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  1. #21
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    Seen the Carter Flip-Pod system in the USA. Looks good, but does rob quite a bit of Z-axis movement. Also my exerience is that the pods are only availale in multiples of 100 (at multiples of around $1300/$1900)

    Nice to see that the range of available pods is now so wide

    Scrit
    from the Sunny Pennines, England's Backbone


  2. #22
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    yes they are salty not really for home setup we spent $10,000 for 5'X12' router and we had 29 HP. (sulair?) rotary vacuum pump.

    But it is still good to see if you are thinking of some kind of modular vacuum fixture good ideas can be made from those pics make your own on a 1/4 scale or something.


    mace



  3. #23
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    Jeff, you might want to look at this.

    http://www.m-powertools.com/products...m-holddown.htm

    They sell kits or just the individual valves.

    Gerry

    Gerry

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    JointCAM - CNC Dovetails & Box Joints
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  4. #24
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    You mite want to check out this site;
    http://joewoodworker.com/veneering/welcome.htm
    Under part 4-Misc.Info click on Vacuum Clamping.



  5. #25
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    Ger21,

    Good find for another source for Vacuum tape and stuff.

    Thanks

    Jeff Davis (HomeCNC)
    http://www.homecnc.info


    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)


  6. #26
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    Default Compressed air powered vacuum clamp

    Without trying to make this sound like a blatant advertisement, the Vac-Clamp website is worth a look to overcome the problems being faced by all the home CNC guys.
    Powered by compressed air (venturi) and generating very usable holding force.
    Regards,
    Errol



  7. #27
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    Quote Originally Posted by Vac-Clamp
    Without trying to make this sound like a blatant advertisement, the Vac-Clamp website is worth a look to overcome the problems being faced by all the home CNC guys.
    Powered by compressed air (venturi) and generating very usable holding force.
    Regards,
    Errol

    You're products look really good, can they be used for metal work?

    Thank You,
    Paul G

    Check out-
    [URL="http://www.signs101.com"]www.signs101.com[/URL]


  8. #28
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    No problems with metals. Anything non-porous works very well. Aluminium, stainless, tool steel etc etc. We have a few people using them on CNC mills pocketing aluminium using the appropriate feed rates. When they bolt in a VC4 a skim cut of known height is made and then they zero set from there with the relevant tool offset, and away they go.
    Stainless and tool steels can be held but I think that the feed rates might be too slow to be viable, but then again you never know till you try.

    Brief tech spec Ambient air pressure 14.7psi. Vac-Clamps generate a holding force of about 12.5 psi (100 psi supply pressure). So more surface area equates to more holding power

    Errol



  9. #29
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    One thing to keep in mind is surface area! If your running a vacuum system thats low on horse power & CFMs, try to get as much surface area under your workpiece as possible!
    I've seen 40hp vacuum systems pull the warp & twist out of 8/4 oak & cherry, and it sounds like a gun shot! But this is on a pieces of material that's 12" wide & 8' long. The same system still has trouble holding on to 4" diameter cut out made of 3/4" ply.



  10. #30
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    Surface area is indeed the key to a good hold, however Vac-Clamps work a bit differently to "blower" type or "rootes" type vacuum pumps. These types of vacuum pump are very good in nested based cutting on semi porous materials, as they flow a lot of air at quite reasonable levels of vacuum. Think of them as superchaged vacuum cleaners. Vac-Clamps run a built in vacuum generator which is powered by compressed air, they use a flow of air to generate a vacuum.

    What limits all vacuum systems is ambient air pressure. At sea level air pressure is about 1 atmosphere or 14.7 psi ( relative to absolute). At the summit of mount Everest the air pressure has dropped to approx 0.37 atm or about 5.4psi. It is this air pressure pushing that will generate the holding force. Even a 40hp vacuum pump flowing 90cfm will not be able to create more force than ambient air pressure will allow.

    Vac-Clamps work well with non-porous materials as they create a vacuum between the clamp and the workpiece. Ambient air pressure will push the workpiece onto the clamp. The better the seal the higher the vacuum level this equated to more push or holding force. Our single sided clamp VC4 uses about 1cfm but generates 12.5psi of vacuum.
    It doesn't use a lot of air but it doesn't flow a lot of air either. So with very porous materials, such as thin MDF and cardboard, the air gets pulled through, and only a small vauum is created. Small vacuum level less hold.

    Referring to the small item (4" round, 3/4" ply) I would guess that it does have a large bed and equally large blower system. To go back to the vacuum cleaner analogy, air is probably being drawn around the workpiece, and a vacuum will not be able to be created. No vacuum, no air pressure to hold the workpiece. The same 4" ply round on a Vac-Clamp would be held on with a force of 73lbs (33.3kg). This is more than enough clamping power. The opening page on our website http://www.vac-clamp.com shows a piece being machined which is 2" x 4".

    Vacuum clamping performance is not directly related to lots of horsepower and large cfm rates. It is more a function of air pressure imbalance, and using this to our advantage.

    Best Regards,
    Errol Weber
    Vac-Clamp



  11. #31
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    I read in one of the woodworking trade magazines that the large pumps on most big routers only pull around 7 psi, but the large volume makes up for it. And I'm pretty sure the venturi pump I use for veneering would hold better than our big pump at work does, especially on small parts.

