. i have a few important questions for the wise and willing.

1. 1" tool diameter 4" depth of bore- effective cutting depth = 2": carbide/cobalt endmill vs. indexable

2. i have 1.625" of stock to take off the brim about .75 thick, should i use: endmill vs face milling

3. climb cut vs. conventional (removing stock off face and boring ID 4" npt)

4. helical interpolation vs. step cutting


thanks- B

Depending on what your largest size drill is, I like helical interpolation for finish pass. You can get a straighter hole than steping it.
I don't understand the brim thing, if it is a face then face mill it. Since the advent of close to zero lash ball screws climb milling is the norm, and in most applications advisable since the cutting action won't pull the cutter into the cut. But there are times when conventional is the best option. In a hole climb is the only way to go.

I have done some NPT of that size. Mill cut should be fine. Definatly climb cut. I use a 4 deg. included mill for the thread portion. I use a 1.0 dia. 6 flute carb thread mill and climb cut from bottom to top. Don't know about programming because I have Gibbs Cam and it has a drop down list for creating the tapered thread tool path. Depending on material might want to make 2-3 cuts with a .004 finish cut. Don't spring cut isn hard steels because it will chatter and leave a bad finish. Not to mention dull your tool.

thank you. im not using any cad program, just interpolation. i have a kennametal 6 flute tapered npt threadmill and im cutting into aluminum. would you recomenend clockwise rotation or ccw threadding ? thanks

b

Originally Posted by brentanthony

im boring/threading a 4" npt hole in a production job outta 60/61 aluminum. i have a few important questions for the wise and willing.

1. 1" tool diameter 4" depth of bore- effective cutting depth = 2": carbide/cobalt endmill vs. indexable

2. i have 1.625" of stock to take off the brim about .75 thick, should i use: endmill vs face milling

3. climb cut vs. conventional (removing stock off face and boring ID 4" npt)

4. helical interpolation vs. step cutting


thanks- B

1. I wouldn't use a 1" tool. Instead, I'd use a 2" or 2.5" facemill on a 4" arbor. Helical bore counterclockwise.

Try this: Ripper Mill MITSUBISHI BXD

but with a 4" arbor.

2. Use the same facemill as #1
3. Climb cut
4. Definitely helical

If you are not using a Cad program rember that the thread is tapered. Check the Machiney handbook. You wil have to to some trig to get the proper angle and I would segment the arc's at no more than 120 degrees for a proper sealing fit.