# Drill bits: 118° vs. 135°



## NelsonFlashlites (Aug 23, 2006)

I'm thinking of getting a decent 115 pc drill bit set. Which is more appropriate for general machining: 118° or 135°???


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## mahoney (Aug 23, 2006)

Either will work for general purpose work, 135 degree is better for thinner metal, especially ground split-point style.


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## blahblahblah (Aug 23, 2006)

Make sure to get a drill doctor too. I have one and I love it. I have several drill bit sets. I also bought 50+lbs of used/new drill bits from a machine shop that was closing down. I sharpened all of them and now I have tons of spares. The drill doctor will also allow you to change from 118 to 135 and back if needed. You can also make/sharpen split points.


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## Anglepoise (Aug 23, 2006)

My drill index consists of 118 degrees.

I purchased 135 degree drills with Cobalt added for SS and Titanium use.

I agree 100% ^^^^ that a sharpener is paramount. Darex or drill doctor will be fine.


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## zelda (Aug 24, 2006)

_I also bought 50+lbs of used/new drill bits from a machine shop that was closing down._  

How many days tooks to sharp them? 

zelda


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## Data (Aug 24, 2006)

The two drills have different uses and cost. The 135 cost more to make and sharpen and are more fragile when cutting steel. The 118 does not cut a hole at the center, it smashes and scrapes the material out of the center. The 135 cuts all the way to the center and in doing that it starts easier and starts truer.

Say you want to drill a 1/2" hole through a steel or aluminum plate. If you are going to use a CNC mill to do it the 135 drill or the 118 drill will cut a perfect hole but the 135 will start in a truer position and use less horse power. If on the other hand you are going to use a drill press or hand drill then the 135 drill will cut through with less press force required. However I often use a 118 in this case so the cutter does not start to chatter. The 118 does not cut at the center so when drilling through a plate it self limits it's tendency to dive in to fast. If it dives in, it will stall or chatter or chip the edge of the drill.


Cheers
Dave


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## MoonRise (Aug 24, 2006)

Ummmm, Dave, the drill being able to actually drill to the center is more a function of a split-point or not. The tip angle is a different criteria. And drill bits with a 135 tip don't cost more to make than drill bits with a 118 tip, but 135 split-point bits do cost bit more to make and usually sell for more of a premium.

For general purpose use, either will work. For general purpose use, split-point or not doesn't make a big difference. If you know or have an idea of what most of what you will be drilling will be, than that can help us give a better recommendation. Drilling hardened steel? Use a cobalt 135 split-point. Drilling wood and you want the holes to be smooth? Maybe a brad-point bit. Thin sheet metal? A 135 split-point, but cobalt not usually needed. etc, etc...

Regarding the DrillDoctor, some models can do split-points and some can not. If it's important to you, double check the capabilities on the particular model you are looking at.


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## Data (Aug 24, 2006)

Almost all jobber length machinist 135° drill bits are ground with a split point and all 118° drill bits are ground with the spade like tip at the center. In general the angle at which the flute is ground and the type of tip that is ground work together as a system. Both systems have distinct uses and so both are commonly available.

There are exceptions to this, but they are specialty bits designed for a very particular material/purpose and they do not come in 115 piece sets from suppliers like MSC and HF.

NelsonFlashlites, I would recommend you purchase a set of good grade drills made with HS or even better Cobalt. My favorites are Cleveland Twist and Chicago-Latrobe but you would be OK with most of the moderately priced USA made companies. If the price is under $100 for a 115 piece set, check them out before you buy.


Dave


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## NelsonFlashlites (Aug 24, 2006)

Data said:


> ...If the price is under $100 for a 115 piece set, check them out before you buy...



Yeah, I got a 135 degree set from Menard's and took a good micrometer to them and they were either really off, or put in the wrong holes. Then again, it was $40. I'll be returning it.


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## Rothrandir (Aug 24, 2006)

a while back i picked up a 0-60 cobalt 135 split point screw machine length set from j&l industrial o-zone. for $60ish (was $130)
a few weeks later i picked up a letter and number set as well for 60-80% off 
all precision twist drill brand.

not bad getting $400 worth of drill bits for about $150!