    Gerry

    UCCNC 2017 Screenset
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    Mach3 2010 Screenset
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    JointCAM - CNC Dovetails & Box Joints
    [URL]http://www.g-forcecnc.com/jointcam.html[/URL]

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)


  12. #32
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    The figure of 7 psi vacuum does sound very achievable, and many would pull more than this. The large flow of air allows for losses or leaks.

    For example, glass is non-porous and a small plastic suction cup will hold almost indefinitely. The same suction cup will not hold on MDF because it allows a flow of air, it is porous. If we could keep pulling the air out of the cavity between the suction cup and the MDF it will hold, this is why large pumps work well on large tables. They keep up with the leaks very well.

    If you work with relatively non-porous materials (eg chipboard, melamine faced board, plexiglass, plastics, aluminum, stainless steel, etc, etc,) a venturi based system will, and does, work very well.
    Errol Weber
    Vac-Clamp



  13. #33
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    I use closed cell foam door insulation from home depot for around $.30 a foot ($3.00 for 10 ft) works really well.
    post #9 at this link
    http://cnczone.com/forums/showthread.php?t=6001&page=2

    Tom



  14. #34
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    I agree that a non-porous material does allow for a more complete seal, but that same material usually posses another problem. The hard smooth surface can cause the parts to move or slide even with the neopreme seal.
    Both of my routers have the same grid system as your Vac-Clamp, yet I still have issues with small plastic and aluminum pieces moving. I've got 4 vacuum pumps ranging from 3.5-5 hp, pulling 30-40+ CFMs each. And that's on a 5'*8' & 7'*14' tables.



  15. #35
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    Quote Originally Posted by CNC Pro
    Both of my routers have the same grid system as your Vac-Clamp, yet I still have issues with small plastic and aluminum pieces moving. I've got 4 vacuum pumps ranging from 3.5-5 hp, pulling 30-40+ CFMs each. And that's on a 5'*8' & 7'*14' tables.
    Like I said above, even though your pulling a lot of cfm, the Vac Clamp most likely is pulling more vacuum, giving more holding power. A lot of cfm is good for mdf and large panels, but small parts need more vacuum, and you probably don't have enough.

    Gerry

    UCCNC 2017 Screenset
    [URL]http://www.thecncwoodworker.com/2017.html[/URL]

    Mach3 2010 Screenset
    [URL]http://www.thecncwoodworker.com/2010.html[/URL]

    JointCAM - CNC Dovetails & Box Joints
    [URL]http://www.g-forcecnc.com/jointcam.html[/URL]

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)


  16. #36
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    I think that a vacuum gauge could help CNC Pro with his moving plastic and aluminium problem. It is fairly obvious that there is enough power there, we just need to know how much vacuum (or negative pressure) there is.
    An air flow of 30 to 40 cubic feet per minute sounds very usable, but with without the vacuum, small parts will move.

    To give an example. A dust extraction system will move huge volumes of air, possibly in the hundreds of cubic feet per minute, but the vacuum level is quite low. Typically these are on the order of 9 to 10 percent of absolute This will only yeild one and a half pounds per square inch of holding force. A 4" disc will be held on with a force of about 12.5lbs in optimum conditions.

    The venturi based vacuum clamp that we manufacture flows only about 0.8cfm per pad, but generates a vacuum of better than 80 percent of absolute. Under the same conditions as above the holding force will be more than 157lbs for the same 4" disc. This makes it ideal for smaller items, and works nicely on large items when ganged in groups.

    Errol Weber
    Vac-Clamp



  17. #37
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    I have to say Errol that I’m skeptical that your product would perform better than what I'm currently using, but I’m also open to new ideas and I’m not opposed to investing in something that works. Do you have one I could try? Being able to tackle small, difficult to hold jobs would have me singing the praises of Vac-Clamp.



  18. #38
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    This sounds like a good idea CNC Pro. Please go to our website and use the contact email there to pass on your address through there.
    We do not usually send product out on approval, but in the spirit of this forum I think that this is an ideal test case.
    Our website ishttp://www.vac-clamp.com go to the reseller pages
    Alternatively Vac-Clamp Email will find us

    Errol Weber
    Vac-Clamp



  19. #39
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    Quote Originally Posted by Vac-Clamp
    This sounds like a good idea CNC Pro. Please go to our website and use the contact email there to pass on your address through there.
    We do not usually send product out on approval, but in the spirit of this forum I think that this is an ideal test case.
    Our website ishttp://www.vac-clamp.com go to the reseller pages
    Alternatively Vac-Clamp Email will find us

    Errol Weber
    Vac-Clamp

    CNC Pro I hope you take Vac- Clamp up on this offer and report back with the results.



  20. #40
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    Hi i have used Errols Vac-Clamp it worked very good for me ;but only tested on larger parts look at pics

    Attached Thumbnails Attached Thumbnails Vacuum Hold down for wood.-dsc00539-jpg   Vacuum Hold down for wood.-dsc00540-jpg   Vacuum Hold down for wood.-dsc00543-jpg  
    Last edited by cncnick; 11-24-2004 at 09:30 AM.


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