Long masonry drill bit for Combi Drill?

[Homervanderjazz]

Hi folks,

Need to drill through internal and external wall. Only have a combi drill and wanted to know if you can buy a long drill bit for the job? Have had a look online but such drill bits seem to only be for SDS drills. Any advice would be greatly appreciated.

 

[cdbe]

Don't know, but if you get really stuck, if you put it in the chuck carefully you can just about use an SDS bit in a normal chuck. I've got a metre long SDS bit that works ok. But I'm sure I have a few 300mm long standard bits as well.

 

[JohnD]

I think you will find it doesn't work well.

With a small bit, the drill stays still and hammers it.

With a large and heavy bit, in the wall, it's the drill that gets hammered.

 

[Harry Bloomfield]

Need to drill through internal and external wall. Only have a combi drill and wanted to know if you can buy a long drill bit for the job? Have had a look online but such drill bits seem to only be for SDS drills.

That's because it needs an SDS, rather than a simple hammer drill. Even if you could fit the SDS bit into a hammer drill, it would not be very effective against anything hard like brick.

 

[JohnD]

Do you have many to do? You can get a cheap Titan SDS+ from Screwfix for about £60 including a starter set of tools.

It comes with an alternative chuck for heavy non-sds work like fenceposts, and chisels to break up concrete.

I don't say it's high quality, but with a good guarantee you'll get your money's worth out of it. If it's still working after two years when the guarantee runs out, you're quids in.

It is heavy.

 

[Homervanderjazz]

Thanks for the replies folks, don’t have many holes to drill so that’s why was looking to use the combi. However, will check out the Titan drill as suggested. Thanks

 

[JohnD]

I used to use drill extensions sometimes. It screws onto the end of a drill that is threaded for the purpose (good long drills in large sizes are expensive and need a big toolbox)

They are still around but don't seem to be common.

 

[Deleted member 174758]

Well, you can use SDS bits in a chucked combi drill, but it can be a faff getting them centred in the chuck and firmly held. I do do this sometimes when I can't be bothered to bring an SDS to the job (e.g. when I'm working at home and can't be bothered trapsing to my lock-up!) and it works passably well for softer masonry such as blockwork, soft brick, etc. The difference as stated above is that even the best mechanical impact drills such as combi drills are very restricted in impact strength when compared to even basic SDS drills. Unlike an SDS drill there is also the tendency for the bit to slip in the chuck (something the splines on an SDS stop completely) which further reduces the power of the impact blow. To my mind that means that if you are attempting to drive a large diameter drill (say over 10mm) there isn't enough of a hammer blow to actually penetrate harder materials with a smaller combi drill. Maybe why there used to be large, low-speed, high-torque hammer drills around with 3/4in and even 1in chucks. I would have thought that there is also a tendency for longer drills to flex (bend) and that this might also reduce the power of the impact with the drill bit absorbing some of the kinetic energy intended for the wall (ever noticed how short percussive drill bits are when compared to same diameter SDS bits, and how much more clearance they have for waste materials?). Another thing to bear in mind is that when drilling longer holes it is advisable to start with a shorter drill bit then switch to a longer one as this avoids putting a permanent bend into the long bits

 

[Homervanderjazz]

So I have been looking on the screwfix site for SDS drills. I am going to go for a corded one as I am only going to use the drill around the house.

I note the power of the drills varies drastically; there are ones at 1500W to ones at 600W which are a lot smaller and lighter.

My question is will the lower W ones do the job I need it to? My current need is to drill into brickwork but if in the future I need to drill down into the concrete driveway for example will the lower W SDS be able to do this task? Thanks

 

[Deleted member 174758]

I've been using 2 and 3kg class SDS drills since the early 1980s. For holes up to about 24 or 26mm (so 99% of the holes that I ever drill as a joiner) plus light chiselling (e.g. small concrete chipping tasks, removing tiles, etc) they are generally in the 600 to 850 watt power area which is perfectly adequate and more to the point this is the class of drill that the vast majority of tradesmen carry with them on installation jobs. Actualy my very first SDS in 1981 was a 550 watt Bosch model (drill only, no rotation stop, no reversing) which still ran rings round any previous impact/combi drill I'd ever owned or used because it could drill Accrington (engineering) brick. The big (cheap) 1500 watt machines generally weigh in at 6kg or above and are a complete PIA to work with for any length of time because of the weight (try drilling a concrete ceiling with one, or even just a series of holes at just above head height and you'll see what I mean). I occasionally use breakers which are that sort of weight and if I'm working above chest height, as you need to when pocketing for joist ends and the like, I really know about it very quickly. Not at all pleasant to use.

When buying an SDS drill I'd say the things to look for are impact strength (measured in Joules) - which should be 2 to 3J in a 2kg tool - and weight. The efficiency of the SDS mechanism is far more important than the power input IMHO. In any case on the rare occasions that you need a heavy breaker it may well be easier to just hire one

 

[SpecialK]

You dont say what size hole you need - What about a core cutter? I use the small ones with my dewalt battery drill...

 

[Tigercubrider]

You can buy long non sds bits for not much
I have used sds bits in a non sds ryobi 18v combi no problem
Obviously - up to about 12/13mm

 

[Homervanderjazz]

You dont say what size hole you need - What about a core cutter? I use the small ones with my dewalt battery drill...

Don’t think I would need a core cutter tbh, current holes are for wiring a camera doorbell, need to run wire from inside to outside the house so holes themselves don’t need to be big in terms of diameter.

 

[JohnD]

A combi drill will easily do an 8mm hole.

But not 18mm, especially if a long heavy drill.

I don't know where the cutoff is, but those are two common sizes I do.

 

[Tigercubrider]

Two things- drill the hole slightly downwards from inside- (make a drip loop)

It is easier to drill a small hole and make it bigger than one big hole straight off