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How do you identify good steel from bad in tools like drill bits

by Whiskers
posted 12-14-2012 06:47 AM


18 replies so far

View Rob's profile

Rob

285 posts in 1722 days


#1 posted 12-14-2012 07:06 AM

You could try scratching materials of varying known hardnesses to find out the hardness of each drill bit. Where it lies on the hardness spectrum determines how well it holds its edge, how brittle it is, and more, which is why different types of drill bit materials are better suited for drilling different types of materials.

Another fairly simple approach that doesn’t take much time would be to get a Drill Doctor and just sharpen them. I was a bit hesitant to get one myself, but decided if each grinding wheel for the Drill Doctor costs $20 and supposedly sharpens about 200 bits before needing to be replaced, it’ll pay for itself over time—plus, it’s more convenient than having to run to the hardware store to buy a new bit (or a new set of bits) whenever I wear one out. They do now have a newer model that also sharpens spade bits, but it costs about $100, compared to $50 for the entry-level twist bit sharpener.

View gfadvm's profile

gfadvm

10850 posts in 1341 days


#2 posted 12-15-2012 03:17 AM

Rob- I have sharpened WAY more than 200 bits with my Drill Dr and it was used when I bought it off CL. It has paid for itself many times. I’d just sharpen what you’ve got as it doesn’t take great quality steel to drill most woods.

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

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Whiskers

389 posts in 678 days


#3 posted 12-15-2012 03:28 AM

pulled out one of the antique 7/16 inch spade bits tonight cause I needed to drill 4 holes thru 2 2×8’s I had married together with some kreg screws for another project, and dispite the fact the bit was kind of funky looking, pitted, has whiteish corrosion on it, and some traces of rust, wonder what that white stuff is, anyway it still cut thru those 2×8s with ease. Definately a argument for cleaning and sharpening these old antique bits. I bought me a wire brush for my bench grinder couple months ago, think i’ll install it gonna go to town on them with it. Next time I go to the library I’m also going to look up about how to sharpen spade bits. Seems like it should be easy from looking at them. Drill doctor is worthy consideration, but I also have a dremel tool that might be able to do the job. Anyone ever use those for that?

View crank49's profile

crank49

3421 posts in 1622 days


#4 posted 12-15-2012 03:39 AM

For what it’s worth, some folks on LJ make their own brad point bits from regular HSS bits.
It’s a great idea because a brad point bit ground from high speed steel will last about forever.

I think the Drill Doctor is a great idea. I wish I had one.
One other justification for one of these is that you usually only use a few bits from a set. If you go and buy replacements for the few that are dull you pay way more per bit than you would for a set.

I can sometimes get a bit sharp on the grinder, but it’s trial and error.

As far as knowing the quality of the steel, some of the better bits will be stamped with HSS to let you know they are high speed steel, the basic standard choice. If a bit has been used very long after it became dull and overheated (visable by discoloration) it will not be much good for anything. Most likely will not hold an edge if sharpened.

I like to buy Cobolt Steel bits in sets from places like HF or TSC. They hold up extremely well and are the very best for drilling stainless steel.

One way to test the hardness of the steel in a drill bit is to try to file the end of it with a cheap file. Good steel is harder than a cheap file and will round off the teeth on the file.

-- Michael :-{| “If you tell a big enough lie and tell it frequently enough, it will be believed.” ― A H

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Whiskers

389 posts in 678 days


#5 posted 12-15-2012 03:56 AM

lol crank, but I’m not sure I want to kill my files. Than again, my files are antique too, so that probably won’t work with what I have on hand, they probably wouldn’t qualify with what you define as a cheap file. Guess I’d have to go to HF to buy a cheap file. TSC? Tractor Supply? The cobalt drills bits are extremely expensive, and I’m mostly interested in working with wood right now. Interesting enough, I have no brad point bits, my father never bought any even though he worked only with wood. I can only assume they weren’t invented in his lifetime or he would have had them rather than standard twist drill bits. He died when I was 17. I been websurfing various places getting a feel for the price of them, think I want a set but will probably watch and wait awhile and see if I can’t pick up a sale item from someone like rockler, woodcraft, amazon etc. I didn’t know harbor freight carried cobalt steel bits, seems kind of high end for them. I do know that the bits I have are useless for drilling steel of any kind. I’ve tried in the past and it a no go. Now it may be they too dull. It didn’t seem to damage them, it just wasn’t possible. They do fine thru wood though. I would like to be able to drill thru steel. Not necessary for any super stainless titanium type alloys, but for instance into my utility trailer to add features. Pefect example is my new tractor supply trailer has the license plate mount in a really stupid place that as soon as I hit a good bump, the license plate and it’s sturdy plastic mount will probably go Bye Bye. That definately could use a revision.

View gfadvm's profile

gfadvm

10850 posts in 1341 days


#6 posted 12-15-2012 04:02 AM

Whiskers- Couple of thoughts on drilling steel: cutting oil is definately worth the effort and slow speed is your friend. High speed hand drills do a poor job in steel and usually wind up ruining the temper in the bit from overheating.

