What makes drill bit sets different?

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Bill Kahn

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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
 
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.
 
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.
 
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.
 
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.
 
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.
 
mikey said:
Bill, may I ask what you're doing with railroad spikes - just curious.
Click to expand...

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
 
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!
 
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