HF 115 piece Drill Bit Sets question.

[leehljp]

HF has three different 115 piece bit Sets.

The Cobalt set is the more expensive, but is it worth it? Does the Cobalt hold their edges longer? Are they harder to sharpen?

Are 135° split point bits better than 118° regular bits?

Below are the different ones they have on sale online. I bought the 118° set last fall and am looking for a set to take back to Japan with me in a couple of months. I can't complain about what I have, but I wonder about the other two sets - the benefits, if any.

Comments?

http://www.harborfreight.com/cpi/cta...%20TOOL%20BITS

1611-2VGA 115 PIECE TITANIUM NITRIDE COATED M2 HIGH SPEED STEEL DRILL BIT SET 118° tips
Reg. $59.99 / Sale $39.99

47653-1VGA 115 PC. COBALT DRILL BIT SET
$99.99 / Sale $79.99

32928-3VGA
115 PC. 135 DEGREE SPLIT POINT TITANIUM NITRIDE COATED HIGH SPEED STEEL DRILL BIT SET
$49.99 / Sale $39.99


All have
Sizes:
29 fractional sizes 1/16'' to 1/2'' by 64ths
26 letter sizes A to Z
60 numbered wire gauge sizes 1 to 60

[LCHIEN]

hank, here's a quick sumary of what I know about drill bits:
In the order of expense:

There's plain ordinary HSS.
Then there's (probably HSS) coated with TiN, titanium nitride.
Then, there's coated with Cobalt (-oxide?)
and taking a huge jump,
Then there's those with Carbide inserts.

The coatings cost some but are not hugely expensive being a chemical surface traeatment. The purpose of the coatings is to reduce friction and thereby reduce operating temperature and prolong the life of the bits.
I think the coating on the side reduces the friction and not the coating on the drilling point but of course maybe that's where it gets the hottest.
Still the lower temperature will reduce loss of temper of the bit and it will be sharp, when you sharpen it and take off the coating on the tip.

The 118° is the standard angle across the point of the bit. which means


The 135° bits are less prone to skating/walking and may cut somewhat better, but the 118° has been the standard for years. the cheaper drill doctor models don't sharpen the 135° bits, but the better models do.
Or, you can use the 135's and when they dull, reshape them to 118's in your old sharpener (but that would be a lot of wear and tear on your Drill Dr. diamond wheel).

Anyway that's it in a nutshell.

If I already owned a 118° set and was going to buy another, I'd get the 135° just to see what the fuss is about. That's assuming that sharpeneing these with an existing Drill Dr. is not a concern. And I'm making assumptions about what you are going to be cutting.

[leehljp]

Thanks Loring for replying. I was hoping you would give your input.

I have the 750 Drill Doctor and I think it will do the 135° bits.

If you read this again, Are cobalt bits worth the extra money?

[LCHIEN]

Thanks Loring for replying. I was hoping you would give your input.

I have the 750 Drill Doctor and I think it will do the 135° bits.

If you read this again, Are cobalt bits worth the extra money?

Re: Cobolt worth extra money - I was wrong, it's not a coating. Its a cobalt alloy steel, very hard. In general usage with uncontrolled, non-similar experiments (different jobs) its hard for guys like me to make an informed comparison. read the Irwin Q&A below. Sounds like for first use the TiN coated bit is better but for repeated sharpeneings, the Cobalt bit will be better.

http://episteme.arstechnica.com/grou...05922731/inc/1

and this from Irwin:
Q: Are Irwin cobalt drill bits coated like the titanium ones? If the cobalt bits are rockwell hardness 66 - 67 HRc, what hardness are the titanium bits? Once you sharpen a cobalt bit and the gold coating is gone, is it just a regular bit? A: Cobalt bits are not coated, they are cobalt steel through and through. At the end of manufacture a cobalt bit is baked in an oven to turn the surface color of the steel a dull gold color. This is done primarily for easy identification by color. If the gold wears off or is ground off in sharpening on a cobalt bit, it is still solid cobalt steel. Our cobalt drill bits are made of M42 cobalt steel which has 8 percent cobalt content. The Rockwell is approximately 65.5 to 67 Rockwell C. Irwin titanium drill bits have a hardness of approximately 64.5 to 65.5 Rockwell C. The titanium coating is much harder at approximately 82 Rockwell C. If you sharpen a cobalt bit it is still as good as a new bit, assuming it was sharpened correctly. If you sharpen a titanium bit its performance will drop because the coating is gone on the tip; however, you still have the benefit of the titanium coating in the flute of the bit and on the sides of the bit. It will still perform better than a standard bit.

