Masonry bits. vs. Hammer drill bits
I had assumed they were the same. Maybe not?
Hammer drill bits seem very expensive. The cheapest was $4.50 and I think that one was small. A lot are 40 dollars or more. That's more than the drill was.
They are the same thing.
Twist drill bits CUT a hole in the material being drilled, like aluminum, steel or wood. Masonry bits or hammer drill bits BATTER a hole in the material being drilled. That's why a "dull" masonry bit works nearly as well as a brand new one. A dull twist drill bit no longer cuts well, but a dull masonry bit bashes masonry into dust just as well when it's dull as it does when it's new.
Cost is not always indicitive of quality. The tungsten carbide at the front of the bit comes in different hardnesses and you pay more for harder tungsten carbide. You'll find that retail stores tend to charge more because each and everything they sell is vaccuum sealed onto a card, and you're paying mostly for the packaging. Phone around to see who sells these bits "in bulk", where you buy the bits loose with no individual packaging and you should get a much better price on each one.
There are similarities but the rotary hammer drill bits have a different base, generally the standard SDS pattern in the smaller drills, rather than just a plain 'drill' shaft found on your typical masonry bit. An SDS bit could be used as a simple rotary bit although I can't imagine why anyone would while a regular masonry bit won't fit any sort of hammer drill I've ever seen. I've never seen an SDS bit that was as flimsy as your typical hardware-store masonry bit and I've never had a SDS dull or fail in any way which inhibited their operation while I've had regular masonry bits grab and fail catastrophically.
You can't use an ordinary masonary bit in a rotary hammer. Well, you can, but the chuck you put the masonary bit in will be shaken apart. Those Jacobs chucks are press fit together, and normally that's enough to keep them in one piece for decades. But, if you mount it in a rotary hammer, you'll shake it apart.
Years ago I bought a Hilti TE-10 rotary hammer. It had both "rotation only" and rotary hammer modes on it. For use with the Rotation Only mode, it came with a keyless Jacobs chuck mounted on an SDS shank so that I could use twist drill bits up to 1/2 inch diameter in it. However, the owners manual for the tool warned never to use ordinary masonry bits in this Jacobs chuck for drilling masonry because the pounding action would shake the press fit Jacobs chuck apart, thereby wrecking a $75 or $80 accessory. The SDS system (patented by Bosch) allows for the forward and backward movement of the drill bit while it's turning, and is designed to stand up to that shaking.
The SDS bits have a shaft that's pressed, hard to explain. I doubt they would fit a regular chuck. Anyone know?
CY: Masonary bits are designed for hammer drills, eh? Why would a hammer drill fall apart cause you're using the bit designed?
CY: Now we see a bit more detail.
CY: Ah, so you can't use a detachable Jacobs chuck for masonry.....
because the
CY: Mine was Metabo, and I was very pleased with it.
Yes, you _could_ chuck up an SDS bit in a regular drill. The shaft size is
10mm so virtually any drill would accommodate one although you'd want a keyed chuck since a keyless might not tighten enough to hold. Why anyone would want to do this is beyond me though.
No, SDS drill bits have special machining at the base of the shank. But, because the SDS chuck is a standard size, for drill bits smaller than 10 mm, the shank is larger in diameter than the drill bit itself.
Other than that, they're ordinary masonry drill bits and I expect you could probably fit one into a 3/8 or 1/2 inch Jacobs chuck if you weren't too concerned about how well they fit. Certainly, you could slip some 10 mm plastic tubing over the SDS end, and then put that into a Jacobs chuck.
Like this:
'The SDS Carbide Tipped Drill Bit ~ Concrete Fastening Systems'
The machined slots is where the torque is applied to the bit. The shallow ovals is where a ball bearing rides on each side of the bit. When you turn the collar on the SDS chuck, those ball bearings tighten up in their slots and hold the bit steady as well as prevent the bit from falling out of the SDS chuck if you hold the drill in a downward orientation. The SDS bit can still move back and forth in the chuck even when the chuck is rotated to lock the bit in place.
