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Hardest drill bit material

KurskKnyaz

Senior member
Dec 1, 2003
871
1
81
I make clocks out of computer hard drives and sell them.

http://s66.photobucket.com/alb...w&current=IMG_0089.jpg

The problem is that the bearing in the center of the motor is impossible to drill through. I usually end up hammering it out. I have tried bits made of steel, titanium coated ones, and cobalt. The cobalt seem to work but they snap (I got them on eBay). Are there any stronger/harder materials out there? I was thinking of purchasing titanium Dewalt bits but I remember from working at an auto shop one of the guys had some carbon coated bits which could drill through stainless steel. By the color of the bearing I think it is cobalt. What do you recommend?
 

Ronstang

Lifer
Jul 8, 2000
12,427
10
81
Carbide drill bits would be your best bet but they are also brittle and rather easy to break.
 

Fenixgoon

Lifer
Jun 30, 2003
28,135
3,466
126
tungsten carbide FTW (i'm guessing that is what people mean by "carbide" bits). great idea for the clocks, btw.
 

Ronstang

Lifer
Jul 8, 2000
12,427
10
81
Originally posted by: Fenixgoon
tungsten carbide FTW (i'm guessing that is what people mean by "carbide" bits). great idea for the clocks, btw.
Yes, but the clocks have been around for 20 years. I had one back in 1990.
 

skyking

Lifer
Nov 21, 2001
19,557
1,317
136
Carbide is the right tool, but you really need to chuck the piece in a drill vise and use a drill press.
Any chatter/motion, even imperceptible amounts, will result in breakage. If you are deep in the part, now you have a piece of the hardest material to try and remove.
That blows.
 

Fenixgoon

Lifer
Jun 30, 2003
28,135
3,466
126
Originally posted by: Ronstang
Originally posted by: Fenixgoon
tungsten carbide FTW (i'm guessing that is what people mean by "carbide" bits). great idea for the clocks, btw.
Yes, but the clocks have been around for 20 years. I had one back in 1990.
i was only 3 in 1990 :p
 

mooseracing

Golden Member
Mar 9, 2006
1,711
0
0
Originally posted by: KurskKnyaz
The cobalt seem to work but they snap (I got them on eBay). Are there any stronger/harder materials out there?

Do you know how harder things work, especially metal? The harder and better they are for drilling the more brittle they get. You can break some just by dropping them on cement.

Cobalts are about the best quality you can get for drilling through hard materials, as well as carbide like what is used in lathes and mills. You do also understand you should be going less then 500rpm on your drill as well?

Slow and steady with oil is the best way.
 

alkemyst

No Lifer
Feb 13, 2001
83,967
16
81
also I am assuming you are using a drill press...even a cheap 10" or smaller would be adequate for this.
 

Howard

Lifer
Oct 14, 1999
47,989
9
81
Strange that the titanium-coated ones aren't working. The TiN coating is harder than any steel (cobalt HSS included).
 

Bignate603

Lifer
Sep 5, 2000
13,897
1
0
Bearing races are about as hard as high speed steel, my machine shop on campus refuses to drill them. You may be better just buying/building a puller.
 

KurskKnyaz

Senior member
Dec 1, 2003
871
1
81
Originally posted by: mooseracing
Originally posted by: KurskKnyaz
The cobalt seem to work but they snap (I got them on eBay). Are there any stronger/harder materials out there?

Do you know how harder things work, especially metal? The harder and better they are for drilling the more brittle they get. You can break some just by dropping them on cement.

Cobalts are about the best quality you can get for drilling through hard materials, as well as carbide like what is used in lathes and mills. You do also understand you should be going less then 500rpm on your drill as well?

Slow and steady with oil is the best way.
How does titanium hold up? I can't find good quality Cobal bits at Home Depot (all I see is titanium) and the ebay stuff is shit. What kind of oil?
 

KurskKnyaz

Senior member
Dec 1, 2003
871
1
81
Originally posted by: alkemyst
also I am assuming you are using a drill press...even a cheap 10" or smaller would be adequate for this.
Nope, just a 12V craftsman. I would drill into the aluminum on both sides and than hammer the bearing out. That bearing is the most difficult piece of metal I've ever had to experience.
 

mooseracing

Golden Member
Mar 9, 2006
1,711
0
0
Originally posted by: KurskKnyaz
Originally posted by: mooseracing
Originally posted by: KurskKnyaz
The cobalt seem to work but they snap (I got them on eBay). Are there any stronger/harder materials out there?

Do you know how harder things work, especially metal? The harder and better they are for drilling the more brittle they get. You can break some just by dropping them on cement.

Cobalts are about the best quality you can get for drilling through hard materials, as well as carbide like what is used in lathes and mills. You do also understand you should be going less then 500rpm on your drill as well?

Slow and steady with oil is the best way.
How does titanium hold up? I can't find good quality Cobal bits at Home Depot (all I see is titanium) and the ebay stuff is shit. What kind of oil?
I haven't used any good quality titanium bits, they've all sucked. Use cutting oil. For drill bit also check locksmith webpages to see if they sell any, I found one but it was a British site.

you also have the choice of snap on for quality cobalt drills. But you do pay, 1/16" is 4 bucks up to 1/2" which is 30 bucks. These are for individual drills 135 split points. Or you could get a complete set for 175-320 dollars.

http://buy1.snapon.com/catalog...931&store=snapon-store
 

Squisher

Lifer
Aug 17, 2000
21,207
65
91
If they can be hammered out then I think you should continue hammering them out. Make yourself a jig that'll hold the motor and the punch solidly in the correct position and it'll make your life easier.

