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SDS. What is it?

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Peter G. Shaw07/11/2020 10:49:52
1311 forum posts
44 photos

Ok, a simple question. Well, I could have put "a silly question"! But anyway, I keep seeing, and reading, about SDS drills. But not having one, I don't know what they are, or what they do. I think I understand that they are some sort of hammer drill, in which case what advantage do they offer over my trusty 40+ year old 400W B&D 2-speed mechanical gearbox plus electronic speed control and hammer function?

I should point out that I have no intention of buying one - my days of drilling stone/concrete/whatever are well and truly over so it's for information only.

Incidently, said B&D on low speed, if it jams, is quite capable of twisting through 90 degrees with a consequent strain on the arm, and this does make me wonder if in fact now that advancing years are taking their toll, if in fact it could just be getting a mite too powerful for this septuagenarian. Do other people have strength problems like this?


Peter G. Shaw

ega07/11/2020 10:57:45
2255 forum posts
186 photos

German abbreviation for something like "push, twist, fixed"

IanT07/11/2020 10:58:51
1895 forum posts
184 photos

Well, I don't have an SDS drill but I do have some SDS drill 'bits'.

SDS Drills are obviously a "hammer" action drill but they also use a particular type of drill shank. It has slots in it, so I'd guess they are a feature of the SDS drill chucks too. I've used SDS bits in my Bosch (heavy duty) drill (in hammer mode) because I needed a longer drill and a certain size. I don't know where I got them from but they worked fine - although I'm sure it's not ideal in theory. I'll guess that the slots are to hold the bit more securely (presumably there's a matching feature in the chuck) given the vibration of the hammering rotation involved. It would stop the drill bit rotating in the chuck as can happen with a plain shank.



Edited By IanT on 07/11/2020 11:02:09

David Jupp07/11/2020 11:34:26
785 forum posts
17 photos

The SDS arrangement for attaching bits to the drill eliminates the heavy conventional chuck - so the hammer action isn't wasted trying to accelerate that additional chunk of metal. That should mean it transfers energy more efficiently into breaking concreate/masonry.

Also quicker to change bits.

Some SDS drills have a 'rotation stop' option - these can be used with chisel bits.

blowlamp07/11/2020 11:35:17
1516 forum posts
98 photos

I don't know for sure, but I think SDS drills hammer at a much lower frequency and each hammer blow is much more powerful.


Dave Halford07/11/2020 11:37:02
1726 forum posts
19 photos


They are like your Black & Decker only on double dose steriods. Whereas your B&D (and mine) wont drill a concrete lintel over a window an SDS will, like butter. I borrowed one for that job, then went straight out and bought my own.

You can get them that do hammer only, like a kango, drill and hammer drill.

So far it's taken down a single brick wall in a bathroom, taken out old fence post concrete as well as drilled holes.

Bo'sun07/11/2020 11:52:55
514 forum posts
2 photos

I think the problem with drilling concrete with a B&D style "hammer" drill is that, as soon as you hit a stone the drilling comes to a halt. Whereas, with SDS, the specific impact action is able to shatter stones.

Clive Foster07/11/2020 12:01:30
2835 forum posts
103 photos

Over simplifying SDS is basically a specification for a fixed diameter shank with a sliding key drive.

The key turns the drill and the hammer unit inside bonks the blunt end of the drill. The drill is free to slide up and down the key for a short distance arranged to be greater than the hammer device stroke so the hammer force is transmitted to the work not the drill innards.

The common issue when using a chuck on a hammer action drill is self loosening under vibration. A particular problem with the keyless types used on battery drills. My otherwise excellent Makita 18V drill suffers badly. Best to check the chuck tightness every second or third hole. I'd be unsurprised to discover that extensive use in hammer mode seriously reduces the lifespan of the chuck.


Frankiethepill07/11/2020 12:07:44
19 forum posts

SDS = Special Drill System

nothing more exotic and not an abbreviation for some German phrase.

A quantum leap forward in masonry drilling efficiency! IMO.

Nicholas Farr07/11/2020 12:22:34
2985 forum posts
1352 photos

Hi, further more, you should not use a chuck in an SDS drill while in hammer mode as it will in time wreck the chuck because of the heavier pounding they produce, I know because I have had to use one once with a chuck on hammer and it was a pain to release the drill bit from the chuck and the chuck was useless afterwards. I do believe there are some SDS drills that will cut out the hammer action automatically when an appropriate SDS chuck is fitted.

Regards Nick.

