I melted a bit!

So I pulled out my 2712 and a brand new box of Bosch SDS Plus bits to drill a couple of small holes into the brick around my fireplace. On the first hole, the drill went in around 3/4″ and then just stopped moving forward. I pulled out and saw that the tip was glowing so I took a closer look. This is what I saw.

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Another bit is next to the melted one for comparison. Now, correct me if I’m wrong, but Bosch SDS bits really shouldn’t melt drilling through brick, should they?

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Holy shitballs, I never saw or heard anything like that before. SDS bits should last a while. 

DAMMITT !!!! 

That ain’t good 

Ahhh yes, the new Bosch pecker tip bits! That’s crazy man, did it it feel like you hit something?

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I would contact Bosch, that doesn’t seem right at all

Are you sure you didn’t hit rebar or something else?

Wow!! That’s incredible! How long did you keep the drill going after you stopped moving forward at the 3/4″ mark as you tried to push through?

KnarlyCarl wrote:

15 minutes ago, KnarlyCarl said:

Wow!! That’s incredible! How long did you keep the drill going after you stopped moving forward at the 3/4″ mark as you tried to push through?

Not long at all.  In fact, looking into the hole I discovered something even more fun.  The hole is really only like 1/2″ deep and the melted metal coated the end of the hole.  I tried to continue with another masonry bit in my 2704 and couldn’t get through the melted metal.  I had to drill another hole right next to it and, though it took some time, it went in just fine the full 4″

As for what I hit, I have no idea.  There can’t be any rebar in there – it’s quite literally the middle of a regular red brick.  As a side note, I had forgotten how painful drilling masonry is with a hammer drill.  I’m definitely spoiled.

I would bet the bit snapped just above the carbide so you were just rubbing the remaining part of the bit against the broken part.  It’s something you have to look out for drilling case hardened steel by hand that the big can snap getting close to the end and you hardly notice but it ends up with one part of the bit just grinding against the other.  In that case the bits are usually HSS or cobalt so they don’t melt but SDS shanks are made to be tough not hard and not designed for high temperatures so I could see it melting.

low pressure and slow speed is key, you can heat up a tungsten tip or durium tip and have it fall off or melt the silver solder very fast. As jeff mentioned I see this happening and you think your drilling but your only grinding one thing that is harder than the other so one melts……

I’ve seen these small diameter bits melt frequently. ESPECIALLY when using a traditional drill/hammer drill. I’ll guesstimate I’ve melted over a dozen over the years. You’d think I would have learned but every time, I think it’s just an isolated, one off incident.

Ricky is right the smaller diameter bits don’t seem nearly as durable as the large ones. I think less mass in general is bad for drill bits.

Yea like Ricky Jeff and comp chimed in on you gotta watch the small bits, there is so much energy on the sds drills that it’s very hard in the smaller diameter bits, a lot of times treat it like drilling metal and try not to generate too much friction to jack up the bit, but on the same token I’ve had many bits fail from unexplained reasons too@kruton LOL


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What size bit are you using? The smallest I use any more in my 2712 is 3/16 for tapcons. I decided not to use the next smaller tapcon sizes (5/32″) anymore because I didn’t feel like keeping two different sizes on hand and the 5/32″ just looked like it would snap without much effort in the SDS

KnarlyCarl wrote:

16 hours ago, KnarlyCarl said:

What size bit are you using? The smallest I use any more in my 2712 is 3/16 for tapcons. I decided not to use the next smaller tapcon sizes (5/32″) anymore because I didn’t feel like keeping two different sizes on hand and the 5/32″ just looked like it would snap without much effort in the SDS

It was a 3/16″. I was contemplating using the 5/32, but I didn’t have an sds bit that size and I didn’t feel like a trip to the depot. 

From the discussion, it sounds like I should have kept the M12 sds for smaller tapcons. Oh well, back in the wish list it goes. 

That’s crazy, I use a 3/16 sds bit for those tapcons all the time… It happens to be a DeWalt bit but I’ve never had this happen

I’ve never seen a sds bit do that

You’re not drilling into fire-retardant brick are you?

pancing wrote:

9 hours ago, pancing said:

You’re not drilling into fire-retardant brick are you?

You know, I have no idea. The brick was used to build the central chimney column in my house and it has 3 flues in it for the wood stove and two fireplaces. I suppose it’s entirely possible that it is fire retardant brick. How do you tell?  Is it extra hard? I’ve drilled into it before without problem with a Tapcon branded bit. 

khariV wrote:

1 hour ago, khariV said:

You know, I have no idea. The brick was used to build the central chimney column in my house and it has 3 flues in it for the wood stove and two fireplaces. I suppose it’s entirely possible that it is fire retardant brick. How do you tell?  Is it extra hard? I’ve drilled into it before without problem with a Tapcon branded bit. 

I dunno why i asked that was really really tired and no its not extra hard bit softer iirc