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## James S (Aug 24, 2006)

I dont know anything about the angle, but I can echo the cobalt recommendation. Though I paid a premium for them, the cobalt steel bits I've got are by far the sharpest and longest lasting. Even the titanium coated ones dont match up.

at the local hardware megamarts there are lots of titanium coated but otherwise really cheap and horrible drill bits available. Evidently it's easier to coat a cheap bit than to make a decent one to start with


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## RA40 (Aug 25, 2006)

I find that starting a hole is easier with a 135 split point type. I mostly use screw machine/stub length to reduce walking and deflection but even those can be tough starts depending on material. Cobalt is my preffered choice and the various coated ones. Chicago-Latrobe, Cleavland, Titex (Germany) and more... The Precision brand available from Rutland has been pretty good. I stay away from budget bits.


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## tvodrd (Aug 25, 2006)

RA40 said:


> I find that starting a hole is easier with a 135 split point type. I mostly use screw machine/stub length to reduce walking and deflection but even those can be tough starts depending on material. Cobalt is my preffered choice and the various coated ones. Chicago-Latrobe, Cleavland, Titex (Germany) and more... The Precision brand available from Rutland has been pretty good. I stay away from budget bits.



Amen!!!

Larry


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## milkyspit (Sep 20, 2006)

Data said:


> NelsonFlashlites, I would recommend you purchase a set of good grade drills made with HS or even better Cobalt. My favorites are Cleveland Twist and Chicago-Latrobe but you would be OK with most of the moderately priced USA made companies. If the price is under $100 for a 115 piece set, check them out before you buy.
> 
> Dave



Dave, any possibility you might provide a link or two, or at least point folks (including me!)  in the right direction as far as a good *value *(best bang for the buck, not cheapest) set of drills... where is a good place to get them, prefably online, and what is the specific item/set/kit/stock number we're looking for? After reading this thread, I don't think I've ever had a good set of drills in my entire life! 

BTW, is such a set suitable for both hard metals (stainless for example) and soft (aluminum)?


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## scott.cr (Sep 21, 2006)

I have this set of screw machine (stub length) drills from Enco. They're 135-degree split points good for use in drill presses. Those of you used to paying $20 for a drill index from Lowe's might be shocked at the asking price of $75, but it includes all of the common machining-size drills including those used for tapping metric holes. I'd have to recommend skipping the Drill Doctor and instead discarding one of these bits if it dulls and ordering a replacement (usually under a buck, or sometimes just over a buck depending on the size). Honestly though, I have yet to damage one of these bits due to "hard use" like I have with the cheaper drills, which usually lose their temper after a light drilling job in steel. I have broken the smaller ones after siezing them in aluminum though.

A 135-degree point might be considered more fragile than a 118-degree point, but I think if you're breaking 135ers, your speed and/or feed are probably running at production rates rather than prototyping rates.

The screw machine drills help you produce superior work because your holes will stay more concentric due to less flex and drift of the point when you start a hole. This particular set has very accurately ground flutes with a precisely centered point, so your holes also come out closer to the size of the drill. They're sharp and last forever!!



> BTW, is such a set suitable for both hard metals (stainless for example) and soft (aluminum)?



The screw machine drills I linked above will drill all materials you can drill with a high-speed steel bit, including hardened steels. Fine for aluminum too, but if you need a clean, deep hole in aluminum you'll probably want a "high helix" drill, which is better at clearing chips from holes in stringy materials.


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## Data (Sep 21, 2006)

Scott

Go to the link that scott.cr posted and select the 
"CUTTING TOOLS DRILLS DRILL SETS "
link.

Then put in:

Type Jobber 

Size Range 1/16 - 1/2 x 1/64 

Material Cobalt 

And it will give you two results, both with 135 degree tips. The USA ($100) brand is probably good but I would buy the Triumph ($150) or go to MSC and get one of the brands I listed above like Greenfield, Cleveland Twist and Chicago-Latrobe. I remember buying Triumph drills and as I recall they were very nice.

scott.cr is recommending screw machine length drills and I prefer them too if they are long enough for the task, but jobber length are more useful for everyday use. I also do not sharpen drills, I replace them when they are dull unless they are very expensive drills. 

My best drills never get used in steel unless they are mounted on a drill press or mill. If you are going to use a hand drill in steel then use a 118 degree drill and not one of the expensive ones because there is a possability of chiping it.

Cheers
Dave


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