Magnetic drills and tapping/threading

[Robert Hall]

So as painful as it is I have to admit I know little to nothing about using a magnetic drill to tap holes in plate steel.

I would like to drill several holes in some 1 inch plate for which I have the appropriate drill/annular cutter size and would like to use the mag drill to tap those holes after drilling.

I have read the instructions, something I don't usually do, and it has suggests a method for which to do this but leaves out how I should have the drill hold the bit.

I was thinking of using a 3/4 chuck I have to hold the bit, but would like to know if there is a better way to hold a hand tap (7/8-9) in order to accomplish this.

Suggestions?

 

[J king]

If it will fit in the chuck use it.I assume it has low range.if so use it.One hand on feed handle and one on forward reverse switch.have at it..

 

[joe49]

Helical taps work better. But a hand tap will work. You will just need to go in and out more. The jacobs chuck will work fine and will actually slip, if you don't back out soon enough.

 

[Daddyoneleg]

What size mag drill do you have? What I do on mine is center drill,tap size drill,chamfer,then use a power tap in the 3/4 inch chuck.7/8'' will slip in the chuck. Use a ''gun'' tap that shoots the chips ahead if its a through hole.I use helical taps on blind holes because the chips curl out like a twist drill.Do all steps then move to the next hole. My mag drill has a 250/500 rpm plus variable speed. The taper shank can be removed on my drill then I can use #2 morse taper bits and a #2 morse tap holder. The tap won't slip but you can break a tap if something goes wrong. -Cheers

 

[e-tek]

Some photos would be awesome!

 

[theoldwizard1]

I assume it has low range.if so use it.

This means some kind of mechanical gearing, not just a variable speed.

It is going to take a LOT of torque to tap a hole that size and depth.

 

[dr_clyde]

The torque will be the limiting factor here, especially with a Jacobs chuck. My Milwaukee doesn't particularly like to tap anything bigger than 5/8-11 without a ton of slipping in a 3/4" chuck. If your drill accepts morse tapers, you can get adapters that grip the square end of the tap so you can really apply the torque.

For really big tapped holes, I typically will pilot/center drill/rotobroach the tap size hole, chamfer the hole, start the tap with the mag drill then loosen the chuck, remove the drill and finish the tapping with a T-handle. I break less taps that way.

I would set aside the hand tap, and get a good quality spiral point machine tap.While you're at it, get two or three. I usually try to do this in case one breaks. The tap costs less than my time and gas going to get another one. Hand taps aren't designed to tap a hole in one shot. Especially a 1" deep hole.

 

[willymakeit]

Helical taps work better. But a hand tap will work. You will just need to go in and out more. The jacobs chuck will work fine and will actually slip, if you don't back out soon enough.

Cant resist, This sounds almost like ****.

 

[theknurl]

don't know how big tapping heads go, mine will do #6-1/2" 13mm.....torque adjustable clutch and auto-reversing at 1.75 X tapping speed
they use Jacobs RubberFlex collets to center the tap and a square drive to turn it ....NO slipping at all

mine has a floating spindle, so alignment with the hole isn't critical.....you can tap almost as fast as you can align the hole/tap

 

[Robert Hall]

The model I have is a Milwaukee 4209. It takes a Morse 3.

The taps I have are hand taps. I would love to find a few spiral taps that weren't $60.

Looks like I should find something besides a 3/4 chuck. I'm sure it would slip a bit too much. I'm not sure where to find such a beast however.

I will use the lower gear and the machine touts that it can manage a 1 1/4" tap but I will take their word for it. Why would marketing lie to me?

 

[joe49]

Cant resist, This sounds almost like ****.

Sick puppy you are.

 

[Daddyoneleg]

I lied,my mag drill is the same as yours. It must be #3 morse taper. Here is the tap holder. I do all the operations without moving the mag drill.This holder will only work that way for alignment reasons.Your mag drill looks new and all the slides should be set up tight and that means no wiggle room for tap misalignment.I have had the base slide on me on heavy drilling,so I will use extra clamps or tack weld keystock to the plate to keep it placed. -Cheers