Vacuum pump questions....

[Brian Lamb]

Thinking about a 4x8 CNC router with a vacuum table. I'm somewhat limited on electricity and notice that a lot of units are 12-20 hp for the vacuum pump, and three phase. So given I'd have to use even more amps to convert to three phase... how big of a vacuum pump is really necessary to hold a piece of sheet goods down on the table sucking thru the spoil board?

I see pumps from 5hp and up, so what's the consensus of opinion?

[Leo Graywacz]

Totally depends on how small your parts are going to be. If you are cutting cabinet sides and parts which are fairly large sq ft wise then a lower HP pump would be fine. But if you are making smaller parts, less than 1/2 sq ft then you need to go larger. Usually the pumps are pulling through an MDF spoilboard which has its top and bottom faces sheared off so the vacuum can get through.

[Brian Lamb]

Yes, cabinet parts, so 12" x 10" might be the smallest for a narrow box top or bottom, most parts larger than that.

[Ross Moshinsky]

Look into the "Black box" vacuum setup. You can either DIY or buy via a company. It requires 30A 220V in order to run 4 motors.

[Jerome Stanek]

I have 2 Fein vacs that work good. The Feins have an after cooler to keep the motors cool. Also way quieter then the Black box and runs on 120 you could get 4 for the same price as a black box

[Brad Shipton]

It is going to depend a bit on the machine. If you going with a big industrial machine where you want to use 1/2" diameter bits at 1000ipm or so, then you will want a pump that will give you something like 20" Hg or higher with an open CFM of something like 200cfm or more. That will start at around a 10hp pump. If you are going with one of the smaller machines like many of us have, then the black box vacuum is a very good fit. The nice part of these is they have a high open flow (400cfm or so) and low electric demand. The downside is the vacuum level max's out at around 10" Hg.

It will also depend on what you will cut the most. If you envision lots of MDF, or melamine, then the black box works wonderfully. With perfectly flat stock it does not take much vacuum. I have cut 1/2 melamine sheets with 1/2 the table uncovered (being lazy) where the vacuum has dropped to as low as 6" Hg and I was still able to cut stretchers. I do tend to use an onion skin for a final pass, so that helps. When I try cutting pre-finished Birch that has a small bow, I have had a few problems now and again with the stock bowing up after the cut.

[Brian Lamb]

Thanks for all the information. I will research the black box idea and see what I can come up with. I found an older thread with more details too, so that was helpful. Looks like a much better way to go for a relatively low volume use and a lot easier on the electricity meter.

[Jerome Stanek]

One other thing with the Fein vacs is that when I run both I can still carry on a conversation

[Jim Becker]

The Black Box Hurricane is a popular vacuum setup for 4x8 machines, especially those that don't run at super high speeds, etc. They are reasonably priced, too. Do keep in mind that because they use "vacuum motors", there may be some occasional maintenance and need to replace one or more of the motors as they do wear out. But for a machine that's not going to be high volume production where you want the utility of vacuum hold down for sheet stock, it can be a good solution. The fact that they run on 240v single phase is also an advantage to many small shops. They do have occasional sales, too.

[James Biddle]

Brian, I've got a ShopSabre F4 vacuum pump for sale and I need a big square and a parallel fence for the slider...

[Brian Lamb]

Hi James,

Contact me at blamb11 at cox dot net and we can discuss that. Shipping might be a killer...

[Jim Becker]

Brian...good excuse for a "recreational field trip". :) :D

[Brian Lamb]

From AZ to MI? My old butt can't handle that sort of drive any more. And cold weather/snow and my wheelchair don't mix...

[Jim Becker]

From AZ to MI? My old butt can't handle that sort of drive any more. And cold weather/snow and my wheelchair don't mix...

Makes perfect sense, Brian. Hopefully, you'll come up with a reasonable shipping cost with a bit of shopping around.

[Mark Bolton]

Late to this. Black Box F4 style here as well. As long as parts arent pourous down to 8x8 is reasonable with conservative cut strategies. No one is going to try to plow a 1/2" cutter single pass and be asking about conservative vac hold down. Your in the 50HP of vac range at that point if you want any kind of reliability.

Im not selling the F4 but for us personally running full sheets of ply or melamine we run all day long with only 2 zones energized. Thin/small part in MDF not so much. All four zones and even some zone isolation but the F4 has been a winner for me. But we arent processing 150 sheets a day and running our machine wide open at 600IPM while I always wish for faster, is plenty fast enough.