Confusion Of Style Of Taps To Purchase

Just today, I had great success power tapping 10-32 holes in 1/4 and 3/8 steel, using a cordless drill and spiral point flutes. First time I tried it!
 
Not a bad idea to get a cheap "general use" carbon steel tap and die set from McMaster Carr, I got them in both metric and standard. They seem to have the best price on low end taps sets. I find it is handy to have a cheap set of taps, I'm not going to dump good money on an expensive tap just to make a few holes. They are also really good to have around for when you are making fixtures or taping the castings on your machines. On harder materials, drill for 60% thread and you will never break one, and never be able to tell the difference in thread strength. I like to save my good taps for stuff that is important.

I usually get my good taps from MSC when they go on sale. I like 4 flute HSS sets that include plug, taper, and bottoming. I order the ones I need before I start a project. I usually have a good idea what projects will be upcoming for a few months, so I just keep them in my basket and order when I get a good coupon.
I do not care for spiral point (gun) taps. They are really meant for through holes, and can be a pain on blind holes. Spiral flute taps are really nice, but I don't find the threads are any better than 4 flute taps, so not worth the extra cost. I power tap with 4 flute with no problems on the lathe, mill, or cordless drill. Spiral flute taps do use less power, so they are better for holes over 3/8".

To re-iterate what the others have said, you start with a taper tap, and bottom with a bottoming tap. Use the plug tap for blind holes that do not need bottoming or through holes.
Dies are really handy to have for cleaning up single pointed threads when you didn't support the work properly, or finishing off a thread that didn't get cut deep enough. I cut most threads under 3/8" with a die anyway. Single point is best for larger threads.
 
The first thing I would do is buy the 60 Pc SAE & Metric Tap and Die Set from Harbor Freight, Item#35407, $40. These are little better than thread chasers, but usable. My go to solution for cleaning up threads.

Then I would buy good quality spiral point taps in the sizes you think you need. Spiral point taps come in starting, plug, and bottoming. I personally like the taps from Fastenal. Very high quality, but I don't know who actually makes them. Hertel and OSG from Enco are good taps also. Buy more than one in each size and style, it sucks to break one on a Saturday and be stuck.

Also don't forget to buy tap drills, again Harbor Freight is a good source. Their 115 piece sets are a pretty good buy, I have several of them, wait for the 20% off coupon.
 
I endorse the spiral FLUTE taps that Coolege recommended. They are unexcelled for power tapping, and work well with hand tapping, too. In blind holes (not thru) the chips come up the flutes, are not driven ahead of the tap as Spiral POINT taps do.
 
When does MSC have their best sales and how much off? I am going with a combo of guhring and harbor freight ( gluten for punishment I know )


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Is it necessary to have a different type of taps for aluminum and brass? It was mentioned that I think two flutes for soft metals and three flutes for hard metals is this a constant in machining?


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Get on the Enco and MSC email list they have sales quite frequently OR most sales and the codes are posted here on the hobby forum like 30 seconds after the email goes out. Its almost a contest around here to see who can post the codes the fastest. Mind you an MSC sale really means they are willing to sell you the item at the normal cost vs the jacked up over MSRP listed price. Something fishy about that. :cautious: Also note that MSC sales say "up to" 35% off I typically get less than that for items I purchase.

Enco is where the real deals can be had. They frequently have 20% off sales, on occasion 25% off and when you can stack those on top of items already on sale in the Hot Deals section you can get close to 50% off. Enco is also the place to shop for Kurt vices, they drop ship from Kurt with free shipping, slap a 20% off Enco sales code on a D688 and your out the door for around $470. That's not much more than many import vices.
 
Is it necessary to have a different type of taps for aluminum and brass? It was mentioned that I think two flutes for soft metals and three flutes for hard metals is this a constant in machining?


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In a CNC machine with rigid tapping I'd say yes, hand tapping or manual mill tapping you can probably get away with using the 3 flute steel taps. Certainly for brass. Aluminum is gummy galling yuck metal hence fewer flutes. I decided to give the two flutes a try but I have used standard taps on aluminum forever and the sky didn't fall. I just had to be careful.
 
I'm with Coolidge, you can hand tap using just about anything. Just make sure you use a good taping fluid, break the chip often, and clean out the flutes.
 
I'm with Dan, tapping fluid and backing out frequently to clean the chips out of the flutes is key with standard taps.
 
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