Black Box Vac Source

I have two LH 220 vacs in a modified black box (I built it for 2 motors) and am getting 8hg with both on. I haven't sealed my bleeder board down yet but on one zone (2' x 2') I threw on a piece of 1/2" mdf just big enough to cover the zone and I couldn't move a 12"28" piece of hickory. Hope that helps, I plan on trying to put down a full sheet of 3/4" mdf this weekend and will know more then. I really hope I did everything correctly and it works :cool: but it looks like it will. I will update this thread when I have completed it.

Joe

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Originally Posted by kenkelsey

I do not have my vac gauge yet, but others using the same black box configuration have reported 8 inches with the recommended vent hole open and up to 10 inches closed with two motors. I do not know what shop vacs pull in inches, but mine is at least as powerful (if not more than) two LH 220v vacs. I should be in operation tomorrow. Sealed the plenum tonight and putting the new spoil board in place tomorrow. Will advise how it well it holds various materials over the next week. CFM is also an important.

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I checked my shopvac over the weekend and it pulled 4hg when completely sealed, its just a 4hp standard shopvac.
Attachment 24241

Allen,
Thank you, that is what I like to see on the forum. Some experiments and the outcome. I am totally new to vac hold down. When I first got my plenum and spoilboard and piping complete I hooked my shopvac to the manifold and was pulling 3hg with the zone totally covered. However, the edges of the zone was not sealed, and PVC was not glued. So your test tells ME that I was losing 1hg somewhere in the edges of spoilboard and/or the not yet glued PVC. I have the PVC glued, box done now with filter. Today I plan on hooking up the box (FINALLY) to my manifold and let her rip. Although, still have not sealed edges of spoilboard but it is interesting to see first hand the results of how much leakage can come from different parts of the puzzle.

Thanks for sharing the pic and description.

Dave

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Originally Posted by David Iannone

Allen,
Thank you, that is what I like to see on the forum. Some experiments and the outcome. I am totally new to vac hold down. When I first got my plenum and spoilboard and piping complete I hooked my shopvac to the manifold and was pulling 3hg with the zone totally covered. However, the edges of the zone was not sealed, and PVC was not glued. So your test tells ME that I was losing 1hg somewhere in the edges of spoilboard and/or the not yet glued PVC. I have the PVC glued, box done now with filter. Today I plan on hooking up the box (FINALLY) to my manifold and let her rip. Although, still have not sealed edges of spoilboard but it is interesting to see first hand the results of how much leakage can come from different parts of the puzzle.

Thanks for sharing the pic and description.

Dave

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No problem, I was kind of shocked that it was that high, considering some people are saying that the LH motors only pull 5hg when sealed. I would expect them to do much more by just looking at the stats listed on the LH website. I guess I will just go ahead and order one and put the gauge on it to see.



So i just went back and reread the first post, looks like a single LH motor will pull 10hg, so that is much better than what I get with my shopvac. I am guessing that as you add additional motors the Hg doesn't really increase, however you do get additional CFM which is what you would want for more coverage.

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Originally Posted by barrowj

I have two LH 220 vacs in a modified black box (I built it for 2 motors) and am getting 8hg with both on. I haven't sealed my bleeder board down yet but on one zone (2' x 2') I threw on a piece of 1/2" mdf just big enough to cover the zone and I couldn't move a 12"28" piece of hickory. Hope that helps, I plan on trying to put down a full sheet of 3/4" mdf this weekend and will know more then. I really hope I did everything correctly and it works :cool: but it looks like it will. I will update this thread when I have completed it.

Joe

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You have any pics or designs you would like to share? I will be building a something similar in the next 2 weeks. Do you plan on running both motors all the time or running only both when necessary? I'm trying to decide if I will need some sort of check valve if I only want to run one at a time.

Allen,
I plan on sometimes running just one vac when I am using a small zone. BUT, I don't know if you need a check valve or not. I don't know if the second motor not turned on with no check valve will cause a "leak" so to speak. Good question. Someone with more knowledge will chime in I'm sure. In my case, once I learn a little more about this stuff I think I am going to add two more motors to have 4 total. If you have the room to build the 4 motor box, consider that and just seal the other holes for now, then you can always just throw two more motors in. Just my two cents worth.

Dave

Just ordered a LH motor, gonna do some testing when it comes in and compare to my shopvac. Will post any results I find.

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Originally Posted by allen00se

Just ordered a LH motor, gonna do some testing when it comes in and compare to my shopvac. Will post any results I find.

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I just fired up my 2 LH motor box this weekend. With one vac motor I get little to no vac at the table. I believe that one vac motor may suck through the other and not give any vac at the table.

With both LH motors running I get good hold down. I did cut out cabinet parts from a full sheet of 3/4 plywood and the hold was solid even with completely cut-through cabinet profile cuts.

I have a vac gauge coming today sometime and I will advise the Hg I get with both motors running. Whatever it is, its working well for me. From other posts, I am expecting 8 to 10 inches Hg with 2 motors running.

A few notes from the sidelines:
This thread was started with the best of intentions. An effort to give information that I had gained back to a community that had helped me greatly. It was my intent to post information about a vacuum system that had served myself and a number of others well, so that it could be refined and improved upon and possibly bring users that would not ordinarily be able to afford an "off the shelf" system into the world of vacuum hold down for an affordable amount. An effort to increase their production so that they might afford a "real system".

As I have watched this thread progress, reading most of the 175+ posts over 4 1/2 years I find it somewhat disheartening to have started it. Hundreds of posts that include misinformation, attempts to commercialize the product, and seemingly endless Facebook type attaboys with no value have made the real information nearly impossible to find and sort out.

Going forward, just in case someone wants to do their homework and do a good job with this design, here are some things you may want to know:
This product was sold commercially and when a better design was in the works, the old design, in generic form (pictures, not CAD drawings) was posted to start this thread for this (ShopBot) community

I have not, and will not take credit or approve information from any posts that I have not made. This includes information, drawings or provided files of any kind.

The original design was made from Melamine. Read as stable and non porous. There was no information stating that any type of plywood or MDF would be suitable, and in my opinion are not. All vacuum chamber joints must be sealed thoroughly. This includes plumbing and plenum connections also. Vacuum is air pressure... if you don't seal it, IT LEAKS!

I didn't assume all would use an expensive digital vacuum gauge like I did, but use your heads, its like gas in the car, without the gauge how do you know what you have?

Those that "have used their own ideas" have burned up dozens of motors. Apparently no figured out that with a little adjustment the vacuum exhaust actually created a venturi effect and aided motor cooling.

The Lighthouse motors have a minimum flow requirement to cool the motors. I use a preset check valve that ensures this. A 1/4" hole per motor will also work for the frugal.

I have posted nowhere that a 2 motor setup will be adequate for a 4 by 8 table.

Since I have a financial stake in the commercial products known as the Hurricane, Cyclone and Storm vacuums currently being produced by Black Box Vacuum Solutions, Inc. I will, by agreement, not contribute further to this thread. Neither will I respond to email or PM questions concerning it or variations of it. Sales are approaching a couple hundred units, as the new design, with integrated relief valves, thermal overload and onboard fan cooling has been received very well.


I would also request that my name not be associated with any other individuals design. I have seen nothing posted here in the last year or more that even vaguely resembles the design that I had posted. Sorry for the rant, and good luck with your projects.
Gary