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What makes drill bit sets different?

Bill Kahn

Active Member
Active Member
#1
Beginner's question...
I have a cheap 115 piece HSS drill bit set. Works fine on softer materials. But there are steels it does not work on. (I do not know how to evaluate steel--but I am working on old railroad spikes now. Carbide end mill works on it. My cheaper HSS end mills do not.)
My drills bits do not drill the railroad spikes.
So, how do I figure out what drill bit set to buy that can work on such harder steel?
I look at HF say and see https://t.harborfreight.com/115-pc-...886.html?utm_referrer=https://www.google.com/ for $110. (Yeah 20% coupon is available).
But also I see https://t.harborfreight.com/115-pc-...620.html?utm_referrer=https://www.google.com/ for $40. There must be a real difference. How can I tell what each can drill? And how about http://littlemachineshop.com/products/product_view.php?ProductID=3418&category=-456343308 for $500. So, how is that different?

And for $945 https://www.amazon.com/Cleveland-C7...83604&sr=1-1&keywords=115+piece+drill+bit+set

Are there carbide sets too?

So, I need to select length (Jobber seems good for my PM25 mill).
I need to select tip angle (why 118 and why 135?)
I need to select material/brand/grade. How does one make this selection?

And, in particular, if I want to drill holes in hard steel what should I buy? (I have given up on drilling into ball bearings. But as my carbide end mill does well on the rail road spikes that suggests it is doable.)

Drill bit selection must have been covered before. Any pointer to some such old thread much appreciated--my search did not turn anything up.

-Bill
 

RJSakowski

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#2
Cheap drill bit sets are sometimes not HSS even if they say they are. Beyond that, a properly hardened drill bit has to go through a proper heat treating, not always the case with cheap drill sets.
IMO, buying cheap drills is always a crap shoot. You may get lucky and actually get a set with reasonable steel but chances are good that you won't. Even if the steel is good, the sets may have mislabeled drills, drills that are bent or drills with an improperly ground cutting edge. They will usually work on wood, and some times on soft metal but often fail when drilling harder materials.

The best bet is to buy name brand drills. This can set you back a bit though. I have had good luck with Interstate drills from Enco, now MSC. Big box DIY drills can be poor quality unless you get a name brand. For a general purpose set, I would get the jobber drill set. screw machine drills or spotting drills can be useful, as can aircraft drills.

As to the tip angle, I have seen the 135º tip on split point drills. 118º is the classic angle for drilling metal.
 

Old junk

Active Member
Active Member
#4
This may sound harsh but do yourself a favor and don't waste your money at hf.the time alone you will waste trying to use those bits can be spent making your projects.it seems expensive when your looking at that China tool flyer compared to some quality tools but when you want to get something done I can't put a price on it.said it before good tools ain't cheap,cheap tools ain't good.
 

T Bredehoft

Active User
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#5
I must admit that I do own each of the three sets of drills. I bought the boxes (three of them) then filled them slowly at work. (as I needed a drill I'd get it from the crib until I had most then I took the box to the crib and filled them. Now I buy the bits I need individually in lots of 3 or 6. I find that the ones I need I use up, the others just sit there waiting their turn.
 

Desolus

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#6
I buy strictly American manufacture M42 drills. M42 can come in 8% cobalt up to 10% they slice through stuff like crazy and are very very hard and very very heat resistant...
 

Desolus

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#7
I just looked at the sets you linked, the more expensive ones are M42... a note about M42, because of its hardness, it may shatter and inbed it's self in your eyeball if you use it in a non rigid setup like a cordless drill...

So for drilling things like work hardened stainless steel, M42... and plunge agressively.
 

mikey

Active User
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#8
Bill, may I ask what you're doing with railroad spikes - just curious.

You will find that 118 degree drills are the most common twist drills and therefore can be found for the lowest prices. Typically, 118 degree drills are for softer materials like mild steels, brass, aluminum and plastics. 135 degree drills are better for harder materials or materials that work harden. Materials like stainless steels usually drill easier with 135 split points because the flatter included angle contacts the work more readily and the drill presumably cuts faster and cooler. I have drills with both point angles and use my 118 points most of the time.

For hard materials, I use cobalt drills. They hold an edge better under the higher heat conditions encountered when drilling harder materials. Cobalt drills will cost more because the material costs more but if you drill hard materials often then it is worth the cost.

If you have the money and frequently drill high carbon steels, then a 140 degree carbide drill might be what you're looking for. Big bucks, though.