Edited By Nicholas Farr on 07/11/2020 12:24:46

Speedy Builder507/11/2020 12:25:39
2407 forum posts
191 photos

Also known as Slot Drill System. Especially useful for larger masonry bits and those SDS drills that can be used with masonry chisels. I did see wether you could 'set' a rivet with one, but it was far too powerful and jumped all over the place !


Mike Poole07/11/2020 12:33:46
3071 forum posts
72 photos

The difference between a good hammer drill and an SDS machine is night and day. I bought a Screwfix cheapie to do one job which it made very easy and haven’t used it since, still well worth it though. The impact power of different drills is usually quoted and covers quite a range. My cheap one is obviously near the lower end of impact power but is still a beast compared to a normal hammer drill. They are very useful as a mini breaker with the rotation switched off.


Michael Gilligan07/11/2020 12:47:19
18923 forum posts
941 photos

Curiously enough ... Wikipedia has a brief description, and useful diagram of the devious chuck arrangement:


... which I mentioned in this recent thread: **LINK**


Chris Evans 607/11/2020 13:02:30
1959 forum posts

I bought mine about 18 years ago. Best investment I ever made, I've used it and lent it to people who are simply amazed at what it can do. 100mm hole through 9" of brickwork for a vent was achieved in a few minutes. Used with roto-stop and a chisel it makes short work of removing wall and floor tiles. Only downside of mine being an early design is it is a bit bulky and heavy compared to todays offerings.

Derek Lane07/11/2020 13:05:38
524 forum posts
96 photos

I have two Bosch drills one is a standard chuck type with a chuck key and the other is a SDS drill. The SDS was designed for quick changing of the bits and a more positive drive.

I know that we now have the keyless chucks for fast changing of bits and the added bonus of not loosing the key which many seem to do.

Also as stated the difference is amazing the SDS drill goes through concrete very fast indeed compared to the standard drill.

I would not be without either now as each have their merits

Gary Wooding07/11/2020 13:10:32
872 forum posts
227 photos

Years ago I needed to install secondary double glazing on a large picture window.Since I had a powerful Bosch hammer drill I didn't expect any problems in drilling 30 odd holes in quarry tiles and concrete. Was I wrong! After spending more than 5 minutes on the first hole I decided to see what the local hire-shop could offer. They showed me a Bosch SDS drill, which looked exactly like my hammer drill with a strange chuck. They told me to try it and, if it didn't do the job, they would refund my money.

It did the job. It was like chalk and cheese. It was so easy. I was so impressed I bought one for myself and never regretted it. At one time I had to make a hole into concrete, holding the drill in one hand, at arm's length, with the drill at right angles to my arm, whilst standing on a ladder. Try that with a hammer drill.

Derek Lane07/11/2020 13:19:14
524 forum posts
96 photos

Just a small add on to my last comment.

The internals of a hammer drill and the SDS are also quite different the hammer drill tend to use a a ratchet type gear to preform the action. where as the SDS uses a piston style system. hence the difference in the hammer action and feel

DC31k07/11/2020 13:24:37
571 forum posts
1 photos
Posted by Michael Gilligan on 07/11/2020 12:47:19:

Curiously enough ... Wikipedia has a brief description, and useful diagram of the devious chuck arrangement:


In your travels, have you by chance ever seen a _specification_ for the SDS shank?

Right now, to make things to fit an SDS, I have to buy either a 1/2" UNF male threaded drill chuck adaptor or a 1/2" BSP male threaded core drill adaptor.

It would be good to be able to roll my own.

Fatgadgi07/11/2020 13:26:15
176 forum posts
25 photos

SDS drills have key ways in them so that they can slide in and out whilst being rotated. I think the name was penned by Bosch originally.

The reason why this arrangement is used is that the drill hammer action is different and much more effective than a normal ratchet type of hammer drill using a standard Chuck. The hammer action is almost universally pneumatic, meaning a lump of steel is thrown against the back of the drill (almost) by compressed air using a piston and cylinder. The frequency of strike is low, but the energy is huge.

Ratchet hammer action, by contrast, is accomplished by having the whole spindle, drill bit and chuck move backwards and forwards 40 (ish) times every revolution by a small amount. These are normally good enough, and cheap and simple. But performance and cost is much less than a pneumatic hammer drill.

Phew .... my brain hurts, back to my DIY

cheers Will

Martin Kyte07/11/2020 13:38:42
2558 forum posts
45 photos

The other very usefull action is hammer but not rotate. This way they can be used as an auto chisel. With a wide bolster style blade they are very usefull for removing plaster and chasing walls. Can also be used for cutting sheet metal such as oil drums.

regards Martin

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