Does anyone else have trouble with “melting” the carbide tip right off SDS bits? I believe it was a case of melting because the failure happened rather suddenly on my 12th or so 5/32 inch by 4 inch deep hole. I was running them in succession, but never dreamed I would generate sufficient heat for bit failure. Is this common? It was a good bit. Bosch. I was using it with my Bosch Bulldog. When it suddenly stopped making progress, I pulled it out to see a completely blunt end.
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Replies
Check this months FHB article on rotary hammers and their usage as you may have a problem with how the holes are made; i.e. too much pressure on the tool.
Good luck!
The undisciplined life is not worth examining.
I don't think so. (I read the artical too.) I put very little presure on the hammer while drilling... The bit is free to "float' in the hole as I progress.
I used an identical set up (Bosch Bulldog with 5/32x6" SDS bits) to drill 600 holes for tapcons in a floor slab to set sleepers. I think I used about three bits altogether. One did what you described, the others just broke (long skinny bits'll do that...). But that Bulldog just sank into the concrete like it was foam board. All I had to do was hold it in place and yank the trigger. 5 seconds per hole average time, LOL....
Dinosaur
'Y-a-tu de la justice dans ce maudit monde?
Hard aggregate or rebar and hammer mode will do that to those small dia bits. Excessive holding pressure doesn't help either.
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming....
WOW!!! What a Ride!
Some rebar has clinkers and other ceramic-like inclusions that are similar to, as far as I know they might be, solid carbide. I tend to use smaller masonry bits, usually less than 1/2" and have repeatedly 'reforged' the tips on these inclusions. The other bug is quartz river rocks and chert used on some Florida houses. Sometimes not an issue some particular models of these eat carbide for lunch, especially cheaper bits. I have a few 3/16" and 1/4" diamond bits for sinking Tapcons and common expansion anchors. They were not cheap, relative to the normal carbide versions, but they come in mighty handy.
Has anybody tried water cooling for this? Did it help?
-- J.S.
my dentist's drill is watercooled..I think if ya hit rebar, no matter what..the bit is trashed.
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Spheramid Enterprises Architectural Woodworks
Repairs, Remodeling, Restorations.
What kind of dentist do have?
Won't those braces rust???Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming.... WOW!!! What a Ride!
My dentist breaks out a rotary hammer and I'm out of there.
I have had the same thing happen, and think Bosch bits are over rated. I burned up 4 bits setting pins ito ledge rock 1 Saturday- replacing them at the rental yard where I gotthe drill. To finish the job on Sunday I bought a new bit at the depot "drilltech" brand. The depot bit drilled more holes than 4 bosch bits did and was still serviceable when done.
To bad the depot doesnt sell them anymore, now that they are in bed with Hilti (junk also).
I have not ruined a Bosch bit yet but I have tried to run them thru an aluminum threshold and melted aluminum to the beginning of the bit but it still drills.
What i have noticed is how much faster a new bit is verse an old one, so I have accumulated about 20 or so bits and its getting a little crowded in the drills box.
ANDYSZ2I MAY DISAGREE WITH WHAT YOUR SAYING BUT I WILL DEFEND TO THE DEATH YOUR RIGHT TO SAY IT.
Remodeler/Punchout
I don't know if this will shed any light, but my hammerdrill is a Milwaukie and I've always used their SDS bits. I've worn the carbide off a couple over the years and even bent a couple of the longer bits....
I've hit rebar, drilled through some really old and hard concrete, even drilled some basalt and granite rocks to make some candle holders for DW (a 7/8's bit for that application, by-the-way), but I've never had a bit do a meltdown as you describe.
I regularly used them to drill holes in concrete to fix down ply sub-base.
I found that the bit lasted a lot longer if I kept the hole clear of dust and if I touched up the cutting edge occasionally on a diamond hone.
I have melted the tips off when I've used a bit long after it's dull but you usually get a bit of warning from the 'blueing' of the shank.
IanDG
It will also help if you slow down the rpms. I know it's nice to go fast but hey now look what you did.
I was telling a speedo framer that was trimming some old lath on a transition to new work- that every time you get to the red light and it greens does that mean you have to floor it till the next light? Get off the gas.