Is there a go-to set that ARF can recommend?


I'd like to cover the smaller SAE and Metric sizes pretty well, but I'd rather not buy a $180 kit.

any recommendations?

(I have never used T&Ds before, but I'm extremely DIY when it comes to pretty much all aspects of gunsmithing..)



I'd use them to:
*add upper tensioning screws to stripped lowers
*thread safety detents for allen screws
*thread a non threaded shotgun receiver
etc.

I have an Irwin-Hansen set that seems decent. If you buy a set, make sure it has sizes you'll actually use.

We use cheap ass Interstate from Enco taps at work for hand taps. Tool and die shop. We break enough of them but it's in tool steel and we're tapping more holes with each one than you'll probably tap in a lifetime. I honestly don't know that I've seen a die in the place, and I've been there for a year.

Not to be all flag waving (not that there is anything wrong with that) but if you want to buy dies and taps that will last and stsy sharp, buy US made stuff.  I have been on the wrong end of too many Chinese made taps and dies over the years and will advise you usr them only as a last resort.  I was not paying attention a couple years ago and ordered three 1 / 4 x 28 taps and dies off some tool company on the net and they ended up being made in China.  They were galling and stripping threads right out of the package, dull as a butter knife.  You get what you pay for...

In my world I've learned to stay away from carbon steel taps because they just don't last.
Nearly every carbon tap that I use regularly at work has been replaced with HSS ( High Speed Steel)
If you are only going to use them on aluminum maybe the cheapie hardware store carbon taps will work fine.
If you have no other use for taps and dies I would save some money and only the individual taps you need for gun building.
And IMHO HSS taps are sharper out of the box than carbons and they make better threads.

HSS taps and dies are the only way to go. Cheaper carbon ones don't cut as clean and do not stay sharp for long.

For threading the holes you mentioned you probably will not find a set that has any that small. Just buy what you need from MSC Direct or McMaster-Carr. Their prices re good and selection is second to none. Both places have many different brands and qualities available. You will receive the stuff in a day or two typically.

If you're looking for gun taps, don't buy a set.  Your typical set will be #4 through 1/2, and generally only course thread under #8.  Gun screws are fine thread or extra fine, and #5-48 (not found in any set I've ever seen) is fairly common.  You also won't likely find much use for the metric taps in a set working on guns.  M3-.5 and M4-.7 are about the only metric sizes I've encountered on firearms, aside from muzzle threads.

Irwin or Vermont American HSS are as cheap as I'd go on taps.  And personally, I hate using standard straight flute plug taps.  I use mostly spiral flute taps, usually bottoming type, sometimes interrupted thread.  Spiral flute taps are much better for chip clearing, especially in blind holes.  

Whatever you use, be sure to keep from applying lateral pressure, use an appropriate cutting fluid, and clear chips as necessary for the tap profile and material you're threading.   Exerting lateral force or binding up on chips is what breaks taps.

Dies?  You'll really want adjustable type of high quality if you want threads to cut clean and straight.  Solid hex dies are fine for chasing, but suck for cutting new threads.  Be advised, getting a die to run perfectly true without a machine guiding it is really difficult.  

If you're not in a hurry, I'd suggest cruising ebay and watching for good deals on high quality tooling.

ok.

I'm sold on buying individual taps that I'll use and sticking to HSS from American companies.
I saw a couple recommendations on sites to visit, I'll check them out.

Dies wouldn't be used for anything except probably chasing an existing thread, I only mentioned them because typically you find kits that do both (on the lower end, anyway).

Is there an easy way to figure out what threads I have on existing bolts? (just measure and count?)

thank you for the advice.

I would only buy as you need them and get US made. Brownells, McMaster Carr and Granger are good choices. Better is a local tool supply but they normally don't  like dealing with the public.  
I agree on not using carbon taps but on the plus side they are cheaper and if you bust one in the hole they can be chipped out.  HSS (high speed steel) needs to be burned out as tap extractors only work in 1 out of 8 cases for me.
as for drills I would get HSS (high speed steel) and not cobalt, easier to sharpen.
You can find charts on the net that will tell you what size drills to get for different screws but basically you take the OD of the screw and subtract the pitch and that will be the drill size. For example a 1/2 x 13 is .500 diameter of screw minus the lead or pitch in thousands in this case 1 /13 =  .077 so .500 - .077 = .423 drill. I would go up to a 7/16 (.437)

They make pitch gauges that can measure up to 72 pitches.  Just find the leaf that matches your threads, I think Brownells sells one.
Or lay the end of a one inch ruler at the top of one thread, skip that thread and start counting until you reach the one inch mark.
http://www.brownells.com/gunsmith-tools-supplies/measuring-tools/thread-pitch-gauges/straight-thread-pitch-gauge-prod7666.aspx

Small ball end carbide end mills in a dremel are the best way I've found to remove broken machine screw taps.  I've successfully removed broken taps as small as 1-72 this way.  You just have to be careful to not break the cutter deep inside, as once you lodge carbide in the hole, you're pretty much done.  



