Masonry Star Drills... anybody use them?

[CountryBoy19]

How much work am I getting myself into? I need a hole somewhere around 1-3/4" through 4-6" reinforced concrete. I can get a 3/4" pilot hole no-problem (thanks to a friend with an SDS-Plus roto-hammer) but the bits to go to my size are very expensive for a single hole and he doesn't have them that large. So I'm considering use an old star drill (star shaped masonry chisel). I remember my dad using one of these when I was little, it was much smaller, but it didn't take him much more than about 10 minutes to go through 8" of concrete and that was laying on his back underneath the deck swinging the hammer above him.

I'm not afraid of work and I'm trying to avoid the 2 hrs of wasted time messing with renting the right tool (I live in the boonies). But if it's going to take me a couple hours to pound a hole through concrete I may as well go get a core-drill and be done with it.

 

[CHCRandy]

I would go get the drill......

 

[CountryBoy19]

I would go get the drill......

1-1/2 hr round-trip to pick it up and 1-1/2 hr round-trip to drop it off ... I definitely understand that is the easy way out, but it's hard to justify that trip... my time for the foreseeable future is at a premium, even if I combine the pickup or drop-off with getting other materials, I still have a 1.5 hr trip for the specific purpose of returning it... 2" star drill is $16 delivered to my doorstep.

Have you used star-drills before?

 

[BigBoxaJunk]

I remember using one years ago, but the one I used was only about a half-inch, and I was drilling through mortar, not concrete.

Seems like it would definitely speed things up with a pilot hole, but I could also see the star-drill getting wedged in easier. The other thing is that the star-drill will try to wander sideways if you go through a harder (or softer) spot, or if you hit rebar. But the pilot hole will keep it mostly straight.

If I wasn't pressed for time, and if I didn't need a perfect hole I might try the star-drill.

 

[CountryBoy19]

if I didn't need a perfect hole I might try the star-drill.

a piece of pvc conduit is going to pass through then be sealed in place with concrete epoxy (because I have some anchoring epoxy leftover from a previous project).

 

[snapping turtle]

Mark your hole. Then use the SDS drill with say a 1/4 inch bit to chop out the size hole you need the chisel the finish on the sides like a pro mansion of the 1400's with a hammer and chisel. Once a series of 1/4 inch holes are around the circle the chisel will work very well finishing off the hole.

 

[snapping turtle]

And if you rent the drill and bit to do that size hole make sure the drill has the autobreak. Nothing worse than the bit sticking and the drill then spinning.

 

[churchmouse]

Geet the drill or find someone to borrow one from. I have beat myself stupid using Star bits.

 

[Alpo]

If you have an air chisel, it's not all that difficult a job. I remember as a lad making a 10" diameter hole in a tiltup wall for A sprinkler riser. It is not fun. In fact, I'd drive 1 1 1/2 hours in a Ford (shudder) to go get an air chisel.

 

[2ADMNLOVER]

It's gonna SUCK either way but it'll suck less with the drill .

 

[2A_Tom]

Do you have a star drill or is this academic?

In the time it took to read and reply to this thread I could have had this done.

 

[ghitch75]

Geet the drill or find someone to borrow one from. I have beat myself stupid using Star bits.

+1.....star bits suck.....

 

[JimH]

Mark your hole. Then use the SDS drill with say a 1/4 inch bit to chop out the size hole you need the chisel the finish on the sides like a pro mansion of the 1400's with a hammer and chisel. Once a series of 1/4 inch holes are around the circle the chisel will work very well finishing off the hole.

This is the answer you need.

 

[1911ly]

And if you rent the drill and bit to do that size hole make sure the drill has the autobreak. Nothing worse than the bit sticking and the drill then spinning.

I watch my boss whack him self in the face with the drill handle when we were putting a 4 inch hole in a concrete wall. He about broke his jaw and got a hell of a shiner. I finish the job with a chisel and some eblow grease.

Op, If you were close I have a Redhat drill and another (maybe a Milwaukee) I haven't used them in a very long time, you would be welcome to use them if I can find them. I might have a bit too.

 

[Bigtanker]

I watch my boss whack him self in the face with the drill handle when we were putting a 4 inch hole in a concrete wall. He about broke his jaw and got a hell of a shiner. I finish the job with a chisel and some eblow grease.

Op, If you were close I have a Redhat drill and another (maybe a Milwaukee) I haven't used them in a very long time, you would be welcome to use them if I can find them. I might have a bit too.

You also have a .50 BMG that will do the job.

 

[Butch627]

I would drill the pilot, then use a smaller bit to make a series of holes around the perimeter, then use a chisel in the rotary hammer to open it all up. I am sure that if your buddy has a rotary hammer he has all those attachments.

 

[CountryBoy19]

If you have an air chisel, it's not all that difficult a job. I remember as a lad making a 10" diameter hole in a tiltup wall for A sprinkler riser. It is not fun. In fact, I'd drive 1 1 1/2 hours in a Ford (shudder) to go get an air chisel.

Doh, didn't even think about my air-chisel... good advice!

Do you have a star drill or is this academic?

In the time it took to read and reply to this thread I could have had this done.

You're welcome to come over and do it. It took my 5 minutes to text my buddy to see if he had a bit that big, determine the cost of a star-drill that big, then post this thread. If you can do it in that time and you're willing, I'll provide pizza a beer!

No, I don't have the star-drill that big, but I can acquire one and have it shipped to my door (as my post says).

I would drill the pilot, then use a smaller bit to make a series of holes around the perimeter, then use a chisel in the rotary hammer to open it all up. I am sure that if your buddy has a rotary hammer he has all those attachments.

I think I'm going to do this. If my buddy doesn't have the right size chisels I'll use my air-chisel.

 

[Tactically Fat]

have the compressor capacity to run the air chiesel?

 

[CountryBoy19]

have the compressor capacity to run the air chiesel?

Maybe not 100% duty cycle but enough to be functional. I've never run the air-chisel for any length of time on my compressor so I don't know. Either way, its not like I won't be able to find something else to do while it's pumping up. I have a lot of outdoor conduit burying/mounting/etc to do. Lots of hand-digging near other buried utilities as well.

 

[1911ly]

You also have a .50 BMG that will do the job.

It's a little aggressive and a bit loud... but yeah.