"Existential Angst" wrote in message
...
"Wild_Bill" wrote in message
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You haven't said what the application is. Roger may feel like he wasted
his time responding, if you're asking about mounting the chin-up bars
you've been talking about lately, but his post is informative.

You've been around enough, and it should be apparent to you that you need
to mention what it is, you're asking about.
There isn't much point in responding to questions when the person asking
is being vague, IMO.. many times it takes a couple of days before the
details are eventually presented.

If this is the same question asked again, about mounting the chin-up
bar.. what're ya gonna do, keep asking until someone says it's a good
idea to use DW screws?

I don't like using DW screws for much of anything other than drywall.
Ever notice that sharp "snap" when they're overtightened?
The common DW screws are hard and brittle, and will break suddenly under
certain circumstances.
I definitely wouldn't use them in metal, but that's me.

You should be examining real screws.. self-tapping or other style for
mounting a chin-up bar.
Generally, the most secure method will be to get as many threads as
possible into the thickness of the material that the part is being
attached to, which means a fine-thread, self-tapping type screw, most
likely (or nut-sert type products that were mentioned previously).
If the fasteners that you recommend fail, the user could sustain a
laceration, or possibly brain trauma. Good luck fending off the lawyers.

If you're trying to come up with a simple solution for the end user to
mount a product that you intend to sell, safety should be the primary
factor. If some doofus can't install the product, then they'll return it
to the seller, or improvise a solution (not your problem).

Well, the real Q is along the lines you've mentioned.
"Real" sheetmetal screws, such as hvac ductwork, really can't put ANY
threads in the material itself, ductwork is just too thin. I always
thought the tek-type screws were the wrong thread design for this
application.

Even 16 ga is sort of thin, but chassis screws seemed to have been
developed for this purpose, which is why I mentioned them in the earlier
thread, but no one picked up on this. Roger touched on these, which I'll
continue in a response to him.

Chassis screws seem to be a discontinued item, so I wonder how practical,
under load conditions (not really found on radio chassis) threads in thin
material is.

Which is why I'm asking about threading vs. *binding* of thin material
together, via a larger ratio of major to minor diameters.

I keep mentioning SR screws, because the coarse thread screws really seem
to have a much better major/minor diam ratio, and I believe I've seen
specialty-type screws that used this strategy.

If the answer is, STFU and buy a box of self-drilling sheet metal screws,
then I'll do it, but this never really seemed to be the "right" solution,
on basic geometrical/mechanical grounds, for the above threading reasons.
--
EA

A good threadsert that will accept a machine screw will be much stronger
than sheet metal screws.