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  1. #41
    I'm not sure I get how that works? Is it the sucker-cup action, rather than the vacuum pulling through the mats that holds the work? So when the seal on one sucker is broken it will still keep the vacuum seal. Since there are lots of them, even if a few are broken it will hold most work shapes. Then why do they say the mats have tiny holes, if it is the sucker action it wouldn't need it?

    ..hmm maybe those small holes are just to stop the suckers being pulled right onto the vacuum plates when no work is on top?

    I wonder how well it works with less smooth materials like MDF.
    Last edited by Tenson; 08-01-2014 at 04:02 PM.

  2. #42
    It's rubber to get a high coefficient of friction, so for a given vacuum pressure (i.e. close to atmospheric pressure) you get a higher holding force than a more 'slippery' material.
    The small hole is there so that when the seal is broken not much air can flow through, which reduces the power required from the pump to maintain the vacuum.

    If the system is sealed then (ideally) zero power is required to maintain the pressure difference and clearly the power required goes up with the size of the aperture to leak through. If you don't have their mat and cut through, the apeture is large (the size of the cut), so it's difficult to maintain a sufficient pressure to hold the part. If you keep the apeture small by only 'revealing' a tiny hole when cut through, as their mat does, it's then possible to maintain sufficient pressure as the leak is only small. When you first clamp the part, you just need the hole to extract the air in a reasonable time, so a tiny hole is fine as the air volume is small.

    You could probably achieve the same thing with an array of O-rings positioned in an array of cutouts on an aluminium bed, with suitable channels to direct the air underneath and a very small hole in the center of each ring. Some eperimentation with the size/thickness/amount protruding/type of rings would berequired, but once you've done that it's a cheap system to maintain as the O-rings don't cost much to replace. I'll try it when I get my vacuum pumps working.
    Last edited by Jonathan; 08-01-2014 at 04:11 PM.
    Old router build log here. New router build log here. Lathe build log here.
    Electric motorbike project here.

  3. #43
    Tenson, another friend uses a special d/s tape that he said is very easy to remove and does not leave a residue. I will contact him and post the details - what it is, where to buy etc. G.

  4. #44
    Quote Originally Posted by GEOFFREY View Post
    Tenson, another friend uses a special d/s tape that he said is very easy to remove and does not leave a residue. I will contact him and post the details - what it is, where to buy etc. G.
    Yeah - at school they got that for the CNC router, but I can't remember the brand...
    Old router build log here. New router build log here. Lathe build log here.
    Electric motorbike project here.

  5. #45
    That would be great, thanks! Does it stick to MDF too, or HDPE?

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