Tapping 6-32 in aluminum

Ignoramus10114 fired this volley in news: snipped-for-privacy@giganews.com:
What's the application? The 8-32 would be a stronger bolt, with more thread cross-section. But it may not be necessary for whatever you wish to hold.
L

Ignoramus10114 fired this volley in news: snipped-for-privacy@giganews.com:
PS... a lot of heat-sink _component_ mounting hardware comes in M2.5x.45 size, for mounting things like TO-3 and TO-220 packages. That's smaller than 6-32.
L

strength not an issue

Ignoramus10114 fired this volley in news: snipped-for-privacy@giganews.com:
Then one sizes it according to what you want to mount.
I mentioned 2.5x.45 metric... some also use 3 x 0.5mm, but even that's smaller than 6-32.
If you need to mount through screw insulators (like for mounting a transistor or a floating-case regulator like an LM-317, you may be hard- put to find any insulators that will fit even 6-32... metric has more-or- less filled that market.
Lloyd

With a rapidly expanding international market where demand for metric outstrips demand for trade (in everyplace but the US), its not surprising.

Either would work, assuming the aluminum is thicker than 1/16 inch.. you never want less than two threads. Be sure to check/flatten the machined surface (I sometimes rub it down with a whetstone) if there's any deformation, or the flat-to-flat heat transfer interface will be compromised.

That has little to do with it. Except for construction and transportation equipment, it's mostly a matter of whether the industry is heavily involved with science, in which case US fasteners are metric fasteners, just as they are everywhere else, or if it has an international supply chain.
It's useful to look at three markets: the market for off-road equipment (mining, construction, etc.); the market for automobiles; and the market for electronic devices.
In the first case, the issues are that the market is truly global and that the equipment has to be repairable around the world. Thus, Caterpillar was the first large US company to go 100% metric, beck in the '70s.
In the case of automobiles, US-built cars have never had much of a global market but they are now the end of a global *supply chain*. It is cheaper, and more flexible, to use metric fasteners for US-built cars, when they may be built from parts supplied by 20 different countries.
Electronic devices are designed and built in an environment that is close to the underlying science, where metrics have been the lingua france in the US for most of a century. Metrics are followed in the engineering and in the assembly; repair is a miniscule economic issue. Also, the supply chain is not only multinational, but also ad hoc; you may not know this week where your parts will be coming from next week.
The upshot is that, with 70% of our economy based on domestic consumption, there is little or no economic advantage to making sweeping changes to metrics in other industries. Thus, change is slow. And it has little advantage for anyone other than those industries described above.

Both are 32 threads per inch, so how is one "less course"?

70% of every product purchased in the U.S. is made in the U.S.? Wow, I didn't think it was that high.

whit3rd fired this volley in news:07594162-52db-470a- snipped-for-privacy@googlegroups.com:
That would truly be a sin on a nicely anodized heat sink!
If it's not flat, it's junk anyway, I guess.
Lloyd

70% of our GDP is domestic consumption. That's net of imports and exports.

6-32 works fine. I do these often. A good, sharp tap (not the horrors from the local hardware store) work quite well. I use "Alum-Tap" from Wibro as a tapping fluid, it is incredible stuff. Makes the tap go in like it was already threaded.
Jon

Jon Elson fired this volley in news: snipped-for-privacy@giganews.com:
Oh, I don't know... if I want a 'standard' straight-fluted tap without having to wait, Hansons are pretty good quality. 'Never got a dull one, nor one not accurately-cut. They cut freely and don't leave any more burrs than any other reasonably well-made tap.
I prefer spiral-flute taps for most work, because about 3/4 of my stuff is blind holes; but there's nothing wrong with a Hanson tap. That's what ACE carries - carded, one per. I don't know about your local hardware store.
LLoyd
LLoyd

The dollar percentage of durable goods sold in the US and made in the US was 66.6% in 2010. The overall percentage of dollar value of consumer imports, in all categories including oil, was 11.5%, of which the actual cost was 7.3%. The remaining 4.2% goes to US transportation, wholesaling, and retailing markups.
If you follow US manufacturing and trade for a decade or more, you'll realize that almost every popular conception about our manufacturing and trade is wrong.

Both are the same pitch, 32tpi, Ig. So what's your real question?
Yeah, original posters, please don't say what it's _for_.

6-32 is a course, ie nc, thread. 8-32 is a fine thread, ie nf. The fine threads do less cutting relative to the screw's major diameter. The 8-32 will be less likely to break than the 6-32 which, in steel, is a consideration. In aluminum probably either one would free of worry. Maybe the 8-32 would be a little freeer.
Hul
Ignoramus10114 wrote:

"Ignoramus10114" wrote in message news: snipped-for-privacy@giganews.com... I've never had a breakage problem with good-quality 6-32 taps in aluminum, if that's your worry. If possible I use two flute spiral point (gun) taps in through holes and kerosine etc for the lubricant, and I don't start the tap without some sort of squareness guide, either the mill or a hand-held fixture like this:
Some people prefer cubical ones.
-jsw

I learned something cool, I do not need to tap anything! If I drill a 1/8" hole, a 6-32 screw taps it for itself very nicely.
i

"8-32 is a fine thread, ie nf"
No, 8-32 is UNC.
MikeB