You have a smaller, low power, light benchtop mill. If I were you, I would consider a 118 degree point HSS screw machine drill set from a good maker. Precision Twist Drill, Triumph, Cleveland all make good drills. You can also buy wire size, fractional and letter sets instead of buying a whole 115 piece set at once. Jobber drills are okay but tend to be longer and chew up more space in Z. Screw machine drills are shorter, stiffer and take up less room on Z. Buying cheap drills is not worth the time and money; buy good drills.

I also suggest you buy a 120 degree spotting drill for use with the 118 degree drill sets or a 140 degree spotting drills if you use 135 degree drills.
 

Bill Kahn

Active Member
Active Member
#9
Bill, may I ask what you're doing with railroad spikes - just curious.
I bought a cheap angle plate (from JTS) as I am making plans to do some angle drilling on the PM25. The angle plate has T-channels. Very nice. But, the slots are smaller than on the mill. So the mill's t-nuts don't fit.

How hard can making a t-nut be?

I had these old rusted spikes found along an abandoned railroad. Hey--free material to turn into chips. After ruining a $20 HSS end mill on them I found that a $100 carbide end mill worked and lo and behold I have the T-cross section cut out. Slides nicely in the slots. So, next step is to drill some #7 holes every 3/4" and tap them (for 1/4-20) (And then bandsaw and finish the ends. Easy.). Surprise. My drill bits do nothing. Ruin a 3/16" HSS end mill. So, next step is ask smart guys (this list) what to do. I guess I could have bought a nice set of t-nuts, but, this is a hobby. All about the journey.

I am learning a lot about material. I think I was attracted to all this for the geometry. But turns out materials are interesting too.

Maybe my best path is to avoid hard materials. Figure out what is soft steel and stay with that. At least while I am a beginner. But I seem to like the challenges. (Though drilling ball bearings I did give up on.)

-Bill
 

mikey

Active User
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#10
Funny but the longer I'm in this hobby, the more I find myself buying things that I can easily make but that are cheaper to just buy. For me, T-nuts would fall into that category but when I started out, I tried to make everything myself just to learn how to do it so I get it. I would suggest you try it on mild steel, though!
 

JimDawson

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Staff member
Director
#11
The Harbor Freight cobalt drill set seems to be pretty decent. I have no idea what the RR spikes are made of. I have a few out in the shop so I'm going to have to try machining one. I'm guessing cutting at around 50 FPM would work with HSS.
 

DaveInMi

Active Member
Active Member
#12
I bought a cheap angle plate (from JTS) as I am making plans to do some angle drilling on the PM25. The angle plate has T-channels. Very nice. But, the slots are smaller than on the mill. So the mill's t-nuts don't fit.

How hard can making a t-nut be?

I had these old rusted spikes found along an abandoned railroad. Hey--free material to turn into chips. After ruining a $20 HSS end mill on them I found that a $100 carbide end mill worked and lo and behold I have the T-cross section cut out. Slides nicely in the slots. So, next step is to drill some #7 holes every 3/4" and tap them (for 1/4-20) (And then bandsaw and finish the ends. Easy.). Surprise. My drill bits do nothing. Ruin a 3/16" HSS end mill. So, next step is ask smart guys (this list) what to do. I guess I could have bought a nice set of t-nuts, but, this is a hobby. All about the journey.

I am learning a lot about material. I think I was attracted to all this for the geometry. But turns out materials are interesting too.

Maybe my best path is to avoid hard materials. Figure out what is soft steel and stay with that. At least while I am a beginner. But I seem to like the challenges. (Though drilling ball bearings I did give up on.)

-Bill
What will this hard material do to a bandsaw blade? A hacksaw blade is less expensive to replace.
 

mikey

Active User
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#13
... So, next step is to drill some #7 holes every 3/4" and tap them (for 1/4-20) (And then bandsaw and finish the ends. Easy.). Surprise. My drill bits do nothing.
Missed this the first time around. If your HSS drill bits won't drill a hole in that material then I hope you have a good supply of taps because they will very likely snap on you. I'm not familiar with a tap that requires a #7 drill in hard steel; a #7 is usually used for a 1/4-20 tap in soft stuff like aluminum, brass or plastics. In any case, I suggest you go one or two steps bigger on the drill before trying to tap that stuff.
 

darkzero

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Staff member
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#14
The Harbor Freight cobalt drill set seems to be pretty decent.
Believe it or not, I have to agree. I have the 118 pc & the 29pc cobalt sets from HF that I purchased yrs ago. I use them in 303, 304, & 6Al4V all the time. I told myself I would buy a nice USA made set someday to replace them but surprisingly they have been serving me well. A couple of them may have had poor grinds on them but nothing a resharpening couldn't fix. Of course their indexes suck, I put them in Huot indexes.

