Cobalt and Carbide Drill Bits

mack1

Howlin' Wolf
What's the difference here?
I see the BossDog has some solid Micrograin Carbide bits on his Site now.
I need to drill through hardened steel(ie: a knife), and there's that difference in price.
I know(think) both are brittle, so I should get more than one.
Need an answer, so's I can place my Order, and the BossDog hasn't responded yet. :D
 
You definately need Carbide for hardened steel.

I tried to drill a hardened blade on my drillpress with a Cobalt bit. The bit welded itself into the blade, the blade came out of my hand, proceeded to spin at high speed and was then flung across my garage! I was very lucky I was not sliced open or impaled...
 
Chris, I thought I was the only one this has happened to. I just didnt speak up....lol It actually has happened more than once. Dangerous...once you start hearing that squeeling its time to pull out....LOL Scary stuff.


I need to order some Carbide drills from Tracy as well.

Chris
You definately need Carbide for hardened steel.

I tried to drill a hardened blade on my drillpress with a Cobalt bit. The bit welded itself into the blade, the blade came out of my hand, proceeded to spin at high speed and was then flung across my garage! I was very lucky I was not sliced open or impaled...
 
I would imagine having a drill bit actually weld itself to a knife would come as quite a surprise. huh1
The first time, anyway. :D
Just teasing.
 
LOL...The stupid stuff we do in our learning steps:eek: This is why I use a face shield, respirator and leather apron while playing with knives. I am still learning so I take no chances:(

Hope you get them babies drilled out Mack!!!!

I would imagine having a drill bit actually weld itself to a knife would come as quite a surprise. huh1
The first time, anyway. :D
Just teasing.
 
huh1 Now I don't need 'em.
Figured out what I wanted to do wasn't possible. :unsure:
Need to talk to T.
 
Chris, I thought I was the only one this has happened to. I just didnt speak up....lol It actually has happened more than once. Dangerous...once you start hearing that squeeling its time to pull out....LOL Scary stuff.


I need to order some Carbide drills from Tracy as well.

Chris

I think anything we have happen to us has happened to someone else at some point. I figured it was best to spill the beans so Mack1 didn't have to learn the hard way!

I put all my blades in a vise on the drill press now whether they are hardened or not. I don't relish the thought of a home apendectomy!
 
The buffer is the most dangerous tool in the shop due to the velocity it can hurl a knife at you but the drill press hurts more people in the shop. It is amazing how strong even a small bench top model is and how fast a blade or other metal piece helicopters back around to slice you good.

When using carbide, go fast with lot's of cutting lube. No lateral loads. Keep everything perpendicular. Don't try to use carbide in a hand drill.
With cobalt (fixed typo), go medium speed with cutting lube.
With HSS go slow.

Keep in mind it isn't just speed but feed rate. A steady feed rate where you are getting good production of curl or chips. Don't let a drill sit and spin in a hole or baby it so it heats up. Drill with some pressure so you produce swarf at a consistent rate or you just dull the bit and get oblong or 3 lobe holes.
 
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When using carbide, go fast with lot's of cutting lube. No lateral loads. Keep everything perpendicular. Don't try to use carbide in a hand drill.
With carbide, go medium speed with cutting lube.
With HSS go slow.

I think you meant cobalt in line 2 above. :D

Erin
 
Along with Tracy's comments about the swarf. If the swarf is blue you are drilling to fast. Use the step pulleys and slow it down. I have my drill press set on its slowest speed when drilling mild steel and normalized carbon steel.
 
So far, I haven't had reason to take mine above the "Slow" setting. :D
I appreciate the lessons peoples. cool 1

And Moe's a good lookin' boy. 2thumbs

Here's our's.
Marshall. Now about a year old. Rescued from an abusive former owner.
I'd say he adjusted well. :sleeping dog:
 

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