Spiral Combination M3 M10 Automatic Spring Review

I've used M3 to cut some holes in 3mm 6061 aluminum, it worked well, I'm a little weaker than I wanted screw fit wise and overall satisfied. This is for cutting thin materials only. If your material is more than half the depth of the thread gauges, it will likely fail.

They'll cut threads if you first machine or drill the right size hole. You don't drill a hole AND you don't make a thread in one operation. With the right use of cooling lubricant, you can easily cut the threads and the desired hole is already drilled / machined here. "A mini lathe, these projects used taps of almost every size. None failed, and all cut good threads with minimal start-up effort.

The concept is good, but there are problems with the implementation. First, you have about 1/2 inch or less depth between the drill bit and the tap. So if your material is thicker you will have trouble grabbing a portion of the tap and starting the thread before the hole is all the way through and the tap cannot be used at a reasonable RPM for drilling, not to mention that too the swarf from the drill has nowhere to go until the chisel breaks through. When you are drilling and the tap starts…