Vacuum system evolution

[beacon14]

Here's my latest contribution to the art and science of vacuum table engineering. I started with a goal of not using any PVC pipes or valves but in the end decided that maybe in moderation I could live with a little.

This system was designed and installed for a new friend of mine in St Augustine Florida. The shop-made valves allow for 3" PVC risers for each of the eight zones. We automated the valves, which use spoilboard cover from All-Star as gasketing in both the open and closed positions, using low-voltage actuators. All he has to do to open or close a zone is flip a switch. We made this system for two Fein vacs but it could be modified for any vacuum motor(s).


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the videos show it best

http://www.youtube.com/watch?v=Jlv8w-0ZIKw
http://www.youtube.com/watch?v=fcXeoXTPAAc
http://www.youtube.com/watch?v=_z153yQ855A

[cip]

Really nice pattern Dave does it make a diff. in the hold down?

[knight_toolworks]

pretty cool though a bit overkill I think (G)
whats wrong with pvc? airflows best in a round tube.

[Gary Campbell]

David...
Great Job!!! I agree with trying to minimise the plumbing. How does the hold down compare to your rectangular plenum grid?

Steve...
Using these low pressure vac motors dont give much room for wasted vacuum. Even the smoothest pipes restrict flow, and a 90 degree PVC elbow is equal to around 12 feet of pipe. Every fitting or valve adds turbulence.

When you start with around 7 inHg, lose 2 to 2.5 in thru a spoilboard, the systems needs all the help it can get to recover from open areas resulting from cutting thru. These "cut thru's" can reduce vacuum another couple inches or more. As these occur, flow increases. That is exactly when we need our systems to be as efficient as possible.
Gary

[br928]

David,

That's very cool. What type of low-voltage actuators were used and where did you get them?

And Steve,

Overkill? What's that? I personally represent that statement!

[knight_toolworks]

yes I sometimes do too (G)

[Gary Campbell]

David...
Here is another option for those who want to automate vacuum switching on their table and have air available.

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This is a Valterra Valve (ABS Version) with a 2.5" air cylinder attached. These valves have very nice rubber O-ring type seals and work easily even with 30# of air.

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I am showing the small toggle switch that I used to control it for testing, but could easily be controlled using a switch or from the control software with valves like this:

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You can also make extensions for the actuator rod on the valve that would allow you to operate them from any side of the table. This would allow all valve handles to be on one side of the table for convenience. You could save some bucks, but not have anywhere near as much fun!
Gary

[beacon14]

Thanks Gary, if I had known about those I might have used them.

Gary has the right idea, the manifold system looks complicated but I was actually trying for the simplest system in terms of airflow. Least amount of pipe and least restriction of the air movement from the plenum to the motors. I was also looking for something I could make easily using regular woodworking materials and tools. It looks difficult but it was actually very easy and quick to build once I developed the technique and drew the parts. It was also easy to seal so I know there are no leaks in the manifold or risers.

The shop-made valves were partly to prove to myself that I could do it but also to be able to use 3" pipe without having to buy expensive valves. Even the manual version of the valves Gary shows would be $25 each or $200 for my 8-zone table. Of course the actuators made this table much more complicated and expensive but they are an optional add-on and without them the system is pretty streamlined. (I found the actuators at e-motion.com (http://www.e-motionllc.com/) but I don't think I'd use that model again, we had a lot of problems with them.)

I think with some effort I can design a vacuum system that will work well and cost under $100 in materials (not including the motors of course or the table itself). I'm considering putting this concept together as a kit or possibly as a turn-key package for anyone wanting a vacuum system without having to re-invent the wheel. Anyone interested?

As for the spider-web pattern, it seemed to make sense especially with the off-center zones that were required to work around the steel cross-rails. I can't directly compare its performance with the old grid since I also changed the manifold so it's not an apples-to-apples comparison. In reality the width and depth of the grooves probably makes more of a difference but I figure every little bit helps. Plus it's cool looking.

[porscheman]

Gary,

I'm wondering on the pneumatic gate valve how the opening/closing action works. Is pressurized air introduced into each end of the cylinder (but only one end at a time) and this causes the piston/actuator to move? Or does the cylinder have a spring that keeps the valve in one position, until the pressurized air counteracts the force of the spring and moves the valve to the other position?

If air is alternated at each end of the cylinder to open and close it, what brand of valve/switch are you using to control the pneumatic cylinder?

Any info would be appreciated.

John

[Gary Campbell]

John...
Yes, air pressure to either end to move the piston. There are single action cylinders that have a spring return also.

The valve was a 5 port toggle that I had, but think was purchased from McMaster. The valve configurations are 2,3,4 and 5 way and it is important to know what you want the actuator to do before ordering a valve. In some cases, flow thru the valve makes a difference also.

There are many brands out there, but most of what I buy is off ebay or from McMaster and buy by specs, not brand number for mechanical air switches. When it comes to electropneumatic solenoid valves I am partial to SMC as I know their numbering system.
Gary

[wayne_walker]

I have some of the Bladex Valterra valves for sale. Also, some brush material for dust vacumn shrould. If interested, please contact me off forum.

Wayne