Irwin Tools IRWIN Step Drill Bit, 3/16-Inch to 7/8-Inch, 3/8-Inch Shank (10234)

This is the 3rd Irwin cobalt Unibit I've bought over the last few years. (3 various sizes) A quick summary: Irwin tools are dependable and are of very good quality. I know I can get the job done if I'm using an Irwin tool or bit. My last Unibit was used to drill 120 nickel sized holes into stainless steel plating. (about 1/8" thick) (used a drill press). I was in a hurry and didn't use any drilling oil. The Irwin survived that task but reached its limitation which was more than I expected. I bought this particular Irwin 10234CB to drill a 13/16" hole into my Weber 10020 Smokey Joe Silver Charcoal Grill, Black . I wanted to install a 3" River Country (RC-T3W) Adjustable Professional BBQ, Grill, Smoker Thermometer (50 to 550F) (see my photo on product page) and this Unibit did the job effortlessly. (ate through that lid like it was plastic) Irwin Unibits are pretty expensive compared to other brands, but if you want the very best and longevity, definitely get Irwin cobalt bits. *** Don't forget to use drilling oil (or any oil for that matter, even olive oil) to extend the life of your bits.

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 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.

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.

It works

Anyone familiar with the Irwin name knows that they are producers of high quality machine tools. Be careful, like a lot of companies, some Irwin products are made offshore. When this bit arrived I put it to use immediately. I had previously been using a set of old Harbor Freight step bits, back when they actually made a reasonably industrial product. These bits lasted years until the TiNi coating wore off. I recently moved to harder steel grades and had to use cobalt bits for certain production runs. Even with slotted holes that would normally destroy a stepped drill bit as a result of chipping, this bit held up just fine and still cuts mild steel like it was made of butter. I would not hesitate to buy another one of these bits in other shapes. I can probably expect this bit to last several more years. I only wish that the bit was a twin fluted design for better chip clearing, but no complaints yet.

I had to drill 7/8” hole in 1 1/4” tubing on one side only, and so, I couldn’t use full size step drill bit for being too long. This half size bit did the trick beautifully. It’s very sharp and the hole came out very clean. I’m very happy to find this unique bit.

I used to use bits like these when I installed whiteboards and projectors in schools for a living. I used them for cutting holes in the pole that connects the ceiling bracket to the projector mount, because often I had to cut the pole down and so the factory-machined retention hole would be lost at one end. I have found them to be the fastest way of drilling thin walled metal (< 4 mm) round and square pipe on site, and they leave a clean circular hole with little to no burr. They are also good for drilling plastic if the need arises. This Unibit has stayed sharp and true for my home usage requirements. I've used it manufacturing gym equipment at home and for making existing holes bigger. I give this product 5 stars.