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  1. #49
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    Default Re: 4'x8' vacuum table build questions

    I was going to say 8 inches or so around the perimeter and in the center but routalot is correct in that you just need to make sure it doesn’t shift as when the table turns on, it will pull everything down. The main thing is that the table is tightly screwed down wherever you set table-height or don’t zero the table height without having the vacuum table on.

    ALSO, OF BIG IMPORTANCE, NEVER SURFACE THE TABLE WITHOUT THE VAC TABLE TURNED ON OR YOU’LL HAVE AN UNEVEN SURFACE.

    David Gage
    Deep Sea Sound


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    Default Re: 4'x8' vacuum table build questions

    Thanks Routealot - yes it is a huge relief. This has seemed like the never ending project.

    Wmgeorge -Thank you I've tried to be very careful putting this together & making it as precise as I'm able to. I'm excited. I'll put a small bead around the edge just to be safe.

    David - 8" is exactly what I was thinking but I see Routealot & your point that I don't need a lot of screws.

    My plan is to countersink the screws between 7/16" - 1/2" so I wouldn't hit the heads when I surface the spoil boards. Then when I get down to the screw heads I know it's time for new spoil boards. Do you all think the counter sunk holes will need sealed to keep from leaking?

    Anyone that is using a pressure gauge, what amount of pressure should I aim to maintain & does it change with different materials (wood, aluminum, PVC, etc.)?

    Thanks
    Gary



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    Default Re: 4'x8' vacuum table build questions

    Gary its actually a vacuum gauge 0-30 Inches. Reminder that 30 inches of vacuum is a 14.7 psig, (nominal) its an absence of atmospheric pressure. When I was doing refrigeration work when we got below 29 inches we switched over to a micron gauge to measure ideally we looked for 500 or below microns.

    . Hey where do you live, I am down in central Iowa we only got 2 inches here but other places got 11 inches of snow.

    Retired Master Electrician, HVAC/R Commercial union shop and Lots of hobbies. FLA Saturn 2 4x4 CNC Router


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    Default Re: 4'x8' vacuum table build questions

    Wmgeorge - I've never messed with any of this. Please explain this like you writing the book vacuum gauge for dummies. what number am I looking for?

    I live in Northwestern Pa (right off of I-80) we got about 12" over this weekend.

    Thanks
    Gary



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    Default Re: 4'x8' vacuum table build questions

    Quote Originally Posted by Gary-Wiant View Post
    Wmgeorge - I've never messed with any of this. Please explain this like you writing the book vacuum gauge for dummies. what number am I looking for?

    I live in Northwestern Pa (right off of I-80) we got about 12" over this weekend.

    Thanks
    Gary
    You can buy those gauges wilthout a problem, my guess you can find them on Amazon. But my estimate and I really do not know for sure but but a vacuum table will not even get close to 15 inches. I hope somebody will chime in that knows.
    https://www.amazon.com/2-1-Filled-Va...s%2C164&sr=8-3

    Retired Master Electrician, HVAC/R Commercial union shop and Lots of hobbies. FLA Saturn 2 4x4 CNC Router


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    Default Re: 4'x8' vacuum table build questions

    I ordered & received the Jegs 41008 gauge



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    Default Re: 4'x8' vacuum table build questions

    Don't get too hung up on numbers for the level of vacuum.You need enough to hold the job in place and obviously the force holding the job in place will increase in line with the area of the piece.For a full 8X4 sheet at 15" of vacuum you would have well over 30,000 lbs acting on the sheet-that won't be going anywhere will it?It is important to keep in mind the distinction between workholding force and a gas tight plumbing system.You will have leakage just from the porosity of the spoilboard and more of it gets exposed as you cut through the sheet you are working with.A high vacuum system doesn't like that sort of leak but the high flow workholding system will be working well.I would be surprised if you ever saw 22 inches of vacuum and you may have a pump that has to have some throughput of air at all times.some systems have a vacuum relief valve to allow for some entry of air if the seal is too good and the pump at risk of damage.Check the data sheet for your pumps perhaps?



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    Default Re: 4'x8' vacuum table build questions

    I remember reading the DIY vacuums usually pull 6-10” of vacuum though with your 4 motors you should be on the top end of that if not more. The main thing for you is to establish the baseline for your system and location (above sea level). Once you get a good idea for how much vacuum your system pulls with different materials and situations/needs, you use that to determine when you need to turn on/off motors for a given project.

    David Gage
    Deep Sea Sound


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    Default Re: 4'x8' vacuum table build questions

    Maybe a little too late to the discussion, but you have seen this design/approach?





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    Default Re: 4'x8' vacuum table build questions

    KOSH - yes I've seen that video, I'm not sure if you saw my photos of my table design but I have T-slot that boarders my 4 2'x4' zones, which will hopefully give me the best of both worlds.

    I was wondering where to run the pressure gauge so I knew where to set the relief valve?

    I think this job is literally being a never ending job, I went out to the building to work on attaching the spoil board & out new (less than 2 month old ) Mitsubishi hyper heat mini split wasn't working & my router building was freezing cold so I had to call our HVAC company, they came & looked at it & said a circuit board is out so now I have to wait to see how fast they can get it working & let the metal & plastic all warm back up before I get in there & start ripping & tearing

    Thanks
    Gary



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    Default Re: 4'x8' vacuum table build questions

    Gary I just installed one of those mini split HP and since I am a HVAC guy (retired) I did it myself. My son is a service mgr and estimator for a commercial HVAC Co. so I got it wholesale. He says they do not ever have problems with the Mitsubishi units. Mine has been in since October 2018 and so far, so good.

    Retired Master Electrician, HVAC/R Commercial union shop and Lots of hobbies. FLA Saturn 2 4x4 CNC Router


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    Default Re: 4'x8' vacuum table build questions

    Yeah we have had a large Mitsubishi unit in our sign shop for a few years ( it's not a Hyper Heat ) and we haven't had any issues with it. It's my luck & just another thing to keep me from finishing this vacuum table. My brother & I call it Wiant luck, pretty much same as Murphy's law.



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