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

View bandit571's profile

bandit571

6950 posts in 1334 days


#7 posted 12-15-2012 04:07 AM

I’m not sure, but doesn’t drill bits for drilling steel use a different angle at the tip?

-- A Planer? I'M the planer, this is what I use

View Whiskers's profile

Whiskers

389 posts in 678 days


#8 posted 12-15-2012 04:11 AM

lol, yeah glad, I know that now, didn’t know it when last I tried to drill steel which was a long time ago. Web is a wonderful place, you can learn anything from it. But still the bits I have didn’t even dent it. They are visibly dull. That why I’m asking about this. I got all these old antique twist drill bits, and I want to find out whether I should refurbish them to make them good, or just splurge and buy new. A drill doctor is about $100, that a alternative, a new set of good bits is also about $100. Considering all bits dull, well the math is simple if I have good bits.

View crank49's profile

crank49

3421 posts in 1622 days


#9 posted 12-15-2012 04:12 AM

True, the cobolt steel bits are spendy when bought from a machine tool supplier, but TSC (yes, Tractor Supply) often have small sets, 1/16 up to 3/8, for $10. A nice full 1/16 to 1/2” x 64ths set in an indexed metal box from HF will set you back $40 to $60, but thats way less than machine tool supplier prices. The quality is probably not up to machine tool standards either, but they are really good by HF standards.

I just got a TSC trailer this last summer. Ditto on the Liscense bracket.

-- Michael :-{| “If you tell a big enough lie and tell it frequently enough, it will be believed.” ― A H

View Grandpa's profile

Grandpa

3127 posts in 1326 days


#10 posted 12-15-2012 04:15 AM

gfadvm is giving good advice on spped and drills. If a drill is running the correct speed and it is sharp, it will cut and you should see longer pieces of metal coming from the drilled hole. If you see dust or very small fragments then you are usually running at a high speed or you need to sharpen the drill. With that said you have to run smaller diameter drills at a little faster speed than the larger diameter. The larger drill goes further (outside diameter) than the smaller drill in a revolution. I have found that good drills are sometimes a shot in the dark, especially on the least expensive end. I bought a Harbor freight set about 25 years ago and I still use them. They were pretty good. I have bought other lower end drills that were nopt so good. They a known brand on them too. Usually more expensive means they should be better but…..it can be a shot in the dark there too.

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Whiskers

389 posts in 678 days


#11 posted 12-15-2012 04:23 AM

lol, well my bits when put against steel just kind of make a little polished dot at the moment where I point them, no shavings, no dust, nothing. I used to watch my dad alot as I grew up, He sharpened lots of stuff and I watched him. He was quite crafty, made violins. LOL, couldn’t play one. I swear he was tone deaf. Sounded like a cat caught in machinery, but he made good violins cause when others played them they sounded beautiful. So I saw and learned about sharpening some things. But for the life of me, I never seen him sharpen a drill bit, and from what I know he didn’t have equipment for it. He never had a bench grinder for example which is one way to do it. But here I have all these old well used twist bits.

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Whiskers

389 posts in 678 days


#12 posted 12-15-2012 04:50 AM

Okay, I think I have made a decision, good bits are expensive. Very expensive. Crappy bits are cheap. I’m going to continue watching and waiting for a good set of brad point bits to go on sale cause I have none, and that what I need since twist bits tear out bad as they go thru wood. As for the twist bits and spade bits, I’m going to research sharpening methods and put the camel on the drill doctor. I’m also going to wire brush those spade bits to clean them up. Meanwhile the spade bits seem functional, but they are messy when they tear thru. I’m going to also put the camel on the new desiign bosch spade bits, they seem really good. They only about $30 normally, but might as well let that camel work for me and see if I can’t get them for $20. Historically it shows it very possible. The Bosch spade bits have a edge like a brad point to cut the outside of the hole first so there is little tear like with normal spade bits. The reviews are really good on these. If the camel comes thru I’ll have new tech bits for a good price, if not, I’ll eventually have sharpened up old good steel spade bits. I really also need to survey the bits to see if I’m missing any important sizes. I have quire a few, so might be surprised.

View Rob's profile

Rob

285 posts in 1722 days


#13 posted 12-15-2012 05:02 AM

gfadvm, I think the manual mentioned it could sharpen 200 bits, but if it handles even more, that’s great!

Whiskers, you could probably use a grinder or Dremel; the Drill Doctor just makes the job easier and helps ensure you get the proper angle on the tip.

