Itinerant Air-Cooled

When shopping for a tap and die set, what sizes are the ones to have? Do tap/die measurements match bolt head/nut measurements? I mean, does a 10mm tap tap a hole a 10mm bolt would fit into?

yes, and don't go to Harbor Freight to get one. Try to find a nice metric set that is quality that will last for years without snapping in two the first time you tap a hole.

The most useful taps/dies I've found are the M6x1.0, M8x1.25, M10x1.5, and every other one that I've needed when I needed it. But those three listed are ideal for cleaning up existing holes from dirt/rust/grime on any old metric car.

Really though, the most life-saving tapping missions I've been on have been drilling out a hole to the next size up and tapping that way to make new threads. For example, when mom's bug's previous owner/gorilla tightened down the six oil strainer nuts, he/she/it stripped two of the M6 magnesium studs out of the crankcase. I used an M7 tap to make new threads and found specialized M6-M7 step studs. If it wasn't for that odd sized tap, I would have had to drill it larger, and we all know how great drilling into an unfiltered crankcase could be………

One of my machinist teachers told me that an old tap can shatter if its been used/heat cycled too much, so I would avoid buying a used set, unless it's a high quality set that hasn't been used much, if at all. I've only had one tap shatter on me, and it was an older bit, but during use in very mild steel.

I also find it handy to have standard AND metric taps for my VW, because sometimes you'll find an "in between" size as a workaround. For example, when I surfed for the last three years and stood on my rear bumper to tie the boards down to the roof rack, I eventually stripped out the left rear bumper hole from the weight. The next metric size up would have been a HUGE drilling project, potentially thinning the metal out too much to be strong. But one standard size up left me with plenty of metal to bite into, without even needing to drill a new hole.

My three cents,
Robbie

Also make sure you have a nice set of the right size quality steel drill bits to drill holes the correct size for tapping. I have a set of cobalt boron steel bits just for this as they are harder than most steel you drill into and drill steel like it's butter.
There are special thread cleaning taps to that the threading isn't tapered but set up to clean up threads in a hole with a dead end all the way in so a stud with hold with all the depth of the threads....

whc03grady wrote: Do tap/die measurements match bolt head/nut measurements?

No, the head (i.e. wrench) size is pretty much independent of bolt/nut thread size. For instance, I have on hand M8x1.25 nuts which take 11, 12, 13 (the most
common by far on VW's), and 15 mm wrenches. A "10 mm bolt/nut" means it has an M10 thread, not that it takes a 10 mm wrench to turn it. Taps and dies
are always denominated by the thread size and pitch.

If you buy a set, there will probably be many items included you rarely or never use before others are worn out. If you live in reasonable vicinity to a decent
hardware store, I'd recommend just buying taps & dies on an as-needed basis, and to get duplicates of the more commonly used, small-sized taps which are
subject to occasional breakage.

I have been looking at this set for a while but I have not crowbarred my wallet open wide enough yet....I had to buy a few SAE ones a few years ago for some project and they are also Irwin. For the money, I thought they were pretty well make

http://www.amazon.com/IRWIN-Tools-Metri ... nd+die+set

I sprang for that exact Irwin set awhile ago. Have had no cause to regret it. I think I paid about $20 more than that current price on Amazon.

I just ordered this...thanks for the tip!

I've also been eying this tap and die set for itty-bitty-widdle screws. For $13, it looks like a bargain.

In fact, the vendor, American Science and Surplus, is my new favorite place to waste time on the Internat browsing their catalog. Very eclectic oddball offerings at reasonable prices. Was a great resource for finding stocking stuffers this year.

Visited this place a couple times when I lived in Milwaukee, cool store!

So this one is too cheap?

whc03grady wrote:So this one is too cheap?

It's got the sizes you'll most frequently need, but keep in mind that Craftsman tools aren't what they were 20 years ago.

Whatever you do, steer clear of the "Master Mechanic" sets that True Value used to sell -- the last few we got at work were terrible. The entire tap & die line was replaced with Irwin last spring, but I'm sure there's plenty of old stock floating around out there...

Of course the other thing to keep in mind is what are you really likely to use. I like to clean up the threads using the wire brush in most things and on the hardware that I put back together so I am really only using about 6-8 different taps and dies 95% of the time.

Truth be that you could likely do 80% on a bus with just a 6x1.0mm and a 8x1.25mm tap/die in your toolbox.

Having the fine and course threads can be a real saver on some jobs. Not so much on the VWs but things like the snowblower, Ikea hardware, and Subaru hardware seems to come with really cheap metal that need the clean up help. I treat most the cleaned up hardware with Gibbs lubricant anymore (or any other lubricant) so it really doesn't strip out as often.

Randy in Maine wrote:Of course Subaru hardware seems to come with really cheap metal

Please . . . . inform us.
Colin

Amskeptic wrote:

Randy in Maine wrote:Of course Subaru hardware seems to come with really cheap metal

Please . . . . inform us.
Colin

Mostly cheap pot metal that does not hold threads well. I was unimpressed.