Worth It To Shorten Drill Bits?

[CarlosA]

I have probably 2-3 complete sets of drill bits kicking around, and have gotten really good with the drill doctor.

Is it worth it for me to sacrifice the worst of the bits? I`d like to have some that are just really short for quick use on the mini lathe/mill without any fumbling around. A lot of these are junk anyway.

Is the worst part of this the effort/time that will go into cutting them off and resharpening?

On a side note ... I finally got my mt2 drill bit set complete, and won`t be messing those up!

 

[pineyfolks]

You'll probably have to thin the web after shortening them. I've never done a whole set. I just do them as I need them.

 

[Bob Korves]

Are you thinking about cutting them off at the sharp end or the shank end? The webs on drill bits get thicker as they get closer to the shank. That leaves more chisel point and less cutting edges, which makes for hard pushing to get them to penetrate the work. You can use the split point feature on the Drill Doctor to thin the points for a very short distance, and that helps. You can also thin points using professional equipment ($$$), or learn to do it freehand. If the bits are junk anyway, you have nothing to lose, but you also may not get results you can trust, because of what you started with. I use screw machine (stub) length drill bits regularly, they are useful to use as a single tool drilling system because their rigidity can start a hole more accurately than a longer bit, without a spotting drill. They also make tool changing much easier on milling machines because they are generally closer in length to the other tooling you are using, saving time and effort. I have sets of high quality screw machine drills in fractional, number, and letter sizes. They are often my 'go to' drills. 135 degree split points are also good for general metalworking drills. Yes, good sets are not cheap, but they are a one time investment (plus occasional replacements) and just make life a lot easier in the shop and produce better work.

 

[Karl_T]

In addition to the web getting thicker, the OD gets smaller. So the drill will rub on the sidewalls harder if you go deep. Also it may cut a smaller diameter hole. (the thicker web tend to make it cut larger - so this might offset.

 

[CarlosA]

That makes sense, I should have known. Forgot about the web getting thicker, been a long time since "how to grind a drill bit" class. I will just buy a set of stubbies and sharpen these for spares for a bad/late night.

 

[Dave Smith]

I have found a lot of short and broken bits at flea markets and auctions and are really inexpensive----I cut the bits like you are wanting to do and just grind the web thinner on the tip---cut the shank end off first ----just need enough to still grip it in chuck----I then take the tip portion that I cut off and silversolder it on a 12" or longer shank for my extra long needed bit collection---that helps justifying making short bits out of good ones-------actually I have hundreds of very short bits that I just remembered about---you may want to watch for these and you won't have to worry about thick webs--they are aircraft bits and can be found on ebay---they have a 1/4-20 thread on them---you can make an adapter for them to thread into or just cut the threaded end off----maybe I can take a picture of them tomorrow to include with this post---Dave

 

[Tozguy]

I have probably 2-3 complete sets of drill bits kicking around, and have gotten really good with the drill doctor.

Is it worth it for me to sacrifice the worst of the bits? I`d like to have some that are just really short for quick use on the mini lathe/mill without any fumbling around. A lot of these are junk anyway.

On a side note ... I finally got my mt2 drill bit set complete, and won`t be messing those up!

Not sure what quality of drill bits you are talking about but if they are junk why put any time and effort into them?
If you are already good with a Drill Doctor why not stick to buying/using good quality bits and keeping them sharp?
Once I had a taste of quality bits they seemed like a bargain in enjoyment. Its not the same steel. My budget drill sets are kept sharp but are now reserved for drilling wood only.
If you need shorter bits for lathe or mill work I say buy some quality ones for the purpose intended.

 

[Dave Smith]

when cutting drill bits shorter--I use a very thin cutoff disc in a small Dremmel type tool so it cuts easy and doesn't overheat the bit--I also cut each side at approx. the angle I want, so not much grinding is needed to resharpen the bit----to answer your question--yes it is nice to already have good short bits to use when needed----as you can see--I am not short on short bits--and I have many more than I took pictures of-------Dave

 

[intjonmiller]

Once I had a taste of quality bits they seemed like a bargain in enjoyment. Its not the same steel. My budget drill sets are kept sharp but are now reserved for drilling wood only.

I grab packs of cheap drill bits when I see them on clearance racks. I bought four sets of the Ryobi bits at Home Depot in one trip, because they were $5 per set. http://www.homedepot.com/p/Ryobi-Black-Oxide-Drill-Bit-Set-34-Piece-A973401/204790876

It's the kind of set with multiples of common sizes. They're my "beater" bits for whatever projects I'm doing in mystery metal or woodworking (when a Forstner or brad point bit doesn't make more sense), and for throwing in the truck. I particularly like them for having four 9/64" bits per set, as that's a great size for doing 1/8" pop rivets, and there's no sense using expensive bits for that kind of sheet metal work. And if one gets dull or breaks, no big deal.

For anything important I have HSS bits with rules: No bit comes out of the case until I verify that all bits are in place. Two years since I bought the current set and I still have all of them and they're all still sharp. That's only practical because I have the beater sets as well.

 

[chips&more]

Are you thinking about cutting them off at the sharp end or the shank end? The webs on drill bits get thicker as they get closer to the shank. That leaves more chisel point and less cutting edges, which makes for hard pushing to get them to penetrate the work. You can use the split point feature on the Drill Doctor to thin the points for a very short distance, and that helps. You can also thin points using professional equipment ($$$), or learn to do it freehand. If the bits are junk anyway, you have nothing to lose, but you also may not get results you can trust, because of what you started with. I use screw machine (stub) length drill bits regularly, they are useful to use as a single tool drilling system because their rigidity can start a hole more accurately than a longer bit, without a spotting drill. They also make tool changing much easier on milling machines because they are generally closer in length to the other tooling you are using, saving time and effort. I have sets of high quality screw machine drills in fractional, number, and letter sizes. They are often my 'go to' drills. 135 degree split points are also good for general metalworking drills. Yes, good sets are not cheap, but they are a one time investment (plus occasional replacements) and just make life a lot easier in the shop and produce better work.

A +1 on what Bob said and if your budget can handle it. Get the screw machine/stubby drills in "cobalt". That’s all I use/grab 99% of the time. The regular length HSS bits I have collect dust…Dave.