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View Full Version : Nice 115pc Cobalt Drill bit set....



3 Phase Lightbulb
01-06-2005, 03:23 PM
I got this 115pc Cobalt bit set the other day for $79 and they are great. I think I paid around the same price for my last 29pc Cobalt bit set:

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=47653

-3Ph

Herb Helbig
01-06-2005, 04:20 PM
3 P L - Have you rolled them on a surface plate to see if they are straight?

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3 Phase Lightbulb
01-06-2005, 04:57 PM
Yup, they are straight. I haven't checked every single one, but the ones I've used so far are good.

-3Ph

BillH
01-06-2005, 07:58 PM
I have the tin coated version, some drills are not straight, others are just fine. I think most are fine. They do not look to be ground the same way as a US made drill bit I bought which cuts great.

brunneng
01-06-2005, 08:31 PM
I have the same set in the tin coat. A cheap starter set of bits.

The two problems I had were inconsistant hardening/alloy and on the number sizes, they could be off by several thou to the point that one labled #43 could mic to a #45.

They come in handy for a beater set. But, yeah, you might have better luck with the cobalt. I've been buying them on an as needed basis in US brands and man can they cut.

mrchurchill
01-07-2005, 07:05 AM
Got a very similar set in TiN from Costco for $40 or thereabouts.

Surprisingly, they cut quite well. Just used them to complete a machining project in the shop (toolpost) and had no issues with them at all.

ajr

Derek13
01-08-2005, 12:29 PM
In general how are cobalt drills run differently than regular HSS ones? IE. on avergage do you run it a certain % faster? use less coolant? or are they more or less just handier for going through harder materials?

3 Phase Lightbulb
01-08-2005, 12:51 PM
I use colbalt just like HSS but they just last so much longer.

-3Ph

Evan
01-08-2005, 01:08 PM
I have a very similar set that I bought recently. I got it mainly to have a full set of number and letters drills. They work OK. I always check my drills with the calipers before using just to make sure I have the right one since I usually don't feel like changing my glasses to try and read the itty bitty markings. I have a lot of metric drills around also so it is easy to pick up one that looks right but isn't.

I seriously doubt that those drills are really cobalt alloy drills. They are probably cobalt coated. True cobalt alloy drills are much superior to ordinary HSS and will drill heat treated 4130 steel with ease.

Forrest Addy
01-08-2005, 01:18 PM
Dispelling a few myths.

Of course new drill work great. They are fresh and sharp from the factory and there is the "placebo effect" assosiated with every new purchase. Some use and a few hasty free-hand sharpenings and the new drills will perform no better than your beater set.

Cobalt HSS is intended for cutting tough alloys like stainless and alloy steel where heat and abrasion are factors in the cutting environment. Cobalt HSS offers no particular advantage in drilling wood, mild steel and non-ferrous metals.

If the drill is indeed cobalt HSS it's strongly made for severe duty meaning thick webs and smaller flute spaces. Consequently chip clearance will be more of a problem.

My experience is that cobalt HSS is a trifle less durable than M1 HSS ("plain" HSS I guess you'd refer to it) when drilling 7000 series aluminum alloys.

Marketers are quick to pick up on popular conceptions and exploit them ruthlessly: a colorful coating is cheap to apply and it suggests to a prospective purchaser an allegedly superior alloy.

Thus we see "cobalt" HSS drill sets at HF and other low-rent suppliers. Whether they actually conform to a cobalt bearing HSS alloy (M42 or equivalent) we have no way of determining by appearance alone. It's only when we get them to the shop and attempt to sharpen one can we tell by the sparks (sparse orange streamers) and abrasion resistance (high) can we be assured we got the genuine article.

Unless you're drilling stainless, very hard bronzes, or heat treated alloy steels, or titanium alloys, so-called "cobalt" drills are overkill. Presently they are a both a scam to the average home shop purchaser and an extra cost expended more often than not for no particular gain.

Consult your work load and make a purchase decision on the basis of actual need and materials. The performance superiority of cobalt HSS (M42) drills over M1 HSS in their reccommended application is significant. If conventional HSS drills perform poorly in your particular line of work then moving up to a cobalt bearing HSS drill is a good idea.

It's the metallurgy that makes the difference in drill performance and while budget Asian import tooling is improving with time their metallurgy still sucks. Therefore I strongly suggest you purchase your M42 drills from a quality supplier, not from knock-off sources and then only the sizes you need. Expect to pay $200+ for a real 115 Pc cobalt drill set.

