Buddy of mine brought over his system yesterday for me to try. Pretty amazing, and different in one critical aspect from all the ones I have read about. He has an empty propane tank between the pump and the rotating adapter on the headstock! The vacuum from the tank provides the stability and the pump just motors away to keep the tank up to the proper level. When the elec. power goes off, frequently here in VA, the work piece stays solid until the lathe is turned off and the valve shut. So, you get to catch the piece at zero airspeed vice 100 kts, thanks to the brilliant engineering of my friend Bob Wilkes, MIT '55 & '56.
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Vacuum chucks
- Thread starter pfduffy
- Start date
That's a great safety tip!
Potential Problems
I can forsee about 3 potential problems from this set up -
1) Just because a tank can hold pressure does not been it is vacuum safe and will not implode. I would need to check the specs on propane tanks to make sure they can take vacuum safely.
2) I would be very worried about someone using a tank that has a residual of propane left in it and blowing up or burning down a shop.
3) The new tanks have an internal safety valve to prevent overfilling that may cause a problem with this usage.
Just items for thought!
Wilford
I can forsee about 3 potential problems from this set up -
1) Just because a tank can hold pressure does not been it is vacuum safe and will not implode. I would need to check the specs on propane tanks to make sure they can take vacuum safely.
2) I would be very worried about someone using a tank that has a residual of propane left in it and blowing up or burning down a shop.
3) The new tanks have an internal safety valve to prevent overfilling that may cause a problem with this usage.
Just items for thought!
Wilford
Seen the reserve tanks used in vaneer presses where the vacuum is pulled and maintained over night, but it would seem to me that in a power failure the lathe's going to slow down and stop before the vacuum will bleed away enough to release the bowl. In my cave (basement shop) I'm more concerned about stumbling around in the pitch dark when the lights go out.😱 Still, that extra vacuum volume could make the system more tolerant of leaks or porosity in the wood. I've got a few of those old grill tanks kicking around after the propane guy wouldn't fill'em anymore, have to see about hooking one up.
Good idea, Thanks 😀
Good idea, Thanks 😀
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Wilford Bickel said:
Wilford,
You'd have to remove the gas valve anyway to set up for vacuum pipe fittings so any gas in there would be gone. You would also do well to rinse out and check the interior anyway to make sure you don't have any rust or flaking paint in there. Run some rust flakes or paint chips into your vacuum pump, and you can start looking for a rebuild kit or a new pump. Unless it's really rusted or damaged, a 20lb steel tank should work just fine without imploding.
Mark
Agree
Mark,
I had been hauling hay all evening so my comments were tired and short. I agree that the steel tank SHOULD be able to hold but if not checked for damage/rust could be a source of an implosion. I was told that the reason they changed tanks a while back was because of the number failing recertification on pressure testing! I was worried about someone not taking out the valves and trying to use an old regulator hose hook up and connecting to a tank with residual gas - big bang theory in action!!
Years ago when a Chief of a Volunteer Fire Department we made pressure regulating manifolds out of 6 inch and larger pipe about 2 feet long. Capped at both ends and fittings welded in these worked great for regulating pressure changes when nozzles were cut on and off suddenly - the theory on the tank is sound providing the tanks are inspected, cleared of gas and properly connected. I learned long ago not to rely on our species using good common sense when they get in a hurry!! 😉
Like you, my lathe would stop long before my vacuum came off of my system. What my power company does to me is a quick off/on cycle that has my lathe slowing and then starting suddenly. You learn to pull your tools back from the piece in a hurry after the first time!
Wilford
Mark,
I had been hauling hay all evening so my comments were tired and short. I agree that the steel tank SHOULD be able to hold but if not checked for damage/rust could be a source of an implosion. I was told that the reason they changed tanks a while back was because of the number failing recertification on pressure testing! I was worried about someone not taking out the valves and trying to use an old regulator hose hook up and connecting to a tank with residual gas - big bang theory in action!!
Years ago when a Chief of a Volunteer Fire Department we made pressure regulating manifolds out of 6 inch and larger pipe about 2 feet long. Capped at both ends and fittings welded in these worked great for regulating pressure changes when nozzles were cut on and off suddenly - the theory on the tank is sound providing the tanks are inspected, cleared of gas and properly connected. I learned long ago not to rely on our species using good common sense when they get in a hurry!! 😉
Like you, my lathe would stop long before my vacuum came off of my system. What my power company does to me is a quick off/on cycle that has my lathe slowing and then starting suddenly. You learn to pull your tools back from the piece in a hurry after the first time!
Wilford
Cutting edge, conceptual threads like these keep me racing back to read whats written next in here. Thanks for sharing this--I think its a fantastic idea. Ive got 2 old tanks in the garage that my wife and I were just trying to figure out how to dispose of them...
Thanks again for this, and all the other great threads in here.
Warmly,
Jeff
Thanks again for this, and all the other great threads in here.
Warmly,
Jeff