Cleaning and picking nits on (cheap-o, carbon-steel) Forstner bit assortment packaging

HerpDerp Mucking About With Things The Diary of Lupin Pooter TØØLS

I picked up a 2nd assortment of cheap-o carbon-steel Forstner drill bits a while ago. The bits in the new set have thinner shanks, so they’ll fit in my beater cordless drill’s smallish keyless chuck, which is just barely too small for the girthier Irwin-brand Forstner bits. Their shanks are also hexagonal and less slippy than the round-shanked Irwins. Last Sunday, I got around to cleaning ’em with WD-40 and coating them in Fluid Film to ward off rust. Hong Kong is subtropical, so it’s hot and humid almost year-round, and weeks or months may pass between occasions when making large-ish (the smallest bits in both sets are 1/4-inch, equivalent to 6.35mm), flat-bottomed hole in something. It would be dispiriting indeed to find them rust-flecked the next time I need to use one of them.

My process is the same for drill bits as for hand tools: WD-40 followed by Fluid Film. The WD-40 aka Water Displacement, 40th formula is for getting rid of surface moisture and (if needed) carrying away loosened dirt, metal chips, Mainland mystery grease of unknown pedigree, etc. WD-40 does confer some protection against corrosion and may actually do a better job at it than many specialized anti-corrosion products, but Fluid Film is even better against rust than WD-40, so on it goes.

Rust Prevention

Whereas you should glove-up while using WD-40 — the WD-40 MSDS [PDF] doesn’t make the stuff out to be transdermally-absorbed heart attack juice, but the consequences of prolonged skin contact (e.g. defatting) don’t sound very rosy — Fluid Film is advertised as being non-toxic, environmentally friendly. FF claims to be made from lanolin and various secret herbs and spices. You can purchase lanolin in pure formNOTE and it smells exactly like FF. The product’s barnyard aroma is off-putting to some but doesn’t particularly bother me.

As an aside, I’ve switched from aerosol cans of WD-40 and Fluid Film to, respectively, a trigger-style pump bottle that can deliver a dribble on target instead of an indiscriminate shotgun-blast of droplets that speckle everything within a half-meter radius in front of the nozzle, and an 8-ounce brush-cap can of FF. Less wasted WD-40 and Fluid Film and cleanup is faster and easier.

Screen capture from Stuart de Haro's 6-month update video relating the interim results from his anti-corrosion product trial. He's given highest marks to Fluid Film and LPS 3.
Screen capture from Stuart de Haro’s 6-month update video relating the interim results from his anti-corrosion product trial. He’s given highest marks to Fluid Film and LPS 3.

On using straight lanolin in place of Fluid Film

This is something you might try if you like the non-toxic-ness of Fluid Film but run out of the stuff amidst a global PaNDeMiC and can’t find a way to get more, for love or money, anywhere and some poking around online seems to suggest you might be able to use pure lanolin as a substitute. Pure lanolin (can) come in a little tub and is semi-solid, buttery, and tacky. Using lanolin didn’t go so well for me, but YMMV. It may constitute an alternative to commercial long-term anti-corrosion products that create a thick, waxy layer after application, but, then again, maybe not. Pure lanolin seems to never stop being sticky, but it doesn’t degrade plastic, so perhaps slathering canned goods you’re laying up for the apocalypse before loading the cans, in turn, into plastic totes you’re going to bury or stow away somewhere could make sense.

Stuart de Haro has been running a trial of his own comparing the rust-blocking performance of Fluid Film, plain WD-40, and several other products applied to two groups of L-shaped pieces of sheet metal, one group mounted indoors and the other outdoors. The image above is a screenshot showing the outdoor arm of the experiment, from the currently still-latest video in that series, posted about a month ago: What is the Best Rust Preventative? – 6 Month Update. Note that De Haro characterizes the discoloration on some of the metal test pieces (like the one dosed with a Loctite product) as residue of the product under test rather than corrosion, so glancing at that picture alone might be misleading and you should give his video a watch if you’re interested in the topic. Hopefully, when he wraps up his testing, he’ll post a video showing the surfaces of the metal coupons with the rust preventative products stripped away but any corrosion left in place.

