First off, the spade bits--they are really ancient bit typed originally used in brace-&-bit (hand crank) drilling setups--don't really belong in a set of electric powered drill accessories and they will not effectively "scrape" their way through metal ... an application for which they were not designed or ever specified. With "twist" type drilling bits (the rest of the set except the (socket) driver bits) the only limiting factor is how long the bit will last given its hardness relative to that of the material to be bored through. So, accordingly, most all the bits will cut repeatedly through wood because of its relative softness compared to metal and masonry. Some however, such as the split-points intended to drill thin-gauge (sheet) metal will be have their non-skating tips quickly ruined by very hard, rock-like materials such as brick or concrete, and gradually even by successive cuts through metal . . . all drill bits are self-destructing through use over time. It would be nice if some manufacturer, instead of just "throwing" bits in a case in order to sell a few or only one, would instead also include a center punch ... and even a larger assortment of twist bits ... for both sheet and full-thickness metal. Finally, masonry bits are most appropriate for drilling max-hardness, max-abrasive, rock-like material such as (relatively soft) brick up to (relatively hard) well aged concrete. With such materials and such bits the user might find better cutting effectiveness using a "hammer drill" type drill which provides both a "normal" drilling setting for "typical" materials and a "hammer-while-turning" setting to enhance drilling of materials harder than any drill bit can be made. Finally, while plastic encased bit sets can prove convenient (except they usually do not fit in hard-case portable tool boxes), they generally last only as long as their bits last, so might not be as effective, long-term as their indestructible metal case predecessors which once were the standard. Many owners find that plastic display case sets such as this one are best left safely at home or in the truck, removing only the bits needed for that day or that project, after which the bit (unless lost or ruined) can be returned to its (depleting) carry case with handle. Since all bits, in this case and otherwise, have been available practically "forever," it is inappropriate to speak of what they were "designed" for; however, the "carry" case does involve design work, mostly for appealing shelf display in stores, but also for self obsolescence and carrying: and mfrs well know that the more their drill cases are swung by their handles while being carried, the shorter will be their life times: plastic boxes might well be "shatter" proof; but, like glass, they are not break proof (or hinge-fail-proof). So, just use the twist bits (split type or not) for drilling metal. And expect this or any "set" to gradually die from loss or normal ruining of the bits inside.
Answered by: Steffie
Date published: 2019-02-26
