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I need ideas to get a hole though concrete

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Forum topic by ohtimberwolf posted 07-05-2021 08:08 PM 982 views 0 times favorited 22 replies Add to Favorites Watch
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ohtimberwolf

1112 posts in 3634 days


07-05-2021 08:08 PM

Topic tags/keywords: hole saw help

I am setting up an electric run for some new tools and ran into a problem.

I need a 12” long extension that will hold a 3/8 inch diamond hole saw for sawing deep into concrete to make a hole large enough to pass a ¾” plastic conduit through. (a 1 ¼” diameter hole). My extension has two screws that holds a round shank on the diamond hole saw unit.

My extension will only hold a ¼” hole saw shank and that won’t do it, I need it to hold a 3/8” shank. I drill a 3/4” hole first then the 1 ¼ hole over top of it and then chip the residue out as needed and continue on to complete the larger hole.
I can drill from both sides if necessary.

I can’t seem to find an extension that will accept a 3/8” round shank.
I thought this would be a simple thing to find but it is not. Any help?

larry

-- Just a barn cat, now gone to cat heaven.


22 replies so far

View Redoak49's profile

Redoak49

5417 posts in 3270 days


#1 posted 07-05-2021 08:28 PM

For something like this, I would rent a big drill and bit from a tool rental.place.

View tvrgeek's profile

tvrgeek

2299 posts in 2931 days


#2 posted 07-05-2021 09:31 PM

Yea, get a “real” hammer drill. Carbide masonry bit and forget the diamond stuff. You can get 18 inch bits.

View splintergroup's profile

splintergroup

6015 posts in 2504 days


#3 posted 07-05-2021 09:53 PM

+1 on the hammer drill. The diamond bit can give a smoother finish if used wet, but if all you want is a hole for conduit, the hammer drill is far easier. Get a pilot hole first for dust clearance then go bigger.

View corelz125's profile

corelz125

3868 posts in 2258 days


#4 posted 07-05-2021 09:56 PM

Renting a sds max hammer drill with a long 1 1/4” bit is the easiest way to do it. If there’s no tool rental near you go the harbor freight way buy one of their drills and bit.

View bandit571's profile

bandit571

30031 posts in 3965 days


#5 posted 07-05-2021 10:54 PM

Lots of water helps….unless you like breathing the dust…and the bit will last longer.

Just hope you do NOT hit any metal inside…..rebar can break your wrist..FAST.

-- A Planer? I'M the planer, this is what I use

View ohtimberwolf's profile

ohtimberwolf

1112 posts in 3634 days


#6 posted 07-05-2021 11:01 PM

Thanks guys, I’ll get the right stuff tomorrow when the big guys open back up from the holliday. I have a 3/4 inch hole the whole way through so I have a start. larry

-- Just a barn cat, now gone to cat heaven.

View corelz125's profile

corelz125

3868 posts in 2258 days


#7 posted 07-05-2021 11:07 PM

Sometimes its easier drilling a new hole than trying to open up a smaller hole. Be prepared in case you have to do a little hammer drill wrestling.

View bandit571's profile

bandit571

30031 posts in 3965 days


#8 posted 07-05-2021 11:18 PM

And…have a helper standing by….to disconnect the power cord, just in case….( NO, you just can’t let go of that trigger fast enough….DAMHIKT)

-- A Planer? I'M the planer, this is what I use

View Dark_Lightning's profile

Dark_Lightning

4930 posts in 4391 days


#9 posted 07-05-2021 11:32 PM



And…have a helper standing by….to disconnect the power cord, just in case….( NO, you just can t let go of that trigger fast enough….DAMHIKT)

- bandit571

Heh! It’ll be like MR Bill spinning on the end of the drill bit! Not going to be fun.

-- Steven.......Random Orbital Nailer

View MPython's profile

MPython

398 posts in 1094 days


#10 posted 07-06-2021 03:36 AM

You want a “rotary hammer,” not a hammer drill. They are not the same thing. An SDS drill is a rotary hammer. They east through concrete much faster than an ordinary hammer drill.

View AlaskaGuy's profile

AlaskaGuy

6770 posts in 3591 days


#11 posted 07-06-2021 03:56 AM



You want a “rotary hammer,” not a hammer drill. They are not the same thing. An SDS drill is a rotary hammer. They east through concrete much faster than an ordinary hammer drill.

- MPython

This

-- Alaskan's for Global warming!

View mel52's profile

mel52

2277 posts in 1546 days


#12 posted 07-06-2021 05:07 AM

Nothing I can’t fix with the proper amount of explosives. LOL.

-- MEL, Kansas

View wingless's profile

wingless

93 posts in 1024 days


#13 posted 07-06-2021 03:50 PM

My Bosch RH540M SDS-Max hammer drill w/ my 16 inch Bosch HS1904 point bit would poke this hole w/ little effort. Hearing and eye protection is required.

The Quikrete 1241-56 FastSet Repair Mortar is a very handy product for fixing the area around this work.

View xedos's profile

xedos

451 posts in 582 days


#14 posted 07-07-2021 12:27 PM



Sometimes its easier drilling a new hole than trying to open up a smaller hole. Be prepared in case you have to do a little hammer drill wrestling.
- corelz125

Sometimes it is. I don’t think this is one of them being a 1-1/4” hole. The 3/4” pilot hole is a nice start.


My Bosch RH540M SDS-Max hammer drill w/ my 16 inch Bosch HS1904 point bit would poke this hole w/ little effort. Hearing and eye protection is required.

- wingless

A chisel is absolutely NOT the tool for this job.

View ohtimberwolf's profile

ohtimberwolf

1112 posts in 3634 days


#15 posted 07-07-2021 12:28 PM

Thanks guys for all the help and good advice. I have learned much from this site. The hole has now been drilled and I can get on with the rest of this stuff before the concrete people get here (they are over loaded).
I’ll keep this post handy for the future. larry

-- Just a barn cat, now gone to cat heaven.

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