"reduced head" flat head cap screws?


Awl --
I need to use 1/4-20 FH cap screws, but the head on these is really large,
and a pain to c-sink.
It seems that a head size of about a #10 or #12 FH screw would do me just
fine.
Also, smaller heads allow you to c-sink thinner material for such a screw.
Is there such a thing as a 1/4-20 thread, with a smallish flat head (allen)?
I know I've seen these, just can't remember where, or if they were custom
jobbies.
Name of this item, if any? Sources?
Reply to
Existential Angst
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Any reason you couldn't go smaller and use more of them? I've seen and used socket heads with the one size smaller head, but they came with the equipment, not something I got off the shelf at a hardware store. I look on the use of specialty stuff like that as a failure in design. Leads to the "missing tooth", where somebody drops the screw, can't find it and can't replace it off the shelf, so the hole remains empty. If you do it, provide some blind tapped holes for spares.
Stan
Reply to
stans4
Self-clinching studs might be a possibility. Several kinds are illustrated at and [*] and
[*
] Picture is from article an article with other relevant links:
Although self-clinching studs are specialty items, they aren't subject to the particular problem you mention because they are fastened in place (interference fit).
Reply to
James Waldby
There are "undercut flat head" screws for use in thin material. The head diameter is normal, but the cone of the head is truncated where it joins the screw's body. But I've never seen them with hex sockets.
You are aware that hex socket flat heads are larger in diameter than standard machine screws?
Reply to
Ned Simmons
If a head size of #10 or #12 will do you, why do you want to use 1/4-20 screws. The larger diameter body of the 1/4 - 20 will not give more strength if the head is going to rip out.
Now if you are fastening high strength materials, look at 1/4-28 screws.
Dan
Reply to
dcaster
Consider going with a smaller thread or rater than FH socket head cap screw go with 100 deg flat head machine screw.
Socket head (allen), 82 deg., head diameter .531, head length .161 Flat head machine screw, 82 deg., head diameter .477, head length .153 Flat head machine screw (phillips or slot), 100 deg., head diameter . 470, head length .110
For thinner material it is possible to go with flat head machine screw undercut head. The head length is reduced to 70% of the normal screws (above). Down side, you need to make sure mating part countersink is to the proper depth and diameter.
Pavlov
Reply to
noneya
"Low head" --Mcmaster-Carr has them
If you search using the astm spec you will most likely find other suppliers who stock them.
Here is an example having 1/4in long threads :
92220A181 Alloy Steel Low Head Socket Cap Screw 1/4"-20 Thread, 1/4" Length In stock at $5.52 per Pack This product is sold in Packs of 10
Head Style Low Material Type Steel Finish Black-Oxide Class Not Rated Drive Style Hex Socket Inch Thread Size 1/4"-20 Length 1/4" Thread Length Fully Threaded Thread Direction Right Handed Tip Type Plain Self-Locking Method None Screw Quantity Individual Screw Hex Size 1/8" Head Diameter .375" Head Height .127" Rockwell Hardness Minimum C39 Minimum Tensile Strength 145,000 psi Thread Fit Class 3A Specifications Met American Society for Testing and Materials (ASTM) ASTM Specification ASTM F835
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Also--if you want to eliminate counter bore / sinking altogether then you might consider using "button head" instead--the head on which is domed and so they won't easily snag clothing etc.
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Reply to
PrecisionmachinisT
Something like this?
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part number 91253A533 if the link won't take you there.
Later,
Charlie
Reply to
Charlie Gary
Something like this?
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part number 91253A533 if the link won't take you there.
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Sheeit Charlie, the head on that screw is bigger than what I've got!! .531 vs. 500!!
I would like the head diameter to be .375.
Regarding the other suggestion to just use a smaller screw, I think 1/4-20 is the minimum I can use, as there is a torque situation, which I can't address by using more. Regarding the other comment on a smaller head pulling out, I don't think that would be an issue -- the torque situation is not THAT bad!!.
I spose I could always turn down these heads, from the bottom of the head on out, at 82 deg... if I can grab enough of the thread in a collet. Iow, I'd be making a bit of a shoulder FH screw.....
It would also be nice to get these in SS, and I certainly won't relish turning those down, but I may not have a choice.
Reply to
Existential Angst
Yes, this is exactly what you want:
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I use these kits for many metalworking fixturing tasks.
Reply to
Richard J Kinch
Well, you certainly can't tell from the link/page that these are reduced-head flat heads.... or that they are flat head *at all* -- typical HF. Also, I'd be buying a lot of other crap in this kit just to get one sized screw -- IFF that size is even in the kit.... hmmm, it seems there are 10 of the size I need.... hmmm, 10 out of 383.... :) :(
And what, HF don't give prices anymore?? Not even in the shopping cart....
You know, I joined that Inside track club thing, it took HF over a year to sign me up.... what a waste, afaict, but then I haven't really explored it. Any real benefits?
I seem to recall some security torx-type screws with reduced flat heads.... not sure. MH should have sumpn sumpn on this, but I don't know if the 24th ed would have a complete list, as some of these heads seem sort of recent/modern.
I have an idea I'll wind up turning these things down, much as I would like not to.... Altho, if I got set up to do 1,000 at a time, or sent out 10,000, it might not be that bad.... a cheap source certainly would be better, tho.
Mebbe for 10,000, I could order a run from a screw house.
'Course, you know what will happen, right? I'll order their minimum run, proly 10,000, and after I use 10 of'em, the design will change.... goodgawd....
Reply to
Existential Angst
This kit is something like $10, has what you want, and will serve for many other future projects. If the time you'll spend hunting for the same thing in a perfect retail quantity is not worth $10, then I'm sorry for suggesting it.
May I also suggest you look in the furniture fixit hardware bits at Home Depot, where they sell similar thin flathead screws.
Reply to
Richard J Kinch
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Mutial Screw company. This is a link to the web site where the 100 degree flat head screw instead of the normal 82 degrees. Allows for a larger screw in thin material. R. Wink
Reply to
rwwink

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