Back to Cleaning

If necessary, after wetting a tool or other metal object with WD-40, I scrub it with a toothbrush (nylon bristles) or, if there’s enough grime and crud and it’s stubborn enough to warrant it, a brass-bristle brush. If loosened-up debris is hanging around, irrigating it away with with WD-40. When applying the Fluid Film, if there are lots of nooks and crannies, I’ll use a toothbrush to make sure that the FF gets everywhere. If the thing may not be touched or seen for a while and it’s going to be stored in something with non-permeable inner surfaces (like, say, a blow-molded plastic case and not something like one of Wera’s textile boxes, I apply FF generously enough to leave a visible brown-and-goopy layer.

I’ve had the Irwin Forstner bits shown for years and they were all cleaned and greased-up at least once (more than once, for those I’ve used) but I gave them all the same treatment as the new set (Intoo aka Linrui Tools, a PRC brand). The photos of the Forstner bits included in this post were taken before this round of cleaning, so the honey-hued spots on the afaict-never-used 2-inch Irwin bit below is ye olde Fluid Film residue.

A bit of comparison between the Intoo and Irwin bits

Side-by-side images of the 2-inch Forstner bit from both carbon-steel Forstner bit sets: 2-inch Intoo Forstner bit (LEFT) and the 2-inch Irwin Forstner bit (RIGHT).
Side-by-side images of the 2-inch Forstner bit from both carbon-steel Forstner bit sets: 2-inch Intoo Forstner bit (LEFT) and the 2-inch Irwin Forstner bit (RIGHT).

Below are some numbers for the 2-inch Forstner bits above (Intoo on the left and Irwin on the right). The shank size given for a tool with a hexagonal shank is of its short-diagonal, the distance between two parallel faces of the hexagon. When a hex-shank bit is described as having a 1/4-inch (or 6.35mm) shank, for example, and you close unlocked digital caliper jaws over two of its flat sides and then twirl the bit, the jaws ought to expand to about 7.33mm (Hexagon Calculator).

Intoo 2-inch Forstner bit Irwin 2-inch Forstner bit
shank thickness 8mm (5/16-inch) 9.5mm (3/8-inch)
body thickness (mm) 13 15.1
weight (g) 124 197

The Intoo box (INTOO Hex Shank Forstner Bit Set 16 pcs Multi Sided Shank Wood Drill bit Set is how it’s listed on has 16 pieces, a few more than the Irwin (I’ve got the IRWIN Marples Forstner Bit Set, 14-Piece [1966893]) and the Irwin set has two 1/4-inch bits, which is fine. The smallest Intoo Forstner bit in this set is 1/4-inch, same as in the Irwin, but the largest Intoo is a 2-1/8-inch bit versus a 2-incher in the Irwin box. For the comparison pictures above, I used the 2-incher from each set because differences in size, shape, weight, etc. are more readily apparent at larger scales than they would be in, e.g., the quarter-inch bits. It’s also one that I know has gone unused thus far, so there’s no wear on the Irwin bit.

A bit about how both sets are made of carbon steel

Figure from a review paper comparing the hardness of several cutting tool materials included here to give a reference for a qualitative comparison.
Figure showing hardness vs. temperature relationships for several cutting tool materials from Materials, properties, manufacturing methods and cutting performance of innovative ceramic cutting tools − a review published in January 2019 Manufacturing Review 6:19 [DOI:10.1051/mfreview/2019016] by Sergey N. Grigoriev, Sergey V. Fedorov, Khaled Hamdy

Both of these Forstner bit sets are made from carbon steel. As you can see from the chart above (HRc and HRa are two of the Rockwell hardness scales), cutting tool materials soften (first gradually and then more quickly) with increasing temperature and… carbon steel is the softest of the classes of materials considered by the authors of that paper. In fact, I can’t recall ever having seen plain-jane, non-funky drill bits for sale made of anything softer than HSS. Tools like thread-repair files or thread-chasing taps and dies made of carbon steel? Yes, because they’ll hopefully wear more/faster than the materials of the things they’re being used to fix. Drills? no.

