Do masonry drill bits get blunt?

[Bill Woods]

Do drill bits for use in ordinary "home use" drills get blunt with the result that they work less well?

I ask this because I recently used my hammer drill to make some 6mm holes in masonry in the concrete ceiling above me and it seemed like very slow work. When I used a smaller drill bit of about 4 to 5 mm in the same masonry material then it was much, much easier to make the hole. I used a vaccum cleaner to suck up particles and to prevent the bit clogging with concrete dust.

Of course the smaller bit makes a hole with a smaller area but the difference seemed far greater than this. I wonder if my 6mm drill bit (and maybe others) need replacing?

This is the type of drill bit I used:

[--s-p-o-n-i-x--]

Yes

[mrcheerful]

buy a real drill and bits, a good quality sds drill at about 100 pounds and some sds bits to go with it, I have found practically no difference in quality between cheap and expensive sds bits (ymmv) but the actual electric drill quality varies a bit, the cheapy heavy sds from the sheds works great but only if you are strong, a good quality bosch or aeg drill is much nicer though.

mrcheerful

[David Hearn]

This sort of reply is probably what I find most annoying about this otherwise excellent uk.d-i-y group. Someone comes and asks whether a masonry drill can get blunt, and the reply he gets is "That looks a poor quality bit - buy a £100 drill and new bits, although cheap bits make little difference."

So, now, rather than looking at £10+ for new bits, he's looking at £100+ for a new drill AND new bits.

Whilst I agree that a good drill is, well, good, many people cannot justify spending that sort of money on tools. In my case, I cannot afford to get people in to do the work, and therefore I cannot also afford to spent large sums of money on quality tools and have to live with a £25 SDS drills from Argos which weighs a ton, but only comes out maybe 3 times a year, and a £30 compound mitre saw from B&Q which did my dado and stair spindles wonderfully.

Anyway - to get back to the point (no pun intended) - I do find that masonry bits do get blunt - and I just buy a new one every so often (< £1 at Screwfix for small bits I think)

D

[Andy Dingley]

It's good advice. if you have a house to maintain, money on an SDS drill isn't going to be wasted.

By the nature of SDS drills, they're also much less susceptible to the effects of blunted drillbits.

[Andy Dingley]

Decent quality tungsten carbide masonry drills for "home use" should maintain an edge for longer than it takes for you to lose them. Maybe if you're in a granite or blue brick house and doing a lot of work you'll wear them out, but for "average" use this just shouldn't be an issue.

Be aware that not all drills with a brazed-in insert use carbide. The market stall crap is now just that - crap. If your drill bits are wearing out, get better drills.

You have little chance of sharpening them, although it's easy to do (much easier than a bit for metal). The right abrasive to do it will cost you more than several year's supply of drills. Although you can easily sharpen the non-carbide inserts, it's not worth it.

And get an SDS drill. You won't look back afterwards.

[manatbandq]

you'll

This is going back a bit, but does anyone know if Plasplugs brand masonry bits (assuming they still exist) still include the offer on the packet to send them back for re-sharpening at =A31 a time?

MBQ

[mrcheerful]

saying yes you can sharpen them won't actually help in the long run, I believe. using Mickey mouse drill bits is likely to lead to frustration and possible injury. some cheapy tools are great, others are a waste of space.

my wicks percussion drill seemed a big expenditure in the early 80's (55 pounds from memory), but it is still working perfectly and I have never worn out a drill bit!, how many black and Decker hammer drills and bits would I have thrown away in that time? Also bear in mind that I work for other people to some extent, so it gets light trade use! I also have a 26 pound pp sds drill (also 26 pounds in weight !), which I lend out.

mrcheerful

[John Rumm]

You seem to be misquoting there...

The "cheap bits make little difference" part is *only* applicable to SDS bits. This is not the case with conventional masonry bits.

[David Lang]

Hi Bill

Yes they do, how fast depends on what you are drilling. My 50's built house has cement render on the internal walls. Masonry nails bend if you try to hammer them in. I destroyed 4 x 6mm drill bits putting in new skirting & dado rails in a 30' x 15' room.

Dave

[David Hearn]

Sorry, I failed to notice that point. I've certainly had some cheap masonry bits which actually untwisted (or twisted up - can't remember exactly) when used! The result was a completely straight piece of metal!

