On Sunday 09 October 2016 01:22:28 MC Cason wrote: > Gene, > > Unless you have a good air dryer, a couple of psi of compressed air > will cause more problems than it's worth. On a rainy/humid day, > compressed air will be wet with water. The bellows will trap the > water, and raise the humidity level around the ballscrew, which will > cause premature failure, due to contamination of the lubricant, and > corrosion. > > A cheap water separator will get part of the water out, but nowhere > near all of it. A coalescing air filter can get most of the water > out, but they are expensive, the replacement ceramic filters are > expensive, and they require fairly constant inspection. They are used > in paint shops as a final filter before the paint gun. > > Why not use a passive way to allow air in and out? You will still > have a problem with humidity, but it will be less than with compressed > air. https://amzn.com/B003Q6CBNY > https://amzn.com/B008OTNGXC
In terms of either passive or thru flow, I have a small filter full of color phase changing silica gel that I use in front of my air brush when I've air brushing a cabinet finish. I wonder how one of those would work as an inlet air dryer? They aren't that expensive, and I've baked this one out in the microwave several times after it turned pink. It takes several days of active use feeding the air brush with just enough air ( 7 or 8 psi )to lay on a 3 part finish similar to Sam's (Sam Maloof) Stuff except I don't use boiled linseed, but teak oil as the 3rd part. Dry's dust free in a couple hours. > BTW, airplanes use air filters that look like fuel filters. Maybe a > cheap fuel filter for a lawn mower could be tested to see how well it > would work as a vacuum break? Attach a hose to the outlet end only, > leave the inlet open to free air, and connect the hose to wherever you > were planning on attaching your air hose. Depending on use, the > lifespan would be on the order of months, but they are cheap, and easy > to replace (Unlike an airplane). True about cheap, good particulate stopper after the desicant treatment maybe? Going back to my broadcasting experience, we tended to frown on the desiccant to make dry air. 10 years later you can tell the diff between dry air for the 3 psi or so pressure in the transmission lines to the antenna. Dry nitrogen is the real stuff, copper is still bright and shiny on the inside after 20 years, but thats north of a hundred dollar bill for a t2 sized refill. Leakage there will cost real money. But plain dry air should outlast both me and those bellows. As for the source of the compressed air, I am inclined to put a cig lighter compressor in, switched on by a furnace draft safety switch running a relay big enough to run the compressor for 3 seconds an hour. Or something along those lines. It won't run long enough or at a high enough pressure to squeeze the water out of the air, and that dessicant cartridge should catch 90% of that if the humidity goes to 100%. I have a humidity monitor out there, and can't recall ever seeing it above 77% when it was pea soup fogg y outside. This is in a heated and air conditioned environment. Thanks MC Cason. I guess I'll just have to try it and see how often the compressor runs to get an idea how leaky the bearing seals are. Not knowing, I won't shoot for any more pressure than it takes to keep it full of dry air. > > This is what a Cessna vacuum air filter looks like (NOT cheap): > http://www.aircraftspruce.com/catalog/inpages/Inline_airfilter.php Doesn't look that expen$ive. > On 10/08/2016 10:11 PM, Gene Heskett wrote: > > Greetings all; > > > > Does anyone know it the end bearings that come with a C7 grade > > Chinese ball screw are neoprene seals or just very close fitting > > dust covers? > > > > I am attempting to come up with a SWAG as to how much leakage per > > hour there might be with 1 or 2 PSIA inside the bellows. The dust > > cover versions I expect the pressure would just drive out the lube > > in a few days is it was high enough to stiffen the bellows > > noticeably. And I'd expect I'd better fit a t so I could rig an oil > > filled vinyl manometer tube off it. Something like RCA did to > > monitor the air pressure across the anode fins of the high power > > tubes they used in the '60's comes to mind. Anything below 14" was > > time to clean things, blowers and filters first. > > > > Cheers, Gene Heskett Thanks everybody. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
