Forrest Addy
Diamond
- Joined
- Dec 20, 2000
- Location
- Bremerton WA USA
I doubt you'll ever have application for trepanning, boring, and reaming through solid stock to make sleeves, hollow shafting, pressure vessels, cylinder tubing etc but this guy in his videos demonstrates several techniques adaptilble for work on a smaller scale. The presenter doesn't talk much so a viewer has to look sharp for nuggets of usable information.
The few times I've used packed bits for boring deep holes the wood bearings had to be turned to size separately. What goes unremarked is how he sizes the wood support bearing for his boring bar. It's quite a simple trick. He's left the stock face as-sawn and indented several facing teeth (like file teeth) with a cold chisel held at an angle. These teeth face off the slightly oversized end grain hardwood block as the bar feeds into the cut. This automatically sizes the support bearing, centering the bar in the cut and providing radial resistance opposing the cutting forces.
This is much the way I learned the technique from Bill Polhamus and Dick Perkins when I was an apprentice in 1963 and the very last ever PSNS made fully machined propellor shafts were being trepanned, reamed, etc. This was on a much larger scale of course, the shafts were to transmit 60,000 HP at 230 RPM for the USS Sacremento AOE-1. The shafting was 23" OD with 44" dia flanged connections 8" thick hollow, with a 13" reamed bore. The longest shaft was 55 feet and had the propellor taper. What I can't recall is how the 7" dia x 7 ft long bore through the propellor taper bottle necks out to merge with the reamed bore.
YouTube
This fellow has many videos all pretty much the same but scattered among them is much information including how to DIY trepanning tooling. Enjoy.
The few times I've used packed bits for boring deep holes the wood bearings had to be turned to size separately. What goes unremarked is how he sizes the wood support bearing for his boring bar. It's quite a simple trick. He's left the stock face as-sawn and indented several facing teeth (like file teeth) with a cold chisel held at an angle. These teeth face off the slightly oversized end grain hardwood block as the bar feeds into the cut. This automatically sizes the support bearing, centering the bar in the cut and providing radial resistance opposing the cutting forces.
This is much the way I learned the technique from Bill Polhamus and Dick Perkins when I was an apprentice in 1963 and the very last ever PSNS made fully machined propellor shafts were being trepanned, reamed, etc. This was on a much larger scale of course, the shafts were to transmit 60,000 HP at 230 RPM for the USS Sacremento AOE-1. The shafting was 23" OD with 44" dia flanged connections 8" thick hollow, with a 13" reamed bore. The longest shaft was 55 feet and had the propellor taper. What I can't recall is how the 7" dia x 7 ft long bore through the propellor taper bottle necks out to merge with the reamed bore.
YouTube
This fellow has many videos all pretty much the same but scattered among them is much information including how to DIY trepanning tooling. Enjoy.