Tapping - is this just the way it is?

M

Maplehead

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Hi All
So a part I make has 48 holes drilled with a #33 bit. I tap them afterwards with a #6x40 plug tap. The tap has three flutes. The way I tap is I only turn the distance of the threaded section. So from flute to flute. That's 1/6" of the diameter of the tap. It's a very small amount and very slow. Each time I turn forward I turn back about a half to a full turn. (Chip removal? I don't knowas I can't see what's going on in the hole.) Anyways, this takes forever to tap a single hole 5/8" deep, and then I have 47 more to do after that. So... is this just the way it is? I can't break a tap in the piece as they are impossible to get out and so I just scrap the piece and have to start over.
All replies/advice is greatly appreciated.
 

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A thread forming or rolling tap would be a good choice if your material is ductile and not sticky. Looks a bit like a woodscrew: no flutes. Wonderful on Aluminum!

Sent from my SM-G892A using Tapatalk
 
These are all through holes. Wouldn't a forming tap not work since the holes are so close to each other? I imagine a forming tap pushing into the other hole space.
Never heard of a spiral tap. Will check out.
 
Starting with a plug tap is going to lead to some pretty high cutting forces. On threads that small I'd go taper, or at least second tap, then back with the plug tap if you're doing blind holes? EDIT: just seen you're doing through holes, so ignore about running the plug tap through.
As mentioned, throw some money at a spiral flute tap, they're so nice to use! They're all I buy now. Lower cutting forces again than the straight flute taper tap.
 
I am going to switch to thread forming taps for smaller than 1/4”. They seem way less likely to break. And the forming taps I have do include a sort of meager flute-like groove. They just work terrifically, with no reversing, no chip buildup, and so far no breakage.

The normal tap drill sizes don’t apply, so look around for a forming tap drill chart.
 
I'm always a bit leery of using form taps in steel, but there's no reason why you can't. Precise hole size is pretty important though.

For your piece though I'd get a spiral point tap with a neck length (before the shank) that's a bit longer than the thickness of your work piece, then power tap on the mill or drill press if you have reverse. If not, get a tapping head :)

I'm making some QCTP holders, each has 4 1/4-20 holes for set screws. Drill all 4 holes, then countersink, then tap each one, takes probably 20min at most including tool changes.
 
No help here, but tapping holes is another of my many completely disheartening failures. Today I drilled and tapped one M6 threaded hole. My tap drill was broken so I resharpened it by hand and eye. The tap was new and went in so smoothly that I nearly reached into my other set to throw away the other tap that I've battled for so long. THIS was confirmation that that other tap was pure crapola! Then when I put a screw in it I found that my hole was oversized, and the screw just wobbled around inside the hole. So whatever effort was involved was pretty well wasted effort. Like I said... no help here... but you're not alone. I'll try this special tap too, but in my case, I think it's just me.
Whatever that thing is you're making is pretty. Looks nice!
 
I ordered four spiral taps. Like I said, I don't think form taps will work for me as I think the holes are too close to each other and the form tap will just push the grooves into the adjacent hole. jwmay, you're not alone. Tapping is a PITA. I have the feel now so I can go for a while without breaking taps but doing so creates a very slow process. The part you're looking at is a tool-less electric guitar bridge.
 
If you are planning on making many of those guitar bridges it would pay to purchase a tapping head for your drill press or mill. With a spiral point tap mounted on it you'll be able to tap all those holes in minutes.

 
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