New to me Vacuum Pump + Bag - VLT 50

[Phillip Mitchell]

This has been “on my list” for a few years now. I apprenticed in a custom woodworking shop for ~5 yrs early on and they are liquidating some equipment and tools and gave me first dibs on the selection. The main result of this aside from lumber is this vacuum pump, bag, platen setup.

I have long wanted to get into doing my own veneer layups for sheet goods in certain projects and this will help with that goal. Also excited to have it around for laminating, etc solid stock in those oddball scenarios when you might not have the right thickness material on hand but have enough thinner stock to laminate. Also curved, contoured laminations in a form could also be a direction I go with this setup.

VLT 50 (1/4 hp, 4.6 CFM) pump, 54” x 12’ poly bag, and a few mdf/melamine platens - 1 is 24” x 48” and the other (not pictured) is 4’ x 8’.

The VLT has vacuum pressure adjustment via a screw/valve on the front panel. What are some resources that would tell me more specific details about when and how to take advantage of that with different thicknesses, adhesives, shapes, etc?

[Jim Becker]

My opinion...you want as much vacuum as you can possibly draw for glue-up and lamination processes, so I see no need to vary anything for your intended purpose. Be sure you have a vacuum gauge on the system, both to know what you are getting as well as to be able to monitor for vacuum loss so you can decide if you need to leave the pump running or if you can give it a rest and learn for how long.

[andrew whicker]

Vacupress's forum is pretty good. They also have a few videos that really helpful.

You can call the owner directly and ask questions as well.

[Phillip Mitchell]

Thanks Jim. Good to know.

I tested it briefly before loading it up at purchase time and it was pulling -25 " HG / ~ -80 kPa consistently with its current settings. It's supposed to have a sensor that auto shuts off at a certain pressure and then auto start to maintain, but haven't gotten that far yet in assessing the unit.

[Patrick Varley]

I'd check out JoeWoodworker/VeneerSupplies. Great source of info (and supplies).

I'm just a novice, but as Jim said I've found that "as much as you can get" generally works. The only time I dial down the pressure is when using porous veneer (like burls). Helps minimize bleed through...though there are other options to control that, as well.

[Warren Lake]

im sorry but Austin Powers ruined me. I have a vac machine from a dental clinic I think used it making molds. No auto shut off, it cant pull the 27 but close enough. Its amazing what they can do and that its even possible.

[John Kananis]

Nice score! And those poly bags are so much better than the vinyl. Enjoy.

[David Stone (CT)]

I second the recommendation to check out the forum at vacupress.com. It's not very active day to day but there are thousands of posts archived over the years covering almost every topic in this specialized corner of woodworking -- and the company owner generally answers most or all questions posted with his expert knowledge. I found it super helpful when I got a vacuum bag and pump.

[Kevin Jenness]

One scenario calling for low vacuum levels is when laminating honeycomb paper core as the glue can soften the card stock in the initial pressing. Otherwise the maximum reasonably available is usually called for. I think you will find that the bag will develop pinhole leaks over time and the leakage will cause the pump to cycle more frequently, perhaps annoyingly so, and you may decide to turn the pressure down a bit. My system currently runs between 21-23" hg and works fine for my purposes. If you can get 25" in practice that's excellent.

My Gast rotary vane pump can run continuously without issues, but I did run into an overload situation with a Vacupress pump with a cover like yours. With a leaky setup and the pump on for a couple of hours it overheated and shut down. It might have been fine with the cover off or with a fan, but beware. You really don't want to lose vacuum before the glue kicks.

There are different ways to lay up the material. I have always used Daryl Keil's method of a waxed 1/4"melamine cookie sheet under the work and a similar platen above. The lower platen aids in sliding the work into the bag but it can be a struggle to keep everything aligned, thus the popularity of frame presses. The upper platen presses out any ripples in veneer, and is not really necessary with thicker stock except that it is easy to soften the platen edges to protect the bag. You don't want any sharp corners, although the polyurethane can put up with that better than vinyl. You can get patch kits from Vacupress.

When laminating curves beware of form implosion. Any hollow forms inside the bag need to be thoroughly braced in all directions. Sometimes it's easier to just put the laminates in the bag and bend them over an external form.