I'm thinking that you'd have better luck putting the SDS bit in a 1/2 inch chuck so that it would go in deeper and the chuck jaws would grab around the round portion of the drill bit shank in front of the machined end.
Masonry bits are intended for rotary drilling only and use cheap carbide and other cheap materials. Hammer drill bits look similar, but use higher grade materials to withstand the percussive forces of a hammer drill or rotary hammer. If you put a cheap $5 masonry bit in a hammer drill or rotary hammer it will be destroyed before it even finishes the first hole.
Pete: Any drill bit with a tungsten carbide point on it is meant to bash a hole in the masonary in front of it. There's no such thing as a masonry bit meant to cut a hole the same way a twist drill bit does. Putting a masonry bit in a drill that only rotates is just going to grind a hole in the masonry, and that will only work for very soft materials like brick mortar.
A friend of a friend borrowed my hammer drill. They didn't ask for bits and I wouldn't have had any anyhow. It came back with a little white dust in the chuck and the message that it didn't work for what they were doing. Maybe because they didn't have the right bits.
This means if I need the hammer part, I'll probably have to plan a bit further in advance.
The drill came from Harbor Frieght. Has a Jacobs chuck which I don't think is designed for SMS bits, and since the chuck is barely longer than any other chuck DOESN'T THAT MEAN THAT AN sms BIT WON'T WORK IN IT?
In fact it's not even labeled a hammer drill. It's called an Impact Drill. (Maybe I shouldn't have bought it, even for $15) **
The drill cost only about 15 dollars, varialbe speed, reversible, and switchable to a regular rotary drill, but isn't one of the ones they sell now. It's all blue with black trim, no metal part to the case (not counting the chuck) . The brand is "Drill Master. "
And I used it Friday to remove two screws from a lawn mower that would come out with torx or flat. I wanted the drill to go SLOWLY, BUT IT WOULDN'T, no matter how careful I was. It would go at different speeds, but none were slow. My Sears variable speed reversible that's 40 years old will go slowly but I think its max speed is lower than one.
Reversible run CCW with a left-handed drill bit will sometimes unscrew a screw while it is drilling off the head, but that didnt' happen to either of these. But it did do enough that I got the cover of the lawn mower off.
**This is the closest to what I have that they are selling nowI would never have spent $80, or even what they charge if it goes on sale, so at least I have a spare drill for not much money. With this extra information, maybe I can find out why my drill didn't work right. Used cheap masonry bits that broke?
BTW, reading wikipedia on SDS, it seems SDS allows only the bit to be propelled at the target, not the whole chuck. Hence the smooth shank and the way it's clamped in. And this is supposed to work faster. Wouldn't it work better with the weight of the whole chuck behind the bit?. Like the difference between one guy trying to break in a door and a guy with a steel battering ram?
Hmmmm. One of the advantages of my 15 dollar drill is its 1/2 inch chuck** And it's pretty deep. I've never seen an SDS bit, maybe I could get it into this chuck after all.
**I've replaced the chuck on one or two other drills with 1/2" instead of 3/8" but this came that way.
Sure they are. You go buy a pack of plastic masonry anchors that include a 1/4" masonry bit, chuck it up in a hammer drill or rotary hammer and see how long it lasts. Then buy a proper quality hammer drill bit in the same size and try that. The quick ID is if it's got an all over silver dip it's a cheap masonry bit suitable for rotary drills only, while bits that have other finishes are likely hammer drill bits, even though superficially they look to have the same style carbide tip.
Pete: You seem to be saying that the cheap masonry bits that come with a package of plastic anchors are meant to be used in a drill that only turns, but doesn't provide a hammering action. Sorry, this simply isn't the case. No matter how cheap the drill bit is, if it has a tungsten carbide tip, it's meant to BATTER a hole, not cut a hole like a twist drill bit does.