OTOH the HF black oxide & TiN drills aren't worth buying IMO. Although I do still have the TiN set, I gave the other set away. I use the TiN set for drilling wood or other general purpose stuff.

I have an older Craftsman USA black oxide set & they are pretty nice drills. No idea who actually made them though.
 

Charles Spencer

Active User
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#15
When I retired and started my hobby shop I had an old set of Black & Decker drill bits to 1/2" and a somewhat newer set from DeWalt to 3/8". In my younger days I had learned how to sharpen drill bits freehand so I had these for many years. I eventually got a set of number drills, letter drills, fractional drills to 1/2", and Silver & Demming drills 1/2"-1". I bought the fractional drills off ebay and found they were USA made drills from ca. 1950s and barely used - on wood. I got the number drills as an incomplete set at a yard sale and ordered what I needed to complete them. The Silver & Demming and letter drills came from Drill Hog on ebay. They are made in the USA and have a lifetime warranty. I've been happy with all of them. And it's really great to have the exact size you need in a decent quality drill. The bits from Drill Hog seem to be well made and reasonably priced. I got the ones labelled Hi-Moly M7:

http://www.ebay.com/itm/Drill-Hog-2...Y-M7-Lifetime-Warranty-USA-MADE-/181752864050

I do like having separate sets rather than one bulky set.

Also - no affiliation with Drill Hog besides being a customer.
 

Doubleeboy

Active User
Active Member
#16
The Harbor Freight cobalt drill set seems to be pretty decent. I have no idea what the RR spikes are made of. I have a few out in the shop so I'm going to have to try machining one. I'm guessing cutting at around 50 FPM would work with HSS.
I took a chance on the 118 piece set from HF, I believe they are the cobalt ones that Jim referenced. They are jobber length 135 split point. They go through the hard scale on A36 like butter and easily drill Air Hardened steel. They are a screaming good deal when on sale and you add on the 20% coupon.
 

4gsr

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Staff member
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#17
On those railroad spikes. If you have a way to heat them up to around 900-1000 degrees hold for about 15-20 minutes at temperature and furnace cool to under 600 degrees and let cool to ambient. That may pull out any high hardness that is making it hard to cut with a standard drill bit.
 

Jonathans

Professional Fish Killer
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#18
For years, I never wanted to spend big bucks on a drill bit set. I mostly used those huge index sets from China. I had a few larger USA silver Demi g bits. Got the job done.
Then I purchased a "good" set of Dewalt bits that had a built in pilot bit at the tip. Good bits that got the job done better.
For hard work I picked up a set of Dewalt cobalt bits. Brittle, but even better.

A month ago I purchased a set of KnKut stubby bits (these are the bits that supposedly can drill through a #8 bolt easily).
I had to mount a swing arm to my Bridgeport and to do so had to drill some 5/16 holes and tap them into the cast (which was MUCH thicker than I had expected).
I first drilled the holes with a Dewalt cobalt 1/8 pilot. Took a long time. Then I drilled out one hole to 5/16 with a Cobalt bit. Took around 10 to 15 minutes, and was difficult.
I then decided to try one of my new expensive KnKut bits. Holy crap! it drilled right through an a minute or so, maybe less! I was amazed at the difference. All bits were new. All were 135 degree.
I guess you get what you pay for sometimes. I'm 61 and spent many years drilling with crappy bits.
 

Bill Kahn

Active Member
Active Member
#19
What will this hard material do to a bandsaw blade? A hacksaw blade is less expensive to replace.
My small HF bandsaw is doing well. I have destroyed many blades in trying to learn to cut lead bricks. (But have something that is working now for that too.). But for most of my work I have been using https://www.amazon.com/gp/product/B010BOLYP4/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1 at high speed. It has cut through hard stuff, like these railroad spikes, that HSS bits have been destroyed by. Not fast but nice thing about a bandsaw is it is largely launch and forget until the noise stops.
 

Bill Kahn

Active Member
Active Member
#20
... I got the ones labelled Hi-Moly M7:
...


