Is it normal for a hammer drill bit to wobble?

Question

Last year I bought a Makita HR2470 for home use from German Amazon, because it had many positive reviews. Since then many negative ones appeared saying that the drill bit wobbles. There is also a user video on their site. It is an SDS-plus drill and I have an adaptor to use normal round bits too. With this I have put a ball pen in it, and touched to a paper when the drill was on, without the hammer function. It made a split pea sized circle on the paper. I also have a Bosch GBM 1600 RE normal drill. This leaves only a point on the paper, as expected.

Recently I have made with the hammer drill + adaptor (hammer function off) holes in tile, and did not know why the tile was chopped around the hole.

I have two questions. Is this a property of hammer drills, they are less precise or mine is defective? I actually sent it back, and now I am looking for a different model. Do you know any hammer drill without this problem? I understand if a more precise tool is more expensive than this.

Answer 1

I have 3 or 4 hammer drills some combo units and 1 is just a large hammer / demo drill model. None of mine have the wobble you are describing brands I have are hilti, dewalt and milwaukee. For tile I would not use a hammer function but a standard drill and a diamond coated or carbide / grit coated bit. I would think the hammer action will crack the tile, I am sure it would on most natural stone tiles as they tend to crack with a wet diamond saw.

Answer 2

I have a Dewalt hammer drill where the hammering action can be turned on and off. With the hammering action off, it's like any other drill. With the hammer on, it does vibrate a lot more, but I can't say it intentionally wobbles.

Personally I have never used the hammer drill on tiles, only concrete.

My hand hurts just thinking about that thing.

Answer 3

My experience with drilling holes in porcelain tile is with a standard drill which makes a clean edged hole in tile, but is slow work.

Disclaimer: I have never used a hammer drill, but I think a hammer drill might be designed to wobble. This would clear dust from the hole allowing faster progress in stone or concrete and prevent jamming of the bit in the hole. A wobble makes a larger hole than the size of the drill which prevents jamming of the bit in the hole.

EDIT

You don't drill into tile with a hammer drill. See Drilling tile

To catch the drilling dust I tape a cereal box to the tile just below where I am drilling. This allows me to use both hands on the drill. After I get a hole started I switch to one hand on the drill and squirt water from a spray bottle on the drill and hole to keep the bit cool. I have found that standard ceramic bathroom tile is easy to drill through with this system, but porcelain tile is still a challenge.

Answer 4

Definitely not supposed to wobble in drill mode. I'm going through this same issue w milwaukee sds with warranty. Had a 21" but that got caught up in a tight space and ever since that it wobbles in drill only.mode luckily its fairly new and under warranty.

Answer 5

SDS drills wobble a bit due to how they are constructed.
The drill is actually secured by two ball bearings and can freely move in and out. The whole purpose of the SDS connection is to keep the bit from falling out and mostly centered, while the actual "hammer" part rams it into concrete (pneumatic or oil operated).
The drill bit hammers into a wall like a chisel.
It doesn't have to be sharp, just sturdy enough not to bend. The only reason it has grooves and rotates at all, is to efficiently remove the powdered debris from the hole. Precision is not a big deal here - the concrete does not chip accurately, and the smallest sds drill I saw was 5mm thick, so being off by a millimeter or two does not matter.

Now compare it to regular drill, where the bit is rigidly screwed into a chuck. It cannot move to the sides and should never move to the sides (if it does, replace the drill).
The drill does not "hammer", it shaves.
HSS drill bits cut the surface. This tool is designed for precision drilling into metal, wood etc. You can get drills starting at 1mm thick. The 'regular' drills often have the 'impact' function, because manufacturers want to brag "it can drill in concrete too", but they always fail to drill a hole in any kind of concrete. The "impact" functionality is just a gear VS the pneumatic operation of actual impact rotary hammer. And you don't want to accidentally impact-drill with metal or wood.

From the points above - when you drill into metal, wood, plastic, etc. use a plain drill with a chuck, preferably get one without the "impact" function. It doesn't have to be powerful - 200-300W is absolutely fine. Even a battery operated will do. I prefer cheap light drill for working with wood, so I can easily hold it with one hand.
Forget about the "impact" mode and conrete - this is not the tool for the job.

Want to drill into concrete? Break out the big boy. A proper sds rotary hammer with pneumatic or oil impact mechanism, 3J or more impact power, and you can get through everything used in domestic building. 500W minimum, 700W recommended. Just make sure yours has a clutch, or it can break your arms when it gets stuck in rebar. Battery operated? Please excuse me for a minute while I laugh my butt off.
(Tangent advice: Hold it with right hand on forward grip and left hand on the trigger. This way, when it gets stuck, it will jump out from your left hand and you let the trigger go. If you use right hand on trigger, it will ram into your hand when stuck, and your finger may keep pressing the trigger which leads it to keep spinning, potentially breaking your hand. Trust me, it hurts when it jams)
You may notice I did not mention the chuck adapter above, because that idea is an abomination invented for people who think they can do all the job with one tool. The adapters exist, but they will be wobbly by nature. Just use the proper tool.