Infusion pump

Discussion in 'Fiberglass and Composite Boat Building' started by Stumble, Jun 1, 2010.

  1. Stumble
    Joined: Oct 2008
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    Location: New Orleans

    Stumble Senior Member

    I am finally getting started making small fiberglass parts, and am working through the rig that I will need to put together. As I envision it, most of the rig though is centered around the pump...

    I am thinking of using a http://www.amazon.com/Robinair-15500-VacuMaster-Vacuum-Pump/dp/B000O1C47M but was also considering http://www.harborfreight.com/25-cfm-vacuum-pump-98076.html . So far as I can tell the difference in them is a minimal for infusions since both can pull a stronger vacuume than I think I need (29").

    Otherwise I am thinking of using pvc pipe for the preassure vessel and resin trap, but I am concerned about if they are strong enough to withstand the vaccume preassure.

    Third does anyone have recomendations for hose? I have seen some vacuume hose, but it seems the same stuff is either very very expensive, way to large, or not rated for the depth of vacuume that I will be using.

    Fourth, Does anyone have a suggestion for a Mac software that can do modeling of resin infusion?

    Thanks ahead of time
     
  2. KnottyBuoyz
    Joined: Jul 2006
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    Location: Iroquois, Ontario

    KnottyBuoyz Provocateur & Raconteur

    The Robinair will do the job. I've produced a few starved parts pulling too much vacuum with mine. I've setup an automatic vacuum switch. You'll find the directions & parts list on joewoodworker.com

    [​IMG]

    Normal PVC pipe will be fine. I use Lowes piping & fittings. For the vacuum line I use the pvc pipe from Lowes used for plumbing water coolers. Cheap and easy!

    [​IMG]

    You can see the resin trap (White) and vacuum reservoir (Black) in the background. I don't know of any Mac software for infusion modeling. You might want to check with these guys to see if they've ported their software over to Mac. http://www.polyworx.com/
     
  3. marshmat
    Joined: Apr 2005
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    Location: Ontario

    marshmat Senior Member

    Small HVAC pumps like those ones can be used for composites work, but I don't think they're ideal. A pressure switch such as Rick describes will shorten the duty cycle and make things easier on the pump. HVAC pumps are generally not meant for continuous heavily-loaded service; they're designed to be run for a few minutes, then shut down.

    Here's the manual for the VacuMaster: http://www.atp-europe.de/download/manuals/robinair/VacuMaster.pdf

    My preference, frankly, is for a beefier, continuous duty pump that can run indefinitely. But an HVAC pump will suffice for a home shop, as long as you take good care of it and don't expect the 40+ year MTBF of good continuous-duty pumps.
     
  4. Stumble
    Joined: Oct 2008
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    Location: New Orleans

    Stumble Senior Member

    Marsh,

    I figured that a cheap pump like these would be limited, and if I ever want to do either large parts, or do production work I would have to get a new one, but for making small one off stuff it seems overkill for a large high quality one. At least unless someone can point to one for around the $100 range.

    Knot,

    Thanks for the tips. I hadn't thought about a switch, but it looks like a good idea.


    Otherwise, I hope to get this up and running just to play with in the near future. Nothing like spending $500 to make a $50 hatch cover! But I swear this is a tool, not a toy!
     
  5. CatBuilder

    CatBuilder Previous Member

    I have a Robin Air in storage (same one pictured) that I used for refrigeration work on boats.

    I had never even considered using it for bagging.

    My designer suggests you can use a ShopVac (with one in reserve). I'm thinking I might go that route, so I don't have to worry about controlling the high vacuum of the RobinAir.

    Any thoughts on that?
     
  6. marshmat
    Joined: Apr 2005
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    Location: Ontario

    marshmat Senior Member

    A Shop Vac will pull enough vacuum to compress a wet hand-laid laminate slightly. It's great for the initial suck-down, and even on its own is probably better than not bagging at all. But I suspect you'd have a pretty hard time getting enough vacuum with one for infusion to work properly. Anyone with experience to the contrary, feel free to chime in....

    Big, sturdy pumps from decades long past can occasionally be found on ebay at good prices. That would be my pick, even if it needs a bit of cleaning up. But the little HVAC ones should suffice for small parts in a home shop.
     
  7. KnottyBuoyz
    Joined: Jul 2006
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    Location: Iroquois, Ontario

    KnottyBuoyz Provocateur & Raconteur

    I agree with Matt on the HD industrial pumps for a large production job. I wouldn't risk 10's of $1000's of materials on a $100 pump.

    I would trust my Robinair to infuse panels say 4' x 8' but I don't think I'd infuse an entire hull with it (no guts)(although I have seen that done). I've seen these pumps used to infuse car hood size panels w/o any problems in a production environment. A large production facility would probably have a number of backups to it's primary pump. The Robinair would fill that role nicely.

    What it boils down to is how good a seal you can get in your layup. If it's constantly leaking the pump will run on and on. If you get a good seal the pump might cycle once in 4 or 5 hours. I've layed up stacks of flat panels with near perfect seals and have the pump only cycle once in 24 hrs. If you're that good, consistantly, a Robinair could infuse a house boat!

    You can get the shop vac vacuum valves IIRC I've seen them on e-Bay. Those things you vacuum down all your sweaters & blankets to save storage space. Space Bags I think they're called.

    We had another conversation not that long ago on vacuum pump size....

    http://www.boatdesign.net/forums/fiberglass-composite-boat-building/vacuum-pump-size-20419.html
     
    1 person likes this.
  8. CatBuilder

    CatBuilder Previous Member

    I don't think it's an infusion process my designer suggests, but then again, I only have half my plans so far. I don't have the "steps to build" documents yet.

    I want the boat to last as long as possible, so maybe getting a vacuum pump is another bit of scope creep. Thanks for the input.
     

  9. AndrewK
    Joined: Mar 2007
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    Location: Australia

    AndrewK Senior Member

    As Rick said there have been a number of good discussions regarding vacuum pumps for infusion, do a search.
    In regards to inexpensieve tubing for infusion, for most jobs I only use the 4 mm hdpe micro irrigation tubing on the vacuum side. For the resin inlets locally there is a 13mm black hdpe irrigation tubing that will not collapse ~$8 for 18m. Likewise there is also a hard variety of CVT (clear vinyl tubing) anything below 10mm ID can take full vacuum.

    Catbuilder, for clamping your ply laminations you do not want 100% vacuum and depending on how slow a hardener you end up going with you may find that you need to maintain the vacuum for 12 hrs or so. The only shopvac that can do this is the one with a separate cooling fan for the motor (ie does not require suction air flow for the cooling) they are available but just as expensive as a good diaphragm pump.
     
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