Yet another Black Box style vacuum box

[ryanjg11]

After pouring through some of the more popular Black Box vacuum box designs, including Gary Campbell's original thread and the SimpleBox from Josh Beckmann, I reached out to Ward at Lighthouse Enterprises who recommended using four Ametek 122178-18 8.4" 240v motors. While a bit bigger and more expensive than the Lighthouse brand LH-7123 motors that have been widely used for these applications, he markets the Ametek motors as having 3x the brush life.

Like many, I have found it difficult to find detailed plans for the box design. I'm setting out to create the box in parametric CAD and will be offering detailed DXFs and BOMs in the near future.

Below are some renderings of my early prototype--subject to much refinement. I'd like to solicit feedback on this design, identifying any issues with the design now, before I move on to designing a final box.

Some notes on this design:

• The renderings below are not complete. They lack many electrical components such as contactors and a mains plug. That will come in my next iteration.
• Overall size is about 41" long by 18" tall by 15" deep. Constrained by the size of the 8.4" motors. Cabinet made of 18mm baltic birch plywood because I have plenty on hand.
• Four pair paths: one for vacuum inlet, which will be carefully sealed; one for the exhaust which runs above the vacuum inlet; cold air escape aided by push/pull fan configuration on the sides; and cold air inlet for each motor on the back of the box. Ametek requires cold air intake and exhaust be isolated. Fan grills and filters used throughout.
• Motors will be controlled via a 3-position switch: OFF, 2 ON, 4 ON. The louvered door in the middle of the vacuum chamber opens only when all four motors are turned on, otherwise only the two vacuums closest to the inlet will be turned on in two-motor operation. I'm not certain if this louver will work; I might need to time the motor activation carefully so that the motors opening the louver start first. What do you think?
• No plumbing modeled yet, but it will be the traditional 3" PVC manifold with 4 knife gate valves, reducing down to 2" PVC going to each of the 4 vacuum table zones.
• Haven't added a vacuum gauge yet, but that will certainly be included in the final design.
• There is very little noise reduction in this design. I may add acoustic sound dampening foam to the walls the exhaust port, TBD. I'm not too concerned about noise as I expect to be wearing hearing protection at all times when the CNC router is running.
• The back panel is on a piano hinge and corner draw latches, designed to open backward in the event of service or motor replacement.

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[ryanjg11]

Here's some more renderings (ran into the five image limit per post).

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Looking forward to your input!

[evan]

Looks good! Nice renderings. "I'm not certain if this louver will work; I might need to time the motor activation carefully so that the motors opening the louver start first. What do you think?" I like the idea but also not certain it will work, the pressure on either side of the flap valve is going to be equal with all 4 vacuums running. A simple solution would be a manual Gate valve. Just my 2 cents

[ryanjg11]

I like the idea but also not certain it will work, the pressure on either side of the flap valve is going to be equal with all 4 vacuums running. A simple solution would be a manual Gate valve.

Duh! I think what would happen is the louver would open, pressure would equalize, it would close, open again, repeat endlessly. A single gate valve is definitely the right solution here. Thanks.

[tuffduck]

What software did you use to create the modeling? Very well done. I second the idea of a gate valve. I am designing a simple one for my build.

[EricSchimel]

Instead of the flap in between the two chambers you could use blackflow valves. That's what I did on my build. This allowed me to use any of the motors at any time. The image below shows my box sitting on it's back before I installed it:

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In fact, if you want those valves I'll sell them to you. I just pulled that box out of service. Which leads me to my next bit of advice: I don't think wood boxes are the best choice for a material for these. The motors get very hot. I had mine enclosed similar to how yours are. I even vented them. Ultimately I had to pull the back panel off of the box to keep the motors from baking.

My box had a cool baffled muffler system in it too, and it did knock down quite a bit of noise, but they were still loud.

When these motors fail, and the absolutely will they often times will spark, in fact when they start up, like most brushed electric motors they spark.

After a couple of failures I decided that it's not safe to run these in a wood box. I ultimately decided to buy the Black Box Hurricane. It's made out of all metal and it's well built. It's also much quieter than what I built, and has an intake filter.

I'm not saying don't pursue this, but I'd be pretty weary of any flammable/wood material. The Black Box seems to be about the best thing you can get that isn't a commercial vacuum system.

[ryanjg11]

Thanks Eric, good advice. I'll PM you on the backflow valves.

[dlcw]

Eric,

That's one EXPENSIVE solution (Blackbox Hurricane). I was really intrigued when you mentioned it in your post, but lost interest when I saw the pricetag.

I built my black box using white melamine from Gary Campbells original design. I've gone thru three of motors in 9 years. I use the Lighthouse 220VAC motors. I have a filter on my intake side and use a simple table top fan to blow air at the filter. I've got vacuum bleeder valves I can open and close depending on how much additional airflow I need into the motors to keep them cool. When I get time, I'm going to move the black box to a different room to cut down the noise. The motors are LOUD, especially when I turn on all 4. I'm at an altitude of 2500' so pulling the levels of vacuum that other people get, at lower altitudes, is not possible for me. But it works really well.

When cutting smaller items, I use a 1" thick piece of MDO that I've cut slots slots into and mounted T-tracks. I use homemade clamps to hold the workpiece down. The MDO is held flat and secure by the vacuum hold down. When cutting plywood (95% of what I do) for cabinets, I use a 1/8" thick piece of MDF and put the plywood on top of that. This way I never cut into my spoilboard. I only surface my spoilboard at the beginning of each cabinet project to make sure the table is perfectly flat. Same thing for long 3D carvings using the MDO to hold the material. I replace my spoilboard about once every 2 years.

Would love a quieter, all metal black box, but at the price point I think I'll stick with my home made one. Thank you Gary Campbell for the design!!

[EricSchimel]

I guess what one considers expensive is a matter of perspective. For me it's a deal when compared to a regenerative blower that's 3x (or more) in cost. As someone who burned a lot of time fooling around with my own design, when it came time to replace it I was glad to have a reliable, and most importantly SAFE way to continue to do vacuum hold down.

For me safety was a concern, also not wasting the time engineering something that someone else clearly put a lot of time and thought into. It shows, that thing does exactly what it's supposed to.

Interestingly though, it's now the weakest point in my system. I've upgraded my drive system and my spindle to an ATC. There are certain jobs that I could cut way faster if I had better vacuum, but it's not enough production work to warrant spending on a commercial vac system. The ATC and drive system definitely was. I make more profit on every job because of those.

So, to me personally this was a great buy, and this is coming from someone who loves to invent their own stuff I augment it with a Omer composite nailer to for fast hold down (I love that thing)

[dlcw]

You're absolutely right about upgrading to the ATC. I did that last year. Took awhile to get it working but what a huge difference in cutting time and no longer having to change bits. The greater horsepower (5hp versus 2.2hp in my old spindle) is huge. Spindle never bogs down.