View Full Version : Using a Mag Drill

08-18-2005, 06:12 PM
I've got some drilling I need to do on a piece of mahinery and I don't won't it to become magnetized.Because of the nature of this piece of equipment a Mag drill will be a convience.Will the drill impart residual magnetisum into the machine?It's imparitive that this machine not pick up any residual magnetisum.Any thoughts?TIA!

08-18-2005, 06:28 PM
Don't use a mag base drill.

On second thought you might experiment on some scrap using a ceiling fan speed control to turn the mag circuit on and off, slow on, slow off.

[This message has been edited by Evan (edited 08-18-2005).]

Forrest Addy
08-18-2005, 08:11 PM
Use a video tape demagnitizee on the area.

08-18-2005, 08:11 PM
If it really cant get ANY magnetism on it no how, then go buy a cheapo $75 drill press at home depot, the little tiny one- and clamp it down to your machine. I have done this before, with a yellow plastic drill press, and it worked great. Drilled several hundred holes in some huge fabrication, quick and easy, and it was WAY cheaper than buying a mag drill, in fact it cost less than renting one. I considered the drill press disposable tooling- the one job paid for it.

Tin Falcon
08-18-2005, 09:10 PM
We use mag drills at work on a regular basis. I have not noticed any signs of residual magnatism ie chips or steel dust hanging around the area that the base sat. Somtimes we are drilling a couple of dozen holes on the end of an I beam. It would not hurt to go with Forests Idea or the Idea of clamping on a small drill press

08-18-2005, 09:14 PM

I'll post that for ibewgypsie

J Tiers
08-18-2005, 09:58 PM
BTW, some mag drills have a demagnetize setting, which is probably intended for its own base, but probably also works on the piece it is stuck to.

But, if you "can't" have ANY magnetism, don't drill, hit, weld, or deform the part in any way. All of those will leave some residual magnetism.

Seriously, if really zero residual magnetism is the goal, you will have to "degauss" it like a WW2 ship after it is installed, and regularly thereafter.

08-19-2005, 07:42 AM
I'll go with that last. Find a friendly TV tech and get him to run a degaussing wand over the job when you're finished.
Rgds, Lin

J Tiers
08-19-2005, 08:17 AM
<font face="Verdana, Arial" size="2">Originally posted by Swarf&Sparks:
I'll go with that last. Find a friendly TV tech and get him to run a degaussing wand over the job when you're finished.
Rgds, Lin</font>

To "degauss" anything of a size to fit a mag drill on, the wand almost certainly won't do the job.

You will have to wind wire around the whole thing, and put AC thru the resulting coil, slowly increasing and decreasing current through it.

ANY fabrication work will result in some residual field, so it is completely unrealistic to expect "NO" field afterwards. And of course, there will ALWAYS be an induced field from the earth.

08-19-2005, 09:02 AM
Huh? ...what's a mag drill?

kap pullen
08-19-2005, 09:10 AM
We use a mag drill on aluminum fabrications.

Just clamp a steel plate on the aluminum and go from there.

How about clamping a steel plate with some other inert material between it and the job?


Forrest Addy
08-19-2005, 09:30 AM
for that matter, hot a welder with AC. Can you get a dozen turns or more of welding lead around the work? 300 Amps of AC can do an impressive amount of degaussing especially if the welded had a continuous current control (that is not switched).

If the work is really massive you can use DC, reversing polarity and reducing current every few seconds until you get to zero.

08-19-2005, 10:43 AM

You have to turn off the AC very gradually or the collapsing field will magnetize the work. That's pretty hard to do with a buzzbox.

08-19-2005, 11:57 AM
I've just countersunk 50 5/8" rivet holes in the side of a boat with the aid of a mag drill, the only permanent magnetising evident is on the counter sink bit, which now holds bits of swarf. This quite likely has nothing to do with the mag base anyway. I'm pretty sure the magnet on this small drill is arranged to turn off gradually, & there's probably enough AC ripple on the magnet supply to make sure, in conjunction with the 'gentle off', that the workpiece isn't magnetised by it. My big mag drill does have a demagnetising setting, but I've never needed it.