Review Cobalt bits from Amazon

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Dominick Maone

Joined
Oct 14, 2018
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181
https://www.amazon.com/dp/B083Z8LV3Z?psc=1&ref=ppx_pop_dt_b_asin_title

These things are amazing. I bought a pack of the 1/4” from this link and 3/16 from another seller. With the delays in shipping I received the 1/4” already. Needed then for weight reduction holes. As you can see in the photos, they work amazing. I probably have close to 250 holes in all this annealed AEB-L (each knife has three or four holes of a different size). Knives are between .1 and .185. I USED ONE BIT!! I cancelled the 3/16 from the other seller and bought them from this link. This is a great deal. First time posting a pic so hope it works.
 
great post. I bought a set of drill hogs which have been awesome but paid a lot more. I may pick up some common sizes of these. That being said, I finally taught myself how to sharpen, and its really easy on a belt grinder.
 
I need to get the bit sharpening down.

I have some 15n20 that is giving me fits.

I have burned a few bits, and it is not even hardened yet! I think I need to torch soften it next time.

I don't have an oven, or forge yet, just a propane torch.
 
I think speed and feed is very important too. Right before I received these I read on here probably that constant pressure and slow speed was needed. I think this helped a lot. I have a WEN from HD and leave it at about 500 RPM, which is the slowest setting. It works very well at that speed and constant medium-ish pressure. I used 3-n-1 oil as lubricant and applied liberally. I have tried sharpening bits before, but failed. And the bits I was using from HF are so crappy I know it would have been a wast of time with them.
 
Bigfattyt said:
I need to get the bit sharpening down.

I have some 15n20 that is giving me fits.

I have burned a few bits, and it is not even hardened yet! I think I need to torch soften it next time.

I don't have an oven, or forge yet, just a propane torch.
Click to expand...
I have no issues as long as I use cobalt. Those cheap titanium coated bits are crap and tend to work harden the steel till you get a squeally pig. Cobalt was a game-changer for me
 
scott kozub said:
I have no issues as long as I use cobalt. Those cheap titanium coated bits are crap and tend to work harden the steel till you get a squeally pig. Cobalt was a game-changer for me
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No , it s not cobalt :) What happens is ......you buy quality drill bits . Ordinary HSS drill bits will work .......quality one , of course ;)
 
What do you folks use for a 3 steel Damascus, where the 15n20, 1095 and W1 don't care to all play nicely and completely anneal at the same time?
Ive had to resort to hot drilling with masonry bits lately, but the almost invariably oversize the hole enough to make the pins fit looser than they need to.
 
scott kozub said:
I have no issues as long as I use cobalt. Those cheap titanium coated bits are crap and tend to work harden the steel till you get a squeally pig. Cobalt was a game-changer for me
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the cheap ones can be 1095/1085/O1, with a ti coating. They are fine for wood, but if they get over 500f, they lose their temper.
 
Bigfattyt said:
I need to get the bit sharpening down.

I have some 15n20 that is giving me fits.

I have burned a few bits, and it is not even hardened yet! I think I need to torch soften it next time.

I don't have an oven, or forge yet, just a propane torch.
Click to expand...

A lot of 15n20 is pre hardened to Rc42-45. Stick it in the oven at 1200f for 2h.
 
Larrin said:
Cobalt bits are high speed steel bits.
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Of course they are high speed steel , cobalt one are HSS-E, HSS-Co /M35 steel/, but there are high speed steel dill bits without cobalt....HSS . Most are M2 steel here , like this one for example .......
IQruLO6.jpg
 
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Willie71 said:
A lot of 15n20 is pre hardened to Rc42-45. Stick it in the oven at 1200f for 2h.
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Isn't it easier to get quality drill bits ? 42-45 Hrc are absolutely no problem to drill with good one drill bit .There are two possibilities, he does not use quality drill bits/or not sharp one or he not use right pressure when drilling so steel harden.....
 
nice, I use those same drill bits and thought they were great for the price. I haven't got past the first one but I'm usually drilling annealed 01.
 
Natlek said:
Isn't it easier to get quality drill bits ? 42-45 Hrc are absolutely no problem to drill with good one drill bit .There are two possibilities, he does not use quality drill bits/or not sharp one or he not use right pressure when drilling so steel harden.....
Click to expand...


Natlek said:
Isn't it easier to get quality drill bits ? 42-45 Hrc are absolutely no problem to drill with good one drill bit .There are two possibilities, he does not use quality drill bits/or not sharp one or he not use right pressure when drilling so steel harden.....
Click to expand...
It’s much easier on the bandsaw too. I do 20 or 30 lbs at at time, then it’s good for whenever I need it.
 
Ken H> said:
Is that from same drill bit without sharpening? If so, that's GREAT drill bits and I'll be ordering
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Same drill bit, without sharpening. I can barely sharpen a knife. When I get that down I will learn to sharpen a drill bit. I put about ten more holes total in two of the knives off to the side of that picture. I might count the holes if I get a chance before I send them off to heat treat. Would be nice to get an idea of how many I can expect from each bit.
 
An update to this thread. Based on the previous posts I ordered a 10 pack of the 1/8" bills from amazon.
The description is "1/8- Inch Cobalt Twist Drill Set, 10 PCS HSS Straight Shank Jobber Twist Drill Bits for Stainless Steel, M42 (3.2mm)" and I paid about $7
I just used one bit to drill 57 holes in 3/4" thick A2, and I wasn't being kind since it is just to profile a handle. It was still cutting very well at the end.
FXViajD.jpg

 
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