I’ve found that not all 3/16” bits are created equal. My favorite for that size is the Tapcon brand you find in the fastener aisle near the Tapcon screws.


Mike.
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[emoji631] [emoji631]

 

Another vote for tapcon

 

Why not Ramset?

 

Ability to relocate.

That first/right hole (pic) -- attempted to reuse hole which I shouldn't have.

Will try tapcon bit. Noticing the design of GRK's thread - could be offering up too much resistance. Tapcons look easier to drive in, so will try them, whatever works.

Guess there too is the chance of hitting aggregate. Likely posing no problems for bits but as far as the thread, I don't know. I do know that I'll soon be running out of hole space around this little bump out. Going to experiment elsewhere.

 

Cut deeper and flush WITH the bit multiple times. We use tapcons of that size all the time, but usually cutting with an SDS rotary hammer drill. Tapcons are brittle, too, so the hole needs to be clean.

Those fasteners look more aggressive, so may be more fickle with the crete.

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Blow out the hole with compressed air, have the vacuum hose next to the hole as you do this. Wear a dust mask (if you can find one). The vacuum itself will not properly evacuate the hole.

Tom

 

Have plenty of dust masks but lacking a compressor.

But -- I do have some "industrial strength" air in a can (cleaning pc) with a thin line nozzle. Will try that

 

with no compressor & small holes you could try using lung power and a piece of tubing or a straw to get the holes clean.

use a piece of wire as a pick to help loosen debris.

you could always rinse them out with water, turkey baster or a large syringe work well. then use your lung power to clean them out.

 

I've used liquid dish soap on the fastener when have to keep things moving.

 

Those holes are too small to flush out with air, the bit is our friend IMO.

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Forgive me - the initial description I gave was in error.

It should have read;

"Second attempt (left): ... turning with my hammer/drill (Milwaukee 5378-20) 'spun the head off before driving flush' rather than 'stripped out easily before sinking'"


The right hole was the one that was stripped out on second/reuse attempt with the hammer drill.

 

I drill plenty deep and usually run the bit in and out a bunch after the hole is drilled. I prefer the hex head tapcons. Compressed air with vacuum to clean out hole. Vacuum won’t do a thing alone.


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I used to have trouble with just about every brand of concrete screw, until I developed a system for it.

I overdrill by a good half inch. Then, run the bit in and out many times, but without drilling any deeper.

Then, blow it out with compressed air. Lots.

I've taken to only setting them with an impact. If it feels like it's starting to bind, STOP immediately and redrill.

If it spins without catching, drill a new hole right next to the one that is too big.

After 3 or 4 holes, you'll get the feel for how much to drill to get a nice tight fit.

Use a nice new bit, and replace it when it starts to wear.

Running the bit in and out has been the single most definitive thing for me to get a properly sized hole.

 

... I overdrill by a good half inch. ...

Was going with a quarter, now 1/2. Will stick with my impact, so that they don't break.

 

Forgot to say, like MW said, hex head are far easier to use, so unless you need to countersink the screw, don't bother with phillips head screws.

Torx are slightly better, but hex is king.

 

1/2" overdrill is a bare minimum IMO. With small holes like that, neither vacuum nor air is going to do a great job of cleaning them out. I long ago quit using either.

Just overdrill generously and when at depth run the drill in & out until it pulls next to nothing out with it. Use a standard driver rather than impact or hammer to sink the screw. I think the jerky action of the latter is more likely to fracture it than a single smooth/steady drive from start to finish.

 

Just drilled the for GRK 1/2" deeper going straight in and out, with correct 3/16 drill size that gave no diff. According to technical data for these "Uber Screws":

"...close tolerance holes drilled a minimum of 1/4” deeper than embedment depth." With a shear listed at 1505 lbs.

Cleaning out with "air in a clean" shot out concrete dust. Once you get partly into that bugle head however the screw starts strip-spinning with little effort. Forget sinking them - unless you maybe want to pre-drill each countersink, which I'd rather not.

Next, on to the tapcons.

 

i find GRK to be far superior then any of the blue painted ones .
I also drill a bit deeper . when installing screw and feel resistance I back it out and run the drill bit through again .
love the soap idea ,will try that sometime .
if screw spins out and i need the hole I shove cheap plastic drywall anchors .hammer into the hole ,more then one for deep holes .then run a construction screw in .

 

Tapcons; drove to where it starts depressing surface-level with regular clutched drill (500ft lbs) on strongest setting. No problems.

.

 

Bottom plates on partition walls have minimal uplift, if at all. Fasteners are there to secure the wall laterally. A bead of adhesive on the bottom plate will help minimize movement and/or noise from fasteners that loose hold in the future.

If you still have trouble, you could put a thin piece of wire down each hole to snug up the difference between teeth to concrete.

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Or the two 16 penny nails slammed together in a 3/16" hole . Love that method . I did not learn it till i was close to 40 . The apprentice that was with me slammed in and i learned something new .

 

If I’m not mistaken I think I might use a 7/32” bit instead of 3/16” over drill and they go in fine.


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One 16 P common/ or duplex head, with a baling wire/tye wire 18-20 gauge/ steel wire ~ 4" long bent into a 'staple' stuck in 3/16ths hole ~2-2.5" deep under 2 x plates in concrete floors...


Not recommended for damp locations....


I have used home made wobble fasteners, bolt cutter cut common 16 nails cut down for stucco mesh nails into masonry drill with hammer drill and carbide bits, nail Bent to bind in masonry backing,, cheap but time consuming, save a trip to yard.

 

Vote for Tapcon. Hex-head is always better and when there is no power source or compressor I use a can of compressed air (like for computer keyboards). Always clean the hole with the drill bit without drilling more depth or wallowing out (in and out).

 

https://www.hilti.com/content/hilti/W1/US/en/services/fasteners-firestop-strut/concrete-anchors.html


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https://www.hilti.com/content/hilti/W1/US/en/services/fasteners-firestop-strut/concrete-anchors.html

Have sunk the expansioin bolts for other reasons (raising sunken floors on cinderblock foundation, decks, etc) that would be overkill for this... but never tried their "screw anchors"