social.makerforums.info is one of the many independent Mastodon servers you can use to participate in the fediverse.
Microblogging for Makers. Part of the Maker Forums community. Maker Forums Discourse: https://forum.makerforums.info/

Server stats:

17
active users

Public
@mcdanlj I'd read that spiral flute taps are weaker and more likely to break for small taps, so I haven't tried them yet. Thanks for the pointers!

RE: https://social.makerforums.info/users/mcdanlj/statuses/111060149655556379
Public

@jmorris I guess maybe less likely to break from chip packing? They readily evacuate a long string chip out the top. The cheapest ones are still cheap of course. I use tap magic most of the time for tapping, too.

I'm trying to remember the smallest I've done. I own an M2 spiral flute tap and it's not broken, but I do so little that's smaller than M3. And the M2 spiral flute tap I own isn't the highest quality.

But yeah, spiral tip should be stronger than spiral flute, and eject the chip ahead of it as long as you aren't tapping a blind hole. (I do plenty of blind taps which is part of why spiral flute taps are my go-to one-and-done.)

@jmorris Oh, #4-40 is only .155mm smaller diameter than M3, so maybe my good experience with M3 carries over...

I do almost always use a tap follower or some other effective guide. I think the spiral flute taps are not at all forgiving of misalignment. But I'm usually doing it on mill or lathe where I have a good normal reference.

I did also make 3D printed jigs for tapping openbuilds v-slot with M5, where I can't typically use either mill or lathe to get that normal reference.

Public
@mcdanlj a mill would be great but I currently have no room for one. Btw, I ended up brute force drilling the broken taps out with a solid tungsten carbide bit (which broke twice), then I was able to drill & tap for 6-32. There was enough slack in the copper spreader to handle some misalignment. The rest of the 4-40 were done very carefully with a form tap and tap magic. I’ll try the spiral flute next.
Public

@jmorris Glad you got it working!

Tap guides are a reasonable form of vertical reference; mill not required. That's why I mentioned what I do for tapping v-slot. They keep the taps straight enough that I've (touch wood) had 100% success power tapping with a drill and a spiral flute tap.

Also, not trying to talk you out of form taps. I want to go in the opposite direction and start using form taps where appropriate.☺

Public
@mcdanlj I’ve tried a YG-1 spiral flute tap here now and it is working well. It seems to need much lower torque than regular or form taps. I think the form tap is more precise and will provide more strength, but this is not critical in my application.