Drilling in concrete. Need advice.

[Coach James]

Hey all,

I have to drill 8 holes in concrete. Each has to be 1.5" diameter and 3.75" deep.

I am pretty sure I will need to use a core bit for this, correct?

I have a rotary hammer and a Milwaukee Magnum half inch drill. Which would be best to use?

Would I also need a pilot bit? These holes have to be in exact position as they are going to be anchors for gymnastics equipment.

I see kits available that include a core bit(s), pilot bit, hex and SDS adaptors. Would that be the way to go?

I have done lots of holes in concrete, but 1" was always the largest and I just used a SDS+ bit. I think 1" is the largest size for them though.

If you went with a kit, what brand to consider/avoid?

Thanks

Coach

 

[p_mori7]

When I had to drill a 3.0" hole in my foundation to run underground cable to the shop, I just went to my local tool rental place and told them what I wanted to do. They hooked me up with the tool and I was done in minutes.

SDS with a diamond core bit. I don't remember if it had a pilot bit.

 

[Advan]

Rent an SDS-Max rotary hammer and a 1.5" bit. Some machines have a built-in depth stop device, otherwise use some electrical tape around the bit so you don't drill too far. No pilot holes, they will decrease your accuracy in both location and hole size.

 

[OCD]

Just did this, but only one hole 1.5" wide and 8" deep...

Went quick and easy with this puppy I rented,

 

[pcmeiners]

Have a Bosh SDS Max, last job I drilled >100 1.5" holes in about 8 hours on a vertical wall, core bit was not necessary. For accuracy, pilot with a small bit.

Rent as Advan advises. The one I have ran $525.

 

[dogdog]

how much you wanted to spend and how neat you needed those holes to be.... they do have those 1.5" diameter sds max bits as well... would finish those holes in less than 15 minutes. Not cheap.... if that is the only job you used them for. if you wanted super super nice , I think HD rents those core drills.... I have seen those marble installer used them, very neat holes and super clean.

http://www.homedepot.com/c/concrete_equipment_rental#core-drills

 

[rharman]

I needed a 3" hole for an A/C drip to empty into. Home depot core drill rental - piece of cake.

Unless you plan on doing this regularly, I would not buy the tool (blasphemy, I know).

 

[ssdave]

I own three rotahammers, and have worn out two 3/4" spline industrial ones already. So, have quite a bit of experience in this. I'd go rent a core drill every time before I'd use one of my drills to cut a 1.5" hole. 1.5" x 3.75" is too big to effectively use a handheld drill, you want the heavy, frame mounted rental tool with cooling water feed instead.

 

[shawhite]

Rotary hammer and 1.5 sds max bit. If you are concerned about the bit warndering build a jig to hold the bit where you want it. 1.5 sds max bit is a little over $100 so you probably want to rent. I think a core drill bit is over kill for this application. Usually core drills are used when you are boring completely thru stone and need a very clean cut so it looks good. If you are just anchoring equipment you just need a whole to put the anchor in

 

[Fixed]

I don't know what your time is worth, but if it was me, I would just take a 1/4" bit with your roto hammer and drill holes in a circle and punch out the slug. But if the hole needs to be neat, or you're not a broke student, I would rent whatever home depot recommends.

Sent from my Nexus 5 using Tapatalk

 

[kctyphoon]

No core bit for a 1.5" hole.. just a big demo drill and sds bit.. if the holes are in the floor, use some compressed air to clean out the holes. If it's a concrete wall you can poke a hole in the top of a water bottle, and just shoot some water in there to clean out the hole.

If the concrete is reinforced with rebar you'll quickly find out if you hit one..

 

[CJM8515]

Echo the demo drill and sds bit. Rent it, it aint worth the cost of one use.

 

[Coach James]

Thanks for the advice guys, keep it coming.

The holes are going to be in the floor. The concrete is fiberglas reinforced, no rebar. No problems drilling other holes in it when I used a good bit(Not Vermont American).

Coach

 

[Roberts210]

I got this Milwaukee Rotary Hammer 'bout 25 years ago. It's a 1960's model--not SDS but 6-sided hex. But I only had 2 bits for it--1" and 5/8ths. A few years ago I was looking on ebay and some place was selling all their Milwaukee hex bits for really cheap. I bought all they had at $10-$15 each, including this 1.5 inch bit. I've used it to punch through concrete foundations for water pipes, etc. Works great. So if you are the kind of guy who will be drilling in concrete a fair amount, get your own Rotary Hammer. But if this is a one time thing, rent one.

Sorry, just re-read your original post. If you go with a core bit you'll have to come up with some way--hammer only with a point--to chip the column out of the hole. You might go to HD or your local rental yard and see what they have in the way of 1.5 inch bits.

 

[FMC1959]

How big is your rotary hammer? You mention sds plus, so I am guessing in the 3/4 to 1" capacity. A 1" or 7/8" could probably handle making 6 holes at 1 1/2". Provided you can find an sds plus in 1.5".....I have seen 1 1/8", maybe 1.5" exists but not common

You need a regular twist bit, not core bit. Core bits won't leave a clean hole unless you go completely through the concrete.

If you can't find the bit, then you need to go to sds max, which means rent or spend a good chunk of change to buy it for 6 holes.

 

[Coach James]

How big is your rotary hammer? You mention sds plus, so I am guessing in the 3/4 to 1" capacity. A 1" or 7/8" could probably handle making 6 holes at 1 1/2". Provided you can find an sds plus in 1.5".....I have seen 1 1/8", maybe 1.5" exists but not common

You need a regular twist bit, not core bit. Core bits won't leave a clean hole unless you go completely through the concrete.

If you can't find the bit, then you need to go to sds max, which means rent or spend a good chunk of change to buy it for 6 holes.

Sorry I missed this. Yep, we ended up renting a Bosch SDS Max from the rental house. They only had 1 bit in 1.5 inch and it is pretty dull and beat up.

Coach

 

[MBfreak]

Rent a Bacho unit I think they are branded Kangoo nowadays?. They have soft start , so you can run them on a decently sized fuse.
They alos have a torque sensing, if the bit stalls it will reduce torque immediately to stop breaking your wrists.
The hammering action is pneumatic and very fast, so minimal pressure is needed, inertia takes care of that.
I rented a 2 kW 220 V unit with a 45 mm( 1 3/4") bit 450 mm long. Drilled two 350 ( 15") mm deep holes in 45 minutes, rental was around $40, worth every cent

Ola

 

[Coach James]

The only one our rental house has is a Bosch and they only have one 1.5 inch bit. No other options unless I buy one myself.

Coach

 

[devoncoolman]

We have a bosch sds max drill capable of drilling 1 9/16 holes with a solid bit. Larger with a core bit. For the application you are using it for. You would need this style drill with a solid 1 1/2 bit. Core bit will not work because the core will still be left there afterwards. Our drill was $500 + bits. Worth the money if using it alot. We installed our new lifts and mounted all our fixed mount equipment when we moved into our new shop. Remting was not really an option had to mount everything at different times. Diddn't want to remt it 5 times would probably negate the savings.