Darryl Keil Last Activity 2025-09-09 11:09 AM
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Andrew

 
Subject : Total Air System: calibrating vacuum?
Posted : 2004-08-28 12:23 AM
Post #31734
Our shop recently purchased a Total Air system. We have used it several times with good results, but it seems that the vacuum pressure may need to be calibrated better.

I would like to maintain as closely as possible the supposed optimal 25" Hg. As it stands, however, if I adjust the vacuum pressure knob to cutoff the flow at around 26", the flow will not turn on again until dropping to around 20" or sometimes even less! If I turn the pressure up so the flow shuts off at 28" then it still drops, though not as far, maybe to 23" or 22".

Is there something I can do to lessen the range between off and on triggers, and maintain as close as possible a steady 25"? Again the results have been good as far as I can tell, but in the long run consistent, increased clamping pressure should produce a better bond.

Many thanks in advance for any advice on this matter.

Andrew Thomspon
Ki Woodworks


 
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Darryl Keil

Posts: 1455

Joined: 2003-05-22
Location: Maine

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Subject : RE: Total Air System: calibrating vacuum?
Posted : 2004-08-31 3:48 PM
Post #31735 - In reply to #31734
Andrew,

The setting you would like to adjust is called the "dead band, the difference between where the pump shuts off and comes back on. Unfortunately this is a fixed setting, so as you adjust the shut off point the turn on point moves also. After much testing and research we have chosen the dead band that you find on your switch. A very close dead band is problematic because it can end up recycling very frequently as leaks develop, and can cause erratic cycling under certain circumstances.

Our testing shows that you will do fine staying within the range the switch provides. It is not until you go down to a much lower vacuum that gluing problems can develop. The final glue penetration is achieved very quickly when full vacuum is achieved (within the first few minutes), after that you are just holding the veneer down until the glue cures.

Sincerely
Darryl Keil


 
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Andrew

 
Subject : RE: Total Air System: calibrating vacuum?
Posted : 2004-09-01 10:09 PM
Post #31736 - In reply to #31735
Darryl,

Thanks so much for the insight.

Best,
Andrew...
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