Irwin Tools IRWIN 10231CB Unibit 1/32-Inch 13-Steps Cobalt Alloy Steel Step Drill Bit, Black

Used this on car doors to apply rustproof coating inside. The bit went through the cars sheet metal very smoothly without denting or crimping the metal. Decent bit. Can't complain.

I bought this bit as part of my tool kit to drill endpin jack holes in expensive guitars to mount the endpin jacks for internal pickups. Any drill bit will make a hole, but I wanted to make sure the wood on the guitars would be in perfect condition after the hole was drilled. Causing serious damage to a $5,000 guitar can ruin a guy's day, especially if he's the owner of the guitar. Typically, if no prior hole exists, a new 1/4" hole is drilled with a sharp brad point drill bit, followed by a precision tapered reamer from a guitar luthier supply house. However, sometimes a smaller hole already exists where a strap button was screwed in or a tapered end pin was press fit into a tapered hole. Perhaps the tapered endpin was even glued into the tapered hole and can't be removed without drilling. If a strap button had been screwed in, then the screw hole could be filled and a new hole could be drilled as if none had ever existed, followed by the precision reamer to safely bring the hole to its final dimension. On the other hand, this Irwin Unibit could be used to drill a tapered hole, using the strap button screw hole as a pilot hole, followed by the precision reamer to bring the hole to its final dimension. I have used the Unibit for this exact purpose, and it worked beautifully, with no damage to the guitar. If a tapered wooden strap button has been glued in, the button can be carefully sawed off near its base, and the hole can be drilled with a brad point bit and then reamed, just like the situation where no hole ever existed. But no sawing is needed if a punch is used in the center of the wooden end pin, a 1/8" pilot hole is drilled with a normal twist metal bit or a brad point bit, and the the Unibit is used to drill through the strap button and into the guitar. Eventually, as the Unibit goes deeper, a tapered hole is formed that is larger than the strap button, and the button is drilled completely away, leaving only a nicely tapered hole for the precision reamer to follow and finish to final dimension.The Unibit can be used after drilling a pilot hole, without using the precision reamer. If that is done, it is best to stop drilling with the Unibit when it reaches the 15/32" step and then finish the hole with a standard 15/32" metal twist bit that will tend to self-center. Or, the Unibit can be used to fully penetrate the guitar base and end block, leaving a 1/2" hole that is slightly oversized for most endpin jacks, but completely usable. Alternatively, buy the 12mm Unibit, which is 15/32", and the hole will be exactly the right size. The precision reamer from the well-known guitar luthier supply house is strongly recommended, but even just the Unibit will safely do a good job. Do put blue painter's tape where the hole will be drilled to help protect the wood from damage. DON'T use the cheap tapered hand reamers, including the one from Irwin -- they do not make good, concentric holes in wood. I've tried -- and failed miserably. The cobalt Unibit is not necessary. The standard (less expensive) tool steel works well, just not as long as the cobalt. For $10 more, the cobalt seems to be the better deal if it is used often.This is a must have tool in a guitar workshop.

I bought this after looking at countless drill bits to find the best one for drilling out the endjack for guitar pickup install. It is a high end $3000. guitar so if I am taking a drill to it i any way, shape, or form, it needed to be the best. A fine guitar is made of fine woods and a fine finish so a drill bit which rips or tears at the finish or even leaves a scratch or rough spot at all is a deal breaker. This bit was easy to use, sharp, and made a very nice clean hole for my endpin jack install. I don't typically write reviews but wanted to write one for this bit for the benefit of other guitarists that are looking for the right drill bit for installing endpin jack for their pickup. The pickup I installed was a K&K pure mini and the guitar is my Martin CEO-7. I had never installed a pickup before and this 1/2 inch unibit worked perfectly. It will get the job done neatly. Of course, make sure you also use blue painters tape on any guitar to protect during drilling.

Después de casi un año de darle duro a esta broca escalonada, puedo decir que es lo mejor que he comprado, la use abriendo agujeros en platinas de 1/2 y es lo mejor

This is exactly what I needed to widen a bunch of holes in 12" X 12". A ship auger bit makes a mess of an extant hole. The idea was to create a kind of pilot hole for it that would be just deep enough so that the auger wouldn't chew up the face of the hole. This did just that. On the holes being widened from 1/2" to 1" the ship auger bit (an Irwin) lined up on center to widen out the holes. In widening 3/4" to 1" it didn't line up quite on center, but it did not stray much (the old hole was widened and no new hole was drilled.) That said, it required quite a lot of force, and the shank is someplace between 1/4" and 1/2" so it didn't fit any of my extensions (I had hoped to pop it on a long extension and push it deeper. If you should try that, I am not sure that the hole would remain straight. I have a longer extension that I could have used to push it all the way through.)

First time drilling steel so I did my research. I used cutting oil, low RPM, as much downward force as I could muster with my arms, and only drilled for a few seconds at a time so the metal being drilled wouldn't get work hardened. I drilled 10 holes through a steel trailer frame. Worked perfectly. Not sure how many more holes it might be able to handle but it drilled the last hole as well as the first. I had 2 different sizes to drill. I used this bit to get to within 1 step size of the final hole and then used a straight bit for the final dimension.

Perfect, compact bit for thin’ish metal work. Quality Cutting oil helps but last longer on steels… so handy and quick work timesaver for drilling and deburring. Enables field accuracy: Center-punch + small twist bit to create center or punch through then unleash this little monster. ;) I like so much I buy as gifts for friends

Appears to be effective, used them a half dozen times or so. No noticeable damage and worked as expected.

Absolutely brilliant. I test fired it on the galvanised steel sheeting of my wheel-barrow before making a hole in the aluminium dashboard of my Caterham 7. I was worried about how controllable it would be but it can't go wrong without some serious input from the user. Check the diameter of hole required and make a note of which step is required, that's about it. The hardened tip makes a pilot hole unnecessary but it won't hurt to drill one. An excellent bit of kit, well worth the money.

I knew the brand Irwin for the replaceable stanley-knife blades, the blue ones, those are very good so I bought this with high hopes.Was quite pleased to see that this stepped bit does work indeed. Even with 0.2mm titanium they would enlarge a hole without jarring. Of course, cutting oil is always recommended while drilling stainless, hardened steel, aircraft grade alloys, or titanium.Big difference from cheap stuff. highly recommended

Well priced and very good for what I need. Each step goes up in increments of 1mm which is very handy as I bought this for drilling guitar fx enclosure pedals and has made the job infinitely simpler. Not used it a huge amount yet so can't comment on longevity but it was a very good price compared to some of the other bits I found

Used to open hole in a modei aircraft proppeler, an was perfekt!

first class worked in plastic ok, a good around 7mm hole