Changing gears for 1 1/4 TPI and using QC gearbox

You're winding wire......forget about the gearing and just eyeball it!
 
Well, maybe. But at that pitch it sounds like it might be for a tank coil for 10, 6 or 2 Meters which is a little more than just "winding wire". :)
 
I wind springs often. I always wind them tight then stretch the finished coil as needed. No worries about so many turns per inch when winding. I do not use the leadscrew when doing this.
 
Yes, but except in a couple of minor cases, the electrical behavior of a coil is unrelated to the mechanical behavior of a spring. If the OP wants to make several interchangeable copies of a coil with an Atlas lathe, there is no practical reason why he can't, regardless of what the gears are made of. The forces acting upon the gears driving the carriage will be the same while winding a coil as they are with the machine just running with no wire being wound. This would of course not be true if the carriage was cutting a thread.
 
Think about this: If the lathe has an 8 pitch lead screw, it has to turn twice as fast as the spindle to make a 4 pitch thread. For an 1-1/4 pitch, it has to turn 10 times as fast as the spindle. Something that little machine was never engineered to do.
 
I, too, misunderstood. thinking of a coil as being just a coil of wire, not an electrical device. Being a tool maker I can't imagine an electrical coil with a spacing of perhaps 1/8 of it's length? or more, or less? A coil to make an induced magnet? or like an ignition coil to make a high voltage spark?
Boy Houdy, how much I don't know!
 
Tom,

I think that you are still not thinking of the proper type of coil. Usage of coils with much more than one diameter spacing between turns is generally for one or both of two reasons. One is that the inductance of a coil used from HF up through UHF is usually such that the total length of the wire in the coil would only be from a few tens of inches down to a few inches. The other is that depending upon the power level and the altitude at which you are operating, you may have to space each turn at least several wire diameters apart just to prevent arcing between turns. For example, the BC-610 plate tank coil for 18 MC is about 4 inches in diameter, made of plated copper tubing, and with a turns spacing of about an inch. Only peripherally related to metal working. But that's just the way things are done.

Derf,

You still aren't getting the picture. To begin with, you can't reasonably call a 12x36 lathe a "little machine" unless you're just trying to be insulting. If you spent your days running a 96x480 lathe (which I did - once) maybe. But there aren't many of those around.

If you were running the spindle at 2000 RPM, even a larger and much more expensive machine would beat its lead screw to death if it were geared to move the carriage forward 1-1/4" every time that the spindle made one revolution. It would be turning at 20,000 RPM! But as I also already said once, running the spindle at 28 rpm, the lead screw is only turning at 280 RPM which is only 4.667 RPS. Well within the capability of all but the Atlas 618, and that only because its slowest spindle speed is 58 RPM. The one precaution that I would take would be to see how long it takes the motor to spin down to a stop after I opened the motor switch, so that you have a feel for how much room you need.
 
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