The HO Scale NMRA Standards Gage Mark IVb provides clearances for early railroads.  In Rp-7.1  they provide additional clearance recommendations for a modern railroad from 1983 on.  At one time the NMRA offered a gage extender for the modern clearances, but it is not currently listed in their online store, and a search of several vendors failed to turn one up.  Searching the MRH website there are several mentions of the extender

Just tweaking my CNC router abilities before I tackle that stone arch bridge that I promised a fellow on the forum. The design, print and cleanup of this building flat took just about 4 hours to complete. Not terribly bad, but a lot of that time was spent getting my z axis to go to the proper depth. A glitch in the code seems to double the output of the cutter from what I put in. Anyway, lemme know what you think on the first building face cutout.

This is meant to be a resurrection of a missing piece of the past that I have missed.  It is a place that gives someone’s Ah Ha without using words.  It is shamelessly reused from the same name used in a popular magazine of my childhood (just after the paper and ink discovery....) and recent past when electrons passed the ideas.  I’m sure you all have a trick or tip that would take a couple pictures to pass on without words.  Let’s have at it!

It's another week . . . post 'em if you got 'em.  There were a few late-comers in last week's post.  Check them out, then come back here afterward.