What did I do wrong drilling these holes?

[etpm]

we use them for lathe work live center support since they are 60 degrees like the center.

That's why they are called center drills. They are drills for centers, which are typically 60 degrees.
Eric

 

[oldtimer 66]

Just to muddy up the waters. Centers as in dead centers that are use on lathes and grinders are generally ground to 60 deg 15 min. The part center that is machined is machined at 60 degs. You don't want to point load the center because that will cause TIR and machining problems.

 

[Williy]

I like to keep some hydraulic oil in an old can so I can
put the bit in every now and then to help keep it cool

willy

 

[LD1]

Center drills with the pilot point make it so the point/tip of the center (rather live or dead) isn't actually contacting the work.

But yes, if you are using a dead center oil is a must

 

[oldtimer 66]

LD this is a pun but you missed the point.

 

[big bubba]

did you drill a center punched pilot hole 1st? i've used Tap Magic as cutting fluid for tapping & drilling as machinist w/good results many yrs, + all about rpm but you know that, regards

 

[tshep]

Too fast on the rpm
NEVER use petroleum lubricating oil. It acts as a coolant at best on steel. Canola oil, or any vegetable oil is 100 times better, but Messy. WD-40 is Worthless for steel, but great for ALU.
Use water to keep thing cool. (100 times better than lubricating oils.) (soda water keeps things from rusting up)

Also, did you mention the size of the pilot hole?, It should be about the size of the web of the final drill.

When drilling steel, MAINTAIN THE CHIP! that is, keep the cutting lips cutting, don't RUB.

As others have mentioned, once the hole gets hot and blues, it's going to take a good High Speed Steel (HSS) or better to penetrate the hard parts. Or a few trips to the grinder to re-point the drill. If the drill bit gets burned, it's a thankless job to re-point. You are best off just to cut off the business end and grind a new point. An acquired art. DON'T Burn the lips when sharpening!

It's all so hard, but as your post testifies, we git it done! I've got hundreds of twist drills with spoiled cutting lips or broken corners*, I'll get to them "someday" (*from my aviation days)

ruffdog and cal - you have changed my life. I came up through a couple of trades where you just drilled holes, were supposed to have been born knowing it. I just did a project where I concentrated on 'chip load', got it done, and put a good bit back in the rack. (Found pressure much more productive than speed.) I gonna' guess it was stuff I should have known, or did know, just hadn't' put it together as 'chip load'.
While you guys are teaching, how to stay perpendicular with a hand drill, and the same with starting and completing a 'large' tap?
THX

 

[CalG]

ruffdog and cal - you have changed my life. I came up through a couple of trades where you just drilled holes, were supposed to have been born knowing it. I just did a project where I concentrated on 'chip load', got it done, and put a good bit back in the rack. (Found pressure much more productive than speed.) I gonna' guess it was stuff I should have known, or did know, just hadn't' put it together as 'chip load'.
While you guys are teaching, how to stay perpendicular with a hand drill, and the same with starting and completing a 'large' tap?
THX

When drilling, I like to set "something square" near the hole location to give my eye a reference in two planes. A square cut piece of wood does just fine.

For starting the tap, I use the tap holder/alignment tool OR drill a hole in a piece of wood using the press drill.

Tap Aligner - - Tap Aligner

www.msdiscounttool.com

 

[bcp]

Long ago had an electric drill that has several bubble levels mounted into the case. That made it really easy to keep it vertical or horizontal. Haven't seen one since, but haven't looked for one.

Bruce

 

[gsganzer]

Another trick when drilling holes in a piece lying flat horizontally is to lay a large flat washer on top of where you're drilling and fill it with cutting fluid. It acts as a reservoir to keep the cutting fluid contained to where you're drilling.

As other have pointed out, work hardening can happen if your RPM is too fast, bit is dull or not enough pressure. It's especially bad with stainless.