The jig could be a couple of pieces of 2" X 6" clamped together with lag bolts in the corners with the motor sandwiched in between and a hole in the center for the punch. With a punch held in exactly the right position I'm sure that bearing would be short work with a 3 lb. sledge.

 

Bignate603

Lifer
Sep 5, 2000
13,897
1
0
Cutting oil is ideal, WD40 is better than nothing. Seriously though, cutting into bearings is hard, using a hand drill is begging for trouble.
 

lurk3r

Senior member
Oct 26, 2007
981
0
0
Originally posted by: KurskKnyaz
Originally posted by: mooseracing
Originally posted by: KurskKnyaz
The cobalt seem to work but they snap (I got them on eBay). Are there any stronger/harder materials out there?

Do you know how harder things work, especially metal? The harder and better they are for drilling the more brittle they get. You can break some just by dropping them on cement.

Cobalts are about the best quality you can get for drilling through hard materials, as well as carbide like what is used in lathes and mills. You do also understand you should be going less then 500rpm on your drill as well?

Slow and steady with oil is the best way.
How does titanium hold up? I can't find good quality Cobal bits at Home Depot (all I see is titanium) and the ebay stuff is shit. What kind of oil?
The 12v drill is whats killing you, either get mini drill press or build a fixture that acts like a bearing press, like other ppl here have suggested.

Low rpm with no torque is only going to break bits regardless of the bit quality.
 

alkemyst

No Lifer
Feb 13, 2001
83,967
16
81
Originally posted by: mooseracing
Originally posted by: KurskKnyaz
Originally posted by: mooseracing
Originally posted by: KurskKnyaz
The cobalt seem to work but they snap (I got them on eBay). Are there any stronger/harder materials out there?

Do you know how harder things work, especially metal? The harder and better they are for drilling the more brittle they get. You can break some just by dropping them on cement.

Cobalts are about the best quality you can get for drilling through hard materials, as well as carbide like what is used in lathes and mills. You do also understand you should be going less then 500rpm on your drill as well?

Slow and steady with oil is the best way.
How does titanium hold up? I can't find good quality Cobal bits at Home Depot (all I see is titanium) and the ebay stuff is shit. What kind of oil?
I haven't used any good quality titanium bits, they've all sucked. Use cutting oil. For drill bit also check locksmith webpages to see if they sell any, I found one but it was a British site.

you also have the choice of snap on for quality cobalt drills. But you do pay, 1/16" is 4 bucks up to 1/2" which is 30 bucks. These are for individual drills 135 split points. Or you could get a complete set for 175-320 dollars.

http://buy1.snapon.com/catalog...931&store=snapon-store
snap-on is hardly a company I'd consider for drill bits.

Any good bits aren't going to be too cheap though.
 

maxrep99

Junior Member
Apr 24, 2021
1
0
6
I need to upgrade drill bits. Some of my cheap ryobi bits are bent and wobbly. I am using a drill press to drill hundreds of precise holes in copper and pvc pipe. I also drill through stainless. Is carbide overkill ? I don't mind getting the hardest, non bending bit so my holes are precise. Or cobalt ? I don't mind spending the money for very precise drilling - so I don't waste materials.
 

deadlyapp

Diamond Member
Apr 25, 2004
5,898
347
126
I need to upgrade drill bits. Some of my cheap ryobi bits are bent and wobbly. I am using a drill press to drill hundreds of precise holes in copper and pvc pipe. I also drill through stainless. Is carbide overkill ? I don't mind getting the hardest, non bending bit so my holes are precise. Or cobalt ? I don't mind spending the money for very precise drilling - so I don't waste materials.
Stainless steel is a very broad statement. Some stainless steels are very soft, and some are quite hard. For copper and PVC I see no reason why you couldn't just use a cheap bit, just set your cutting speed correctly on the drill press.

If your bits are bending, you're trying to drill too quickly. Let it feed itself. I suspect you're using very small bits and no matter what material you use they'll bend (or just snap).
 

herm0016

Diamond Member
Feb 26, 2005
7,644
525
126
sounds more like a speeds and feeds problem mostly.

and the bearings are not "stainless" they are usually 100cr6 and have a hardness of around 64 Rc.

you need to be using a set up that is quite rigid and bits made for hard steel, a modertly slow rpm and quite a lot of quill (down) pressure.

you could try an annular cutter that will drill around the bearing instead of trying to drill though it.

oh hell. necro.

for soft things like plastic i find a brad point makes a better hole. the dewalt ones are fine. for steel you want to get HSS bits that are coated. the Milwaukee ones at the home center that say they are for metal work pretty well, or get a set from Viking or similar, which will be much better. it's really all about getting the proper speeds and feed to produce a nice chip.
 

deadlyapp

Diamond Member
Apr 25, 2004
5,898
347
126
sounds more like a speeds and feeds problem mostly.

and the bearings are not "stainless" they are usually 100cr6 and have a hardness of around 64 Rc.

you need to be using a set up that is quite rigid and bits made for hard steel, a modertly slow rpm and quite a lot of quill (down) pressure.

you could try an annular cutter that will drill around the bearing instead of trying to drill though it.

oh hell. necro.

for soft things like plastic i find a brad point makes a better hole. the dewalt ones are fine. for steel you want to get HSS bits that are coated. the Milwaukee ones at the home center that say they are for metal work pretty well, or get a set from Viking or similar, which will be much better. it's really all about getting the proper speeds and feed to produce a nice chip.
Very good response for a 10+ year old thread though lol
 

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