Quality threading taps

Plug taps will meet most of your needs. The plug tap is in between a taper tap and a bottoming tap. Straight flute taps will chew the chips up as it goes along. Spiral flute taps pull the chips out of the hole and spiral point taps push the chips ahead. They are also known as "gun taps" because they shoot the chips forward. Problematic if you are tapping a blind hole. One thing to know is that a bottom tap still has some incomplete threads on the end, therefore a full thread to the bottom of a flat hole is not possible. I have known young engineers that don't understand this who will call out for a flat bottom hole with 100% thread.

Taper, plug and bottoming tap sets are made for hand use because you can pick up the lead by hand, where trying to use a machine or power driven tapping device will usually end up with crossed or over-sized threads.
 
I started out with a quality set of inch/metric tap and die set made by Snap-On, the generic Chinese sets are worthless no mater what they say. I have used almost every tap size in the set, they are fairly durable. It is important to understand that taps wear out not only from becoming dull, but the metal fatigues with time, especially the smaller sizes. So replace them when they start to look twisted. I buy 2-3 replacement sets for most of my smaller more common sizes (both inch and metric), and when I say set, I mean Taper, bottoming and plug. Cleveland sells them in sets for a given tap size. There are many cases where you thread into a blind hole, and need to thread the whole completely. Also when threading deep holes, I start out with the taper and end up with the bottoming. I usually buy the Cleveland sets when on sale at MSC, sharp and hold up well. Manufactures recommended, anything other than Chinese or house brands, so: Greenfield, OSC, Kennametal, butterfield, Hertel, and older (NOS) Hansen in descending order of preference are worthwhile. Irwin is barely passable. Avoid house brands like Interstate, General .... You can pick up decent taps on eBay in some of the lots, or group sales. Picked up a large lots of 20+ large 3/8-1" taps, old US made Hanson in sealed boxes for around $20. If I went out to buy these it would have been several hundred dollars. So worth looking, but having a quality base set in one box is definitely worthwhile. Get MSC catalog and flier, often they have quality taps at 50-60% off there usual inflated prices. There are other vendors, it just a matter of looking and if they have stock.

Taps and dies are only half the story, the other half is the holders, taping stand and type of dies. The better dies are adjustable for cut, and even with a lathe, I use the dies often. Since I use taps all the time, went out and bought some decent Starrett T handles and some old Craftsman ratcheting handles (NOS ones are made in the US, not current production from India which are junk). These T handles make a world of difference in holding the tap and getting the correct feel, especially with small taps in tough materials. Use a good tapping fluid, not generic oil you have (motor oil).
 
Good taps are ground. I was thinking of buying a set, SnapOn, but why pay all that money for taps and dies I'll never use?
So I've started buying Guhring taps. I like their TiCn PowerTaps for my Aluminum parts. Most all are HSS and Cobalt.
They also have nice thread forming taps. Emuge are great but pricey. If I spend a lot time on a part, I'm not going to screw it
up with a cheap tap. So I buy what I need when needed. Widia makes a decent tap. McMaster has good inventory on Taps and die's.
Get a Huot tap and drill organizer too. ( Starrett tap wrenches are still made in the USA.) Make sure the Taps are ground.
 
I would not rule out the Interstate taps if you get em on sale at Enco and then use the discount code. I have some interstate taps in sizes from #6 to 1/4" that have tapped hundreds of holes each. Not bad for 3 or 4 bucks each. I rate them as good as the current production Cleveland taps.

michael
 
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