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Step drill bit


cymaz
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Cymaz,

 

I have used a variety of stepped drills. They have their uses but one thing you will notice is that when drilling thick material you will end up with a stepped hole. With two deep cutting faces they can grab and snag in some materials. They almost always come in even steps of mm and the only ones I've found in odd mm sizes don't cover the range that would be useful. Tapered drills are handy for getting an exact size hole in thin material but as far as accuracy goes I've never checked, they do make round holes but like all drills they can wander. They are best used in a drill press not a hand-held.

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I find them very useful for making larger diameter holes in thin material. As Ace says, you can drill from both sides for thicker material. I also find they are good for starting a nice smooth round hole (that you can drill deeper with a standard drill bit once the hole is neatly started). Avoids splintering the wood with a big drill when you start drilling a larger size hole.

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Interesting, I'd never heard of a stepped drill bit until this post.  Apart from avoiding the hassle of changing bits for different size holes, is there any other advantage over conventional single-size bits?  A disadvantage would seem to me to be when the size you use most wears out you have to replace the whole bit, at a much greater cost than a single-size bit.

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38 minutes ago, Allan Bennett said:

Interesting, I'd never heard of a stepped drill bit until this post.  Apart from avoiding the hassle of changing bits for different size holes, is there any other advantage over conventional single-size bits?  A disadvantage would seem to me to be when the size you use most wears out you have to replace the whole bit, at a much greater cost than a single-size bit.

I am still using my original HSS step drill (made by Halls of Sheffield) that I bought 35 years ago. Its never been sharpened an is still working well. I also recently picked up a cheap one from LIDL and that works fine too!

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2 hours ago, Tim Hooper said:

I'm a fan of the stepped drill.

 

However, I'm aware that the initial tip is going to get all the wear, no matter what size of hole you're aiming for.  For this reason I like to drill a pilot hole with a conventional bit first.

 

Tim

Tim, yes I tend to do exactly that myself. Drill a pilot hole first.

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1 hour ago, Allan Bennett said:

Interesting, I'd never heard of a stepped drill bit until this post.  Apart from avoiding the hassle of changing bits for different size holes, is there any other advantage over conventional single-size bits?  A disadvantage would seem to me to be when the size you use most wears out you have to replace the whole bit, at a much greater cost than a single-size bit.

The big advantage of a a stepped drill as others have mentioned is when drilling through sheet material as they don't grab like a jobber drill bit does and the holes are quite accurate and round too. Have you ever drilled through a piece of thin metal and noticed the shape of the hole when using a standard jobber drill?

 

 

 

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18 hours ago, Outrunner said:

The big advantage of a a stepped drill as others have mentioned is when drilling through sheet material as they don't grab like a jobber drill bit does and the holes are quite accurate and round too. Have you ever drilled through a piece of thin metal and noticed the shape of the hole when using a standard jobber drill?

 

 

 

Thanks Outrunner.  I rarely drill through thin sheet, but with all drilling I start with a 1mm bit and then work upwards 😀  Looking closely at stepped drills online, I see that they have very little, or no, twist in the cutting edges, which I'm sure must help prevent snagging and odd-shaped holes.  Maybe I'll invest in one.

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10 hours ago, Colin Low 2 said:

Toolmakers tip..........When drilling sheet metal, if you place a about 4 pieces of rag between the drill and where you want to drill the hole. Then drill through the rag into the metal, it stops the drill wobbling and produces a nice round hole. 

Tried this today as I wandered through to turn the house heating off. Mounted in a drill press, thickish tinplate, worked well. 
Only point to make, keep the rags small, you don’t want big bits of cloth whipping round.

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