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Struggling with M12 threaded hole. Any suggestions?

Have you tried the osg vc-10 is there powdered metal tap.

I haven't tried this one. Looks like the chips would jam up pretty bad with that style flute. Is there a VC-10 with normal spiral flute?

We started with an old OSG HY-PRO and got about 100 or so holes out of that one. It was just a random tap kicking around the shop. Then ordered more of the HY-PRO (series 299 I think), and we get about 20-25 holes out of these newer ones. Tried 3 sandvik taps and only got few holes per tap. Also tried the OSG A-Series tap and it disintegrated on the first hole.

Anybody have any luck with those OSG A-series taps? They are highly recommended by osg but I've found them to be complete garbage. Seem way to brittle. Had a 1" UNC A- series tap chip badly after a couple holes in mild steel, and this M12 one busted on the first hole. I even told my operator that these are junk and it will probably break on the first hole. But I figured its worth a try. Sure enough it broke lol.
 
Also there was an article someone else linked on a post before related to rpm, there is a sweet spot.
Which is usually a lot lower than a cutting tool of the same material as the tap.
The TiCN Emuge form taps I use call for like 45sfm in free cutting steels.

IMO, you should be able to form tap 4140 @38rc.
The Emuge TiCN Multi taps call for 26sfm in steel with a tensile of 175kpsi, and their steel specific form taps call for 33sfm up to 205kpsi.
 
I think this style tool would be best. But worry about lack of through coolant. Even if chips are fine I still worry about them floating around in a blind hole, chipping my expensive threadmill. You guys think I will be ok without through coolant? I did see several options without it. But its hard to find this style tool with through coolant in this size.
Thread inside out so the chips or most of them at least pull out.
 
Emuge is high-end tools. If they don't make a tap that does well in any application, I would be surprised.

Even though your tapping a blind hole, is it possible to drill deep enough to be able to use a gun tap? These are typically stronger than any spiral flute tap.

You will have to dig chips out of the bottom of the hole though....

ToolCat
I just run the drill back in .05 of the bottom of the hole and break them up.
 
Not to sound repetitive, but whenever I am tapping a harder material and having issues, I fire off an email to Emuge support telling them the situation and ask them their recommendation.
They are usually quick to reply within the hour and have never been disappointed by their taps.
 
I am way out of my league here and this may be a dumb question, but would it be worth finish milling the hole to a 'perfect' every time size and location to minimize stress on the tap?
 
I am way out of my league here and this may be a dumb question, but would it be worth finish milling the hole to a 'perfect' every time size and location to minimize stress on the tap?
Nah, not worth it, you could just change the drill size by a little.
Only for form taps do you need the hole to be a "perfect size". Even then you can usually achieve that by a good carbide drill that will hold size.
 
So do Reime Noris just have no representation in the US or what? I'm pretty sure every time I've mentioned them on here I've had exactly zero takers...

They are right up there with Emuge, but they are priced about the same too, so I guess six of one...
 








 
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