Can Any Hold Down Vac's Do Double Duty With Vacuum Bags?

[gerryv]

Does anyone know if any of the various hold-down vac's can be used for vacuum bag work as well? I'm vaguely aware that there are different types from Fein on up but have no experience with vac's - other than what the executive director (my wife) provides me practice with.

In trying to justify a larger unit than the Buddy 32, I'm wondering about using the table of a 4'x8' or 5'x10' as a convenient vacuum bag table when not cutting. I'm assuming that the ductwork and bleeder board would not be used but rather just run a flex suction hose from the vac or an extra PVC valve to the bag(s) when needed for laminates or bent wood projects.

This is far from a production volume shop so the table would not be heavily used anyway.

[Brady Watson]

Yes you can. Just add another 'zone' to your vacuum manifold if you want to use it to power your vacuum bag setup. Most vacuum power plants suitable for hold down should be suitable for vacuum bagging in most cases.

-B

[rww]

If you have a really large vacuum pump that will pull 25hg you could use it for a bag as well. I have to use a separate high pressure pump for our vacuum bagging. Most people here opt for a high volume low pressure vacuum for there ShopBot table.

[knight_toolworks]

right you need to pull far higher pressure then a fein can manage.
I went wit the diy method. used one of joe's kits and it works great.
http://www.joewoodworker.com/

[Brady Watson]

15 Hg" or better is usually good for vac bagging. It really depends on how much resistance/spring the laminate has. I've used a Fein for fiberglass bagging & it works well. I use the Fein in conjunction with a Surplus Center 26 Hg" (low cfm) pump for more demanding jobs. The Fein pulls the air out fast and gets it to 7 Hg" - the smaller pump, using a foot valve, seals off the Fein and rapidly pulls the bag down to 26 Hg".

Testing your own setup with your specific material & shape is always the preferred method of confirming if it works or not.

The Joe Woodworker kit is a good value & works pretty well for the price.

-B

[gerryv]

Thanks much guys, I know what to look for a lot better now.

[Gary Campbell]

Gerry...
To add to the above...
Most of our Vac bagging of veneers is done at 18+ inHg. Most of the resin layups were done at 10- inHg. Our pump is adjustable so it can work for both, as its max is 22inHg.

I would assume that our 10 inHg vac motors would work for the resin work, but not the veneer. So, depending on what both your bagging and hold down requirements are will be the deciding factor in whether you can pull off both with one pump, but my guess is, one or the other will suffer with one source, especially the Fein.

What has been seriously understated is how well Brady's check valve setup works. Allows use of a high cfm AND high vac source into one application. He sent one to one of our Camps a while back and I was impressed by its simplicity and effectiveness. Like he says the high cfm source can suck the back flat in a seconds and then allow the high Vac pump to suck it down tight. I cant remember if or where he posted a thread on it, but if anyone has a link, post it.

[billp]

We usually show this at Camps to explain Brady's system.....