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Information
Type: Adjustable Auto-Cycling
Vacuum: Air Powered Venturi
Page: 8 of 9 |
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Final Pneumatic Connections & System Testing
Congratulations! You're almost done. Within the next few minutes you'll be ready to run the vacuum press. Be sure to follow the rest of these instructions carefully.
- Cut the black vacuum tubing to fit from the vacuum controller to the brass barbed fitting on the lower end of the manifold assembly and attach it snugly.
- Now cut a piece of black tubing and connect it between the vacuum port on the venturi and the barbed fitting above the check valve on the manifold.
- Attach the braided vacuum tube to the vacuum valve on the manifold.
- Apply thread-sealing tape to the 3/8" barb to 1/4 NPT-male fitting.
 Attach the barbed fitting to the lock-on connector. Be sure to hold the lock-on connector at the hexagon part of the casting when attaching the barbed fitting. If you hold the head of the lock-on connector and apply too much torque to the barb fitting, the connector will break. - Slide on the lock-on vacuum connector to the open end of the vacuum tube.
The final assembly should appear as shown in the picture below.
Testing and Adjustment
Set your air compressor to put out 95 to 100 psi and attach your compressed air line to the quick connector on the Mac valve. It is ok if your compressor is putting out more than 100 psi. No air should flow through yet. Next, close the vacuum valve by turning the handle to the left or right until it stops.
 Notice that there is a small plastic cap on the vacuum controller just in front of the "common" tab. Under this cap is a black plastic slotted set screw where the adjustment is made for the amount of vacuum inside the system. Using a flat-head screwdriver, turn the set screw counter-clockwise until it is approximately 3/16" from the top edge of the vacuum controller body. In other words, there should be about 3/16" of the female threads visible when you look inside the adjustment area of the unit.
With the light switch on the vacuum press turned off, plug the electrical cord into your wall socket. Flip the switch and air should begin flowing through the venturi and the needle on the vacuum gauge should rise. The vacuum controller should shut off before it reaches 21" of Hg.
For the next stage of testing, you will want to carefully adjust the vacuum setting to 21". Slowly turn the adjusting screw counter-clockwise until the unit creates 21" of vacuum and cycles off. Remember counterclockwise turns of the screw will increase the amount of vacuum required before the vacuum controller will turn off the air pressure at the Mac valve. I've found that most often, 21" of Hg is when there is about 1/8" of threads showing above the adjustment screw.
It will automatically cycle on again when the vacuum has decreased. You can test this by opening the vacuum valve and releasing a bit of pressure from the system. The manufacturer of the vacuum controller claims that the controller will cycle back to the "on" mode within 4" of Hg decrease. This 4" amount of "differential" is not adjustable. In my opinion, this constant increase and decrease in vacuum inside the press bag allows for an even greater bond of the veneer to the substrate.
For venturi systems, the frequent on and off cycling is harmless. During normal operation of a tightly sealed unit, it is still common to have the unit cycle on every 10 minutes for 5 - 8 seconds.
Close the vacuum valve and allow the system to recharge. Watch the needle on the vacuum gauge to see if the system shows signs of a leak. It shouldn't leak if the brass fittings were correctly attached to the reservoir with thread-sealing tape. However, it's not uncommon to have a small leak show up. The fix for this is simple.
Got A Leak? No Problem!
First, remove the manifold system from the reservoirs and tighten all of the brass joints. While it is somewhat possible to over-tighten the fittings, it is more common to find that the fittings are not tight enough. Re-assemble the system and test it again. I've found that this solves 99% of leak problems.
If the leak persists, leave the system charged with vacuum and apply a small amount of silicone to each of the brass fittings and gauge where they attach to the PVC caps. If a leak does exist, the vacuum will pull the silicone into the void area causing the leak to seal itself. Also consider applying silicone to the area around the edge of the PVC caps on the pipe.
After you have applied the silicone, turn the system off and let the air back into the PVC pipe by opening the vacuum valve. Allow the unit to sit overnight so the silicone can cure. |
Your Vacuum Press System is Ready to Use.
Now What?
I've written this short but helpful article that explains what else you will need to begin using your vacuum press. The article also includes a step by step guide to using your system for veneering.
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