[Pappy]

Cobalt should hold an edge better. The only drawback I've heard is their hardness tends to make them break a little easier .

[sacherjj]

I haven't been real happy with the drill bits I've purchased from HF, but I'm also looking for a full set. The sale and 20% off coupon is inviting. Has anyone purchased these sets and had good results?

[AlanJ]

I read somewhere recently about a guy who worked at a storage place and regularly needed to drill out padlocks. (hopefully legitimately ). He ALWAYS used cobalt bits - anything else would not survive a single lock (he got 2-3 locks out of a cobalt bit IIRC). He also swore by Ridgid brand, claiming there was a difference by brand. YGWYPF.

[newbie2wood]

I'm not as technically knowledgeable on drill bits as some of the other members but I can tell you that the HF titanium bits are POS. I have a set. Well, maybe not totally worthless, they are okay for drillling into soft wood. I try drilling into the side of my dust collector (relatively thin sheet metal) and the bits failed. These bits are advertised on the HF websites for metal workers (??).

I got a Husky cobalt bit for BORG and it drill through the sheet metal like butter. I also use the bit to drill a hole in my stainless stell sink with no problem. I don't know about the HF cobalt set but cobalt bits are the way to go.
________
Lovely_Girl

[leehljp]

Thanks again Loring and Pappy for your comments on the Cobalt bits. All of this is probably moot because I don't think my local HF store has the Cobalt set. I will have to order them to get them. My local store only has the 118° bits.

Newbie2wood - The Ti 115 piece set has been great for me. I only use them on wood and I do not hurry the drilling. Since I started pen turning, I have needed very minute' size differences in bits. These sets give me just what is needed. They cut smooth too. A part of smooth cutting has to do with 4 things:
1. setting the speed of the drill to the drill bit size
2. feed rate for the material being drilled
3. and 1 & 2 change if you are doing metal versus wood.
4. Sharpness - I think this is where it gets "iffy" with most HF bits. Their QC lets some get through. I think most people are aware of this and are willing to take the chance for the price. If it is a bad set, they can be returned.

I have a Drill Doctor and can put a sharp cutting edge on them; so this is basically a non-issue for me now.

I have a set here (USA) but I also need a set in Japan. In my opinon, the HF Ti set is a better set at a cheaper price than comparable, more expensive lower and mid range bits at HD; And certainly better than anything you can get at at Wally world.

ON SMOOTH BORING in wood: I cannot find it, but Loring did a comparison of the speed used to make holes, over a year ago, and it was remarkable the difference that speed changes made.

[LCHIEN]

...
ON SMOOTH BORING in wood: I cannot find it, but Loring did a comparison of the speed used to make holes, over a year ago, and it was remarkable the difference that speed changes made.

I could not locate it either, but here's the pic.



These are like 1/4 or 3/8" bit drilled through 3/4 whitewood pine.
Numbers are RPMs. Cut the piece in half after drilling on a D.P.
Looks like the slow speed tears the wood and the higher speeds cut the wood.
Conclusion is to look up and set the correct speed each time I change bits and or wood.

[sacherjj]

Interesting picture. I assume that is the same speed feed rate also? I wouldn't have thought it would be that much of a difference.

[Stick]

The 135° drills work better in hard materials. In other words, for metalworking. 118° works better in wood, plastics, and other soft materials. I've never owned any 118°s, all of mine are 135°. Then again, i do work much more often in metal than in wood.

[Jim Boyd]

I do not have any cobalt drill bits but I do have some cobalt milling cutters. Compared with the TiN coated cutters the cobalt is MUCH better.

[Holbren]

Cobalt should hold an edge better. The only drawback I've heard is their hardness tends to make them break a little easier .

I just bought a smaller cobalt set from HD to get a screw out on my car. Cobalt is made for driller through metal. To Pappy's point, they are more brittle. I broke 4 of them because I has trying to drill through hardened steel and put either too much pressure on the bit.

I looked at selling forstner bits and I keep saying that if you are going to buy Taiwan or China steel product, make sure it is HSS. The low end carbon steel stuff is not worth buying.

Having a drill doctor, I would not hesitate buying on the better end of the imported market.