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IRWIN Unibit 3/8-in 13-Step Drill Bit

15 Reviews
  • Single-fluted cutting edge for greater control and rounder holes
  • Ideal for drilling holes in thin materials such as mild steel, copper, brass, aluminum, Plexiglas, wood and laminates
  • 3-flatted shank won’t slip in chuck


No matter what drilling project you face, IRWIN makes a drill bit to do the job better. Whether the job requires quick, clean holes or precise finish work, there’s an IRWIN bit for it. Our mark of quality is stamped on the shank of our full range of bits for every application and every need.
  • Single-fluted cutting edge for greater control and rounder holes
  • Ideal for drilling holes in thin materials such as mild steel, copper, brass, aluminum, Plexiglas, wood and laminates
  • 3-flatted shank won’t slip in chuck
  • Speed point tip for fast starting
  • Laser marked sizes won’t wear off with use
  • Unibit #3 is engineered with M35 cobalt steel for maximum life when drilling in tough steel
  • Unibit #3 cobalt contains a 3/8-in hex shank and contains 9 hole sizes- 1/4-in-3/4-in (1/16-in steps)
  • Unibit #1 contains a 1/4-in hex shank and will drill 13 hole sizes- 1/8-in-1/2-in (1/32-in steps)
  • Unibit #4 contains a 3/8-in hex shank and will drill 12 hole sizes- 3/16-7/8-in (1/16-in steps)
Weight 0.47 lbs
Dimensions 5.6 × 1.8 × 7.7 in

Latest reviews

  1. Craig

    Step drills. Every tool box should have these. Drills multiple size holes without changing the bit. And will countersink/deburr effortlesslyCraig’

  2. Cheeze

    The car stereo business is a tough job, what makes it even more difficult is trying to drill holes in firewall of engine bay to run wires from battery into the cab. THESE stepbits but others to shame. They cut so well and they’re strong as all get out!! Ive even used these to open food cans… so if for nothing else, buy this to replace your can openers!!

  3. Mick

    I needed a precise hole in dashboard for installing a switch. It needed to be exact to avoid hidden obstacles. This allowed me to position hole perfectly with out having to find and change bits. Saved me time and money. Why I didn’t get it sooner,

  4. BikeSanta

    I was replacing a very old and well-used #1 Unibit, and decided on the 3-bit set after comparing prices. My only disappointment was the image of the product describes the #3 bit as “Cobalt” steel – a superior material. In the set I received, the #3 bit was Titanium-nitride coated. While Titanium-nitride coated bits are slightly more durable than standard HSS, they are not as good as Cobalt-steel. I went ahead with the purchase, as it was still an OK deal, but I was disappointed.

  5. Clowreyjr

    Purchased this set after using some off brand bits to cut thru some Steel Plates to the full limit. These did it with ease and still look like they are Brand New.

  6. ThomasL

    Bits worked well and accomplished what I needed. Looks like a quality product that will last forever for the average DIY homeowner.

  7. Tk

    Bought the set because of the price of 1. Did the job.

  8. Jomeoke

    Love the titanium coating, just wish all 3 were coated

  9. Sunshine

    The #1 bit dances all over the place when it came straight out of the package.Unfortunatly, I’ll be taking this back. No issues with the other 2 unibits 🙂

  10. clifffromutah

    Skeptical that the step down would work on sheet metal but surprisingly it did much better than I expected. No damage to the surrounding metal.

  11. GudOne

    I bought this for some fabrication I was doing to install a roll bar. Cut through metal no problem – very easy to get the correct hole size.

  12. Chris

    Purchased this Unibit set to drill and widen holes in my truck bed for a goose neck hitch installation. They worked great.

  13. Bruce

    Had a problem with the chuck on my drill not handling a 9/16” bit. This baby took care of that!

  14. RLS

    No need for a drill bit set anymore, these 3 bits do it all

  15. Jerbo

    This is a must have for anyone working with light metals.

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