2mm tap

[homebrewed]

I have a project where I need to drill and tap some holes for 2mm screws. These will be the smallest I have ever done. Fortunately the screw holes aren't going to be very deep, about 5mm. I can thru-drill so the chips can drop out, and the material is 6061 aluminum. I know the threads won't be the strongest in the world but the screws just have to hold an Igaging DRO sensor board in place (more on that part of the project in a later post).

The holes will be drilled/tapped on my mill and I have a spring-loaded gadget I can install in the drill chuck to help center the tap while I'm cutting the threads. I have a container of tap magic to use for this and will definitely use it, you betcha!

What I want to know is what sorts of problems I may encounter while doing this.

 

[Nutfarmer]

If you are using tap magic and doing it by hand you shouldn’t have any problems. I would use a new quality tap. No imports.

 

[stupoty]

I would use a new quality tap.

And drill bits , being the wrong size hole for the tap at this size can be baaaaaad

(also do a practice one to check the drill / tap combo)

Stu

 

[Martin W]

You will be surprised how easily these will tap.
Martin

 

[wayback machine]

Spiral point tap will push the chips out the bottom, instead of loading up the flutes - Only way to go.

 

[Winegrower]

Occasionally I like to drill the holes on the mill then use a tap chucked in a battery powered drill motor. You get great control of speed and a good feel for the process. Alignment on these small shallow holes may not be a major issue, depending on the application.

 

[MrWhoopee]

Spiral point tap will push the chips out the bottom, instead of loading up the flutes - Only way to go.

This, or a thread forming tap. Advantage is stronger tap and stronger threads.

In either case, the key is keeping the tap vertical. A tap follower (spring loaded guide) may not work with a tap that small.
I find this to be incredibly useful, especially for small taps.

 

[Eyerelief]

I had a job where I had to tap some size 0 screws into cast zinc. I had great success using cutting fluid, a tap follower, and a two flute tap only. Let the spring pressure from the tap follower be the only pressure that is applied.
I know you said aluminum, but I would still use a real cutting fluid like TapMagic. I am a huge fan of using WD40 on aluminum, but I think in this case, cutting fluid will serve you.

 

[RJSakowski]

The smallest that I have tapped was 1.25mm in 304 stainless. It takes very little force but everything is scaled down so it also takes very little force to break that tap. Sometimes, it seems that just thinking about a move is enough to break the tap. Using a tap follower in the mill will greatly improve the probability of success. A 2-56 thread isa only slightly larger than a 2mm and I have dozens of operations with one without incident.

 

[pontiac428]

My first thought was forming tap too. Of all the things to remember, it's important to use a form tap chart for selecting your hole, the hole will be larger than for a cutting tap. Form taps take more power to turn, which might seem scary with small M2, but form taps are much stronger- which is why I seem to get so many small ones in those $20 eBay coffee can lots.