Vacuum Pump Fitting Question

[Jack Hogoboom]

I finally got my vacuum chuck finished. Now I'm building a veneer system based on the joewoodworker.com plans. In order to go from one to the other, I tried putting in a quick-connect fitting from HD at the pump. Unfortunately, it resulted in an unacceptable 5 Hg drop in my vacuum. If anyone knows of a way to incorporate a quick connection fitting without losing vacuum, please let me know.

Thanks,

Jack

[Steve Rowe]

Most every quick connect available at hardware stores and the borgs are not rated for vacuum. Colder Products makes quick connects rated for this application. VacuPress carries these and uses them on their vacuum pumps.

[Cecil Arnold]

Jack, I set my vac. pump up for verneering, then decided to make up a quick connect for a vac. chuck. I used the standard 1/4" air tool connects and did not notice a significant drop in vacuum. I have my vac. valve set to cut off at about 25" and have no difficulty pulling that on the chuck or a vacuum bag. One thing you may want to check, because it gave me fits, is how well sealed your chuck (the MDF) is. I finally mixed up some thinned yellow glue and smeared it all over the outsede of the MDF and it fixed my vacuum loss problem.

[Jack Hogoboom]

Cecil,

I'm definitely losing some vacuum at the chuck. I sealed it with yellow glue, but may go back and try something else. I can't pull more than 23 Hg, even right at the pump. I may need to learn a thing or two about how to screw the fittings in. :o

I used a quick disconnect from HD and could see the 5 Hg drop. I'd really like to get it to work, but don't know how. I still haven't found one rated for vacuum, although with the help of some folks here, I found a few places to look.

Jack

[Dave Richards]

Jack, I wonder if you could get hold of some Diamond-style quick connect adaptors from your local supplier of medical gases. Around here the company would be Praxair. They are normally used in medical applications and are keyed to prevent mixing connections. The one pictured is for med air--it's yellow. Vac would be white.
http://gehealthcare.com/usen/suction_oxygen/gas_fittings_con/diamond_quick_conadap/images/diamond_hose2_170.jpg

Since you would only need a couple of fittings, you might be able to get hold of them easily enough. The barbed version in the picture is easy enough to stick on a hose. You can also get them with various pipe thread ends.

There's a similar female connector to go on a hose or you could get a wall plate type of female outlet. The nice thing about these things is that they are easily serviced when needed and they are designed to seal either under pressure--med gases are around 50 PSI--or under vacuum.

It's a possibility anyway.

Oh, and if you know anyone in a local hospital's maintenance department, they might be able to help you out, too.

[Mike Swindell]

Contact Joe, something is wrong with your fittings. You'll have to spend some $$ for vac tight fittings, but losing 5 hg is alot.

[Cecil Arnold]

Jack, as a follow up, I found that I had to seal the edges of the MDF as well as the seam between the MDF and PVC that I used for the chuck body. Before I figured out that I needed to apply yellow glue I had already put calk on every joint/seam I could see, including where the faceplate joined the MDF. I also found some plumbing washers, both flat and conical that I used on the vacuum chuck (can't remember the name of it) that I bought from Packard. To make a long story longer, I didn't need the washers and most of the calk was a waste, but who knew. The quick connect (female) I got from the Borg holds 25" even when I disconnect it from the chuck, so I wonder if you may have gotten a faulty connector.

I'm currently getting ready to head out before we have a visit from RITA, but if you will PM me the first of next week I'll get some pictures of my setup and send them to you.