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Forum topic by Eric posted 09-05-2011 01:55 AM 1112 views 0 times favorited 10 replies Add to Favorites Watch
View Eric's profile


216 posts in 1930 days

09-05-2011 01:55 AM

Rank the following drill bits:

Black Oxide
Gold Oxide
High Speed Steel

Naturally, I would think high speed steel would be at the bottom, but where do the others fit?

-- Eric

10 replies so far

View horologist's profile


102 posts in 3158 days

#1 posted 09-05-2011 03:16 AM


You forgot carbide. :o)

Do you have a specific application that you are worried about?

Really, all have advantages and disadvantages. The coated bits are so treated to extend their life, an enhancement that shows results in a production environment but probably won’t show much benefit for the hobbyist. For a woodworker good high speed steel should be fine. I have a set of Chicago Latrobe cobalt bits that I use for my clock work. The cobalt is more forgiving than carbide, yet still can get through most of the odd steels that I run into.

The most important factor is quality. I once bought a couple sets of titanium nitride coated 60 – 80 wire gauge bits on sale from MSC. The first time I tried to use one it destroyed my part (brass) wasting several hours of careful machine work. I haven’t bought a drill bit made in China since. Cheap bits are no bargain!

-- Troy in Melrose, Florida

View Minorhero's profile


372 posts in 2023 days

#2 posted 09-06-2011 03:59 AM

If you are talking about use for woodworking then you will rarely need to use something harder then high speed steel. A bigger concern is brad point or the more traditional twist drill bits. I like brad point bits for wood working because it is much easier to put the bit exactly where you want it, eliminating walking.

The only time you may want to consider harder drill bits is if you have a very very small bit. Even then so long as you don’t bend bit you should be good.

Now if you are not just doing woodworking things change a bit. Cobalt and Carbide bits are better for woodworking. Though carbide can be sensitive to vibration making solid carbide bits not suitable for most handheld drilling applications. I have on a couple occasions had to drill through various types of steel. Whenever I am going through something thicker then sheet metal I reach for cobalt or stronger bits. A good local hardware store (not a big box) could tell you more about specific applications.

View Grandpa's profile


3256 posts in 2094 days

#3 posted 09-06-2011 04:32 AM

I know of a situation where some robotic devices were being installed in a factory. There were holes to be drilled in stainless steel. Some of the devices were installed but many more were left to install. That weekend the workers went home (about 5 hours away) and a call was placed to their local machinist and he was told of the problem. What do we get to drill these parts on location using a hand drill motor with chuck. He said go buy some high speed steel drills with 135 degree split point tips. Forget the 119 degree tips. The 135 split points were bought and all went well. Since hearing this I use them for most metal jobs.

View fussy's profile


980 posts in 2469 days

#4 posted 09-06-2011 08:29 AM

I have Dormer 135* split points i use for metal working, car repair, etc. I can drill 65 rockwell c scale quite easily, but for wood, I use brad points. One set from HF ($8.00 for 29 piece set black ocide) that have worked well (clean entrance and hole and mostly clean exit with a backer), some forstners—both hs steel and Tin coated. Both work well.

-- Steve in KY. 44 years so far with my lovely bride. Think I'll keep her.

View MrRon's profile


3891 posts in 2662 days

#5 posted 09-06-2011 08:47 PM

For woodworking, 118° and 135° drill bits are ok for small holes, like for wood screws, but they need to be run at very high speed for them to cut properly. Brad point and forstener bits should be used for all your woodworking hole making. The other drill bits are best used in metalworking Different steels, coatings and cutting angles apply to metalworking only.

View TopamaxSurvivor's profile


17573 posts in 3094 days

#6 posted 09-06-2011 11:17 PM

Maybe Jim C will pop in here. He set me straight on drills and metallurgy ;-) I don’t but anything that isn’t HSS. Black oxide is just a coating on teh surface, no good past the first revolution of the drill ;-(( Most of the cheap junk will be black oxide.

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View DrillMan's profile


2 posts in 2111 days

#7 posted 09-06-2011 11:42 PM

There are a variety of grades of High Speed Steel, most common are M2, 9341 and 4341, with M2 being the higher grade. All of the brands you find in the Wholesale supply houses, Warehouse Stores and Independent Hardware Stores have lowered their steel grade over the past two years to the bottom of the barrel; 4341 because of the increased cost of steel. and their inability to raise prices to the stores. Any of these grades can be treated with a Black Oxide, Gold Oxide or Titanium coatings. Be carefull, alot of the stuff is roll forge edge ground with bad tips. Quality bits are 100% maching ground from M2 High Speed Steel with 135 degree split point tips and tri-cut shanks. Most of the help in the stores don’t know what they are really selling since the manufactures are continuing to lower the steel grades. Get what you pay for!

For the most part, they do not increase the performance. Cobalt drills are manufactured with M-35 or M-42 steel.

-- Drill Man

View TopamaxSurvivor's profile


17573 posts in 3094 days

#8 posted 09-07-2011 12:32 AM

DrillMan What do you know about Titanium coating?

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View crank49's profile


3979 posts in 2389 days

#9 posted 09-07-2011 12:48 AM

I have to say my experience with HSS containing cobalt is very good, especially when drilling stainless. Irrelevent for drilling wood however.

I do know that cobalt alloys main claim to fame is hardness at high temperatures. The foundry where i used to work make some cobalt alloys for heat treat furnace trays. Some of it was over 50% cobalt. A single set of furnace trays made from this material was almost a half a million dollars. Based on this tidbit of knowledge I expect the advantage of cobalt in a drill bit is it won’t loose hardness when run at high speed in tough material that generates a lot of heat.

-- Michael: Hillary has a long list of accomplishments, though most DAs would refer to them as felonies.

View TopamaxSurvivor's profile


17573 posts in 3094 days

#10 posted 09-07-2011 12:52 AM

crank49 That is a good point. I never thought about the heat annealing the point and edge causing it to dull immediately. Good reason to remember to use cutting oil ;-))

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

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