Drill bit questions

[s_morrison57]

I have no luck buying drill bits, maybe bad advice, maybe buying to cheap but the performance doesn't seem to be there. Lots of choices, carbon steel, hardened steel, carbide etc.. Can anyone explain the difference's? I'm looking for some bits for a hand drill, general purpose, light duty.
What about those Drill Doctor/ Bit Doctor machines, always thought they were a
"house wife" tool but I may have to re-look at my thinking there, I do know that its hit and miss for me when I sharpen a bit on the grinder and way more miss than hit. How often do you sharpen?
Anybody care to give us a lesson on drill bits?
Finn

[manbridge 74]

Lawson bits with cutting oil for me...

The sharpeners work very well at restoring the proper angles.

[unclebilly]

the drill doctor works awesome. the thing about the coated (titanium) bits it that the coating is gone the first time you sharpen them.

Try acklands or a similar industrial supplier for a decent quality drill index.

[dad911]

The trick to drilling is you need to adjust speed and force so the bit is always cutting(making chips). When its spinning on top you are just making it dull and generating heat. Cutting fluid/lubricant for cooling.

[cashflyer]

IMO, most people who are getting poor performance from drill bits are using them incorrectly (assuming they are quality bits).

Different metals require different rotational speeds and different feed speeds.
And you should always use cutting fluid when cutting metal.

Drill Dr. works fine for re-sharpening your everyday bits.
Mine does not work on pilot-point bits.

[dlockhart]

Use the correct speeds and feeds

Drilling Speed and Feed Calculator

chuck the drill as short as possible. ( you can hold on by the flutes )

it is very hard to generate enough feed pressure / rate with a hand drill so you likely need to slow the rpm down so that the drill makes a chip, not dust. A little bit of cutting oil will help a lot too.

[911pcars]

Carbon steel drills are cheap but don't last long between sharpenings.

Suggest high speed steel drill bits as a minimum material.

As descreibed, "coated" drill bits are only coated with a thin film; most effective for advertising (cobalt, ti, etc.).

Suggest learn how to sharpen a drill bit. It's not difficult, but there's a right way to do it.
Yes, Drill feed and speed are important factors.

I often use step drills. It's easier to drill a large hole by gradually enlarging the hole via the steps, especially in thin sheet metal.

Sherwood

[zipinitaly]

You'll have better success drilling metals if you find split tip designed bits. This design minimizes the cutting land thickness and greatly improves chip clearance. Choose drills that have the 'jobber' designation.

Also, when you quit getting chips....stop drilling, you're only ruining the bit and toughening the metal.

[JAR0023]

Originally Posted by dad911

The trick to drilling is you need to adjust speed and force so the bit is always cutting(making chips). When its spinning on top you are just making it dull and generating heat. Cutting fluid/lubricant for cooling.

Came here to post this. J

Sent from my HTC One using Tapatalk 2

[Kraftwerk]

Cutting fluid is essential and it smells like root beer!
If you are cutting circles in metal: Buy these fantastic hole saw drills manufactured by Relton in the good old USA Arcadia, California
(American made quality goes a long way to getting the job done quickly and neatly, don't get me started on Chinese crap!)
They are not cheap but the only thing I will use.
This company will also restore, sharpen and re- tip your Relton hole saw bits for a small fee.

As far as drilling goes: the proper RPM and the right pressure is important, also the tool should be 90 deg. to the surface of what you are cutting.

[cockerpunk]

what are you trying to drill through?

generally machine tools follow a trend of more and more hard, but as the hardness goes up, they get more and more brittle.

you need the hardness to cut harder and harder metals/materials, but you have to be very careful of cutting deflection, because they get more and more brittle.

generally, coatings are used to reduce friction, and heat, not really help with the cutting itself.

generally, unless you are cutting something exotic or hardened steel, i'd stick with high speed steel with a titanium coating (the gold stuff)

[NY65912]

We use Relton holesaws on ceramics with no problem, they are superior for sure.

I like cobalt bits. But it really is about speed, lube, force and the right type of angle of the drill bit.

I start with light force and slow speed and then adjust for the best cut.

[Hydrocket]

Also, most people don't know that the tip of a drill is NOT for starting holes. That's usually how drill tips get ruined and dull. If people would buy a $5 center drill, their drills would last much, much longer.

A center drill is made to start holes in steel.

[RANDY P]

Originally Posted by dad911

The trick to drilling is you need to adjust speed and force so the bit is always cutting(making chips). When its spinning on top you are just making it dull and generating heat. Cutting fluid/lubricant for cooling.

hard materials (steel) low speed high feed...

Soft materials (alum) high speed low feed.

I get it to make curly shavings, perfect.

rjp

[sc_rufctr]

Some good advice already but I wanted to add something.

Your chuck has three tightening holes for a reason. Use one to initially tighten the drill then tighten further using the remaining two holes.
The drill is better centred and properly secured. This is great for larger drill bits and I always do this.

That may not sound like much but it really does make a difference.

[jim72911t]

Holemaking | MSCDirect.com

Drilling and drill bits: 69,409 items, so lots to choose from. Generally, I find cobalt drills to be a good compromise between sharpness, longevity, and versatility.

Pro-tip (machinist for 20+ years here): Unless you need the length of a jobber (regular length) drill, buy stub length drills. They are more rigid, create a truer hole, and generally eliminate the need to c'drill.

Plenty of good advice here, but to be honest, there are so many variables that go into drilling that it can take years to get it right for all materials and conditions.


Good luck

[Flieger]

Can you chuck a suitably-sized center drill into a handheld drill? I've only used them on mills.

[s_morrison57]

Thanks guys, all good advise, looks like my technique is a bit off but I'm way better informed now.
I asked more for general knowledge but I'm ordering an 818 kit from Factory Five.

Finn

[look 171]

A drill press helps A LOT.