Chucking 1" conduit in a 1/2" drill

[clare]

A half inch drill can handle a 4" hole saw, or a 3" forstner bit with no problem. No reason it could not handle the digger if used with a tiny bit of common sense.

[clare]

Hopefully it is a good "D" handle type with a threaded socket for a pipe handle on the top. They are used every day for mixing mortar and drywall compound

[DerbyDad03]

Have you thought about run out?

Any rig that is not perfectly straight is going to have an awful lot of run out 6 feet out from the chuck. I gotta assume that the run out will make the drilling through clay pretty difficult.

Do you also have something to clear the clay out of the hole as you drill?

[Jim Elbrecht]

-snip-

I'm experimenting a bit now- but have to comment that this was a winner of an inspiration. I have some good blu-mole and other hole saws.

My plumbing collection ran out at needing a 1/4" nipple/pipe to chuck-- Went to Lowe's and they didn't have any either. Bought a

1/2" bolt that I figured I could grind some flats on so it wouldn't slip in the chuck.

Then I cam home and read this! One of my hole-saw arbors screws into the 3/8 pipe fitting on my connection 1.0.

I also note that the EMT I have is 3/4", not 1" as I thought. And a 5/8 hole saw fits [loosely] inside. Connection 2.0, if needed, will probably be a split conduit, clamped tight over that 5/8 hole saw. [or, if I pass by an 11/16"/17mm hole saw before I get there, I won't even split the conduit.

Jim [first 5 minutes of trial, I busted the connection between the conduit and the garden tool-- I either need a less aggressive digger or a better connection there-- Otherwise I might be on the right track]

[DD_BobK]

On Sep 29, 8:35=A0am, Jim Elbrecht wrote: SNIP

Jim-

I'm a bit late to the thread but I think you're on the right track.....dry drilling.

I've water jetted and I've hand dug under sidewalks (etc). Water jetting is messy & unless you've got a place for the water to drain away, the used water accumulates. Hand digging undermines the side walk or driveway strips & you run the risk of concrete failure later on.

It's hard to get a good number for the tourque output for electric drills... the mfrs either fail to state or give bogus numbers.

hp =3D rpm x torque

so at normal operating speed you get the drills honest torque rating. The problem is..... a the drill apporaches stall, the torque goes WAY up, hence the tendency for a powerful drill (like a Milwaukee Hole Hawg) to twist your wrists & arms.

My best suggestion for a cheap adapter would be: a piece 1/2" black pipe (we need as small an OD as possible) x ~6" long threaded both ends

1/2" coupling 1/2" x 3/8" reducing bushing ~2" to 3" piece of 3/8" pipe (ideally sch 80)

the one sticking point is.... nominal ID of 3/4" EMT is ~.824 nomimal OD of 1/2" black pipe is ~.840

so we have a theoretical interference of about .008" per side. I'm hoping that the pipe mfr is shorting us on material cheating down on the OD a bit.

You might be able to pound the adapter assembly into the 3/4" EMT.

Whether this scheme works is dependent on the connection from the 1/2" pipe to the 3/4" EMT. My calcs say we'll need about 14 #10 self-drilling / tapping screws through the EMT into the pipe. I'd use three rows with 5 screws per row..staggered spacing.

Getting the pipe into the EMT will be the hard part unless you can machine the OD down to give you a slip fit. Removing .016" with a lath is snap... by hand, not so much. :(

The torques & forces are substantial and I doubt any kind of clamping arrangement will work.

good luck

cheers Bob

[DD_BobK]

Jim-

My apologies.... I did not view the link in your OP. So my post about the connection to EMT is probably useless.

Driving a device such as that garden claw doesn't require all that much torque as long as one can control the "bite" into the soil.

Driving it by hand is safe & easy..... adding 1/2" drill to the mix, not so much.

Even a 1/2" drill like a Milwaukee Hole Hawg on low speed runs at ~300 rpm. A typical post hole auger runs at ~150 rpm.

As in my previous post.... hp= torque x rpm

Any kind of bite by that claw is going to require some decent torque...multiple that torque by 300 rpm (typical low speed drill range) and you're going to need some serious horsepower, way more than a typical 1/2" drill.

Consider renting a soil auger bit that is made to interface correctly with a 1/2" drill.

I once saw a resoanbly priced horizontal soil drilling auger system but I cannot locate it online. :(

check these out

cheers Bob

[DerbyDad03]

The torque issue what I was talking about earlier. I imagine that it's going to be hard to control in the manner intended. I also brought up run out. Putting together a rig tat is going to be perfectly straight is going to be pretty tough. Any offset at the junction is going to be multiplied 6? out.

Controlling a wobbly garden claw installed in a 1/2 drill is going to be very tricky.

Good luck!

[TomR]

Instead of trying to drill/cut one large diameter horizontal hole, couldn't you first drill a much smaller diameter hole (maybe an inch or so), and then widen that hole by pulling out more dirt/clay with a pole with some type of small hook or bent piece on the end?

Or, rent or buy a hand-held post hole digger and just use it horizontally instead of vertically?