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Thread: Vacuum pump

  1. #1
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    Vacuum pump

    So a while back I purchased an 2.5 CFM HF Vacuum pump for working on the AC on my old Tahoe, I've not needed it for anything else, so thinking about building a vacuum rig for veneering small panels and stabilizing blanks for gun grips and knife scales.

    I found the Joe Woodworker site and am thinking about using this design.
    http://www.joewoodworker.com/veneering/EVS/concept.htm

    Since I'm planning to do the stabilizing, I'm thinking I should set it up to do a purge of the reservoirs after pulling in the fumes from the stabilizing tank to keep the fumes out of the pump. Just wondering if anyone else is using a pump that size and if it will be big enough.
    Darren

    To a small child, the perfect granddad is unafraid of big dogs and fierce storms but absolutely terrified of the word “boo.” – Robert Brault

  2. #2
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    Couple of comments. First, the vacuum pumps used to pull air and moisture out of A/C systems are normally low capacity but will pull a very high vacuum. You normally hook them up to your A/C and let it run for a long time so evacuating the system quickly is not a primary requirement. For veneer systems, you want a fairly high volume of air but don't need it to pull as deep of a vacuum. While that HF pump claims to be 2.5 CFM, I'd really question that rating if it will also pull a hard vacuum.

    When veneering, you have to evacuate the air out of the bag, and you normally want to do that quickly before the veneer turns into a potato chip from the moisture in the glue and you get ridges in your final product. There are ways to get around that, such as hooking up a shop vac to the bag first then switching to your vacuum pump but that can be a pain.

    But if that pump will actually pull 2.5 CFM, it's big enough to do veneer work. The kit from Joe Woodworker is good - I've built two vacuum systems using his components.

    Mike
    Ancora imparo
    Go into the world and do well. But more importantly, go into the world and do good.

  3. #3
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    I appreciate the comments Mike. I've seen a couple of posts on other forums where it was used. I most likely won't be doing any large veneer projects, probably only a 2' x 4' bag at most. I plan to use it for stabilizing mostly From what I read on the Joe Woodworker site it takes about 1 cfm to do a 4' x 4' bag and 3 cfm for 4' x 8', but I don't know if that takes into account leakage, which I suspect will happen.

    I figure I'll build the system and if the pump isn't big enough, all I've got to do is upgrade the pump and maybe a couple of fittings.
    Darren

    To a small child, the perfect granddad is unafraid of big dogs and fierce storms but absolutely terrified of the word “boo.” – Robert Brault

  4. #4
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    FWIW - used to teach a class on vacuum technology for woodworkers. With that caveat in mind, a vacuum leak in the system can rearely be overcome by the pump, unless the pump's CFM is pretty high.

    My students home built their systems with some pretty snall pumps - what they could fine in salvage. Once ALL the leaks were dealth with, their systems worked fine for years.

    BTY, this was before Joe Woodworker. He has lots of really good advise and good products. I have a friend that bought his components. I helped him with his systems and it works great. I personally have three pumps, all of them diaphragm pumps. Even the smallest one holds objects for me to run the router and holds them instantly. Vacuum systems are for more than veneering.

    Holler if I can help. But work to eliminate ALL the leaks. Be diligent with the connections. It is not hard.
    ++++++

    Some say the land of milk and honey; others say the land of fruits and nuts. All together my sort of heaven.

    Power is not taken. It is given. Who have you given yours to? Hmmmm?

    Carol Reed

  5. #5
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    Quote Originally Posted by Carol Reed View Post
    FWIW - used to teach a class on vacuum technology for woodworkers. With that caveat in mind, a vacuum leak in the system can rearely be overcome by the pump, unless the pump's CFM is pretty high.

    My students home built their systems with some pretty snall pumps - what they could fine in salvage. Once ALL the leaks were dealth with, their systems worked fine for years.

    BTY, this was before Joe Woodworker. He has lots of really good advise and good products. I have a friend that bought his components. I helped him with his systems and it works great. I personally have three pumps, all of them diaphragm pumps. Even the smallest one holds objects for me to run the router and holds them instantly. Vacuum systems are for more than veneering.

    Holler if I can help. But work to eliminate ALL the leaks. Be diligent with the connections. It is not hard.
    Did you make your hold-downs or do you use commercial versions? I've got a program on the CNC to do drill patterns and grids, so would be interested in how you made them and what materials you used if you did make them.
    Darren

    To a small child, the perfect granddad is unafraid of big dogs and fierce storms but absolutely terrified of the word “boo.” – Robert Brault

  6. #6
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    If you use a commercial vacuum bag, which I recommend for a number of reasons, they don't leak much. When I get to the end of a pressing, I often turn the pump off and just let the system sit until I can get to it. The system stays under vacuum for a long time.

    If you make your own bag, you generally have to double fold the seams. And if you do that, clamping the bag is a problem. With commercial bags you can use the plastic pipe and C shaped tube to seal the bag. Those are quick, easy, light, and hold vacuum very well. Joe includes them with his bags and you can buy them from any place that sells bags. Reason I mention that is because some people cut the bottom end and use a seal on both ends. The reason for cutting the bottom is that it's easier to put things into the bag - for two people - if one person works each end of the bag. For small bags you don't have to worry about that.

    Mike
    Ancora imparo
    Go into the world and do well. But more importantly, go into the world and do good.

  7. #7
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    If by hold downs you mean platens to keep things flat while pulling vacuum, I used 3/4" DS Melamine scored on the table saw every 4" in a checker board pattern. Then I rounded over every edge, including the corners, with a 1/4" RO bit and the router. No sharpen edges to puncture the bag. If you mean something else, enlighten me.
    ++++++

    Some say the land of milk and honey; others say the land of fruits and nuts. All together my sort of heaven.

    Power is not taken. It is given. Who have you given yours to? Hmmmm?

    Carol Reed

  8. #8
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    Quote Originally Posted by Carol Reed View Post
    If by hold downs you mean platens to keep things flat while pulling vacuum, I used 3/4" DS Melamine scored on the table saw every 4" in a checker board pattern. Then I rounded over every edge, including the corners, with a 1/4" RO bit and the router. No sharpen edges to puncture the bag. If you mean something else, enlighten me.
    I was referring to vacuum clamping (http://www.joewoodworker.com/veneeri...umclamping.htm), which is what I thought you were talking about when you mentioned holding down things for routing in your previous post. The platen is a great idea too, making note of it.
    Darren

    To a small child, the perfect granddad is unafraid of big dogs and fierce storms but absolutely terrified of the word “boo.” – Robert Brault

  9. #9
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    I do the same as Carol. When pressing flat stuff, it's good to use a caul on top of the work. You can use almost any scrap sheet goods - I use often use plywood. You cut the caul about 1" larger than the work (1/2" on all sides) and round the edges as Carol described (to save your bag). On problem with doing a lot of veneer work is you wind up with a lot of cauls in the shop. Every now and then I have to find something to do with the old ones.

    If, for some reason, you don't use a bottom platen, you can use plain old window screen (the plastic stuff) in the bag. This allows the air in the bag to get to the hose connection. If you don't do that, the bag can pull tight close to the connection and there will still be air in the bottom of the bag. The commercial stuff is called "breather mesh". It's stiffer so it doesn't bunch up as easily as the window screen, but it costs a lot more than window screen.

    Mike
    Ancora imparo
    Go into the world and do well. But more importantly, go into the world and do good.

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