Taladrado Rápido! Mayor Duración! (Faster Drilling! Longer Life!): Concrete Fasteners, Drills

The high floor-to-near-ceiling metal book shelves have been assembled, but all of our books (except for ones we’ve needed since the relocation) remain in their moving boxes, stacked four and five high nearby. They (the shelving units) are relatively shallow and, though the largest and heaviest tomes are destined to reside on their lowest levels, the prospect of a fully-loaded book shelf teetering and falling over gives one pause.

Securing them to the wall seems like a prudent step to take before filling them up with the contents of our home library.

Knowing precisely where it’s safe (and feasible) to drill is, of course, a concern. Hong Kong residential spaces are almost always concrete-and-rebar, so the “hammer” mode on a regular cordless drill isn’t going to get you very far. You need carbide-tipped masonry bits in a rotary hammer drill to make any headway. Plumbing doesn’t run inside the walls (drains and inlets head directly outdoors and the pipes are bolted onto building exteriors) but electrical conduits are embedded in the walls, along with reinforcement bars and the heftier structural steel elements of the building’s skeleton. Boring into electrical conduit would be bad and grinding away at rebar or a girder would be frustrating.

I needed a wall-scanning device and a rotary hammer drill and suitable fasteners. After some review-reading and mental calculus around how much I need and want to invest in these things, I got Makita’s “sub-compact” brushless cordless rotary hammer (some negative reviews, but mostly positive and it’s compatible with batteries I’ve already got) and a Bosch wall-scanning thingamabob that you switch on and press against a flat surface and slide hither and thither. If nothing is detected inside the wall, the milky white light-diffusing plastic ring around the gizmo’s central bullseye lights up green. If it thinks there’s something inside the wall at a given point, you get a red ring of light, an audible warning, and some icons on an LCD screen representing it’s best guess as to the nature of the hidden object. I’ve tested it using lengths of metal rod and conduit held behind layers of plywood and tile and it seems to be reliable.

With the rotary hammer drill, which I bought on Amazon, I also got an assortment of Makita carbide-tipped SDS-Plus drill bits (shown above). They’re 3-cutter drills because they have three carbide chips embedded in the cutting tip. On Taobao, I saw similar Makita bits but with an additional carbide edges, making them 4-cutters. The former are marked as having been made in France and the latter are Chinese-made.

The four-toothed drills are sold individually and I got one each of a range of diameters because they weren’t too expensive and I wanted to try out several types of fastener (and they’d have different diameters). The merchant from which I purchased mine had them in multiple lengths and, not needing or wanting to drill very deep holes, I went with the short versions.

For the sake of comparison, I’ve cobbled together a photo-montage (shown above) of side-by-sides and close-ups of the 1/4″ (6.35mm) drill from the 3-cutter assortment and the 6.5mm 4-cutter that I bought on Taobao. The bodies of the two drills are different-looking. The spiral on the stubby 4-cutter is visibly shallower, flatter, and fatter than the spiral on the 3-cutter. What that will mean in practice in my amateur attempts to drill into concrete remains to be seen.

As of today, I haven’t yet put any of these things to use. I’m still bogged down assembling other furniture (particle board and cam-lock fasteners galore) but, once that’s done, I still won’t pivot directly to hole-making in actual walls. I’m going to buy some solid concrete paving blocks from a local building materials place and make practice holes and try out different fastener types. The ones I’ve acquired so far are shown in the image that tops this post, the picture with the millimeter-scale stainless steel ruler in the center.

The easiest concrete fasteners to get, in stainless steel, were sleeve anchors and I picked some up, in 304 stainless steel and in M6 and M8 sizes. There’s a lot of room between the bolt threads and the sleeves, which surprised me because it would seem to require larger-than-otherwise-needed holes to be drilled and also likely to have the bolt loosey-goosey at the point of use (wall surface) compared to the far end where the conical bolt head would be pressed hard against the bottom of the widened sleeve. But I’m a complete amateur here so what do I know? The image above shows one of each size from three angles: bolt-end-on, from the side, and bolt-head-on.

The thing about sleeve anchors is that they seem to require relatively girthy holes. Videos I watched online (the starting point for most of my DIY adventures) seem to suggest that wedge anchors like the ones shown above are good to use for fastening things to concrete and they are slimmer than the sleeve anchors, so the holes to be pre-drilled would be close to the bolt diameter. Wedge anchors were difficult to find on Taobao but I finally spotted them being sold for rock-climbing and got some.

Both the wedge anchors and the sleeve anchors work by having you tighten a nut threaded onto the exposed bolt end, which draws the bolt out towards you and brings the cone-shaped head of the bolt into contact with a split annulus of some sort, a narrower and tight-fitting closed-flower-petals sort of thing in the case of the wedge jobbies and a long, oversided sheath for the sleeve anchors. The more you tighten the nut, the further the bolt is drawn back out and the greater (hopefully) the ring of pre-split material is splayed apart against the walls of the hole.