True, but cobalt holds up to high temps much better.  I use cobalt for boring deep holes in Ti, as it will smoke HSS twist drills in short order, even with lubricant. I also like them for really hard steels.  Downside is that cobalt chips and breaks a lot like carbide, and is just about as intolerant of flexing.

OSG. Hands down one of the best there is. You're going to pay for it though

+1 to this.  Don't waste your money on a set you won't use much.  Instead, go to your local hardware store and buy small tap and die handles, plus HSS taps and dies only in the sizes you need for your AR project.  If you need another size later, they are always there at the store waiting for you. - CW

I probably wont use handles.. I'd lock my receiver in a drill press vice and drill the hole, then swap out the drill bit for the tap and rotate the chuck by hand as I tap the hole.
that way everything stays in perfect alignment

(any issues using this method?)

 Not a problem if that's what you prefer.  Due to the odd angles involved, some holes are better tapped by hand, e.g., tapping the little hole that holds the spring for the detent on the rear takedown pin.  That allows you to secure that spring with a little set screw instead of monkeying with the buttstock or carbine end plate to hold it. Aluminum cuts real easy.  - CW

You'll still need tap wrenches most of the time.  Not enough leverage grabbing a drill chuck.  Definitely can start them that way, though.  Many taps & tap wrenches have a dimple or hole at the rear that can be used to guide them with a mill or drill.  I don't have a lot of tapping photos, but this is the differential carrier for a very custom power wheels I built for the kids, being tapped #10-32:



Also, be careful to not exert too much pressure; it will cause thins & shallow threads.  Best to let the tap pull itself in, the machine only guiding, not providing down force.

You either won't be able to spin the tap, or you'll break it doing it that way.  7075 isn't the most fun thing to tap. Absolutely nothing like 6061. You'll definitely want some tap wrenches or handles. You can pick up a set from harbor freight for pretty cheap and they'll do what you need them to do.

Doing it that way will give you trouble. I'm not a machinist but I pretend to be one occasionally. (actually, I had one year of basic machining in college so that officially qualifies me as a hack machinist )

There will be no way to regulate the down pressure with the drill press feed. Do it the way sixtysixduece shows in the pic. Using the chuck only as a guide to keep it square. Down pressure while turning the tap should only be slight and by hand pressure just to get the tap started, then it will pull itself in. Use plenty of lube and put a slight chamfer on the hole, which will help the tap start. In and out several times to clear the chips and everything should go fine. Never run a tap all the way in the first time. In a few turns, back it out, clear chips, repeat.

BTW I've tapped many holes with "eye ball method" for square and they have came out fine. I won't argue that that the drill press method is the right way to do it but not absolutely necessary.
I have a small 2" by 3" machinist's square that helps, too.

Here's a little tip, use Crisco (lard) on the flues of the tap. Will catch the chips, important when tapping aluminum. That and backing the tap out will make great threads.

Yeah, if it's a spark plug hole in a cylinder head.  Otherwise, you want the chips to clear.  Compressed air is best, but it's not like AR lowers are too heavy to flip upside down.  



What on earth are you talking about?  7075 has far better machinability than 6061, as do the rest of the 7XXX and 2XXX series aluminum alloys.  Harder alloys always cut better; they break chips cleaner, and are less prone to galling.  I cut 7075-T6/T651 completely dry, even running cutters two and three times the depth of their diameter with a full width cut.  Do that with 6061, the flutes will clog very quickly.  6061 is a fairly sticky metal.

And as for backing taps out;  only if you can't clear chips any other way.  If you have compressed air and it's a through hole, there is absolutely no reason to back out.  On blind holes, I don't stop until I can feel chips compressing under the tap, or when it bottoms.  This is why I use spiral flute taps; near all of the chips clear to the rear, just like a twist drill.  Remember, every time you back that tap up to clear chips, you're reversing the load, straining the structure in the opposite direction.  Just like working the tab back and forth on a beverage can, it takes a toll on the metal.  Much better to keep going forward if possible.

Do not buy cheap Chinese taps.  They are prone to breaking.  There is nothing worse than trying to remove a broken tap when it breaks off below the drilled surface..