... of cut is difficult to measure so it's a bit of trial and error by cutting a groove and trying the rail for size, hoping I don't go too narrow! The photos show a tool I've made for a .75mm groove, as well as a stock photo of how it comes, with the holder. I've just added a photo of the gauges that particular tool has been used for, for 3mm Society code 60 BH rail. The grooves are just too tight for the code 60 FB I'm using. Cheers, Paul 105_041605_430000000.jpg 105_041606_050000000.jpg 105_041609_570000000.jpg Last edited on 4 Aug 2020 21:10 by Paul Boyd posted: 5 Aug 2020 00:21 from: Rob Manchester Hi Paul, Thanks for the info and the pics. 1.5mm bits are what I use for normal parting in my (small) lathe so will try grinding some down for this. At least brass doesn't need a top rake so there aren't too many angles to grind I have some narrow gauge projects to play with at some point that will need some gauges making. Thanks again. ...