The other day I posted about Dewalt’s new impact-rated step drill bits. In a comment, Fred wondered whether step drill bits wear down quicker than if two separate twist bits are used instead, and if there are any real time savings. This made me think about the benefits of a step drill bit.
I have several step bits in my accessory box, mostly Irwin Unibits, but there are one or two other brands in there as well.
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What are the benefits?
- (relatively) clean holes
- short length for easier maneuverability
- faster drilling
- no need for multiple twist drill bit sizes*
Disadvantages?
- not easily resharpenable (professional sharpening services can do this for you, and there are a number of DIY sharpening tips floating around the web)
- you might still need to drill a pilot hole
- pricey
Unibits and step drills work exceptionally well on sheet metal. They can be used on other materials as well, but you won’t get a straight smooth-walled hole in solid materials thicker than the step height.
Step bits are incredibly useful for one-step drilling operations, but they’re not suitable for all operations. Although I prefer brand-name bits, many DIYers and pros have sung praises for the many low-priced options that have become available over the years.
*Some step drills are self-starting, but the larger ones require a pilot hole. Often you can use a smaller step drill bit to bore the pilot hole for a larger one.
Some people hate step bits, but many love them. They seem to be quite popular with professional users who only need to carry a step bit or two rather than several twist bit sizes.
It can be a hard sell, convincing someone of the merits of a step bit. The price of better quality bits starts at $18 or so, and climbs higher for the larger sized bits, but as mentioned you can get generic-branded bits for less.
My first step bit was the 1/8″-1/2″ Irwin Unibit, and that also happens to be the size I use most often. I also have a 3/4″ bit somewhere, and for larger holes I usually reach for a hole saw.
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Step Drill Bits via Amazon
It feels like I’m missing something – are there any other benefits or disadvantages of Unibits and step drill bits that I may have forgotten about?
Kyle
The MAIN advantage is that they have a straight flute so thin and flexible materials (sheetmetal, plastic etc.) won’t be twisted out of shape when the drill punctures through them.
Also, with sheet metal you frequently want to make large holes that don’t need to be very accurate in shape of size (for panel mounted switches, pass-though fluid fittings etc.). In this case, being able to quickly drill then progress up to the size you need is really nice and often more convenient than using a punch or a hole saw.
Noah
I find them most useful for enlarging existing holes in panels and covers.
As has been said, they also drill very clean holes.
Phil
For sheetmetal work they are tough to beat. When fabbing up control panels or project enclosures, the bits work not solely as drill bits, but deburring and beveling bits as well. Once the bit reaches the step for the size needed, simply “kiss” the surface with the bevel of the next step to clean the sharp edges on that side, flip the work over and do the same on the other side and the hole is perfect with no other prep needed.
fred
I’m guessing that Greenlee and Klein sell them because Electrician’s like them for creating or enlarging holes in electrical enclosures. With these and a set of slugbusters your ready to customize a panel.
Rich
Stuart, with step drill bits, what is your opinion on the Uncle Mike’s brand? The one I found on Amazon is called Uncle Mike’s Step Drill Set 25520 ASIN number B002SCYPRC.
Here is the link. http://www.amazon.com/Uncle-Mikes-Step-Drill-25520/dp/B002SCYPRC/
Thanks.
fred
These would appear to be woodworking (not sheetmetal bits) that are akin to the old Stanley Screwsinks – where their purpose is to dill both a wood screw hole and a counterbore for the screw head with a single bit. In the link you provided – you can click on another source for the bits that comes with 1 customer comment.
Fred
I feel special by the way, thanks for making a whole post just for me : )
When I first asked about that, I was not thinking much about thin sheet metal. I usually carry a hole saw and a few specific bits for doing plubming/electrical work, similar to the cable guy carrying only a 3/8 wrench because that’s all he needs.
I have always been wary of a step drill because it seems like its easy to cut bigger holes than you intend, or as you step up to the next size get off center. Twist bits go off center too, and hole saws if you aren’t careful, but the twist bit sets are cheaper in some cases and most of us have several everywhere.
I’m going to pick up a step bit next time I have something with thin sheets. I wonder, do they do any better in plastics than twist bits or forstners? I learned my lesson with my hole saw dancing all over some poly and acrylic sheets.
fred
For most plastics – nothing beats a drill designed for them – like a Fuller (other brands available too) Plexi-Point bit:
http://www.wlfuller.com/html/plexi-point.html
Fred
Thanks for that link. I have found it’s ‘good enough’ going slow on the press when I can, and cleaning up the holes with a Dremel in some cases. I never knew about those you linked, thanks.
john
I use step drills in poly/acrylic sheeting all the time and they do a great job. Twist drills tend to cause two cracks just as they break thru the other side no matter how careful you are with them. Just don’t press down too hard on the step drill as it bores thru and let it shave the plastic. I use a harder step drills, such as Erwin or a Cobalt alloy, for tougher sheet metal and even stainless, but go slowly and use a lubricant.
Tim
I love the handiness of the step down bits and would like to know where I can take them to sharpen. To expensive as a throw away.
Alan
I like them because I fit a lot of kick plates and push plates to doors and the holes and countersink on them don’t fit the screws so I redrill the holes and countersink with my step drills
Elaine
I purchased a 3 piece step drill set to use on a project with thin sheet metal.
I have read and read online and no one addresses the issue of the difference between the 3 drills. One is a larger size; two are less conical but still in steps;
all have similar measurements. How do I know what each size is needed for?
Swan
I purchased Makita step drill bit with titanium coating, the price is slightly pricy, but overall it worth the money, i am happy for the quality and result.