What makes drill bit sets different?

[JimDawson]

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]

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]

... 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]

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]

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]

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]

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]

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]

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]

... 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?