Can an SDS hammer drill bend a drill bit?

21 Jul 2004
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United Kingdom
I have a HR2470 Makita SDS+ drill from ITSL

It came with a free Makita 17 Piece SDS+ Accessory Set

Whilst using one of the accessory bits (the 8mm * 120mm drill) to drill into a brick wall.

The first few holes went in fine, no issues. I then noticed the bit was jumping a lot inside, and not going in cleanly. So pointed the drill at myself and spun the drill and sure enough it had bent.

I then went to screwfix and bought this bit

Again same issue , 1st few fine then starts going crazy and upon checking it too has twisted.

So question, is the makita accessory set crap as well at the bit from screwfix....or has the sds drill somehow managed to screw up the bits?
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Are the walls you are drilling at all damp? Chances are you are allowing the body of the drill to drop once you've started to drill the hole, thus bending the drill bit.
Hi RF Lighting,

No the walls are not damp at all.

Does the quality of the bit make a difference to the amount of stress the bit can take before it starts bending in the case that the body of the drill dropped whilst drilling?

I'm pretty certain I did not do this, but will have to keep this in mind for next time to make sure.

Hi Benji,

What are you drilling into? Is there a possibility of steelworks hidden in the wall? That may cause a problem....Other than that I agree with RF re the angle... SDS bits are normally pretty solid, try a Dewalt extreme one and see if that does the same.

Did the bits both start to bend when you reached a certain depth (on the hole that caused the bit to bend) ?? That could point to something in the wall impeding the bit.
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Nothing wrong with the drill bits in that set so i'd be looking at other causes.

What do the bits look like when you roll them on a flat surface (the the cutting edges over the end of surface)?
To bend the bits you'd normally have to snag/catch them on something but the clutch would normally slip before any damage could be done.
I was drilling a pilot hole last week and burnt the end off of a 10mm and 12mm x 450mm SDS bit. Never happened before not even in granite. Turns out cottage built of whin stone and drilling with the grain. Powder is very fine but abrasive. Had to get a hilti bit and much larger as seems to get rid if heat quicker so won't burn off tip.

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