pert:
You could also consider using a hot knife cutter...
Heat will leave a bulb on each end. Which is likely to be undesirable.
Unless there is tension on the filament when cut. In which case a tapered thread will be left. Which is likely to be desirable.
Too much heat turns the filament into slag. Which is always highly undesirable. The heat has to be controlled (a big "no" to a simple soldering iron).
An angled cut leaving a slight taper would be a good choice.