I am replacing a very similar set of door handles with these :- https://www.screwfix.com/p/era-door...Vl813Ch3xYAqSEAQYAiABEgJa0fD_BwE&gclsrc=aw.ds The positioning of the screws is ever so slightly different on the old set (out by a few mm) so I also have to replace the latch with one that fits the new handles. (But not the one that came with the kit because it is too short). The problem is that the old latch was ever so slighty narrower than the new one - if I force it then it will almost go all the way home, but not quite. I wonder if it's an imperial to metric type difference? (The old set are probably at least 40 years old). What is the best way to widen the hole for the latch by 1 or 2mm?
Stanley knife. Just cut down to widen. Sometimes you need timber bead to tap in holes then drill if they don't line up. Run a 22mm or the new 25mm type drill down hole if that needs widening for latch
If you clamp another piece of wood on doorstile then drill hole to correct size you should be able to open hole up
The tolerances are too tight in this instance but you can often nest one holesaw into a larger one to overcome the fact that there is no substrate remaining for the pilot bit. I've done this many times to enlarge a hole.
I'm puzzled a bit. Sounds to me a 22mm latch hole but you need to make it 25mm? https://www.screwfix.com/p/erbauer-auger-wood-drill-bit-165-x-25mm/1322v Then these to hold handles on. Screwfix don't sell M3 Door Handle Fixing Screws Use for Door Handle Roses Knobs and Escutcheons 4Pieces https://www.amazon.co.uk/dp/B07Q2N8QRL/ref=cm_sw_r_apan_i_SGAEBYNE289F3JPJBAER?_encoding=UTF8&psc=1
I have all the hardware I need now - the latch is 26mm diameter according to the spec below and I am sure the previous one would have been 1 inch - so a 0.6mm difference - just enough to make it too tight. https://www.e-hardware.co.uk/adjustable-latch-90mm-100mm-backset.html I have had a similar problem in the past and used a spade bit to widen the hole - but it bounced around everywhere and didn't feel safe or accurate - so looks like the auger is the way to go.
You could just chisel it out, it’s probably easier and less chance of tearing a chunk out with an out of control drill bit