These tubes taper 0.005" from start to finish. Leaving between 0.020" and 0.025" for Honing.

I always enjoy seeing your set ups. The serrations on the edge of the tubing to cut the wood to fit the bore is brilliant. Thanks for taking the time to share. Craig

My hat off to you David for keeping such a tight tolerance on long tube. You should be called a magic man for sure. Nice

I liked the way a wooden semicircle was placed to absorb vibration, thank you and wish you well.

I like the ambient steampunk sounds from 1:54-2:30. Your huge shop amazes me

I bet this shop is really liking you, its hard to find experienced machinists that really know what they are doing.

Very impressive. Love that set up.

Very nice and sturdy boring bar.

wao amazing work sir. love from Pakistan

Ahh - the wood trick again :). 5 thou tolerance is quite something to shoot for on work that size.

Hola ....quería comentarle que el sistema para perforar barras grandes es impresionante .....gracias por compartir sus conocimientos.....

Nice. We used fixtures that slipped into prepped bores to secure the first 5 ' of a 17 ' boring bar and a tool located roughly 6 ' back. With this I could cut 300 on the diameter, taking about three-quarter of an inch in two ( knock on wood ) passes. We'd leave about 50 thous for honing on a 122" x 7.775" bore. Man, those Sunnen 210 would scream something fierce while ripping out the stock to a +/- 0.003 tolerance. Great fun.

I've never seen that trick, using a self sizing block of wood as support/guide. Very neat.