Thread milling

[Dragonfly]

96 holes with M2 thread in brass in < 30 minutes.
Ever since I started using the Thread Mill plugin with thread mill cutters I feel like a new man.
I guess I am too conservative with the speeds and could do them faster but do not want to risk the only 0.4 mm pitch cutter I have. Compared to the method with a motorized attachment I made for using ordinary taps it's blindingly fast.

Great plugin!

[Bubba]

Nice work.

[kvom]

How many passes per hole?

[Dragonfly]

Single pass. The material and thread depth allow it.
Milling from bottom to top in climb mode. This allows the tool to descend slowly along the center of the hole and clear eventual burs or tiny chips. Then spiral up with two final turns in the air to make sure the tool is out of contact with the material.

[Bob La Londe]

Your feeds and speeds might not be that far off. You have to remember that when you're doing spiral interpolation whether it be spiral drilling or thread milling you have to calculate your speed and your feed based on the travel of the outside diameter of the tool. That travel is further than the travel of the center of the tool.

[Bob La Londe]

FYI: I also typically single-pass treadmill in softer materials like aluminum or brass.  My most common threads are stored as styles in my style library for the particular machine. When I first set up a hole with a particular cutter for threading I'll do some test passes until I find out exactly how much I need to oversize it to get the fit I want.  I just cut it that way until a screw doesn't fit. That's many hundreds if not thousands of holes usually.

[dh42]

Hello,

Your feeds and speeds might not be that far off. You have to remember that when you're doing spiral interpolation whether it be spiral drilling or thread milling you have to calculate your speed and your feed based on the travel of the outside diameter of the tool. That travel is further than the travel of the center of the tool.

https://cambamcnc.com/forum/index.php?topic=8462.0

++
David

[Dragonfly]

Going to give it a try, David.

And this is the final result of the job. Parts are 8x4x3 mm. Besides the two M2 holes there is another one on a cross plane with M1.6 thread.  The biggest challenge was the fixture to hold them while being cut.
Those are the tiniest parts I ever did in a batch.
The plate from the photo in the first post was glued to a metal plate. Using the method with paper paint mask band and cyanoacrylate glue. Drilled, threaded and then cut into strips. For the strips I had to design a jig with two comb-like jaws to hold them while drilling, threading an final cut.

[kvom]

Most of my thread milling has been outside threads for studs.  My current project has many 3-48 threaded holes in cast iron (.079" tap drill).  I haven't seen any thread mills that small.

[Dragonfly]

Sorry kvom,
but I get very confused with non-metric values and thread standards

Is this ~1.58 mm diameter? 
I am doing M1.6 mm thread, pitch is 0.35 mm, bore is 1.28 mm, the tool diameter is 1.125 mm. HRC (by Chinese seller) = 60.
As long as the tooth angle is 60 degrees I think it can be used for a thread with small differences in diameter/pitch. The smallest thread milling T-shape cutter I've seen on Aliexpress is 0.8 mm.

[Bubba]

0.079 inch = 2.0066 mm

Kwom, just use tap. I have never heard of thread mill that small. Threading cast iron will chew lots of tools. Thread mill will last lot shorter time than tap IMHO.

[Dragonfly]

I thought 3-48 means 3/48 inch but obviously not

This is not advertising, just an example for a thread mill
https://www.aliexpress.com/item/4000964481369.html?spm=a2g0o.productlist.0.0.727254b2mFwwgr&algo_pvid=6e7a815a-d249-42fc-959f-ed7320bce645&algo_expid=6e7a815a-d249-42fc-959f-ed7320bce645-2&btsid=0ab50f6115965621929372146eb77a&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

[Bob La Londe]

Here you go.

https://www.carbidetoolsource.com/single-form-thread-mills/2-solid-carbide-single-form-thread-mill-4-48-64-tpi-316-reach-usa-i8

[kvom]

Most of my thread milling has been outside threads for studs.  My current project has many 3-48 threaded holes in cast iron (.079" tap drill).  I haven't seen any thread mills that small.

I have completed all the tapping.  Using a sensitive setup I've done them all turning the tap with two fingertips.  I was just commenting on the size of the treadmill compared to what OP is doing.