Originally posted by bobwells
have you tried any adapting do it yourself for using nikon lenses on pentax m-42?
For M42, no. For Pentax K-mount (PK), yes. A Nikon AI or AI-S lens has two bits of metal extending from the aperture ring, what I call the "nub and arc". I use a dremel metal-cutting blade to cut those away, then smooth the bottom of the aperture ring. The lens can now be force-fit onto a PK mount. If you want a more secure fit, you can cut a small slot for the camera's lens-lock pin to fit into. I have so modified a few N/AI lenses.
I am very sure that a modification to M42 mount is not possible, not without MAJOR surgery. The inner diameter of my thinnest M42 ring is 39mm. The inner core of several Nikon-mount lenses I just measured is about 40.5mm. It just won't fit, not without machining-away some of the lens core. I am not about to try that!
Good luck.