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

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$33.95

$ 15 .99 $15.99

In Stock

About this item

  • Save time because you don't need to change drills for different-sized round holes in thin materials. Each drill acts as a pilot for the next size.
  • Made from industrial-grade high-speed molybdenum steel heat treated for maximum durability. SpeedPoint tip penetrates faster and prevents walking.
  • Ideal for drilling holes into thin materials such as stainless steel, copper, brass, aluminum, plastic and laminates.
  • Non-skid tip, no need for center punches. 3-faltted hex shank prevents drill chuck slipping. Drill diameters etched in flute for easy identification.
  • Backed by a full lifetime warranty.


Product Description

Irwin 10234 Unibit #4 12-Step High Speed Steel 3/8-inch Step Drill Bit, 1/16-inch Steps (3/16- to 7/8-inch) Save time by eliminating the need to change drills when drilling round holes in thin materials. Each smaller size drill also acts as a pilot for the next size. Made from industrial-grade high-speed molybdenum steel heat treated for maximum durability. Ideal for drilling holes into thin materials such as stainless steel, copper, brass, aluminum, plastic and laminates. SpeedPoint tip penetrates faster than previous Unibits and prevents walking. Non-skid tip does away with the need for center punches; 3-faltted hex shank prevents slipping in drill chuck. Drill diameters etched in flute for easy identification. Backed by a full lifetime warranty.

Amazon.com

The Irwin 10234 UniBit #4 12-Step High Speed Steel Fractional Self-Starting Step Drill has a single-flute cutting edge to give you more control and produce true, round holes. Twelve holes range from 3/16 to 7/8 inches, in 1/16-inch increments. A non-skid tip does away with the need for center punches, while the three flatted shanks prevent slipping in the drill chuck. This drill is made from industrial-grade high-speed molybdenum steel heat treated for maximum durability, and it is ideal for work on thinner materials. The multiple steps mean you don't have to have a toolbox with specific size drill bits, and this drill is backed by a full lifetime warranty.


K_L
Reviewed in the United States on January 23, 2025
Needed fo a project to enlarge a mounting hole for an axle on a lawn trailer. Worked perfectly, round hole unlike a typical twist drill bit.
L-A
Reviewed in Canada on July 14, 2024
Happy with product, great deal , well built,thanks
B. Shamir
Reviewed in the United States on December 8, 2024
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.
A CT User
Reviewed in the United States on October 26, 2024
cuts through plastic like butter literally. Hopefully the coating will make it last as long as I live.
Burke Kilgour
Reviewed in Canada on December 28, 2023
Factory sealed never opened exactly what I needed
Chris
Reviewed in the United States on May 30, 2022
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.
Bradley Barnes
Reviewed in the United States on November 14, 2020
Works great so far, hope the edge stays sharp. Worked on more then a dozen holes as I said, hope it keeps cutting. Got it on time and as described.
Gil
Reviewed in Canada on January 20, 2018
A very good quality tool.
Nick D.
Reviewed in Canada on November 27, 2017
Cuts like a hot knife through butter!
Allan
Reviewed in the United States on June 8, 2015
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.
Pietro
Reviewed in Canada on April 28, 2015
Powerfull
SJK
Reviewed in the United States on January 21, 2014
This Irwin step-drill was reasonably priced and has lasted about the longest of any I've had in this size range. I keep a bit of this size in each of my drill storage cases and since this 1/8" to 1/2" size bit is also the one I tend to use most with my cordless drill, I keep one in the nail set holder of my tool pouch, so it's always ready to go. It is just the right size to make a hole in metal enclosures for the draw stud of my 1/2" Greenlee manual KO punch, which I will often use to make the hole for the draw stud of the larger KO punches, so it gets used quite a bit for that. With this size bit, over time I usually seem to end up snapping off the 1/8" tip then grinding it down to a new larger point so I can continue to use it. So far, this bit has managed to keep its tip, so not sure if it's just luck or if maybe there is something to the titanium nitride coating after all, but either way I'm happy with this step-drill and will buy again.
A. Weed
Reviewed in the United States on September 14, 2012
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.
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