And, even the cheap masonry bits that come with a package of plastic anchors will last longer if used in a hammer drill. Using them in a drill that rotates without any hammering action simply erodes the tungsten carbide tip so that it dulls quickly.
Mickey: There are two kinds of hammer drill: There are "percussion type hammer drills" that generate a hammering action by having two plates, each formed so that there are bumps on it, press against each other while the bit is turning. This "percussion type" hammer drill will give you up to 50,000 BPM (blows per minute) but each blow will have a tiny stroke of maybe only 1/100th of an inch. Also, as those plates wear down, the hammering action gets worse, and on an old drill it doesn't do much except shake the drill.
There are also "rotary hammers" that generate a hammering action by having a piston in cylinder arrangement whereby the piston or cylinder moves forward causing air pressure to push the cylinder or piston which is attached to the drill bit forward. Rotary hammers have a much smaller number of blows (300 to 600 per minute), but each blow has a stroke of about 1/8 inch. Since it's that battering action that pulverizes the masonry in front of the drill bit, rotary hammers work much better than percussion type hammer drills because of their superior hammering action. Rotary hammers come in all shapes and sizes, and the smaller ones generally use SDS chucks to accomodate SDS drill bits. The bigger rotary hammers use drill bits with a splined shank.
But, the bottom line is that there are only two efficient ways for a drill bit to make a hole in something, and that's by cutting a hole or battering a hole. If the drill bit you have has a tungsten carbide tooth at the front, it's meant to batter a hole, and that means you need a hammer drill of some sort. Putting that kind of a bit in a normal "rotate only" drill is just going to dull the bit as you grind your way through the masonry.
I take it you've never actually tried this. Do you even own a drill?
There is absolutely no need to start insulting me, Pete.
If you believe that there are tungsten carbide tipped drill bits that CUT into masonry just like a twist drill bit cuts into wood, then can you explain why a masonry drill bit doesn't have a sharp edge on it like a twist drill bit does?
That is, how would this drill bit:
be optimally designed to _CUT_ into masonry when there are not sharp edges to it? Don't you agree that the only edge that can be argued to be "sharp" might be the one facing directly forward, in which case it's not designed to CUT masonary as it rotates.
On the other hand, it's easy to explain why the shape of that tip is designed to bash the masonry in front of it into dust.
If you look at the front of that bit you can clearly see that the two faces of the carbide tip are ground with relief angles giving the cutting edge. It's not a fine edge like you will find on a twist drill, but it is indeed a cutting edge. Look at some carbide milling / turning inserts and you will also find profiles that are less visibly sharp than you might expect. Carbide is hard but brittle and thin "sharp" edges will fail quickly.
I have and have used multiple hammer drills and rotary hammers from Makita, Hilti and others, and percussion rated masonry bits are indeed a different species from regular hardware store rotary masonry bits. I've also used carbide core bits which also are not intended for percussion use (neither are the diamond ones).
Pete:
I'm sorry to say that the angles at the front of a masonry bit are oriented in entirely the wrong direction to "CUT" into the masonry.
There's no magic here. If a masonry drill bit were intended to "cut" into masonry much the same way a twist drill bit cuts into wood, the masonry drill bit would be designed and shaped very much like a twist drill bit, except perhaps having much harder cutting edges which wouldn't wear down. But, the tip of the bit is not similar to a twist drill bit at all. It's entirely the wrong shape to CUT. It is, however, the right shape to BASH something.
In my view, rotating that forward facing tip against the masonry would only serve to make it duller than it already is.
However, I can easily visualize how having a forward facing tip on the drill bit and hammering that tip against the masonry in front of the bit would pulverize the masonry in front of the tip into dust. And, I also note that the flutes on a masonry bit are designed much the same as those on a twist drill bit, so I expect the purpose of the flutes is undoubtedly to remove the dust created at the front of the bit. It seems to me that the masonry bit is ideally designed to batter a hole in masonry, not cut a hole as you claim.
Perhaps we should just agree to disagree on this one?
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