On 7/31/2014 8:31 AM, email@example.com wrote:
I am going to have to say that socket head cap screws come in a variety
of harnesses. I have run across many, think Ikey furniture assembly
screws, that are less than desirable, the wrench does distort the screw
head. On the other hand I use a higher quality screw to mount my router
to the router table and while these screws seem to get tighter over
time, I have never seen any degradation of the hex recess. These
particular screws have held so tightly that cheaper brand hex wrenches
will actually cam out and or distort. With a quality hex wrench I toss
a towel over the screw and hex wrench and use a short piece of pipe for
leverage. The towel is to catch the shrapnel should the wrench break.
Torx/star provides more contact area between the bit and screw, has no
cam-out tendency, and is less likely to strip out... The risk of snapping
them off in hard woods (physically hard, not hardwoods vs. softwoods)
without predrilling goes up too! Ask me how I know that... ;~)
My experience is that the star has a more positive engagement and the
bit does not need to be as perfectly aligned with the screw to prevent
caming out. And the star bit engages more easily than the square drive
bit. The screw strips when the bit cams out.
One thing I found out. It is easy to get paint out of a slotted screw
to remove the screw. Next easiest is a square drive. I just had to
replace the surface boards on some outside steps. They were fixed
with square drive screws. The holes were full of paint, grit and
crud. I dug most of it out with a slim awl then inserted a spare
square drive bit and tapped it with a small hammer. Then the bit on
the impact driver slipped right in and backed them out. Not sure I
could have done this with a star drive screw, but maybe so.
For general use I vote for the star.
FWIW I have had great success with using an impact driver to remove
screws that are corroded, filled with putty and or paint. The impact
action seems to work the drive bit in with out doing much precleaning of
I've found that a perfectly mated bit/screw combo is the key.
I have a sheetrock Phillips screw bit that holds so tightly to the screw
it can actually be a bit of a PITA to get the screw off when removing.
Same with square head. If I'm driving square heads with a well mated
bit, the bit often comes off the drill extension because it's stuck to
the screw. Star heads have shown promise for me since starting to use
them regularly. Like Marlow said, the bits can round off at tip, so
have some spares.
I honestly don't have a preference, but if I had to choose one to use
the rest of my life it would be the Phillips Square-Driv, which is a
combo square/Phillips head. I like this because you can take them out
with either screw driver. Very convenient. The proper sized bit holds
and drives as well as *any* other bit/head combo I've ever used.
"Playing is not something I do at night, it's my function in life"
I hadn't really noticed the screws wanting to stick on the bits with the
stars. The way they work, transmiting torque via the lobes, it's possible
for the fit to be loose or sloppy and still drive screws perfectly.
On Thu, 31 Jul 2014 16:54:55 +0000 (UTC), Larry Blanchard
Star (Torx) does the same. ...in spades. I'll spend a pretty good
premium to get the star heads. The exception is sheetrock screws,
where the Phillips head really is needed. The Phillips head is
designed to cam out.
On Thursday, July 31, 2014 7:25:50 PM UTC-7, firstname.lastname@example.org wrote:
Square drive/Robertson tips are tapered; the harder you push,
the greater the drive surfaces contact forces become. So, you can drive
them very hard. But when you want to REMOVE a screw, you don't
want to apply a push (this hurts you because it increases friction).
Torx/star tips are straight-sided, you get equal torque limits in
drive and remove operations. So they're easier to remove.
Philips/crosspoint, like Robertson/square, are tapered, and can
be difficult to remove.
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