Please give a few more details. Noel.

Put electro magnet into the search box here and see if you can narrow it down to likely issue numbers, with 189results a bit more detail will help

On 26 February 2025 at 11:07 John Haine Said:

…   If what you are asking is how to wind the bobbin using a drill press, then unless your drill press has a speed control my advice is, don’t try!  Unless you have a proper coil winder that manages the wire you need to take it very slowly to get a neat result.  Also having a vertical axis won’t make life any easier.  …

+1 to that!

I’ve tried to wind coils on my lathe, and it’s difficult.   The lathe grips the bobbin well, and mine can be put in low-gear and speed-controlled to build the coil at a sensible rate, all good.   What the lathe doesn’t do is stop/start: such that the motor accelerate and decelerates smoothly without breaking the wire.  Nor does it tension the wire, control it’s placement in neat layers, or count how many turns have been applied. The user has to compensate, and it’s not nice!   A drill is worse than a lathe, I’ve tried.

Nonetheless, a pillar drill is a quick way of making a messy coil which might be acceptable for rough work.  Or not!  A typical home magnet might require about 2000 turns of 0.056mm Copper Wire, which is quite delicate.   A snatchy too fast pillar drill could break the wire, and it’s hard to judge when 2000 turns have been applied. Worse, a messy pile-wound coil takes up more space than a neat layered one, so not enough turns on the bobbin is likely.  May not matter if the electromagnet is for a non-critical application.  If the pillar drill results in say, a messy 1500 turns, the electromagnet will be a bit weaker and hotter, and not being well-matched to the power supply,  might waste a battery.   Might still pass the “so what” test.

The power of an electromagnet is related to Ampere Turns, and the amps are decided by the power supply voltage.    If a coil has too few turns, it will still generate a similar field because the volts available push more amps.   A 1 turn coil with 2000A flowing in it, is the same as a 2000 turn coil with 1A.   However, the single turn coil will get very hot, and needs a very hard to find 2000A low voltage PSU.  A 2000 turn electromagnet only needs 1A from a modest 6 or 12V supply.    So a pillar drill messy coil with only 1500 turns might well be acceptable, a tad inefficient rather than useless.

I bought a coil-winder, excellent for ordinary size coils, not big ones.

Having found my lathe was too jerky for winding a 1 metre Tesla Coil, I made a wooden hand winder, and got a friend to hand crank and count turns whilst I maintained the wire tension and placed it neatly on the former.   That was a doddle compared with me winding with  a lathe.

Winding with a pillar drill is too hairy for me!   Others might have the knack.

Dave