What did I do wrong drilling these holes?

[5030]

... I might add the TIN coated drill bits are a gimmick. TIN (Titanium Nitride) coated bits, the TIN coating does nothing except promote easier chip flow from the cutting lip. Nothing more and it wears away quickly too.

 

[LD1]

... I might add the TIN coated drill bits are a gimmick. TIN (Titanium Nitride) coated bits, the TIN coating does nothing except promote easier chip flow from the cutting lip. Nothing more and it wears away quickly too.

I dont like the TIN bits either.

Once sharpened....there is no coating on the edge that is cutting....and I have found that the underlying steel just doesnt seem to be as hard as good plain HSS bits.
One good thing I DO like the TIN for is certain alloys of aluminum that tend to want to get "gummy" and pack the flues of the bit and almost gald themselves to it. The TIN seems to be more of a anti-stick coating

 

[sailonner]

As others have said, lower the RPM to SLOW. I concur with others about the type of bits to use. The titanium coated, or cobalt bits tend to hold up longest. When I've manufactured steel or stainless steel parts, I use auto radiator coolant for the lubricant. It evaporates quickly, helps to cool better, and washes off with water. Which is great if you're going to paint the parts.

 

[mapper]

The only TIN bits I have are Brad points for wood, they seem to be ok for that.
My father who was a very smart man and an engineer once told me after I had destroyed a drill bit in metal,( one of his of course) always use the lowest speed available on the drill press.
Good advice, I've broken some small bits on occasion but I don't think I've smoked one in the last 60 years.
My drill doctor has been an invaluable purchase, my hand sharpening was always kind of hit and miss.

 

[Root Cause]

Good info here.
Blue chips are bad unless using carbide cutting tools.

I have a few years working in a machine shop where we drilled water lines in tool steel with HSS bits. Speed and keeping a hole straight were critical.

I use a cheap paintbrush and load it with coolant. (keep a small pan of coolant close by)
Apply light pressure for about 5 seconds then wipe the bit with the brush with my off hand while pulling it out. You don't want to ever see long, stringy chips. This clears the chip, cools the bit, and allows some coolant into the hole. You will get a rhythm to it soon enough and it is the fastest method and increases the life of the bit.

good luck.

 

[LD1]

Good info here.
Blue chips are bad unless using carbide cutting tools.

I have a few years working in a machine shop where we drilled water lines in tool steel with HSS bits. Speed and keeping a hole straight were critical.

I use a cheap paintbrush and load it with coolant. (keep a small pan of coolant close by)
Apply light pressure for about 5 seconds then wipe the bit with the brush with my off hand while pulling it out. You don't want to ever see long, stringy chips. This clears the chip, cools the bit, and allows some coolant into the hole. You will get a rhythm to it soon enough and it is the fastest method and increases the life of the bit.

good luck.

I disagree about never wanting a long stringy chip.....

A long chip is a pretty good indicator that you have good and consistent feed pressure.

Long and stringy chip on a late is not good....but nothing wrong on a drill

 

[ranchito]

Help a novice here. I thought the long stringy chip on a lathe was probably a good thing. What should I look for?

 

[ruffdog]

Long stringy chips can be dangerous and are a pain to clean up. Maintaining chip control means using a chip breaker and correct feed rate to break the chips into small pieces.

 

[oldtimer 66]

I have an old ENCO drill press. I run it at the slowest speed all of the time. I don't use any coolant. I also hand sharpen all of my drill bits. No problems. I have mentioned this before to the machinist on hand, Rule of Thumb, spindle speed = 4 X SFM / Dia. is a starting point for spindle speed for drilling/ milling and or lathe work. HS tooling = 100 SFM, Carbide tooling = 300 SFM. These are just starting points then adjust up and or down for the material. But for my work I run as slow as possible.

 

[ptsg]

Help a novice here. I thought the long stringy chip on a lathe was probably a good thing. What should I look for?

On a lathe, you'll want small chips, preferably with blue colour. That means the heat is coming out in the chip and not staying in the part or the cutter.

Something along these lines:

Of course, this is not always possible due to a lot of different factors like, speeds and feeds, material, cutters, etc.

On a drill press, if the chip is coming out long, I'll just release the pressure momentarily to stop the chip from forming and then apply pressure again. I typically leave my chips getting like 1.5" to 2" long.