[This message has been edited by Forrest Addy (edited 01-08-2005).]

3 Phase Lightbulb
01-08-2005, 01:28 PM
<font face="Verdana, Arial" size="2">Originally posted by Evan:
I have a very similar set that I bought recently. I got it mainly to have a full set of number and letters drills. They work OK. I always check my drills with the calipers before using just to make sure I have the right one since I usually don't feel like changing my glasses to try and read the itty bitty markings. I have a lot of metric drills around also so it is easy to pick up one that looks right but isn't.

I seriously doubt that those drills are really cobalt alloy drills. They are probably cobalt coated. True cobalt alloy drills are much superior to ordinary HSS and will drill heat treated 4130 steel with ease.</font>

Even if they are only cobalt coated, $79 is still a deal..

Is there any easy way of testing if it's just a cobalt coating?

-3Ph

3 Phase Lightbulb
01-08-2005, 01:48 PM
<font face="Verdana, Arial" size="2">Originally posted by Forrest Addy:
Dispelling a few myths.

Of course new drill work great. They are fresh and sharp from the factory and there is the "placebo effect" assosiated with every new purchase. Some use and a few hasty free-hand sharpenings and the new drills will perform no better than your beater set.

Cobalt HSS is intended for cutting tough alloys like stainless and alloy steel where heat and abrasion are factors in the cutting environment. Cobalt HSS offers no particular advantage in drilling wood, mild steel and non-ferrous metals.

If the drill is indeed cobalt HSS it's strongly made for severe duty meaning thick webs and smaller flute spaces. Consequently chip clearance will be more of a problem.

My experience is that cobalt HSS is a trifle less durable than M1 HSS ("plain" HSS I guess you'd refer to it) when drilling 7000 series aluminum alloys.

Marketers are quick to pick up on popular conceptions and exploit them ruthlessly: a colorful coating is cheap to apply and it suggests to a prospective purchaser an allegedly superior alloy.

Thus we see "cobalt" HSS drill sets at HF and other low-rent suppliers. Whether they actually conform to a cobalt bearing HSS alloy (M42 or equivalent) we have no way of determining by appearance alone. It's only when we get them to the shop and attempt to sharpen one can we tell by the sparks (sparse orange streamers) and abrasion resistance (high) can we be assured we got the genuine article.

Unless you're drilling stainless, very hard bronzes, or heat treated alloy steels, or titanium alloys, so-called "cobalt" drills are overkill. Presently they are a both a scam to the average home shop purchaser and an extra cost expended more often than not for no particular gain.

Consult your work load and make a purchase decision on the basis of actual need and materials. The performance superiority of cobalt HSS (M42) drills over M1 HSS in their reccommended application is significant. If conventional HSS drills perform poorly in your particular line of work then moving up to a cobalt bearing HSS drill is a good idea.

It's the metallurgy that makes the difference in drill performance and while budget Asian import tooling is improving with time their metallurgy still sucks. Therefore I strongly suggest you purchase your M42 drills from a quality supplier, not from knock-off sources and then only the sizes you need. Expect to pay $200+ for a real 115 Pc cobalt drill set.

[This message has been edited by Forrest Addy (edited 01-08-2005).]</font>


I tend to always exceed the proper speed/feeds when drilling and tend to burn up my HSS bits pre-maturely. I notice a night and day difference between cobalt and HSS bits.

-3Ph

Evan
01-09-2005, 03:25 AM
Forrest,

I thought that is what I said, with less words. I'm glad we agree. Yeah, thick web etc. Great for drilling hardened steel. I drilled many a hole in C130 wing spars. You can't sharpen them back on the really good ones more than once or twice because the web is thinned at the tip. If you sharpen them then you end up in the thick web and it doesn't work worth a damn.

I guarantee the cheap cobalt drill sets like we have bought are not the real thing. A real quality cobalt drill cost at least a couple of bucks each. Do the math.

3 Phase Lightbulb
01-09-2005, 10:27 AM
Is there any way I can test to see if they are just cobalt coated?

I have some 3/8" square blank HSS bits. Should I try drilling a hole through one using one of the smaller "Cobalt" bits?

-3Ph

Forrest Addy
01-09-2005, 11:08 AM
No. HSS bits might be harder thant your drills. Touch an uncritical part of the drills fluted portion to a grinding wheel in dim light. The sparks shoud be short red streamers without bursts. The usual M-2 drills will show short fine yellow streamers with small bursts.