"TAPS"

[harryset]

I don't know how anyone could do any major body, or engine work, on a VW without a good set of tap and dies. I have worn out a couple of cheap 6 x 1.0 taps already and my 8 x 1.25 is running a close second. It may seem to be a PITA, but I highly recommend chasing all of the screw holes prior to assembly. Forcing myself to adhere to this practice has actually made most of my work go faster.

[Bugfuel]

Fully agree!

Oh and don't waste money on real CHEAP taps and dies. They can do more harm than good.
Spend money on quality tools that don't break and produce a clean cut.

[fusername]

well I actually have had a lot of luck w/ some no name taps, are they piss poor or just consumer grade, I don't know. The biggest thing I can reccomend is actually buying some real taping oil, like tap magick. it is super expensive so it took me a long time to bite the bullet and pick it up when I was doing galley plugs on a T4 engine as that is no place to screw around. I had been using anti-seize or motor oil up untill then. I don't knw how much better it makes the tapping action, but when drilling thick metal I use a bit of tap magick on the bit and it makes worlds of difference in cutting ability compared to using ordinary oil.

[Bugfuel]

The proper cutting liquid for aluminum is alcohol. I prefer dark rum with pepsi, with a splash of lemon or lime, and ice. Mmmmmmm.

[fusername]

I have heard the same thing, but the alchohol never lasts long enough for me to pour it on the tap.

[Ol'fogasaurus]

Be careful with going too crazy with the 'ol tap and dies. Some fasteners have self locking features and you can ruin them by chasing their threads. One piece of advice it to look at the shape of the hole; if it looks slightly elongated (out of round), think twice about it. There are very few threaded holes that are this way but with nut plates, nuts and some bolts, the self locking feature is very common.

I too do believe in chasing threaded holes but (to state the obvious) also be careful about chasing the same hole too often too. Each time you chase the hole you are slightly changing the depth of the thread and changing (wearing away) the width of the threads (especially with the cheaper tap and die sets which may not adhere to the best of standards).

Also use a pitch gage to check the thread count before you cut the hole.

Lee

[fusername]

and for odd/expensive holes, say torsion frame housing, taking a old bolt and cutting one or two slits in it with a cut off wheel will make a good thread chaser. needs to be cleaned often, but works, and should be undersize related to the matching tap and avoid the problem ol'fogosauras is talking about. I have theorised cutting a slit in in a nut would do the same thing, but have never needed it.

[Bruce2]

and for odd/expensive holes, say torsion frame housing, ...

If you're talking about the big bolts in the ends of the frame horns, it's not as obscure as you may think. It's M18x1.5. It is the same as an oxygen sensor. Every auto repair shop will have this one.

[Tom in PA]

When building engines, I chase everything. It makes life sooooo much easier when you're assembling and re-assembling things during mock up. I have a thread chasing kit. I got it at sears, I'm not sure who makes it but every one I've seen is pretty much identical (including a snap on one). They don't really cut the threads as much so they do less damage. When working on old engines, they're priceless in my opinion. They will wear things if overused as described above. Also as described above, you can always make your own buy cutting some slots in a nut or bolt of the size you need. Works great in a pinch.

Tom

[fusername]

yeah thread chasers don't cut, they are undersize from a tap sos to just remove junk and burrs, not new material, so a slit bolt is exactly that. I also have seen some cool expanding ones, for use in spark plugs and o2 sensors, you slip it into the hole, expand it, then clean on the way out keeping debris out of the thing.

[Devastator]

4 flute taps were designed for hand tapping. The 3 and 2 flute taps are stronger, but intended to cut new threads using a machine, (mill, lathe. etc), and not easy to use by hand. I have a small aluminum block that I have drilled to the same diameter as most common tap shank diameters, ( holes covers everything from M1-M6 and 0-80 to 1/4-20), and use it frequently to tap holes that have been drilled. WD-40 works OK for cutting and chasing threads, but dark thread cutting oil, (found at most hardware stores), works well in steel, while Kerosene works well for aluminum. Tap magic, Cool Tool 2, etc, are great, but kinda pricey if you aren't doing a lot of thread cutting. There is also a thread size designation on taps that tell you what size they are "supposed" to cut. I recommend H2 and H3 for most applications.
To much info probably, but what the heck?
Dev