I have see bits labels as M42 (seems like these are good for drilling hard steel). I also see M35 advertised. Are these I gather are also good, but not quite as good as M42. But is M35 good in some other way, like less brittle or something? And I see the M7 label too. Apparently also very good. Is there a list somewhere of the standard material drill bits are made out of what each material is good, and not so good, for?
 

DaveInMi

Active Member
Active Member
#21
My small HF bandsaw is doing well. I have destroyed many blades in trying to learn to cut lead bricks. (But have something that is working now for that too.). But for most of my work I have been using https://www.amazon.com/gp/product/B010BOLYP4/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1 at high speed. It has cut through hard stuff, like these railroad spikes, that HSS bits have been destroyed by. Not fast but nice thing about a bandsaw is it is largely launch and forget until the noise stops.
That is great news. I just ordered from them. Thanks
 

4gsr

Global Moderator
Staff member
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#22
I have see bits labels as M42 (seems like these are good for drilling hard steel). I also see M35 advertised. Are these I gather are also good, but not quite as good as M42. But is M35 good in some other way, like less brittle or something? And I see the M7 label too. Apparently also very good. Is there a list somewhere of the standard material drill bits are made out of what each material is good, and not so good, for?
M7, M35, M42, they are all Cobalt based tool steel. And for the H-M, they will drill just about anything you want them to do. As for one shattering, M42 are pretty tough. I have a few that are M7 material and with the sound they make when bumped I think they would shatter just from dropping. Haven't tried. I've bought several used sets of HSS and Cobalt drill sets off of ebay over the last few years. It's hit and miss on what you are bidding on. You can study the pictures and after a while determine what is good and what is junk.

BTW: They only have one of these left in stock! Don't sneeze! Someone may buy it! "And for $945 https://www.amazon.com/Cleveland-C7...83604&sr=1-1&keywords=115+piece+drill+bit+set ":D
 

Ken from ontario

Active Member
Active Member
#23
M7, M35, M42, they are all Cobalt based tool steel. And for the H-M, they will drill just about anything you want them to do. As for one shattering, M42 are pretty tough. I have a few that are M7 material and with the sound they make when bumped I think they would shatter just from dropping. Haven't tried. I've bought several used sets of HSS and Cobalt drill sets off of ebay over the last few years. It's hit and miss on what you are bidding on. You can study the pictures and after a while determine what is good and what is junk.

BTW: They only have one of these left in stock! Don't sneeze! Someone may buy it! "And for $945 https://www.amazon.com/Cleveland-C7...83604&sr=1-1&keywords=115+piece+drill+bit+set ":D
I would always check the price on amazon Canada, guess what, the one you linked is only $687.93 on amazon.ca, and that is in Canadian dollar so in fact it is around $600 USD:
https://www.amazon.ca/Cleveland-C70...int,+1/16"+to+1/2",+A+to+Z+and+#1+to+#60+Size
 

4gsr

Global Moderator
Staff member
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#24
The M35 grade is more than likely the Chinese destination for their "Cobalt tool steel" they are used to using. Their steel numbers generally follow the DIN/Germany destinations. Why doesn't the rest of the World not follow the AISI system? Oh well! Can't change it now.
 

Eddyde

Active User
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#25
I think a good strategy is to get good quality HSS sets for general work and buy individual cobalt drills only as needed. I have some letter and wire size drills I have never used in 30 years, yes its reassuring to know I have em "just incase" but no need to buy all those sizes in cobalt.
 

terrywerm

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#26
About ten years back I thought I was being smart by purchasing one of those 115 piece drill bit sets from Enco. They weren't bad, but not great, fine for general purpose work. Life was good until the one day when I knocked the entire drill index off of the bench and onto the floor. Spent the next couple of hours measuring most of the drill bits with a micrometer to get each one back into its correct spot.

Now here I am years later, some of the bits are broken, some are lost, but a fair number need replacing. Instead of purchasing another set of the cheap ones, I have decided to purchase separate letter and number bit sets in separate Huot indexes, and purchase higher quality bits while I am at it. I don't think I will regret my decision. At least if I spill an index I know where all of the bits belong much more easily.

As for cobalt bits and end mills, I do have a few of them, purchased individually for specific projects. They all reside in their cardboard or plastic sleeves and are used only as necessary. My cheap bits are the ones that I leave where my adult children can find and use them. The good stuff is hidden away... if anybody is going to break or lose the expensive stuff, it's going to be ME! That way I don't grumble about the replacement expense.