Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Congrats on a tough job well done!

I've done similar to cone the inside of a flintlock flash hole or vent.

You may want to invest in an Optivisor as it gives you a loop for both eyes and is hands free without squinting to hold it in place like a loop requires!

https://doneganoptical.com/product/optivisor/

There are many different sources for these, like most of the standard machinist supply outlets, or even Amazon and the like. There are also quite a few knock-off copycats, but I do like the original and use it all the time!