Irwin Tools IRWIN 10239CB Unibit 2-Steps Cobalt Alloy Steel Step Drill Bit for 1/2-Inch and 3/4-Inch KO, Black

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.

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.

Irwin has always been a great Step Drill when used as it should be with sheet metal. I have used this brand for years when I was building street rods.

I needed to make larger holes in steel sheet metal. Traditional drill bits bind up in the hole when you get close to fully drilling through the hole. Adjustable circle hole cutters and expanding bits can be dangerous if used free hand, and sometimes even used in the drill press. All of these types can twist your wrist badly if you are using them free hand.I decided to try this step bit and see how they worked. It was fantastic! I drilled a large enough pilot hole with a twist bit, and then started feeding the step bit in the hole. It cut smoothly and did not bind up at all. The hole it made was perfectly round and no burs left on the front side. It did leave burs on the backside of the metal, but I simply did a very light drill with this step bit on the back just enough to knock off the burs. Presto...a clean wonderful hole was drilled quickly. I am now a true believer in step bits.This bit also kept its edge very well. I highly recommend this product.

This easily drills sheet metal and angle iron the steps make it convenient, not having to change out drillbits. This is a must have accessory if you do any kind of drilling and sheet metal or an iron iron. I hope this helps.

Great product

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

There were no step size markings as pictured. Worked well, but without the markings I had to measure with calipers. Maybe it was discounted due to this defect.

El producto llegó a tiempo y bien empacado.Mostró una capacidad de corte muy buena.Se los recomiendo.

Happy with product, great deal , well built,thanks

Factory sealed never opened exactly what I needed

Je fais de l’antirouille et je fais des trous dans les portières la voiture et c’est l’outil parfait

The media could not be loaded.