That seems as though it should work and zillions of these things have been sold and used around the world for decades, so it must work, but if plain-old screws (well, concrete-specific versions of screws) would also work, maybe I’d rather use them instead. So I got some concrete screws. They’re 1/4″ 2-1/4″ Tapcons (ITW Buildex part #3369907), made of 410 stainless steel but with some sort of protective layer that gives them a powdery silver sheen. It’s not the trademarked blue Climaseal stuff and it doesn’t seem like stainless steel dust. If anything, it reminds me of anti-seize compound. Briefly handling the screws left a bluish-silvery layer on my fingers that had to be washed off. I’ve emailed the tech support address at the manufacturer and will update this thread if I find out more.

These Tapcon screws came in a box but the glue holding it together failed and it came apart in transit and the pre-perforated tabs on the box bottom gave way as well. Thankfully, the plastic bubblewrap-lined envelope Amazon used for shipping held together until delivery. First thing I did was transfer them to a big screw-top plastic container. The “2-cut” drill jutting up from the screws in the image above was included. Maybe I’ll use it and maybe I’ll go with one of the more-carbide-bits type of drill featured above, but it gives me a hint as to the size of drill one should use with these fasteners. In case anyone (including future-me) is wondering, the body of that drill has a diameter of 4.58mm and the screws’ diameter (including the threads, so the maximum width) is 6.5mm and ITW Buildex has posted a PDF with installation instructions online (tapconinstall.pdf).

Since it was already flattened on arrival, I went ahead and scanned the box (image above is a thumbnail linking to a larger version). A label with the specifics for these particular fasteners had been glommed onto one face of the box, so I clipped that part and stuck it with the screws for future reference before discarding the remainder. Something that struck me as peculiar was the absence of any information about the fasteners’ place of origin. The place where the box was printed is specified but of the origin of the screws themselves… no mention is made.

So, in summation, today’s post consists of a bunch of photos and some paragraphs regarding a small, yet-to-be-attempted DIY project published here mostly for my own future reference. Hope you’re having a good Sunday. Happy Halloween 2024!

More Tapcon screws: 1/4″ 1-3/4″ Tapcon SCOTS Screw Anchors (ITW Buildex part #3358407)

A few days have passed and some shorter Tapcons, coated (except for the heads and the rubber washers under the flange/washer base of the head) with the same silvery stuff, have arrived. These are 1/4″ 1-3/4″ Tapcon SCOTS Screw Anchors (ITW Buildex part #3358407).

Having established a precedent, I scanned these screws’ box too. Notable to me is that the only claims on the Red Head page about the composition of this product are that the washer is made of EPDM and that its head is a 300 Series Stainless Steel Head. Just the head? And which 3XX alloy — 304? 316? If the body of the screw is made from a different and non-stainless steel, which steel alloy has been used?

I haven’t yet received a response from ITW to my email query about the coating on the first type of Tapcon. The sticker on box for these shorter, washer-equipped fasteners says SCOTS SILVER CLIMASEAL so I suppose that’s what’s been applied to both of them. If I hear back, I’ll follow up by asking which Canadian-sourced alloy(s) these SCOTS screws are made from.

UPDATE: ITW replied with answers to all my questions

I forwarded my first email to the same address with the extra questions about the newly-arrived fasteners and got a nearly immediate answer this time. The ITW technical service rep addressed each point that I raised. (1.) The coating is indeed Climashield and, though I didn’t get an MSDS for the stuff, the response included an attached Typical Performance Parameters PDF that characterizes the Climashield material as an Organometallic Polymer. (2.) The SHW4-214 Tapcon stainless steel Heby washer head 1/4-inch by 2-1/4-inch anchors are 410SS throughout but the 1/4-inch by 1-3/4-inch Tapcon SCOTS Screw Anchors have 304SS heads and the rest of each fastener is made of 1022 carbon steel.

The bi-material composition of the SCOTS Tapcon fasteners goes a long way towards explaining their much lower retail cost compared to the first type of Tapcons. If I were more clued-in, I might have read the manufacturer’s product page more closely and interpreted the concave, downwards-facing-bowl shape of the head and the installation of an EPDM washer as a strong indication that the rest of the fastener was not made of stainless steel. It’s no great loss, however, and they will get used at some point. Live and learn.

UPDATE (20241112): Tried out the rotary hammer drill and a 3-cutter drill bit

I’ve installed some of each of the 2 Tapcons shown in this post in a concrete brick and rambled about it here (includes 200x-magnification images of the concrete): Messing around with Tapcons and a concrete brick.