As for the other comments - I don't deny that over someone's lifetime (or more importantly, the lifetime of the tool) that spending money on a good tool isn't actually that expensive and may be the cheapest option - however I'm sure I'm not the only one where money is tight, and whilst you may spend more over your lifetime buying replacement tools - its the short term spend which is the most important. Same with our mortgage - we opted for 30 years over 25 as it made a sizeable difference to the monthly outgoing. If you look at the extra interest paid over the lifetime of the loan it's shocking - but £50 per month saving in the short term is important to us (5 years out of Uni, living in Surrey with wife and kid).

D

[The Real Tom]

Yes, and very Yes when it happens to me.

:)

tom @

[John Rumm]

Yup, I know the type of thing ;-)

As in the other reply, I have certainly found bits like you describe - although not as yet SDS ones. So far all of those seem to be at least adequate.

I was not commenting on that part of your response as such - only the bit about the bits themselves.

We went through many of the cost Vs quality discussions when writing the power tool section for the FAQ - I hope we have at least got a cross section of most points of view on this.

important point however (IMHO for masonry drilling) is using an SDS drill rather than a hammer one. Most folks who have used ones tend to be pretty evangelical about them since they are just *so* much better at the job!

[SteveB]

Absolutely.

Sometimes you will hit rebar or aggregate. Go slow so you can stop before you smoke a bit. For a piece of aggregate, I use a round pin that comes in a wrought iron gate spring kit. It is cold rolled steel, and won't bend. I grind a point on it, and stick it in the hole to break the piece of aggregate. If it is rebar, you will know it by the feel when you hit it. BTW, pulling the drill out occasionally, and letting the cuttings fly away is a good idea.

Unless you do this for a living, just buy run of the mill bits, and visually check them during use. Hold a new good one next to a questionable one. If it is shredded, you will SEE the problem. If it looks much like the new one, you are hitting something in the hole. Masonry bits are more forgiving than regular bits, and sharpening them isn't as exacting. I have a Drill Doctor, but as yet haven't sharpened one bit on it, masonry or regular.

the $200 US for a rotohammer and some bits. If only a weekend warrior, any old hammer drill and bit will do it, just not as fast. The larger drill bits may take longer depending on the sack mix of your original concrete.

[--s-p-o-n-i-x--]

My reply was simple ant to the point!

sponix

[maradcliff]

One of the more stupid questions ever posted on here. ALL drill bits get dull if they are used, as well as all saw blades and anything else thats used to cut material. Scissors get dull cutting paper, chisels get dull, knives get dull cutting food. It's just common sense.

[Rudy]

What you picture is a masonry bit, NOT a hammer drill bit. Yes, that type will get blunt as they are not made to take the pounding from the hammer drill.

It looks like you have 2 choices: use the cheap things and when theyre shot, toss them or buy the proper type which will last. I had 12 - 3" X 1/2" holes to drill in a foundation and used the same type of bit in your picture. Used a 3/8 VSR drill and when I was done, the bit was thrashed but it did the job. It did take a lot of grunt work to get them done !

Later I had to drill another dozen or so of the same holes in another section (for driveway rebar). I rented a BOSCH hammer drill and they included the bit. Probably took 1/3 the time and the bit did the grunt work this time.

Like almost anything else, many tools can be used to do a job but the proper tool will do the best job (but will probably cost more..but will last longer)

Saw this sign in a workshop:

EVERY TOOL HAS ITS PROPER USE.

It was framed on a board and attached to the wall by having a screwdriver driven through the frame

R

[Dave Plowman (News)]

Yes - and it's easily seen if you have good eyesight or use a magnifying glass, the cutting edge gets rounded off. Compare with a new one.

[Dave Plowman (News)]

I well remember the frustration of trying to drill into concrete ceilings with a hammer drill. It's just damn near impossible if it's half decent concrete. The answer is quite simply SDS. With the prices now so low you don't need to wreck many ordinary masonry drills to pay for one. And as you say, the SDS bits tend to last for ever.

[Andy Luckman (AJL Electronics)]

So is posting the right way up and trimming to context, but you seem unabe to grasp that.