View runswithscissors's profile

runswithscissors

937 posts in 676 days


#14 posted 12-15-2012 08:31 AM

I agree, cobalt bits are best for steel. But it doesn’t matter what the metal is, a dull bit won’t cut. Even aluminum needs sharp bits. I often drill stainless, and always use cobalt. In an emergency, there’s another way if you don’t have cobalt, but won’t go into that now. And Drill Doctor is good. Haven’t tried other systems, though I do sometimes sharpen by hand/eye, but it’s hard to get consistent results. As for spade bits, many now have spurs to scribe the circle (way better than the old type), and some kind of fancy grind to provide relief. But how to sharpen them? Before that type ever came on the market, I started sharpening regular spade bits with a rat tail file or chain saw file. I try to use a file with a diameter that spans from the outer perimeter to the root of the point. I then file a hollow (half circle, more or less) in between the edge and the point. By tilting the file a little, I create the necessary relief. It’s possible to sharpen this way and get very nice sharp spurs, and the bits cut far faster and cleaner than a regular spade. Almost as nice a hole as a good brad point. Thing is, I can take a new spade bit and file it this way in about 10 minutes. When they get dull it takes about 2 minutes or less per side to sharpen. I’m convinced they perform better than the patented ones. (I’m not thinking about the Bosch, as I haven’t tried them). Oh, to control break out at the end, either use a backing board that you drill into a little ways, or drill just until the point starts to show. Then flip over and drill from the other side, using the little hole as your target.

View Whiskers's profile

Whiskers

389 posts in 678 days


#15 posted 12-19-2012 12:37 AM

thanks Artie, I’ll check those out next time I go to the library, I’m on dialup at home so youtube is kind of a no go. But I get to the library every week or two anyway. I probably would have found these eventually on my own when I started seeking the info out, but thanks for saving me the time. I pulled out one of them decrepit bits the other day, it was a 1/4 inch and it is all rusty, and corroded looking and at first glance you’d think no way, it going to cut, it should be thrown in the trash, but it went thru the 3.5 inch of a 2×4 4 times with no problem. I imagine if I sharpened it than I would have been even more pleasantly impressed. That’s twice I’ve used these nasty looking things and they performed beyond my expectations. They must be made of something decent to be holding a edge as bad as they look.

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Whiskers

389 posts in 678 days


#16 posted 12-19-2012 12:48 AM

As a footnote, last night since Sears was having a we will ship anything free day I ordered a few things from them, including some boeshield rush remover and protector/lubrican for my tools. I’m hopeing this does a better job than the evaporust I tried on some other tools. That Evaporust seems to get rid of rust, but also turns them a dark color.

View hhhopks's profile

hhhopks

564 posts in 1028 days


#17 posted 12-19-2012 01:05 AM

I have never sharpen twist drill bits myself but I have sharpen auger and spade bits by hand.

I also have observe a die-maker using a grinder wheel and just eye balled it to sharpen twist drill bit. Evidently, it worked great. He proceed to put it on his air drill to complete drilling a hole on cast steel (working on a die). I was impress especially from this particular die-maker who wasn’t known to be the best of the lot. So it can’t be that hard.

-- I'll be a woodworker when I grow up. HHHOPKS

View Whiskers's profile

Whiskers

389 posts in 678 days


#18 posted 12-19-2012 01:25 AM

Yes, I have seen jigs for use with bench grinders, both commercial and homemade on the net. And have read in other forums where people say they do it freehand. I figure alot depends on what you work with and how sharp you really need it. As for twist bits, I’m not overly concerned with those, cause it turns out the only half-way complete set I have I have identified as a set that still is in production, though it may be made better than what you can buy now. It’s a set of Craftsman High Speed Steel with black oxide finish coating in a red plastic box. They still sell what looks like that identical set. This week it is even on sale super cheap. A couple of the small bits are missing, I’ve either broken them or they got loose in among they mystery twist bits. One of the things I bought from Sears was a set of Carbide bits. I did a lot of research and unfortunately couldn’t find a good affordable quality set of Carbide bits to buy. Even the Bosch and Dewalt come from China, so I figured the Craftsman on sale were probably on par, and they had good reviews. I don’t need to drill steel often, but when I do it’s a frigging bear with them HSS black oxide bits. Especially as dull as they are. I probably bought those myself just to have a full set for around the house stuff. I doubt I inherited that set. For wood, I’m going to get a set of brad point bits. Very likely from Harbor Freight as again it looks like I’m stuck with Chinese manufacture, and the HF set is super cheap, and has really good reviews. I’ll check it out and see. Main reason I’m getting those is so I will have a separate set for wood and won’t be messing up my carbide bits for when I need them. The HF set $12.99 for a 29 piece set in a nice steel case. If nothing else, it a good set to learn how to sharpen those kind of bits, lol, won’t cry too hard when I mess them up and have to replace them.

I’m a big believer in buying sets of tools so you have all possible sizes when you need them. Others argue just buy top end quality when you need it. Well, I don’t want to have to freaking run to the store every time I go for my drill, and I figure If I find I wear a particular size out badly, than I’ll replace it with top end. That way, on those rare occasions I still get jobs done, but end up with the high end tools I really need over time. I’m sure the 1/4” will probably be the first size I need to buy a really good bit for, but I may never use the 7/32”

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