Forstners made of harder stuff and/or with tungsten carbide teeth exist, but I didn’t see any sets on Amazon from recognizable brands. I’m using them on plastic, wood, and sawdust-and-glue materials. Theoretically, if the need arises, I can sharpen them up, piece-of-cake lickety-split, with a triangular diamond-grit file. There are demonstration/tutorial videos of this process on YouTube, mixed in with all of the totally legit life-hacks videos, like the ones showing how to repel mosquitos by rubbing and scraping bars of bath soap along picnic table edges, door jambs, etc. There’s no way of knowing until I try, I suppose.

Laser-etched and printed-on product information sucks bigly, don’t you agree?

Both sets of bits are laser-etched with the manufacturer’s name and the size. I hate laser-etched product information because it’s very easily obliterated and small, already-faint/low-contrast text on a curved surface doesn’t need very many licks from a brass brush or abrasive pad or (enough times) a rag or wipe pushing microscopic grit around to become illegible. Manufacturers, please stamp or deeply engrave or etch crucial product info into tools. Printing/painting, rather than embossing (or debossing and maybe filling in with a high-color-contrast material), the text or product info onto plastic or rubber hand tool grips is similarly evil.

The blow-molded plastic box for the Intoo (green box at left) set has a handle. The Irwin case (blue box at right) has no handle.

What’s good (and double-plus ungood) about each box

There is a pair of plastic snaps on the front of each box, but the snaps are made of the same material as the box and the only thing holding them on is a built-in hinge of non-textured plastic that could fatigue and crack or get busted off if the box fell and hit the ground at an inopportune angle. The clamshell hinge holding the lid onto the bottom half of each box is made the same way, but it’s longer and isn’t being subjected to the same forces as when human fingers pry the dogs open or press them hard enough to snap them shut again.

Fronts of the two boxes, showing the plastic dogs/snaps.
Fronts of the two Forstner bit set boxes, showing the plastic dogs/snaps that are doomed to break long before the cases themselves would otherwise become unusable.

The Intoo set’s container has a handle. That’s useful for carrying it around but even more useful it’s also something that can be zip-tied (preferably with a reusable zip tie) shut. The Irwin set’s box, instead of a handle has a shallow, vaguely handle-shaped depression on both the upper and lower halves of the box roughly where a handle ought to be located. If either or both of the snaps on the Irwin box breaks off, I could poke or cut through the box somewhere in that handle-shaped dimpled region for a zip tie.

The Irwin case (blue box on the left) has a snugly-fitted clear polycarbonate window pane but the green Intoo case’s clear plastic panel is shoddy and was shoddily installed.

The Intoo box’s clear polycarbonate window is loose, rattles, and has a tendency to partially pop out and sag towards the bits. In the photo above, you can see that somebody had a go at some spots along one edge to remove some material at the spots where they contact two of the retention tabs in the green plastic. The middle tab on that side of the frame is left to do all of the work and this is part of the reason the clear window is loose and easily dislodged.

The one in the Irwin box is much better. Its clear plastic window has curved corners and fits snugly into a matching curved frame. Rectangular horizontal crossbars, set at a 90-degree angle to and glued onto the inner face of the clear plastic sheet, run horizontally across the case and, when the case lid is shut, rest on the bits’ bodies (the part of the shaft below the shank) and the raised flat spots of the case bottom between the wells that hold the bits. The purpose of these crossbars may be to help keep the bits securely seated in their wells (unnecessary, at least thus far, because the bits all snap firmly into place) or they may be there to provide some support to the window pane itself, in the event that something heavy-ish is briefly placed on top of the closed box.

As nicely designed as the window in the Irwin case may be, though, I’d just as soon both cases be windowless. Most regular drill indexes don’t come with little plastic viewports and I’ve never keenly felt their absence, so it’s not something I’d really miss if it weren’t a feature of these Forstner bit assortment boxes either.