WOOHOO! Good weather = time to build

[nachoman]

It's sometimes bad luck if a wheel set that is at the very min/max side meets a turnout that is at the opposite min/max side. In that case the NMRA gauge may fail because both components are marginal within the specs. I use my digital caliper in such cases.

That is usually what I find. Most of the cars make it through fine, but one wheelset is a little out of gauge. The reason it doesn't derail at all the turnouts is because that one particular turnout is also a little out of gauge. You may have one wheelset *slighty* wide and one turnout *slightly* narrow. All wheelsets that are exactly in spec will make it though the turnout okay, but the one wheelset that is just a tad wide will have problems.