Mental specifics of transformer winding

[50AE]

By breaking the grain of the wire, I guess you mean straightening the wire from its coiled "memory"? My simplest trick to do so is offseting the wire tensioner, so it feeds the wire to the machine at an angle, which seems to straighten the wire. When reversing the feeder direction, for some copper wires I have to change the offset to the other side.

 

[Fuling]

This video was a major source of inspiration when I built my winding machine:

 

[Elvee]

However I recently took apart a tfmr someone had wound, what they'd done was after finishing a layer, they'd done 1 turn of 10mm yellow insulation tape on each end of the layer first, then put of the paper or whatever insulation.

Another bug ger is securing the ends of a winding if you don't have solder lugs to secure to

Having a cyanoacrylate tube handy is an easy cheat: one drop on the start, wait a few seconds then the same at the end .
You can also use an old winder's trick: fold a thin ribbon of mylar or textile around the start of the first turn, and when subsequent turns are added, they secure the ribbon and the first turn.
The trick is also usable for the last turn, but you need some ingenuity

 

[50AE]

Yes, on flangeless bobbins one can use a strip, or rely on glue action and waiting time. It depends of your methodology and application. Instead of a strip, one could use fishing thread (green/blue color), which are quite strong. To secure the wire end, one can place the strip an equivalent of 5-30 turns before finishing the layer. The final windings will kind of secure the strip, but still let you slide it with some force. After you insert the wire end through the strip loop, you can pull the strip end with pliers and secure your wire.

 

[astouffer]

I used to wind eddy current probes which were just two identical coils on a bobbin. We had adjustable wire tensioners but I always felt more comfortable using my fingers to keep tension and help guide the wire.