How to use a hammer drill?

[tod]

Could someone tell me why I'm struggling so much to drill holes into the brickwork in my garage with a hammer drill? It takes forever to drill a hole to the depth I want and just now had to stop as the bit became red hot and left a loose piece of itself in the hole.  I'm using a corded XU-1 hammer drill (not rotary) and a size 8 masonry (Sutton Tools) bit.  Maybe I'm forcing it too much?

[MikeTNZ]

Hi there @tod ,

Welcome along to Bunnings Workshop!

You shouldn't put a lot of pressure on a masonry bit, the tip is the part of the bit that does the actual "drilling".

What can often happen with drilling into brick-work and the like, is that there is the likelihood that you'll strike a reinforcing rod or two, this will blunten the tip of the drill bit and no amount of pressure will do any good.

If you look at the tip of your masonry bit, the tip should be wider than the shank of the drill bit, if it isn't, the tip is damaged.

You have got the drill in actual hammer mode haven't you, this will make a HUGE difference, if it isn't.

One other thing, you are running the drill at it's highest speed, when drilling?, this makes things a lot easier on the drill bit.

I hope this has been of some use to you.

Cheers, Mike T.

[Vis-á-vis]

Hello Tod,

Some bricks are harder than others. I have very hard bricks at my place and they can be tough to drill into. I have Milwaukee hammer drills and it once took me about 15 minutes to drill a 10x40mm hole. 

With hammer drilling power is everything. RPMs are largely irrelevant as are BPMs (number of impacts per minute). What you need is plenty of joule in a rotary hammer drill. A regular hammer drill will take forever to drill through hard brick. Buy or borrow a rotary hammer or keep going and be patient with the one you have.

[MikeTNZ]

Hi @Vis-á-vis,

When you say that the speed of the drill and number of impacts per minute is irrelevant, that is quite un-true.

The actual power of the drill is irrelevant, unless it is way under-powered for what you are trying to do, in this day and age it is very unlikely that you would have a drill that is under-powered for say masonry drilling.

The speed of the drill is important for the drill bit to clear the waste out of the hole, so as not to overheat the tip of the drill.

Also, the drill motor (the drill unit itself) needs to have a high speed to ensure that the motor inside the drill stays cool with air being drawn into the casing, if you ran that at say half speed, the motor windings would eventually overheat through lack of cooling, especially during masonry drilling, given that the impact section of the motor drive puts extra load on the motor.

With a cheap drill, this will eventually kill the motor and quite possibly the planetary drive as well.

Cheers,

Mike T.

[Vis-á-vis]

Hi Mike,

When I say the speed is irrelevant, what I mean is that almost any drill you buy will have enough 'speed', so focussing on RPM is irrelevant. Whether you have 1000 rpm or 4000 rpm, both would be fast enough for masonry drilling. Therefore when buying a drill the speed is irrelevant.

As far as impacts per minute. Also largely irrelevant. 500 or 5000 BPM will do the job.

I own a Milwaukee hammer drill (useless for masonry drilling), a Milwaukee cordless Rotary hammer which is quite good at masonry drilling but not as good as the two (much cheaper corded) Bosch rotary hammer drills, a GBH 2-26 and GBH 8-45, and can't touch a Hilti TE 70 which I also have. All serve different purposes. The Hilti is great for the odd big hole but at more than 10KG is too heavy for frequent use.

The Hilti draws fewer watts (power), has fewer beats per minute, and yet will plow through a 300mm concrete slab far quicker than the GBH-45 because it delivers more than three times the power on each strike...something like 15 joules compared to 4 joules on the Bosch.

So when I say that RPMs and BPMs are largely irrelevant and power is what counts then I stand by that.

Remember, when a manufacturer gives a 2000RPM rating then that is under 'no load'. Just making something spin quickly doesn't make it powerful. Stick a drill bit into a very hard brick and your RPM can drop to just a tiny percentage of the quoted no-load RPM.

So when I am buying a drill, first thing I'll look at is the force per strike (quoted in joule), that gives me an honest interpretation of the drill's ability to move through very hard material quickly. RPM and BPM are largely irrelevant because I know they will be enough to do the job if the motor is able to deliver that much energy.

[EricL]

Hi @tod

Thanks for sharing your question about using a hammer drill. It's great that you've received fantastic recommendations from @MikeTNZ and @Vis-á-vis. There's always every possibility that you've hit a supporting steel bar in the wall. This will blunt your drill bit and will make it seem like you are drilling forever. 

Because the first bit is already broken, I suggest getting a new one. What are you trying to mount on your wall? Gym equipment? A hook for your bike? If you can give us a bit more information about your project, we'll be able to give you better advice.

Overheating is not good for your drill bit or your drill. A good masonry bit should cut through brick quite easily. Clearing out the hole made by the drill bit quite often will help in the process. If you feel the bit and drill are getting warm stop for a moment and let it cool down. 

Forcing the drill to stay in one position is not recommended. I suggest pushing it in and pulling it out to help with clearing out the hole. 

Please keep us updated with your progress, we look forward to seeing your mounting holes properly drilled.

Eric

[tod]

Thank you all for your in-depth and helpful replies.  After I posted my question I copped the fact that I was using the drill on its highest speed, which seemed to have been causing my problems - eg the bit overheating and becoming red hot.  So, I've reduced the speed right down and, like EricL advised, moving it in and out of the hole as I go.  My project is going much better now as a result, even if the bricks do seem to be pretty tough ones.  I haven't hit a a supporting steel bar, but it's good to learn that that can be a possibility - thanks. @EricL I'm mounting some high up shelves on the walls (my garage has an incredibly high ceiling) with heavy duty brackets to store stuff like Christmas decorations etc. to get them off the floor and out of the way.  It's a decluttering effort so I can get a start on building a system of cabinets for the garage with one long continuous bench top.  Thanks again. 

[EricL]

Hi @tod

That's fantastic to hear, I'm sure @MikeTNZ and @Vis-á-vis will be pleased to hear their suggestions worked. There's nothing like the joy of organizing your garage to create more space! I suggest having a look at this project - Garage storage makeover by @lcooksey88. It's a fantastic makeover and doesn't overwhelm the garage. The best part is that there is room to grow.

Please keep us updated with your progress, we look forward to seeing the start of your garage project.

If you need further assistance, please let us know.

Eric

[tod]

Fantastic, thanks Eric. Will keep you posted.