Try not to reinvent the wheel...Size your zones to the size panels you mostly cut. I would do 7 Zones:

1) 24x24"
2) 24x24"
3) 24x48
4) 48x48
5) 12x96
6) 24x60
7) 24x60

This combination will give you the ability to hold down a 2x2', 2x4, 4x4, 4x8, 5x8, 5x10, 5x12 by just turning zones on or off.

6.6 Hg" isn't a lot to work with. You would need a min of 4 Fein vacs to do anything for real and probably more like 6. Lighthouse motors are another option & cheaper.

Small parts with the Fein? I wouldn't count on it unless you are an expert on vac hold down...However there are ways around this. Look for my 'Vacuum Film Technique' on this board.

Remember - there is no replacement for displacement. The aspiration here is limp along using the Feins and other 110v solutions until you can afford a real vacuum pump made for production. This was the idea behind the Lighthouse vacuums - just a bandaid...so keep that in mind. There are no 110v (or 220v single phase) solutions out there made for production duty...so expect whatever you are running to die. Not to be all doom and gloom...but I call a rose a rose.


Knuckle Dragger's Guide to Vacuum Math:

In an ideal world, you would get 100% of what your vacuum was capable of delivering and have zero leakage from your setup. In the real world, this never happens...so trim your numbers off a bit.

The entire weight of the atmosphere is holding down your parts when you apply a perfect vacuum to it - In this case, 29.92 inches of mercury (Hg") OR 14.7 pounds per square inch (psi). These two are equal. If you live up on a mountain, you'll have less pressing down. In Death Valley, you'll have more.

You need to ask yourself if the surface area of your part at a given vacuum value results in enough pounds per square inch of hold down to resist the cutting forces of the router. If it isn't you can cheat by selecting a different tooling profile (downcut, straight) or by cutting with a lighter chipload, with more RPM and/or slower speeds.

If a 12" square is to be cut out with a total available vacuum of 6 Hg" (we'll take off 10%, very optimistically) The calculation is as follows:

12x12 = 144 square inches

6 / 29.92 Hg" = .200 X 1 (14.7/29.92 [these are equal so they represent 1 as a conversion factor to psi]) = 2.94 psi

Total hold down on part = psi value x square inches

144 x 2.94 = 423 total pounds of down force

As the part approaches 0x0" in size, the law of diminishing return comes to play. You aren't going to hold a 1" square down with 2.94 psi - so there comes a point where vacuum just isn't the right tool for the job, or you need to combine methods to make hold down reliable. Furthermore, you need to account for when your cutter breaks through the sealed off material and exposes the cutting kerf where it meets the bleeder board. The surface area of all kerfs can add up quickly and your part hold down will fail in the middle of the job. Gotta small vac? Program for turning on/off zones as you machine, when it is practical. It sucks...but take a portion of your profits and save for a pump. It's a nice luxury when you've been doing this stuff for a while.

Good luck - search this forum. I've dispensed countless tips and tricks involving vacuum over the years and so have others.

-B