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6-32 Taps...what did I do wrong?

I have always found for the most part 2 flute tapered taps cut with the least amount of force
and I prefer TINI in stainless. That is if you have plenty of room at the bottom for chips in a blind hole or the hole goes through. I must ask is that a good quality 303 stainless? I have gotten crap rounds in the past without certs that was worse than typical 304 to turn, drill, and tap.
 
I was nowhere near the bottom of the hole....usually by the time I was about .187 in, there were problems.
Ask for high performance taps next time. And what I experience is that if I don't specify a class of fit then all I get is GH-3.
 
It’s the ratio of thread depth to minor diameter. On paper it’s the easiest tap to break. The thread depth is quite deep for the small minor diameter hence the easy breakages with that size.
I've looked at them strange and had them break...now as soon as I feel resistance I stop.
 
Yeah they aren't real strong. I look at them sort of like a torsion spring. When I feel a little springy twist, time to stop.
Been hand tapping a lot of blind 10-32s in relatively hard material (likely 4140 or 1045, in the Rc 40-45 range). When I see the flutes start to twist I stop and reverse. Had to pitch my favorite SP tap, it was requiring too much effort and making me nervous. I started using some no-name imports. They cut fine, but snapped one in the hole with no warning when it found the bottom. It took a couple of hours with a snag-ground carbide spade drill to remove the remains. Pitched all of the remaining and ordered some R&N SPs I found on eBay. Good taps are expensive, but not as expensive as cheap ones.
 
"Using my lathe to hold the rod, and a spring-loaded tailstock center as a guide, and cutting oil....the taps really took and uncomfortable level of torque to turn. I tapped about half the holes using lots of patience and lots of chip breaking and hole cleaning. Eventually, they both snapped."

As mentioned earlier your original taps appear to be straight flute. When you say you did "lots of chip breaking" how often did you reverse direction and for what distance. My experience when using this style tap in stainless is that it must be reversed be at least 1/4 turn for every 1/2 turn forward. Straight flute taps have no built in chip breaking ability and can often bind on the chips they just cut when advancing even one full turn before reversing. Keep in mind the chip not only has to be broken but must be small enough to fit in the gullet to avoid being run over as the tap advances.

While you were successful using the spiral point tap it still wouldn't be my choice for a blind hole. In this case you're trying to stuff 2 strings of tough metal into a distance of less than half the depth you're trying to tap. If the strings stay intact, you stand the chance of recutting one or more as the tap nears the final depth.

My choice for this application (if hand tapping) would be to start tapping 2 or 3 turns with a spiral point tap. Then remove the tap, blow out the hole and finish with a spiral flute tap with a 20* or less helix. This slow helix will generally raise the chip slow enough that it will stay intact and not break and fall back into the hole. When doing the same job by machine I would use the spiral flute tap only.

Personally, I avoid using straight flute taps on anything but cast iron.
 
I needed to tap 48 holes in the end of 303 stainless rod, .437 deep.

I drilled the holes .600 deep and a little oversize (.109 instead of .106).

I bought two new taps from McMaster, a plug TiN and a 2 flute bottoming tap...both decent quality.

Using my lathe to hold the rod, and a spring loaded tailstock center as a guide, and cutting oil....the taps really took and uncomfortable level of torque to turn. I tapped about half the holes using lots of patience and lots of chip breaking and hole cleaning. Eventually, they both snapped.

Not wanting to wait for Tuesday to roll around, I looked on Amazon and they had some no name taps for a little over $5, next day shipping included. I bought one and it arrived...a two flute tap with no sort of normal (plug, taper, bottoming) end.
You guessed it - the Chinese tap cut the thread with about 1/3 the effort. No cleaning, no nothing. I was able to run the tap in the full 7/16" without even a thought. Smooth and easy. The last 24 holes took about /1/24th the time of the first 24.

So...why did the good taps suck and the sucky tap be good?
The first 2 taps appear to be what is comonly called a HAND tap.No one in a tool and die or mold shop has used these in the last 50 years.The GOOD tap is a spiral point tap that EVERYBODY uses. Mcmaster also sells these. Also , the lazy bums that made your spiral point tap ,ground it between centers and left the male center on the tip of the tap.This takes up needed chip space at the bottom of the hole. You should allways grind that tip off. Edwin Dirnbeck
 
I needed to tap 48 holes in the end of 303 stainless rod, .437 deep.

I drilled the holes .600 deep and a little oversize (.109 instead of .106).

I bought two new taps from McMaster, a plug TiN and a 2 flute bottoming tap...both decent quality.

Using my lathe to hold the rod, and a spring loaded tailstock center as a guide, and cutting oil....the taps really took and uncomfortable level of torque to turn. I tapped about half the holes using lots of patience and lots of chip breaking and hole cleaning. Eventually, they both snapped.

Not wanting to wait for Tuesday to roll around, I looked on Amazon and they had some no name taps for a little over $5, next day shipping included. I bought one and it arrived...a two flute tap with no sort of normal (plug, taper, bottoming) end.
You guessed it - the Chinese tap cut the thread with about 1/3 the effort. No cleaning, no nothing. I was able to run the tap in the full 7/16" without even a thought. Smooth and easy. The last 24 holes took about /1/24th the time of the first 24.

So...why did the good taps suck and the sucky tap be good?
Whenever I see BOTTOM TAP ,I think that these CAD desingers should be required to wear a shocking dog collar that is activated when a BOTTOM TAP is required to make the part. Edwin Dirnbeck
 
McMaster is my preferred supplier for almost everything.

But the taps recently have been Widia and I've had a bunch of issues across several sizes. To the point I have stopped purchasing taps from them except in an emergency. I would prefer is McMaster would raise their prices and stock a more premium tap.
 
The SS Is was using was 303 purchased from McMaster. I could believe it had some hard spots; some holes tapped easier than others.

As a side note...I have a bunch of different tapping fluids but the best results seem to come from using Ridgid Nu-Clear cutting oil, the kind they sell for pipe threaders.
 
Did a search. I have bought cutting tools from Western for 20 years.

OSG for S.S. It was the only SS tap for the spiral category.

OSG for "Hard" material:

Rapidkut? Apparently they are popular because of the price:

Guhring cobalt taps are probably some of the best:
 
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I can name at least four different tool houses in the Houston area that carry just about any style or brand of taps you would ever need when you need it. Have you tried talking to any of them?
 
"I can name at least four different tool houses in the Houston area that carry just about any style or brand of taps you would ever need when you need it. Have you tried talking to any of them?"

Well...I didn't know I needed different taps until a couple days ago, so no. But really....when I walk into a tool house the counter guys seem to not know where to find the door. I usually have to give them a part number or an exact description to get anywhere. DXF, Bass, and the old CW Rod. I used to go the J&L's store when they were here, too. The Bass guys are fairly sharp, and a couple guys at DXF are too - but they aren't machinists.
 
Yeah, C W Rod used to be our "Go To" too, back in time. Bass Tool screwed me on a double shipping charge that still pisses me off. Now if I need anything out of Houston, I get a hold of Cutting Tools, Inc. But you're right, you have to hold their hand and guide them to the watering hole now days.
 








 
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